Our previous study has found the anti-tumor activity of oleandrin in osteosarcoma cells in vitro, but the signal transduction process of cell apoptosis induced by oleandrin is uncertain, which is explored in this study. Fluorescence staining and flow cytometry (FCM) was performed to detect the cell apoptosis, intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Caspase-3 activity was detected using a commercial kit. The protein expression of cytoplasmic cytochrome c, mitochondrial cytochrome c, bcl-2, bax, caspase-9, Fas, FasL, caspase-8 and caspase-3 was detected using western blot. A pan-caspase inhibitor, z-VAD-fmk, was applied to block the apoptotic pathway and the apoptosis status were re-tested. We found that oleandrin significantly induced the increased apoptosis of U2OS cells. Meanwhile, the intracellular ROS was elevated, but the MMP decreased. The cytochrome c in mitochondria was notably decreased but increased in cytoplasm. The caspase-3 activity was also enhanced with the increase of drug concentration and treatment time. Oleandrin also down-regulated the level of bcl-2, but remarkably up-regulated the expression of bax, cleaved caspase-9, Fas, FasL, cleaved caspase-8 and cleaved caspase-3. Furthermore, the pre-treatment with z-VAD-fmk almost completely reverted the oleandrin-induced apoptosis. The results suggested that oleandrin induces the apoptosis of osteosarcoma cells via mitochondrial- and death receptor-dependent pathways.

Ferruginol is a promising abietane-type antitumor diterpene able to induce apoptosis in SK-Mel-28 human malignant melanoma. We here aim to increase this activity by testing the effect of a small library of ferruginol analogues. After an screening of their antiproliferative activity (SRB staining) on SK-Mel-28 cells the analogue 18-aminoferruginol (GI50=10 µM) was further selected for mechanistic studies including effects on mitochondrial viability (MTT assay, IC50=10 µM p<0.0001), induction of apoptosis (DAPI staining, p<0.001), changes in cell morphology associated with the treatment (cell shrinkage and membrane blebbing), induction of caspase-3/7 activity (2.5x at 48h, 6.5x at 72h; p<0.0001), changes in the mitochondrial membrane potential (not significant), and effects on 2D cell migration and 3D cell invasion (modified Boyden assay, not significant). The results were compared to those of the parent molecule (ferruginol, GI50»50 µM) and paclitaxel (GI50=10 nM) as a reference drug. In conclusion, we demonstrate here that derivatization of ferruginol into 18-aminoferruginol increases its antiproliferative activity 5 times in SK-MEL-28 cells as well as changing the apoptotic mechanism of its parent molecule ferruginol from activation of caspases without depolarization of mitochondrial membrane.

Background: Persistent up regulation of NF-κB leads to chronic inflammation and subsequent microglial activation and takes neurons towards death by activating death receptor domains and the p53 pathway. Thus, inhibition of NF-κB may lead to more effective treatment for Parkinson’s disease. Therefore, we have used mangiferin, specific inhibitor of NF-κB in this study. Method: The study utilized male Wistar rats weighing 200-250 gm (n=8 in each group). Stereotactic surgery of rats was done to induce 6-OHDA lesioning in rats. On day 42, rats were subjected to behavioural studies to evaluate effect of mangiferin and their brains were taken out after euthanasia to perform biochemical and molecular studies. Results: Mangiferin significantly increases locomotor parameters in 6-OHDA lesioned rats. It also decreases activity of Cyclooxygenase enzyme which then leads to decrease concentration of inflammatory cytokines. Microglial inflammation was also substantially reduced by reducing MPO concentration. Oxidative stress burden was also reduced after treatment with mangiferin as indicated by increase in Total Antioxidant Capacity, SOD and Catalase and reduction in concentration of MDA. Treatment with mangiferin also reduces burden of oxidative stress by increasing the activity of NRF2/ARE pathway. Activity of Caspase 3 and 9 was also significantly reduced after treatment with mangiferin. Significant decrease in activity of both Cox1 and Cox 2 was also observed. Maximum improvement in all parameters was observed in rats treated with grouping of mangiferin 45mg.kg-1 and levodopa 10mg.kg-1. Treatment with levodopa alone has no significant effect on biochemical and molecular parameters though it significantly improves behavioural parameters. Conclusion and Implications: Results of this study suggest that mangiferin has protective effect in hemi-parkinsonian rats by inhibiting NF-κB. Current treatment of Parkinson’s disease does not target the underlying problem of the disease. Therefore, combination therapy of mangiferin and levodopa can be helpful in better management of Parkison’s.

Apoptosis, necroptosis, and autophagy are cellular mechanisms by which cells are programmed to die under a wide range of physiological and developmental stimuli. A multitude of protein mediators of programmed cell death have been identified and apoptosis, necroptosis, and autophagy signals have been found to utilize common pathways elucidating the proteins involved. This narrative review focuses on caspase-dependent and caspase-independent programmed cell death systems. Included studies of caspase-dependent programmed cell death include extrinsic pathway apoptotic mechanisms including phosphatidylserine (PS), FAS (APO-1/CD95), Tumor Necrosis Factor (TNF) Receptor type 1 (TNF-R1) and TNF-Related Apoptosis-Inducing Ligand (TRAIL) and intrinsic or mitochondrial pathway such as Cytochrome C, the Bcl-2 family of proteins and Smac/Diablo. The Bcl-2 family has apoptotic mediators Bcl-2-associated X protein (Bax) and Bcl-2 homologous antagonist/killer (Bak), Bcl-2-Interacting Protein BIM (Bim), Bcl-2 agonist of cell death (Bad), Bid, Bcl-2 adenovirus E1B 19kDa-interacting protein 1 NIP3 (Bnip3), BMF, HRK, Noxa and PUMA and anti-apoptotic proteins such as Bcl-2 itself, Mcl-1, Bcl-w, A1, and Bcl-XL. Moreover, caspase-independent programmed cell death pathways include the mitochondrial pathway with the protein mediators Apoptosis Inducing Factor (AIF), and Endonuclease G, the pathways Necroptosis, and Autophagy. Understanding programmed cell death from those reported in this review could shed substantial light on the processes of biological homeostasis. In addition, identifying specific proteins involved in these processes is mandatory to identify molecular biomarkers as well as therapeutic targets. This knowledge could provide the ability to modulate the programmed cell death response and could lead to new therapeutic interventions in a wide range of diseases.

The many limitations of implementing anticancer strategies under the term “precision oncology” have been extensively discussed. While some authors propose promising future directions, others are less optimistic and use phrases such as illusion, hype and false hypotheses. The reality is revealed by practicing clinicians and cancer patients in various online publications, one of which has stated that “in the quest for the next cancer cure, few researchers bother to look back at the graveyard of failed medicines to figure out what went wrong.” The message is clear: novel therapeutic strategies with catchy names (e.g., synthetic “lethality”) have not fulfilled their promises despite decades of extensive research and clinical trials. The main purpose of this review is to discuss key challenges in solid tumor therapy that surprisingly continue to be overlooked by the nomenclature committee on cell death and numerous other authors. These challenges include: the impact of chemotherapy-induced genome chaos (e.g., multinucleation) on resistance and relapse, oncogenic function of caspase 3, cancer cell anastasis (recovery from late stages of apoptosis), and pitfalls of ubiquitously used preclinical chemosensitivity assays (e.g., cell “viability” and tumor growth delay studies in live animals) that score such pro-survival responses as “lethal” events. Studies outline herein underscore the need for new direction in the management of solid tumors.

Navigating growth cones are exposed to multiple signals simultaneously and have to integrate competing cues into a coherent navigational response. Integration of guidance cues is traditionally thought to occur at the level of cytoskeletal dynamics. Drosophila studies indicate that cells exhibit a low level of continuous caspase protease activation, and that axon guidance cues can activate or suppress caspase activity. We base a model for axon guidance on these observations. By analogy with other systems in which caspase signaling has non-apoptotic functions, we propose that caspase signaling can either reinforce repulsion or negate attraction in response to external guidance cues by cleaving cytoskeletal proteins. Over the course of an entire trajectory, incorrectly navigating axons may pass the threshold for apoptosis and be eliminated, whereas axons making correct decisions will survive. These observations would also explain why neurotrophic factors can act as axon guidance cues and why axon guidance systems such as Slit/Robo signaling may act as tumor suppressors in cancer.