Viral infection activates the transcription factors IRF3 and NF-κB, which synergistically induce type I interferons (IFNs). Here, we identify the E3 ubiquitin ligase RNF138 as an important negative regulator of virus-triggered IRF3 activation and IFN-β induction. Overexpression of RNF138 inhibited virus-induced activation of IRF3 and transcription of the IFNB1 gene, whereas knockout of RNF138 promoted virus-induced activation of IRF3, and transcription of the IFNB1 gene. We further found that RNF138 promotes ubiquitination of PTEN and subsequently inhibits PTEN interactions with IRF3, which is essential for PTEN-mediated nuclear translocation of IRF3, thereby inhibiting IRF3 import into the nucleus. Our findings suggest that RNF138 negatively regulates virus-triggered signaling by inhibiting the interaction of PTEN with IRF3, and these data provide new insights into the molecular mechanisms of cellular antiviral responses.

Phosphatase and tensin homologue (PTEN) and SH2-containing-inositol-5’-phosphatase 2 (SHIP2) are structurally and functionally similar. They both consist of a Phosphastase (Ptase) domain and an adjacent C2 domain, and both proteins dephosphorylate phosphoinositol-tri(3,4,5)phosphate, PI(3,4,5)P3; PTEN at the 3-phophate and SHIP2 at the 5-phosphate. Therefore, they play pivotal roles in the PI3K/Akt pathway. Here, we investigate the role of the C2 domain in membrane interactions of PTEN and SHIP2, using molecular dynamics simulations and free energy calculations. It is generally accepted that for PTEN the C2 domain interacts strongly with anionic lipids and therefore significantly contributes to membrane recruitment. In contrast, for the C2 domain in SHIP2 we previously found much weaker binding affinity for anionic membranes. Our simulations confirm the membrane anchor role of the C2 domain in PTEN, as well as its necessity for the Ptase domain in gaining its productive membrane binding conformation. In contrast, we identified that the C2 domain in SHIP2 undertakes neither of these roles, which are generally proposed for C2 domains. Our data support a model in which the main role of the C2 domain in SHIP2 is to introduce allosteric interdomain changes that enhance catalytic activity of the Ptase domain.

Phosphatase and tensin homolog (PTEN) is a negative regulator of the phosphoinositide 3-kinases/protein kinase B (PI3K/AKT) signaling pathway. Notably, its active site harbors a cysteine residue that is susceptible to oxidation by hydrogen peroxide (H2O2). This oxidation inhibits the phosphatase function of PTEN, critically contributing to the activation of the PI3K/AKT pathway. Upon stimulation of cell surface receptors, the activity of NADPH oxidase 2 (NOX2) generates a transient amount of H2O2, serving as a mediator in this pathway by oxidizing PTEN. The mechanism underlying this oxidation, occurring despite the presence of highly efficient and abundant cellular oxidant-protecting and reducing systems, continues to pose a perplexing conundrum. Here, we demonstrate that the presence of bicarbonate (HCO3-) promoted the rate of H2O2-mediated PTEN oxidation, probably through the formation of peroxymonocarbonate (HCO4-), consequently potentiated the phosphorylation of AKT. In essence, our findings consolidate the crucial role of HCO3- in the redox regulation of PTEN by H2O2, lead to the presumption regarding HCO4- as a signaling molecule during cellular physiological processes.

Phosphatase and tensin homolog (PTEN) is a tumor suppressor due to its ability to regulate cell survival, growth and proliferation by down-regulating PI3K/AKT signaling pathway. In addition, PTEN plays an essential role in other physiological events associated with cell growth demands, such as ischemia-reperfusion, nerve injury and immune response. Therefore, recently PTEN inhibition has emerged as a potential therapeutic intervention in these situations. Increasing evidence demonstrates that reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), are produced and required for the signaling in many important cellular processes under such physiological conditions. ROS have been shown to oxidize PTEN at the cysteine residue of its active site, consequently inhibiting its function. Here we provide an overview of studies that highlight the role of oxidative inhibition of PTEN in physiological processes.

Canine hemangiosarcoma (HSA) is a relatively common neoplasia, occurring mainly in the skin, spleen, liver and right atrium. Despite the numerous studies investigating the treatment of canine HSA, no significant improvement in survival has been achieved in the last 20 years. Advancements in genetic and molecular profiling presented molecular similarities of canine HSA with human angiosarcoma. It could therefore serve as a valuable model for investigating new and more effective treatments in people and dogs. The most common genetic abnormalities in canine HSA have been found in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and neuroblastoma RAS viral oncogene homolog (NRAS) pathways. Mutations are also found in tumor protein p53 (TP53), phosphatase and tensin homolog (PTEN) and cyclin dependent kinase inhibitor 2A (CDKN2A). Known abnormal protein expression could be exploited to trial new target treatments that could be beneficial for both canine and human patients. Despite the high expression of vascular endothelial growth factor (VEGF) and its receptor (VEGFR), no correlation with overall survival time has ever been found. In this review, we explore the most recent developments in molecular profiling in canine HSA and discuss their possible applications in the prognosis and treatment of this fatal disease.

Background: Exposure to inorganic arsenic (iAs) remains a global public health problem. The liver is the main target organ of arsenic, leading to arsenic-induced liver fibrosis. Autophagy is involved. Phosphatase and tensin homology deleted on chromosome ten (PTEN) may participate in arsenic-induced liver fibrosis by regulating autophagy, but the exact mechanisms remain unclear. We established a mouse model of arsenic poisoning through the drinking water, and a fibrosis model using the huma stellate cell (HSC) line LX-2, which was exposed to NaAsO₂ for 24h. HE and Masson staining was adopted to observe the degree of liver fibrosis. The cells were transfected using PTEN overexpression plasmid. Western blot and qRT-PCR were used to determine the levels of protein/mRNA expression. The in vivo results were confirmed in HSCs exposed to NaAsO₂, with changes suggesting fibrosis as seen in mice. NaAsO₂ upregulated the expression of the autophagic markers microtubule-associated protein light chain A/B (LC3), recombinant human autophagy effector protein (Beclin-1), hairy and enhancer of split homolog-1 (HES1), but downregulated PTEN. α-smooth muscle actin (α-SMA) expression was significantly upregulated in all NaAsO₂ groups. PTEN overexpression altered NaAsO₂-induced autophagy which LC3, Beclin-1 were downregulated. Notch1, HES1, α-SMA, and collagenⅠexpression were all downregulated in the NaAsO₂ groups. In conclusion, PTEN overexpression might decrease autophagy and inhibit fibrosis progression caused by this toxin. The NOTCH1/HES1 pathway is likely to be involved in this process. Most previous studies did not investigate PTEN and arsenic-induced liver fibrosis specifically. The present study highlights the importance of targeting PTEN for the management of arsenic exposure.

Background: Breast cancer is the leading cause of cancer mortality and morbidity among Indonesian women. Identification of biological pathways leading into therapeutic resistance through in vitro model is an important step to develop alternative effective therapy in breast cancer. Loss of PTEN expression has been associated with resistance to chemotherapy by involving PI3K/PTEN- dependent apoptosis pathway. We conducted in vitro experiment to investigate the association of hsa-miR-21 and PTEN expression in Doxorubicin-resistant MCF-7 cell line. Methods: Parental MCF-7 cells were periodically incubated with Doxorubicin to obtain specific Dox-resistant variant determined by IC50 using MTT assay. PTEN protein expression was analyzed using immunocytochemistry. Expression of mature has-miR-21 was measured using qRT-PCR. Results: The IC50 of Doxorubicin in parental MCF-7 and Doxorubicin-resistant MCF-7 cells (MCF-7/Dox) was 0.68 and 5.78 µg/ml, respectively. Hsa-miR-21 was significantly overexpressed in MCF-7/Dox cells compared to parental MCF cells (7.94 fold changes). Conclusion: PTEN and hsa-miR-21 expression levels were negatively correlated in Doxorubicin resistant-MCF cells. Further study to confirm the causal relationship of miR-21 overexpression and PTEN downregulation in MCF-7/Dox is required.

Focal adhesion kinase (FAK) and its close paralogue, proline-rich tyrosine kinase 2 (PYK2), are key regulators of aggressive spreading and metastasis of cancer cells. While targeted small-molecule inhibitors of FAK and PYK2 are showing promising antitumor activity, their clinical long-term efficacy may be undermined by the strong capacity of cancer cells to evade anti-kinase drugs. In healthy cells, the expression and/or function of FAK and PYK2 is tightly controlled through modulation of gene expression, competing alternatively spliced forms, non-coding RNAs, and proteins that directly or indirectly affect kinase activation or protein stability. The molecular factors involved are frequently deregulated in cancer cells. Here, we review the endogenous mechanisms controlling FAK and PYK2, and discuss how these mechanisms could inspire or improve anticancer therapies.

The PI3K-AKT-mTOR signal transduction pathway regulates a variety of biological processes including cell growth, cell cycle progression and proliferation, cellular metabolism and cytoskeleton reorganization. Fine-tuning of the PI3K pathway signaling output is essential for the maintenance of tissue homeostasis and uncontrolled activation of this cascade leads to a number of human pathologies including cancer. Inactivation of the tumour suppressor phosphatase PTEN and/or activating mutations in the proto-typical lipid kinase PI3K have emerged as some of the most frequent events associated with human cancer and as a result the PI3K pathway has become a highly sought-after target for cancer therapies. In this review we summarize the essential role of the PTEN-PI3K axis in controlling cellular behaviors by modulating activation of key proto-oncogenic molecular nodes and functional targets. Further, we highlight important functional redundancies and peculiarities of these two critical enzymes that over the last few decades have become a central part of the cancer research field and have instructed hundreds of pre-clinical and clinical trials to better cancer treatments.

Glioblastoma (GBM) is a representative malignant brain tumor characterized by a dismal prognosis, with survival rates of less than 2 years and high recurrence rates. Despite surgical resection and several alternative treatments, GBM remains a refractory disease due to its aggressive invasiveness and resistance to anticancer therapy. In this report, we explore the role of fibronectin type III domain containing 3B (FNDC3B) and its potential as a prognostic and therapeutic biomarker in GBM. GBM exhibited a significantly higher cancer-to-normal ratio compared to other organs, and patients with high FNDC3B expression had a poor prognosis (p < 0.01). In vitro studies revealed that silencing FNDC3B significantly reduced the expression of Survivin, an apoptosis inhibitor, and also reduced cell migration, invasion, extracellular matrix adhesion ability, and stem cell properties in GBM cells. Furthermore, we identified that FNDC3B regulates PTEN/PI3K/Akt signaling in GBM cells using MetaCore integrated pathway bioinformatics analysis and a proteome profiler phospho-kinase array with sequential western blot analysis. Collectively, our findings suggest FNDC3B as a potential biomarker for predicting GBM patient survival and for the development of treatment strategies for GBM.

Borderline ovarian tumors (BOTs) show intriguing characteristics distinguishing them from other ovarian tumors. This unique type of non-invasive neoplasms is characterized by atypical growth of epithelial cells, nuclear atypia, and a moderate-level mitotic activity that places BOTs between benign tumors and invasive cancers. Similar to invasive carcinomas, BOTs can be categorized into six histological subtypes based on the type of epithelial cells present. The most prevalent subtypes are serous and mucinous BOTs, whereas endometrioid, clear cell, seromucinous, and borderline Brenner tumors are diagnosed less often. Noticeably, molecular changes found in BOTs can vary on a case-by-case basis, which warrants further research on the molecular landscape of these tumors. Identifying carcinogenic mutations through molecular analysis and developing targeted therapies represent significant advancements in the diagnosis and treatment of ovarian malignancies. A growing body of evidence indicates that BOTs often remain clinically dormant for extended periods before a molecular trigger initiates increased cell replication, potentially leading to carcinoma development or recurrence. Continued research in this area is crucial for improving risk assessment and developing personalized treatment approaches. While molecular studies have contributed significantly to our understanding of BOT pathogenesis, substantial research is still required to elucidate the relationship between ovarian neoplasms and extraneous disease, identify accurate prognostic indicators, and develop targeted therapeutic approaches. The aim of the present systematic review was to analyze the spectrum of molecular changes found in BOTs and discuss their significance in the context of the overall therapeutic approach.