REVIEW | doi:10.20944/preprints202306.1251.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: mTOR; gut microbes; metabolites; therapy
Online: 16 June 2023 (14:02:23 CEST)
The mammalian or mechanistic target of rapamycin (mTOR) integrates multiple intracellular and extra-cellular upstream signals involved in the regulation of anabolic and catabolic processes in cells, and plays a key regulatory role in cell growth and metabolism. Activation of the mTOR signaling pathway has been reported to be associated with a wide range of human diseases. A growing number of in vivo and in vitro studies have demonstrated that the gut microbes and its complex metabolites can regulate host metabolic and immune responses through the mTOR pathway, and result in disorders of host phys-iological functions. In this review, we summarize the regulatory mechanisms of gut microbes and mTOR in different diseases, and discuss the crosstalk between gut microbes and their metabolites and mTOR in the disorders in gastrointestinal tract, liver, heart and other organs. We also discuss the promising appli-cation of multiple potential drugs that can adjust the gut microbiota and mTOR signal pathways. Despite the limited findings between gut microbes and mTOR, elucidating their relationship may provide new clues for the prevention and treatment of various diseases.
ARTICLE | doi:10.20944/preprints201809.0153.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: diabetic nephropathy; exosomes; autophagy; mTOR
Online: 10 September 2018 (06:26:55 CEST)
Background: diabetic nephropathy (DN) is a serious complication of diabetes mellitus and a common cause for end stage renal disease. Autophagy has a defensive role against kidney damage caused by hyperglycemia. The mesenchymal stem cells (MSCs) derived exosomes are currently considered as a new promising therapy in chronic renal injury. However, the renal protective mechanism of exosomes on DN has not been completely understood. We examined the potential role of MSCs derived exosomes in enhancement of autophagy activity and its effect on DN. In our study we used five groups of rats; control, DN, DN treated with exosomes, DN treated with 3-methyladenine (3-MA) and chloroquine (inhibitors of autophagy) and DN treated with 3-methyladenine (3-MA) and chloroquine and exosomes groups. We assessed renal functions, morphology and fibrosis. Moreover, autophagy markers; mTOR, Beclin-1, light chain-3 (LC3-II), and LC3-II/LC3-I ratio were detected. Additionally, electron microscopy was used for detection of autophagosomes. Results: Exosomes markedly improved the renal functions and showed histological restoration of renal tissues with significant increase in LC3 and Beclin-1 besides the significant decrease in mTOR and fibrotic markers expression in renal tissue. All previous effects were partially abolished by the autophagy inhibitor, chloroquine and 3-MA. Conclusions: we conclude that autophagy induction by exosomes could attenuate DN in a rat model of streptozotocin-induced diabetes mellitus.
ARTICLE | doi:10.20944/preprints201806.0083.v1
Subject: Medicine And Pharmacology, Anesthesiology And Pain Medicine Keywords: anesthesia; neurotoxicity; synapse; mTOR; neurodevelopment
Online: 6 June 2018 (10:36:51 CEST)
Human epidemiologic studies and laboratory investigations in animal models suggest that exposure to general anesthetic agents (GAs) have harmful effects on brain development. The mechanism underlying this putative iatrogenic condition is not clear and there are currently no accepted strategies for prophylaxis or treatment. Recent evidence suggests that anesthetics might cause persistent deficits in synaptogenesis by disrupting key events in neurodevelopment. Using an in vitro model consisting of dissociated primary cultured mouse neurons we demonstrate abnormal pre- and post-synaptic marker expression after a clinically relevant isoflurane anesthesia exposure conducted during neuron development. We find that pharmacologic inhibition of the mechanistic target of rapamycin (mTOR) pathway can reverse the observed changes. Isoflurane exposure increases expression of phospho-S6, a marker of mTOR pathway activity, in a concentration-dependent fashion and this effect occurs throughout neuronal development. The mTOR 1 complex (mTORC1) and the mTOR 2 complex (mTORC2) branches of the pathway are both activated by isoflurane exposure and this is reversible with branch-specific inhibitors. Upregulation of mTOR is also seen with sevoflurane and propofol exposure, suggesting that this mechanism of developmental anesthetic neurotoxicity may occur with all the commonly used GAs in pediatric practice. We conclude that GAs disrupt the development of neurons during development by activating a well-defined neurodevelopmental disease pathway and that this phenotype can be reversed by pharmacologic inhibition.
REVIEW | doi:10.20944/preprints201806.0056.v1
Subject: Medicine And Pharmacology, Pathology And Pathobiology Keywords: mTOR; mTORC1; mTORC2; rapamycin; rapalogues; rapalogs; mTOR inhibitors; senescence; ageing; aging; cancer; neurodegeneration; immunosenescence; senolytics; biomarkers
Online: 5 June 2018 (09:49:19 CEST)
Chronological age represents the greatest risk factor for many life-threatening diseases including neurodegeneration, cancer and cardiovascular disease; ageing also increases susceptibility to infectious disease. Current therapies that effectively tackle individual diseases may have little impact on the overall healthspan of older individuals, who would still be vulnerable to other age-related pathologies. However, recent progress in ageing research has highlighted the accumulation of senescent cells with chronological age as a probable underlying cause of pathological ageing. Cellular senescence is an essentially irreversible proliferation arrest mechanism that has important roles in development, wound healing and preventing cancer, but it may limit tissue function and cause widespread inflammation with age. The serine/threonine kinase mTOR is a regulatory nexus heavily implicated in both ageing and senescence. Excitingly, a growing body of research has highlighted rapamycin and other mTOR inhibitors as promising treatments for a broad spectrum of age-related pathologies, including neurodegeneration, cancer, immunosenescence, osteoporosis, rheumatoid arthritis, age-related blindness, diabetic nephropathy, muscular dystrophy, and cardiovascular disease. In this review, we assess the use of mTOR inhibitors to treat age-related pathologies, discuss possible molecular mechanisms of action where evidence is available, and consider strategies to minimize undesirable side effects. We also emphasize the urgent need for reliable, non-invasive biomarkers of senescence and biological ageing to better monitor the efficacy of any healthy ageing therapy.
ARTICLE | doi:10.20944/preprints202203.0001.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: CMT1E; Trembler-J; curcumin; Hsps; autophagy; mTOR
Online: 1 March 2022 (02:52:34 CET)
Charcot-Marie-Tooth (CMT) syndrome is the most common progressive human motor and sensory peripheral neuropathy. CMT type 1E is a demyelinating neuropathy affecting Schwann cells due to pmp22 mutations, modelized by Trembler-J mice. Curcumin, a natural polyphenol com-pound obtained from turmeric (Curcuma longa), exhibits dose- and time-varying antitumor, antioxidant and neuroprotective properties, however, the neurotherapeutic actions of curcumin still remain elusive. Here, we propose curcumin as a possible natural treatment capable of enhancing cellular detoxification mechanisms, resulting in an improvement of the neurodegenerative Trembler-J phenotype. Using a refined method for obtaining enriched Schwann cell cultures, we evaluated the neurotherapeutic action of low dose curcumin treatment on the PMP22 expression, and on the chaperones (HSF1 and Hsp27) and autophagy/mTOR (HDAC6 and ribosomes) pathways in Trembler-J and wild-type genotypes. In wild-type Schwann cells, the action of cur-cumin resulted in strong stimulation of the chaperone and macroautophagy pathway, whereas the modulation of ribophagy showed a mild effect. However, despite the promising neuroprotective effects for the treatment of neurological diseases, we report (demonstrate?) that the action of cur-cumin in Trembler-J Schwann cells could be impaired due to the irreversible impact of ethanol used as a common curcumin vehicle necessary for administration. These results contribute to expand our still limited understanding of PMP22 biology in neurobiology, and expose the intrinsic lability of the neurodegenerative Trembler-J genotype. Furthermore, they unravel interesting physiological mechanisms of cellular resilience relevant for to the pharmacological treatment of the neurodegenerative Tremble J phenotype with curcumin and ethanol. We conclude that the analysis of the effects of the vehicle itself is an essential and in-escapable step to comprehensibly assess the own effects and full potential of curcumin treatment for therapeutic purposes.
REVIEW | doi:10.20944/preprints202102.0278.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: ncRNA; miR; NCDs; onco-miR; cancer; mTOR
Online: 11 February 2021 (11:04:50 CET)
Discovery of microRNAs (miRNAs) twenty years ago, has advocated a new era of “Molecular Genetics”. About 2000 miRNAs are present, that regulate one third of the genome. MiRNAs dysregulated expression may contribute to several diseases including tumor growth. Their presence in body fluids, reflecting levels alteration in various cancers, merit circulating miRNAs as the “next generation biomarkers” for early stages tumor diagnosis and/or prognosis. Herein, we performed a comprehensive literature search focusing on the origin, biosynthesis and role of miRNAs and summarized the foremost studies centering on miRs value as non-invasive biomarkers in different non-communicable diseases, including various cancer types. Moreover, during chemotherapy many miRNAs were linked to multidrug resistance, via modulating numerous biological processes and/or pathways that will be highlighted as well.
REVIEW | doi:10.20944/preprints202004.0530.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: CDK1; eIF4F; mTOR; mRNA translation; M-phase
Online: 30 April 2020 (13:46:44 CEST)
Cyclin dependent kinase 1 (CDK1) has been primarily identified as a key cell cycle regulator in both mitosis and meiosis. Recently, an extramitotic function of CDK1 emerged when evidence was found that CDK1 is involved in many cellular events that are essential for cell proliferation and survival. In this review we summarize the involvement of active CDK1 in the initiation and elongation steps of protein synthesis in eukaryotes. During its activation CDK1 influences the initiation of protein synthesis, promotes the activity of specific translational initiation factors and affects the functioning of a subset of elongation factors. Our review provides insights into gene expression regulation during the transcriptionally silent cell cycle/M-phase and describes quantitative and qualitative translational changes based on the extramitotic role of the cell cycle master regulator CDK1, to optimize temporal synthesis of proteins to sustain division-related processes: mitosis and cytokinesis.
BRIEF REPORT | doi:10.20944/preprints202306.1357.v1
Subject: Medicine And Pharmacology, Reproductive Medicine Keywords: mTOR; rapamycin; PRP; platelet cytokines; ovarian reserve; IVF
Online: 19 June 2023 (12:55:06 CEST)
No major breakthroughs have entered mainstream clinical fertility practice since egg donation and intracytoplasmic sperm injection decades ago, and oocyte deficits secondary to advanced age continue as the main manifestation of diminished ovarian reserve. In the meantime, several unproven IVF ‘accessories’ have emerged including so-called ovarian rejuvenation which entails placing fresh autologous platelet-rich plasma (PRP) directly into ovarian tissue. Among cellular responses attributed to this intervention are reduced oxidative stress, slowed apoptosis, and improved metabolism. Besides impacting the existing follicle pool, platelet growth factors might also facilitate de novo oocyte recruitment by specified gene upregulation targeting uncommitted ovarian stem cells. Because disordered activity at mechanistic target of rapamycin (mTOR) has been shown to exacerbate or accelerate ovarian aging, PRP-discharged plasma cytokines combined with mTOR suppression by pulsed/cyclic rapamycin represents a novel fusion technique to enhance ovarian function. While beneficial effects have already been observed experimentally in oocytes and embryos with mTOR inhibition alone, this is the first discussion of intraovarian platelet cytokines followed by low-dose, phased rapamycin. For refractory cases, this investigational, tailored approach could amplify or sustain ovarian capacity sufficient to permit retrieval of competent oocytes via distinct but complementary pathways—thus reducing dependency on oocyte donation.
REVIEW | doi:10.20944/preprints202306.0952.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: mTOR; CD8 T cell; NK cell; cytokine signaling
Online: 13 June 2023 (15:45:23 CEST)
CD8 T cells and Natural Killer (NK) cells are cytotoxic lymphocytes important in the response to intracellular pathogens and cancer. Their activity depends on the integration of a large set of intracellular and environmental cues, including antigenic signal, cytokine stimulation and nutrients availability. This integration is achieved by signaling hubs such as the mechanistic target of Rapamycin (mTOR). mTOR is a conserved protein kinase, controlling cellular growth and metabolism in eukaryotic cells and therefore is essential for lymphocyte development and maturation. However, our current understanding of mTOR signaling comes mostly from studies performed in transformed cell lines, which constitute a poor model to comprehend metabolic pathway regulation. Therefore, it is only quite recently that the regulation of mTOR in primary cells has been assessed. Here we review the signaling pathways leading to mTOR activation in CD8 T and NK cells, focusing on activation by cytokines. We also discussed how this knowledge can contribute to immunotherapy development for intracellular pathogen and cancer treatment.
ARTICLE | doi:10.20944/preprints202304.0797.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Heart failure; Malnutrition; Exercise; Amino-acids; mTOR; Deptor
Online: 23 April 2023 (08:45:26 CEST)
Malnutrition, clinically evident primarily with sarcopenia, is present in more than 50% of CHF patients and is an independent factor of morbidity and mortality. Several pathophysiological mechanisms, such as reduced appetite, metabolic imbalance and altered protein synthesis/degradation rate, due to the blood increase of hypercatabolic molecules, have been proposed to explain this phenomenon. Nutritional supplementation with proteins, amino acids and vitamins have all been used to treat malnutrition, acting through mTOR stimulation. However, the success and efficacy of these procedures are often contradictory and not conclusive. Interestingly, data on exercise training show that exercise reduces mortality and increase functional capacity, although it also increases energy expenditure and nitrogen providing substrate needs. Therefore, this paper discusses the molecular mechanisms of integrated nutritional approaches that would stimulate metabolic anabolic pathways. Pivotal in our opinion, is the relationship between exercise and Deptor, a subunit of the mTOR complex. Consequently, we propose a combination of personalized and integrate nutritional supplementation as well as exercise to treat malnutrition and related anthropometric and functional CHF-related disorders.
HYPOTHESIS | doi:10.20944/preprints202110.0373.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Zika virus; Microcephaly; Neurogenesis; Retinoic Acid; mTOR signaling
Online: 26 October 2021 (11:12:37 CEST)
Microcephaly has been regarded the most remarkable consequence of the Zika virus (ZIKV) epidemic in Brazil 2015. It remains to be determined whether there are factors that contribute to the degree of brain lesion associated with ZIKV infection during pregnancy. Previous studies showed that socioeconomic conditions correlate with ZIKV-associated microcephaly. Certain nutritional deficits display the potential to interfere in the mechanistic target of rapamycin (mTOR) signaling, which plays a major role in the pathophysiology of ZIKV-associated microcephaly. We hypothesize that a nutritional or environmental co-factor that interferes in mTOR signaling correlates with ZIKV-associated birth defects. To assess this hypothesis, we plan to: 1) develop a mouse model of ZIKV-associated microcephaly through intravenous injection of ZIKV and rapamycin for a straightforward interference on mTOR receptor; 2) determine in the experimental model and in cases of ZIKV-associated microcephaly the epigenetic signature (DNA methylation pattern) in neurons and muscle cells harvested by biopsy, and in hematopoietic and mesenchymal stem cells sorted from blood; 3) analyze through mass spectrometry in serum of pregnant female mice submitted to ZIKV and rapamycin injection and in serum of mothers of children with ZIKV-associated microcephaly the metabolomic pattern of cholesterol (a nutritional status marker), vitamin A and its metabolite retinoic acid, folate, and other metabolites related to these three nutritional factors; 4) check whether pregnant female mice submitted to intravenous injection of ZIKV and feed with a deficient diet of the most likely co-factor found in this study give birth to microcephalic mice with features that mimic clinical cases. In summary, our general objective is to develop an experimental model that mimics ZIKV-associated microcephaly cases and to find a co-factor involved in the microcephaly outbreak in Brazil 2015.
ARTICLE | doi:10.20944/preprints202110.0003.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: AP5M1; BAIAP2L1; ENTPD2; MTOR; AKT2; FKBP9; TBRG4; TMEM186
Online: 1 October 2021 (11:16:39 CEST)
Many years and $$$ spent for research did not yet produced a universally effective gene therapy of prostate cancer (PCa). Our studies indicated that not only each human, but even each cancer nodule in the same tumor has unique and dynamic gene expression profile, control and coordination. The tumor heterogeneity of the transcriptome topology is a strong argument in favor of personalized gene therapies, tailored on patients’ primary tumor unique characteristics. Here, we propose a bioinformatics procedure by which to identify the Gene Master Regulators (GMR) of cancer cells from transcriptomic data and predict consequences of their experimental manipulation. The procedure, based on our Genomic Fabric Paradigm (GFP), can determine the most important gene in each cancer nodule whose controlled alteration would selectively kill the cancer cells. In this report, the method is applied to our microarray data on two men PCs (each with three distinct cancer nodules) and two standard human PCa cell lines (DU145 and LNCaP). We expect the industry to produce ready-to-use CRISPR constructs for all genes allowing the clinical oncologist to prescribe the adequate personalized CRISPR cocktail for his/her patient. Thus, the GMR approach may provide the most effective, yet affordable solution in fighting cancer.
ARTICLE | doi:10.20944/preprints202101.0232.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: CaSR; Homer1; mTOR; osteoblast; osteocyte; AKT; chaperone function
Online: 12 January 2021 (17:21:02 CET)
We recently found that in human osteoblasts Homer1 complexes to CaSR and mediates AKT initiation via mTORC2 leading to beneficial effects in osteoblasts including -catenin stabilization and mTORC1 activation (doi: 10.1074/jbc.RA118.006587). Herein we further investigated the relationship between Homer1 and CaSR and demonstrate a link between the protein levels of CaSR and Homer1 in human osteoblasts in primary culture. Thus, when siRNA was used to suppress the CaSR, we observed upregulated Homer1 levels and when siRNA was used to suppress Homer1 we observed downregulated CaSR protein levels using immunofluorescence staining of cultured osteoblasts as well as western blot analyses of cell protein extracts. This finding was confirmed in vivo as the bone cells from osteoblast specific CaSR(-/-) mice showed increased Homer1 expression compared to wild-type. Furthermore, when the commonly used osteosarcoma cell lines MG63 and SAOS-2 were compared to primary osteoblasts, higher levels of Homer1 protein were associated with increased protein levels of the CaSR as well as mTOR and Rictor. CaSR and Homer1 protein were both expressed in osteocytes embedded in the long bones of wild-type mice, and immunofluorescent studies of these cells revealed that Homer1 protein sub-cellular localization was markedly altered in the osteocytes of CaSR(-/-) mice compared to wt. The study identifies additional roles for Homer1 in the control of the protein level and subcellular localization of CaSR in cells of the osteoblast lineage, in addition to its established role of mTORC2 activation downstream of the receptor.
ARTICLE | doi:10.20944/preprints201805.0076.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Oral cancer; mTOR pathway; secreted glycoprotein; drug resistance
Online: 3 May 2018 (12:47:14 CEST)
Oral cancer is a major public health burden worldwide. The lack of biomarkers for early diagnosis has increased the difficulty in managing this disease. Recent studies have reported that neutrophil gelatinase-associated lipocalin (NGAL), a secreted glycoprotein, is upregulated in various tumors. In our study we found that NGAL was significantly downregulated in primary malignant and metastatic tissues of oral cancer compared to normal tissues. The downregulation of NGAL was strongly correlated with the degree of differentiation and stage (I-IV), and can serve as a prognostic biomarker for oral cancer. Tobacco carcinogens were also found to be involved in the downregulation of NGAL. Mechanistic studies revealed that knockdown of NGAL increased oral cancer cell proliferation, survival, and migration, and also induced resistance against cisplatin. Silencing of NGAL activated mTOR signaling and reduced autophagy by the LKB1-AMPK-p53-Redd1 signaling axis. Moreover, cyclin-D1, Bcl-2, and MMP-9 were upregulated, and caspase-9 was downregulated, suggesting that silencing of NGAL increases oral cancer cell proliferation, survival, and migration. Thus, from our study it is evident that downregulation of NGAL activates the mTOR pathway and helps in the progression of oral cancer.
ARTICLE | doi:10.20944/preprints201801.0144.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: MMP-1, EGFR-TKI resistance, lung adenocarcinoma, mTOR
Online: 16 January 2018 (13:57:04 CET)
Lung adenocarcinoma with EGFR-TKI (epidermal growth factor receptor-tyrosine kinase inhibitor) resistance was reported to harbor higher ability of invasion and migration than those sensitive to EGFR-TKI, but the function of MMPs (matrix metalloproteinases) has not been explored in EGFR-TKI resistant lung adenocarcinoma. In this study, the correlation between immunohistochemical status of MMP-1 and clinicopathological factors were analyzed in 89 lung adenocarcinoma. We performed microarray, migration assay and invasion assay using EGFR-TKI sensitive cell lines and EGFR-TKI resistant cell lines. To clarify the mechanism of MMP-1 induction, we treated lung adenocarcinoma cells with EGF and rapamycin, performed phosphorylation antibody array and analyzed the correlation between MMP-1 expression and EGFR or mTOR (mammalian target of rapamycin) pathway. As a result, we firstly demonstrated that MMP-1 played an important role in migration and invasion abilities of EGFR-TKI resistant lung adenocarcinoma, and that mTOR pathway could be associated with an induction of MMP-1. We demonstrated the significant positive correlation between MMP-1 status in lung adenocarcinoma cells and the history of smoking, and the subtype of invasive mucinous adenocarcinoma. In conclusion, This study provides insights into the development of a possible alternative therapy manipulating MMP-1 and mTOR signaling pathway in EGFR-TKI resistant lung adenocarcinoma.
ARTICLE | doi:10.20944/preprints202311.0851.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Estrogen receptor a; sigma receptors; TMEM97; mTOR; S6K1; tamoxifen.
Online: 14 November 2023 (09:28:12 CET)
Aberrant estrogen receptor (ER) signaling is a major driver of breast tumor growth and progression. Sigma 2 receptor has long been implicated in breast carcinogenesis based on pharmacological studies, but its molecular identity had been elusive until TMEM97 was identified as the receptor. Herein we report that TMEM97/sigma 2 receptor is highly expressed in ER positive breast tumors and its expression is strongly correlated with ER and progesterone receptor (PR) but not with HER2 status. High expression levels of TMEM97 are associated with reduced overall survival of patients. Breast cancer cells with increased expression of TMEM97 had growth advantage over the control cells under both nutrition limiting and sufficient conditions, while knockdown of TMEM97 expression reduced tumor cell proliferations. When compared to their vector control cells, MCF7 and T47D cells with increased TMEM97 expression presented increased resistance to tamoxifen treatment and also grew better under estrogen depleted conditions. TMEM97/sigma 2 receptor enhanced ERα transcriptional activities and increased the level of transactivated ERα, especially the nuclear soluble and chromatin bounded ERα. Increased TMEM97 also stimulated mTOR/S6K1 signaling pathways in MCF7 and T47D cells. The increased level of active, phosphorylated ERα, and the enhanced resistance to tamoxifen treatment with increased TMEM97 could be blocked by an mTOR inhibitor. Knockdown of TMEM97 expression reduced ERα and mTOR/S6K1 signaling activities, rendering the cells with increased sensitivity to tamoxifen. The observations suggest that TMEM97/sigma 2 receptor is a novel regulator of ERα activities in breast tumor cell growth.
ARTICLE | doi:10.20944/preprints202302.0250.v1
Subject: Medicine And Pharmacology, Other Keywords: AI drug discovery; mTOR; rapalog; C. elegans; cancer; longevity
Online: 15 February 2023 (02:42:57 CET)
The mechanistic target of rapamycin (mTOR) kinase is one of the top drug targets for promoting health and lifespan extension. Besides rapamycin, only a few other mTOR inhibitors have been developed and shown their ability to slow aging. We used machine learning to predict novel small molecules targeting mTOR. We selected one small molecule, TKA001, based on in-silico predictions of a high on-target probability, low toxicity, favorable physicochemical properties, and preferable ADMET profile. We confirmed TKA001 binding in silico by molecular docking. TKA001 potently inhibits both TOR complex 1 and 2 downstream signaling in vitro. Furthermore, TKA001 inhibits human cancer cell proliferation in vitro and extended the lifespan of C. elegans, suggesting that TKA001 can slow aging in vivo.
REVIEW | doi:10.20944/preprints202105.0367.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: PI3K/mTOR signalling; feedback loop; crosstalk; nonlinear dynamics; cancer
Online: 17 May 2021 (07:54:13 CEST)
The PI3K/mTOR signalling pathway plays a central role in the governing of cell growth, survival and metabolism. As such, it must integrate and decode information from both external and internal sources to guide efficient decision-making by the cell. To facilitate this, the pathway have evolved an intricate web of complex regulatory mechanisms and elaborate crosstalk with neighbouring signalling pathways, making it a highly non-linear system. Here, we describe the mechanistic biological details that underpin these regulatory mechanisms, covering a multitude of negative and positive feedback loops, feed-forward loops, competing protein interactions, and crosstalk with major signalling pathways. Further, we highlight the non-linear and dynamic network behaviours that arise from these regulations, uncovered through both computational and experimental studies. Given the pivotal role of the PI3K/mTOR network in cellular homeostasis and its frequent dysregulation in pathologies including cancer and diabetes, a coherent and systems-level understanding of the complex regulation and consequential dynamic signalling behaviours within this network is imperative for advancing biology and development of new therapeutic approaches.
ARTICLE | doi:10.20944/preprints201901.0018.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: pyruvate kinase M2; prostate cancer; cancer metabolism; mTOR; autophagy
Online: 3 January 2019 (12:32:52 CET)
Pyruvate kinase M2 (PKM2) is essential for aerobic glycolysis and is highly expressed in various cancer tissues. Although high PKM2 expression is observed in prostate cancer tissues, its functional role in cancer metabolism is unclear. Here, we investigated the role of PKM2 in regulating autophagy and its associated pathways in prostate cancer cells. PKM2 expression was silenced using various PKM2 small interfering RNAs (siRNAs) and then we measured PKM2-related cellular pathways associated with autophagy. PKM2 siRNA-transfected prostate cancer cells showed significantly reduced viability. Acridine orange staining and immunoblotting analysis showed that PKM2 downregulation markedly increased autophagic cell death. Results of western blotting analysis showed that PKM2 knockdown affected protein kinase B/mechanistic target of rapamycin 1 pathway, which consequently downregulated the expression of glycolytic enzymes lactate dehydrogenase A and glucose transporter 1. To the best of our knowledge, this is the first study to show that PKM2 inhibition alters cancer cell metabolism and induces autophagy. Thus, the present study provides a strategy for the development of PKM2-targeted novel anticancer drugs for the treatment of prostate cancer.
ARTICLE | doi:10.20944/preprints202304.0254.v1
Subject: Biology And Life Sciences, Toxicology Keywords: cancer cells; quinones; mTOR; antiproliferative activity; molecular descriptors; molecular docking
Online: 12 April 2023 (07:57:34 CEST)
A series of 2-phenylamino-3-acyl-1,4-naphtoquinones were evaluated regarding their in vitro antiproliferative activities using DU-145, MCF-7 and T24 cancer cells. Such activities were discussed in terms of molecular descriptors like half-wave potentials, hydrophobicity and molar refractivity. Compounds 4 and 11 display the highest antiproliferative activity against the three cancer cells, therefore, they were subject to further studies. The in silico prediction of drug likeness, using pkCSM and SwissADME explorer online, shows that compound 11 is a suitable lead molecule to be developed. Furthermore, the expression of some key genes was studied in DU-145 cancer cells. They include genes involved in apoptosis (Bcl-2), tumor metabolism regulation (mTOR), redox homeostasis (GSR), cell cycle regulation (CDC25A), cell cycle progression (TP53), epigenetic (HDAC4), cell-cell communication (CCN2) and inflammatory pathways (TNF). Compound 11 displays an interesting profile because among these genes, mTOR was significantly less expressed as compared to control conditions. Molecular docking show that compound 11 has good affinity with mTOR, unraveling a potential inhibitory effect on this protein. Due to the key role of mTOR on tumor metabolism, we suggest that impaired DU-145 cells proliferation by compound 11 is caused by a reduced mTOR expression (less mTOR protein) and inhibitory activity on mTOR protein.
REVIEW | doi:10.20944/preprints202012.0675.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Breast cancer; Estrogen Receptor; PI3K-AKT-mTOR; anti-estrogen resistance
Online: 28 December 2020 (09:22:17 CET)
Signaling from estrogen receptor alpha (ER) and its ligand estradiol (E2) is critical for growth of ~70% of breast cancers. Therefore, several drugs that inhibit ER functions are in clinical use for decades and new classes of anti-estrogens are continuously being developed. Although a significant number of ER+ breast cancers respond to anti-estrogen therapy, ~30% of these breast cancers recur, sometimes even after 20 years of initial diagnosis. Mechanism of resistance to anti-estrogens is one of the intensely studied disciplines in breast cancer. Several mechanisms have been proposed including mutations in ESR1, crosstalk between growth factor and ER signaling, and interplay between cell cycle machinery and ER signaling. ESR1 mutations as well as crosstalk with other signaling networks lead to ligand independent activation of ER thus rendering anti-estrogens ineffective, particularly when treatment involved anti-estrogens that do not degrade ERa. As a result of these studies, several therapies that combine anti-estrogens that degrade ER with PI3K/AKT/mTOR inhibitors targeting growth factor signaling or CDK4/6 inhibitors targeting cell cycle machinery are used clinically to treat recurrent ER+ breast cancers. In this review, we discuss nexus between ER-PI3K/AKT/mTOR pathways and how understanding of this nexus has helped to develop combination therapies.
REVIEW | doi:10.20944/preprints202307.1695.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: hepatocellular carcinoma; EGFR/PI3K/AKT/mTOR signaling; animal models; Targeted Therapy
Online: 26 July 2023 (10:07:16 CEST)
Hepatocellular carcinoma (HCC) poses a significant global health concern, with its incidence steadily increasing. The development of HCC is a multifaceted, multi-step process involving alterations in various signaling cascades. In recent years, significant progress has been made in understanding the molecular signaling pathways that play central roles in hepatocarcinogenesis. In particular, the EGFR/PI3K/Akt/mTOR signaling pathway in HCC has garnered renewed attention from both basic and clinical researchers. Preclinical studies in vitro and in vivo have shown the effectiveness of targeting the key components of this signaling pathway in human HCC cells. Thus, targeting these signaling pathways with small molecule inhibitors holds promise as a potential therapeutic option for patients with HCC. In this review, we will explore recent advancements in understanding the role of the EGFR/PI3K/Akt/mTOR signaling pathway in HCC and assess the effectiveness of targeting this signaling cascade as a potential strategy for HCC therapy based on preclinical studies
ARTICLE | doi:10.20944/preprints202306.1949.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: homocysteine thiolactone; N-homocysteinylated protein; microRNA; PHF8; mTOR; autophagy; endothelial cells
Online: 28 June 2023 (07:08:26 CEST)
The inability to efficiently metabolize homocysteine (Hcy), which occurs in nutritional and genetic deficiencies, leads to hyperhomocysteinemia (HHcy) thereby causing endothelial dysfunction, a hallmark of atherosclerosis which underpins cardiovascular disease (CVD). The dysregulation of mammalian target of rapamycin (mTOR) signaling, and impaired autophagy play important roles in CVD. Biochemically, HHcy is characterized by elevated levels of Hcy and its metabolites, Hcy-thiolactone (HTL) and N-Hcy-protein (N-Hcy). However, whether these metabolites can dysregulate mTOR signaling and autophagy in endothelial cells is not known. Here, we examined the influence of HTL, N-Hcy, and Hcy on the PHF8/H4K20me1/mTOR/autophagy pathway in human umbilical vein endothelial cells (HUVEC). We found that treatments with HTL, N-Hcy, or Hcy significantly reduced PHF8 protein and mRNA expression, increased H4K20me1, and upregulated mTOR signaling. Autophagy was also impaired (significantly downregulated BECN1, ATG5, ATG7, and LC3 protein and mRNA levels). We also found that these changes were mediated by PHF8-targeting microRNA (miR): miR-22-3p and miR-1229-3p. The effects of HTL, N-Hcy, or Hcy on the miR expression and on the PHF8/H4K20me1/mTOR/autophagy pathway were abrogated by treatments with an inhibitor of miR-22 or miR-1229. Taken together, these findings show that Hcy metabolites can upregulate miR-22-3p and miR-1229-3p expression, which then dysregulate the PHF8/H4K20me1/mTOR/autophagy pathway, important for vascular homeostasis.
REVIEW | doi:10.20944/preprints202210.0230.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: PBDE; dose-response relationships; mTOR signaling; steroidogenesis; metabolic disruption; sperm epigenome
Online: 17 October 2022 (05:37:53 CEST)
Polybrominated diphenyl ethers (PBDE) are a group of flame retardants used in a variety of artificial materials. Despite phasing out in most industrial countries, they persist in the environment and human tissues due to their persistence, lipophilicity, and bioaccumulation. Populational and experimental studies demonstrate male reproductive toxicity of PBDEs including increased incidence of genital malformations (hypospadias and cryptorchidism), altered weight of testes and other reproductive tissues, altered testes histology and transcriptome, decreased sperm production and sperm quality, altered epigenetic regulation of developmental genes in spermatozoa and altered secretion of reproductive hormones. A broad range of mechanistic hypotheses of PBDE reproductive toxicity has been suggested. Among these hypotheses, oxidative stress, disruption of estrogenic signaling, and mitochondria disruption are affected by PBDE concentrations much higher, than concentrations found in human tissues, making them unlikely links between exposures and adverse reproductive outcomes in the general population. Robust evidence suggests that at environmentally relevant doses, PBDEs and their metabolites may affect male reproductive health via mechanisms including AR antagonism and the disruption of a complex network of metabolic signaling.
REVIEW | doi:10.20944/preprints201905.0358.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: alloimmune response; immunosuppressants; calcineurin inhibitors; corticosteroids; mTOR inhibitors; neurotoxicity; neuroprotective effects
Online: 29 May 2019 (16:37:44 CEST)
Although transplantation procedures have been developed for patients with end-stagec hepatic insufficiency or other diseases, allograft rejection still threatens patient health and lifespan. Over the last few decades, the emergence of immunosuppressive agents, such as calcineurin inhibitors (CNIs) and mammalian target of rapamycin (mTOR) inhibitors, have strikingly increased graft survival. Unfortunately, immunosuppressive agent-related neurotoxicity is commonly occurred in clinical situations, with the majority of neurotoxicity cases caused by CNIs. The possible mechanisms whereby CNIs cause neurotoxicity include: increasing the permeability or injury of the blood-brain barrier, alterations of mitochondrial function, and alterations in electrophysiological state. Other immunosuppressants can also induce neuropsychiatric complications. For example, mTOR inhibitors induce seizures; mycophenolate mofetil induces depression and headache; methotrexate affects the central nervous system; mouse monoclonal immunoglobulin G2 antibody against cluster of differentiation 3 also induces headache; and patients using corticosteroids usually experience cognitive alteration. Therapeutic drug monitoring, individual therapy based on pharmacogenetics, and early recognition of symptoms have greatly reduced neurotoxic events. Once neurotoxicity occurs, a reduction in the drug dosage, switching to other immunosuppressants, using drugs to treat the neuropsychiatric manifestation, or blood purification therapy have proven to be effective against neurotoxicity. In this review, we summarize the recent topics on the mechanisms of neurotoxicity of immunosuppressive drugs. In addition, some information about neuroprotective effects of several immunosuppressants are also discussed.
ARTICLE | doi:10.20944/preprints201706.0120.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: sinulariolide; human bladder cancer; migration; invasion; PI3K/AKT/mTOR signaling pathway
Online: 27 June 2017 (06:23:44 CEST)
Sinulariolide, a natural product extracted from cultured-type soft coral Sinularia flexibilis, possesses bioactivity against the movement of several types of cancer cell. However, the molecular pathway of its effects on human bladder cancer remain poorly understood. Using a human bladder cancer cell line as an in vitro model, this study investigated the underlying mechanism of sinulariolide against cell migration/invasion in TSGH-8301 cells. We found that sinulariolide inhibited TSGH-8301 cell migration/invasion, and the effect was concentration-dependent. Furthermore, the protein expressions of matrix metalloproteinases (MMPs) MMP-2 and MMP-9, as well as urokinase, were significantly decreased after 24-h sinulariolide treatment. Meanwhile, the increased expressions of tissue inhibitors of metalloproteinases (TIMPs) TIMP-1 and TIMP-2 were in parallel with an increased concentration of sinulariolide. Finally, the expressions of several key phosphorylated proteins in the mTOR signaling pathway were also downregulated by sinulariolide treatment. Our results demonstrated that sinulariolide has significant effects against TSGH-8301 cell migration/invasion, and its effects were associated with decreased levels of MMP-2/-9 and urokinase expression, as well as increased TIMP-1/TIMP-2 expression. The inhibitory effects were mediated by reducing phosphorylation proteins of the PI3K, AKT and mTOR signaling pathway. The findings suggested that sinulariolide is a good candidate for advanced investigation with the aim of developing a new drug for the treatment of human bladder cancer.
ARTICLE | doi:10.20944/preprints202308.1752.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Intracerebroventricular, ICV; mTOR, mTOR-I, rapalog; Tuberous Sclerosis, TSC; Multiple Sclerosis, MS; Experimental Autoimmune Encephalitis, EAE; Alzheimer’s Disease, AD; Thermostable Micelles, Micellar Liquid Formulation; Ommaya device
Online: 24 August 2023 (12:53:26 CEST)
A large body of evidence, replicated in many mouse models of Alzheimer Disease (AD), demonstrated the therapeutic efficacy of oral rapamycin. Administration of m-TOR inhibitors (mTOR-Is), early after the clinical onset, greatly diminished cognitive impairment, amyloid angiopathy, intracellular beta Amyloid and neurofibrillary tangles load. The daily intake of rapamycin has always been 2.24g/Kg/24h. In humans the maximal tolerated oral dose is a few milligrams/day, and at this dosage patients are severely immunosuppressed. Thanks to rapalogs’ scarce CNS-related side effects, we administered intracerebroventricularly (ICV) high doses of the mTOR-I everolimus in a mouse model of AD (3xTg-AD) without significant systemic effects. The instability of the liquid formulation at body temperature (BT) made the treatment very short. Nevertheless, the efficacy of the treatment was high and much longer lasting than expected. In order to set up a thermostable, translational liquid formulation of mTOR-Is, we loaded everolimus in distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000) micelles by the thin layer method. The formulation we obtained maintained over 95% of activity after 14 days at BT. We can envision short, potentially periodic ICV treatments in AD patients which replicate results obtained on animal models. The treatment could benefit also Tuberous Sclerosis and Multiple Sclerosis patients.
ARTICLE | doi:10.20944/preprints202307.1464.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: bovine skeletal muscle satellite cells; sodium butyrate; mitophagy; apoptosis; mTOR signaling pathway
Online: 21 July 2023 (05:18:58 CEST)
Sodium butyrate (NaB) is one of the short-chain fatty acids and is notably produced in large amounts from dietary fiber in the gut. Recent evidence suggests that NaB induces cell proliferation and apoptosis. The skeletal muscle is rich in plenty of mitochondrial. However, it is unclear how NaB acts on host muscle cells and whether it is involved in mitochondria-related functions in myocytes. The present study aimed to investigate the role of NaB treatment on the proliferation, apoptosis, and mitophagy of bovine skeletal muscle satellite cells (BSCs). The results showed that NaB inhibited the proliferation and promoted apoptosis of BSCs, and promoted mitophagy in a time and dose-dependent manner in BSCs. In addition, 1mM NaB increased the mitochondrial ROS level, decreased the mitochondrial membrane potential (MMP), increased the number of autophagic vesicles in mitochondria, and increased the mitochondrial DNA(mtDNA) and ATP level. The effects of the mTOR pathway on BSCs were investigated, and the results showed that 1mM NaB inhibited the mRNA and protein expression of mTOR and genes AKT1, FOXO1, and EIF4EBP1 in the mTOR signaling pathway, while the addition of PP242, an inhibitor of the mTOR signaling pathway, also inhibited mRNA and protein expression levels of mTOR, AKT1, FOXO1, and EIF4EBP1, and promoted mitophagy and apoptosis, which were consistent with the effect of NaB treatment. In conclusion, NaB might promote mitophagy and apoptosis in BSCs by inhibiting the mTOR signaling pathway. Our results would expand the knowledge of sodium butyrate on bovine skeletal muscle cell state and mitochondrial function.
REVIEW | doi:10.20944/preprints202010.0195.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Autophagy; Amyloid precursor protein (APP); β‐amyloid (Aβ); mTOR; Alzheimer’s disease (AD).
Online: 9 October 2020 (11:07:53 CEST)
Autophagy refers to the degradation of cytoplasmic constituents by a lysosomal-mediated pathway, which plays a critical role in maintaining cellular homeostasis. Importantly, dysregulation of autophagy has been implicated in multiple neurodegenerative disorders. Previous studies reported that autophagy affects the processing of amyloid precursor protein (APP), thus stimulating β‐amyloid (Aβ) production in Alzheimer’s disease (AD) eventually. Although the mechanism of autophagy modulation on APP processing and its pathogenesis has not yet been fully elucidated at the molecular level, but modulation of autophagy has received considerable attention as a promising approach for the treatment of AD. In the early stage of AD, Aβ may prompt autophagy to facilitate its removal via mTOR‐independent as well as-dependent pathways. However, a recent study proposed that autophagy processes are not properly regulated as AD continues to progress, and consequently, the production of Aβ tends to accumulate rapidly. Meanwhile, a number of autophagy-related genes (Atg) as well as APP genes are also thought to influence the development of AD, which may serve as a bi‐directional link to autophagy and AD pathology. In this review, we summarized current observations related to autophagy regulation and APP processing, focusing on their dynamic modifications associated with the progression of AD. Recent findings together highlight the essential role of autophagy in the removal and clearance of APP and Aβ deposition in the pathological condition of AD.
REVIEW | doi:10.20944/preprints202101.0120.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: mTOR; ATP; protein synthesis; autophagy; amino acids; nutrition; adipose tissue; muscle; sarcopenia; mitochondria
Online: 6 January 2021 (14:32:22 CET)
Background. Sarcopenia, defined as the loss of skeletal muscle mass and function, is a major clinical problem in many chronic illnesses, in cancer and in the elderly. Exercise and adequate nutrition, peculiarly dependents on availability of essential amino acids, considered the primary strategies for prevention and treatment of protein synthetic deficits, affect both the efficient scavenging of aged and overused protein molecules and the renewal, by maintaining muscular protein synthesis. Many questions still remain about the regulation of protein syntheses and degradation. Degradation of inefficient proteins or organelles is performed by the sum of micro and macro-autophagy plus ubiquitin-proteasome system, activities known as proteostasis, necessary to preserve and promote protein masses and consequently, the body’s reserves. However, how protein synthesis is regulated, and how activation of the mTOR complex may modulate and transduce the flow of information provided by exercise and nutrition to balance proteostasis and syntheses, is far from being fully understood. We suggest that energy production and availability, thus also mitochondria, may have a pivotal role in synchronizing activity and functional outcomes of protein syntheses, and that those syntheses, since higly energy demanding, are main effectors of AMPK dependent autophagy activation by consuming ATP and producing AMP. Conclusion. While in normal conditions protein syntheses drive autophagy activation by decreasing ATP to AMP ratio, conversely autophagy may be inefficiently activated when chronic both low production and consumption of ATP would result in lowest concentrations of AMP, and therefore both blunted rates of protein syntheses and autophagy would be observed. We suggest that this functional hypothesis may explain sarcopenia in many pathological conditions , as in cancer or in aging muscles.
REVIEW | doi:10.20944/preprints202004.0060.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: COVID-19; coronavirus; cytokine storm; immunity; ADE; cross-reactive antibody; rapamycin; mTOR inhibotors
Online: 6 April 2020 (14:03:00 CEST)
COVID-19 has become a severe global public health concern. The critical illness has a mortality rate of 61.5%, and thus, reducing the severity and mortality is top priority. Currently, inflammatory storms are considered as the cause of critical illness and death due to COVID-19. However, After systematical review of the literature, we proposed that cross-reactive antibodies-associated antibody-dependent enhancement (ADE) may actually be the cause of cytokine storms. If the activation of memory B cells can be selectively inhibited in high-risk patients at an early stage of COVID-19 to reduce the production of cross-reactive antibodies of the virus, we speculate that the ADE can be avoided and severe symptoms can be prevented. The mammalian target of rapamycin (mTOR) inhibitors satisfy such conditions. We recommend that pharmaceutical companies conduct clinical trials urgently.
ARTICLE | doi:10.20944/preprints201807.0297.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: 24-methylenecycloartanyl ferulate, angiogenesis, PPAR-γ2, PPRE, Akt/mTOR, HoxA7, VEGF, LIF, HUVEC
Online: 17 July 2018 (09:10:14 CEST)
We investigated the effect and molecular mechanism of 24-MCF-induced PPAR-γ2 on angiogenesis-related genes in MCF7 cells. cDNA microarray, semi-quantitative reverse transcription (RT)-PCR, and western blotting revealed that 24-MCF mediated the expression of genes related to angiogenesis in MCF-7 cells. Luciferase reporter assay demonstrated that promoter activation of the LIF gene, an anti-angiogenesis factor, was increased upon PPAR-γ2 overexpression and 24-MCF treatment, whereas activation of HoxA7 and VEGF promoters, known pro-angiogenesis factors, decreased upon PPAR-γ2 overexpression and 24-MCF treatment. We identified PPAR-response elements (PPRE) located in the VEGF (-913 to +1), HoxA7 (-1107 to +1), and LIF promoter regions (-9032 to -8403). VEGF promoter activity was abolished by mutation of the PPRE motif. Treatment with 24-MCF inhibited expression of VEGF and inhibited the Akt/mTOR pathway. Treatment with 24-MCF also decreased VEGF secretion in MCF7 cells and PMA-stimulated tube formation in HUVECs. Our findings suggest that 24-MCF induces PPAR-γ2-mediated regulation of anti-angiogenesis via PPRE motifs in VEGF, HoxA7, and LIF promoters or upstream regions. Furthermore, 24-MCF treatment inhibits angiogenesis by blocking VEGF secretion.
ARTICLE | doi:10.20944/preprints202305.0844.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Peptidomimetic; VEGFR2; Angiogenesis; Tumor suppression; PI3K/Akt/mTOR signaling pathway; PLCγ/ERK signaling pathway
Online: 11 May 2023 (10:57:38 CEST)
Vascular endothelial growth factor receptor 2 (VEGFR2) mediates VEGFA signaling mainly through the PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. Here we unveil a peptidomimetic (VGB3) based on the interaction between VEGFB and VEGFR1 that unexpectedly binds and neutralizes VEGFR2. Investigation of the cyclic and linear structures of VGB3 using receptor binding and cell proliferation assays, molecular docking, and evaluation of antiangiogenic and antitumor activities in the 4T1 mouse mammary tumor model showed that loop formation is essential for peptide functionality. VGB3 inhibited proliferation and tubulogenesis of human umbilical vein endothelial cells (HUVECs), accounting for the abrogation of VEGFR2, p-VEGFR2 and, subsequently, PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. In 4T1 cells, VGB3 inhibited cell proliferation, VEGFR2 expression and phosphorylation, PI3K/AKT/mTOR pathway, FAK/Paxillin, and epithelial-to-mesenchymal transition cascade. The apoptotic effects of VGB3 on HUVE and 4T1 cells were inferred from annexin-PI and TUNEL staining and activation of P53, caspase-3, caspase-7, and PARP1, which mechanistically occurred through the intrinsic pathway mediated by Bcl2 family members, Cytochrome c, Apaf-1 and caspase-9, and extrinsic pathway via death receptors and caspase-8. These data indicate that binding regions shared by VEGF family members may be important in developing novel pan-VEGFR inhibitors that are highly relevant in the pathogenesis of angiogenesis-related diseases.
ARTICLE | doi:10.20944/preprints202306.0050.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: ASD; autism; autistic spectrum disease; NSE; Neuron-specific enolase; autism biomarker; neuroinflammation; neuronal apoptosis; mTOR
Online: 1 June 2023 (07:30:35 CEST)
Autistic spectrum disease (ASD) is an increasingly common diagnosis nowadays with a prevalence of 1-2% in most countries. Its complex causality – a combination of genetic, immune, metabolic and environmental factors - is translated into pleiomorphic developmental disorders of various severity, which have in common two main aspects: repetitive, restrictive behaviors, and difficulties in social interaction varying from awkward habits and verbalization to complete lack of interest from the ASD child for the outside world. The wide variety of ASD causes also makes it very difficult to find a common denominator – a disease biomarker and medication – and currently there is no commonly used diagnostic and therapeutic strategy besides clinical evaluation and psychotherapy.It is known that inflammation is present in a majority of ASD children, and blood inflammatory markers, together with metabolic, electrophysiological markers and imagistics are useful for ASD diagnostic validation and treatment; however, they tend to leave out a sizeable proportion of ASD kids who do not have such modifications. Genetic testing – whole exome sequencing or targeted profiling on about 500 ASD-linked genes- may also provide good insight into pathophysiology, however many times its results are more restrictive rather than offering additional therapeutic options.Here we describe a new biomarker for ASD - the neuron-specific enolase (NSE) - which was elevated above the normal clinical range (less than 16.3 ng/mL) in the vast majority of ASD kids tested in our study (40 of 41, or 97.5%). This finding opens up a new direction for diagnostic confirmation, dynamic evaluation and therapeutic intervention for ASD kids.
REVIEW | doi:10.20944/preprints202108.0552.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: antagonistic pleiotropy; insulin/IGF-1 signalling; hyperfunction; quasi-programs; mTOR; theories of aging; programmatic aging
Online: 30 August 2021 (16:11:02 CEST)
The process of senescence (aging) is largely determined by the action of wild-type genes. For most organisms, this does not reflect any adaptive function of senescence, but rather evolutionary effects of declining selection against genes with deleterious effects later in life. To understand aging requires an account of how evolutionary mechanisms give rise to pathogenic gene action and late-life disease, that integrates evolutionary (ultimate) and mechanistic (proximate) causes into a single explanation. A well-supported evolutionary explanation by G.C. Williams argues that senescence can evolve due to pleiotropic effects of alleles with antagonistic effects on fitness and late-life health (antagonistic pleiotropy, AP). What has remained unclear is how gene action gives rise to late-life disease pathophysiology. One ultimate-proximate account is T.B.L. Kirkwood’s disposable soma theory. Based on the hypothesis that stochastic molecular damage causes senescence, this reasons that aging is coupled to reproductive fitness due to preferential investment of resources into reproduction, rather than somatic maintenance. An alternative and more recent ultimate-proximate theory argues that aging is largely caused by programmatic, developmental-type mechanisms. Here ideas about AP and programmatic aging are reviewed, particularly those of M.V. Blagosklonny (the hyperfunction theory) and J.P. de Magalhães (the developmental theory), and their capacity to make sense of diverse experimental findings is described.
REVIEW | doi:10.20944/preprints201809.0364.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: clear cell renal cell carcinoma; hypoxia inducible factors (HIFs); selenium; PD-L1; miRNA; VEGF; mTOR inhibitors
Online: 19 September 2018 (05:10:22 CEST)
In the last two decades, the discovery of various pathways involved in renal cell carcinoma (RCC) have led to the development of biologically-driven targeted therapies. Hypoxia inducible factors (HIFs), angiogenic growth factors, von Hippel-Lindau (VHL) gene mutations and oncogenic miRNAs play essential roles in the pathogenesis and drug resistance of clear cell renal cell carcinoma. These insights have led to the development of VEGF inhibitors, mTOR inhibitors and immunotherapeutic agents which have significantly improved outcomes of patients with advanced RCC. HIF inhibitors will be a valuable asset in the growing therapeutic armamentarium of RCC. Various histone deacetylase (HDAC)inhibitors, including selenium and agents such as PT2385 and PT2977, are being explored in various clinical trials as potential HIF inhibitors to ameliorate the outcomes of RCC patients. In this article, we will review the current treatment options and highlight the potential role of selenium in the modulation of drug resistance biomarkers expressed in ccRCC tumors.
REVIEW | doi:10.20944/preprints202104.0379.v1
Subject: Social Sciences, Psychology Keywords: Substantia nigra; mTOR; SUMO E3 ligase; Huntington’s disease; 3,4-methylenedioxymethamphetamine (MDMA); autophagy; L-Dopa-induced dyskinesia (LID); mitophagy
Online: 14 April 2021 (13:41:05 CEST)
Rhes is one of the most interesting proteins regulated by thyroid hormones that, through the inhibition of the striatal cAMP/PKA pathway, acts as a modulator of dopamine neurotransmission. It is expressed at high levels in the dorsal striatum, with a medial-to-lateral expression gradient reflecting that of both dopamine D2 and adenosine A2A receptors. Rhes is also present in the hippocampus, cerebral cortex, olfactory tubercle and bulb, substantia nigra pars compacta (SNc) and ventral tegmental area of the rodent brain. In line with Rhes-dependent regulation of dopaminergic transmission, several data showed that lack of Rhes enhanced cocaine and amphetamine-induced motor stimulation in mice. Previous studies showed that pharmacological depletion of dopamine significantly reduces Rhes mRNA levels in rodents, non-human primates and Parkinson’s disease (PD) patients, suggesting a link between dopaminergic innervation and physiological Rhes mRNA expression. Rhes protein binds to and activates striatal mTORC1, and modulates L-DOPA-induced dyskinesia in PD rodent models. Finally, Rhes is involved in the survival of mouse midbrain dopaminergic neurons of SNc, thus pointing towards a Rhes-dependent modulation of autophagy and mitophagy processes, and encouraging further investigations about mechanisms underlying dysfunctions of the nigrostriatal system.
ARTICLE | doi:10.20944/preprints201612.0042.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: acute lung injury; mycelium of Sanghuangporus sanghuang; lipopolysaccharide; KAP1/Nrf2 pathway; PI3K/Akt/mTOR pathways; HO-1; HNGB1
Online: 7 December 2016 (11:15:30 CET)
Acute lung injury (ALI) is characterized by inflammation of the lung tissue and oxidative injury caused by excessive accumulation of reactive oxygen species. Studies have suggested that anti-inflammatory or antioxidant agents could be used for the treatment of ALI with a good outcome. Therefore, our study aimed to test whether the mycelium extract of Sanghuangporus sanghuang (SS-1), believed to exhibit antioxidant and anti-inflammatory properties, could be used against the excessive inflammatory response associated with LPS-induced ALI in mice and to investigate its possible mechanism of action. The experimental results showed that the administration of SS-1 could inhibit LPS-induced inflammation. SS-1 could reduce the number of inflammatory cells, inhibit MPO activity, regulate the TLR4/PI3K/Akt/mTOR pathway and the signal transduction of NF-κB and MAPK pathways in the lung tissue, and inhibit HNGB1 activity in BALF. In addition, SS-1 could affect the synthesis of antioxidant enzymes HO-1 and Trx-1 in the lung tissue and regulate signal transduction in the KAP1/Nrf2/Keap1 pathway. Histological results showed that administration of SS-1 prior to induction could inhibit the large-scale LPS-induced neutrophil infiltration of the lung tissue. Therefore, based on all experimental results, we propose that SS-1 exhibits a protective effect against LPS-induced (ALI) in mice. The mycelium of S. sanghuang can potentially be used for the treatment or prevention of inflammation-related diseases
ARTICLE | doi:10.20944/preprints202308.0796.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: anesthesia neurotoxicity; neuropathic pain; neural activity; mammalian target of rapamycin (mTOR); dorsal spinal cord (DSC), dorsal root ganglion (DRG).
Online: 10 August 2023 (08:17:30 CEST)
Patients who have undergone surgery in early life may be at elevated risk for neuropathic pain in later life. The risk factors for this susceptibility are not fully understood. Here, we used a mouse chronic pain model to test the hypothesis that early exposure to general anesthetic (GA) causes cellular and molecular alterations in dorsal spinal cord (DSC) and dorsal root ganglion (DRG) that produces a predisposition to neuropathic pain via an upregulation of the mammalian target of the rapamycin (mTOR) signaling pathway. Mice were exposed to isoflurane at postnatal day 7 (P7) and underwent spared nerve injury at P28 which causes chronic pain. Selected groups were treated with rapamycin, an mTOR inhibitor, for eight weeks. Behavioral tests show early isoflurane exposure enhances susceptibility to chronic pain, and rapamycin treatment improves outcomes. Immunohistochemistry, Western blotting, and q-PCR indicates that isoflurane upregulates mTOR expression and neural activity in DSC and DRG. Accompanying upregulation of mTOR and rapamycin-reversible changes in chronic pain-associated markers, including N-cadherin, cAMP response element-binding protein (CREB), purinergic P2Y12 receptor, glial fibrillary acidic protein (GFAP) in DSC; and connexin 43, phospho-extracellular signal-regulated kinase (p-ERK), GFAP, Iba1 in DRG, were observed. We conclude that early GA exposure alters the development of pain circuits such that mice are subsequently more vulnerable to chronic neuropathic pain states.
REVIEW | doi:10.20944/preprints202307.1284.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Cancer; tumourigenesis; drug resistance; signalling pathways; Wnt/β-catenin pathway; JAK/STAT pathway; PI3K/Akt/mTOR pathway; RAS/RAF/MAPK/ERK signalling
Online: 19 July 2023 (09:14:02 CEST)
One of the leading causes of death worldwide, in both man and woman, is cancer. Despite the significant development in therapeutic strategies, the inevitable emergence of drug resistance limits the success and impedes the curative outcome. Intrinsic and acquired resistance are common mechanisms responsible for cancer relapse. Several factors crucially regulate tumourigenesis and resistance, including physical barriers, tumour microenvironment (TME), heterogeneity, genetic and epigenetic alterations, the immune system, tumour burden, growth kinetics and undruggable targets. Moreover, transforming growth factor-beta (TGF-β), Notch, epidermal growth factor receptor (EGFR), integrin-extracellular matrix (ECM), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphoinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR), wingless-related integration site (Wnt)/β-catenin), Janus kinase/signal transducers and activators of transcription (JAK/STAT) and RAS/RAF/mitogen-activated protein kinase (MAPK) signalling pathways are some of the key players that have a pivotal role in drug resistance mechanisms. To guide future cancer treatments and improve results, a deeper comprehension of drug resistance pathways is necessary. This review will cover both intrinsic and acquired resistance and give a comprehensive overview of recent research on mechanisms that enable cancer cells to bypass barriers put by treatments, and like “satellite navigation”, find alternative routes to carry on their “journey” to cancer progression.