The Anti-proliferative and Pro-apoptotic Effects of Iranian Viper Venom (Vipera raddei kurdistanica) on Human Gastric Cancer Cells (C615) are Mediated by PI3K/AKT/mTOR Signalling Pathway Inhibition.

Gastric cancer (GC) is one of the most common malignancies worldwide. Since the PI3K/AKT/mTOR signalling pathway plays a crucial role in tumour growth and survival, this study aims to evaluate the anti-proliferative and pro-apoptotic effects of Vipera raddei kurdistanica venom on human GC cells (C615). In this an experimental study, C615 cancer cells and normal fibroblasts were treated with 0.63-10 μg/ml of venom for 24, 48, 72, and 96 hours. Cell viability was analysed using MTT and trypan blue staining, and cytotoxicity was assessed by the lactate dehydrogenase (LDH) assay. Apoptosis at the half-maximal inhibitory concentration (IC50) concentration was evaluated using the TUNEL, annexin V/PI flow cytometry, and diphenylamine DNA fragmentation assays. Mitochondrial membrane potential (JC-1), cytosolic cytochrome c levels, and the expressions of apoptosis-related and PI3K/ AKT/mTOR pathway genes were measured. All experiments were performed in three independent biological replicates. Venom treatment significantly reduced cell viability in a time- and concentration-dependent manner. The IC50 values in fibroblasts being approximately 51-59-fold higher than in C615 cells across time points. At the IC50 dose, venom treatment produced a very large effect on apoptosis induction, increasing early and late apoptosis by approximately 84-fold and 463-fold, respectively, compared with controls. DNA fragmentation (15.7-fold) were significantly elevated (P<0.001). Venom exposure exerted a reducing effect on mitochondrial membrane potential (37%, P=0.032) and increased cytochrome c release (2.31-fold, P=0.001). Gene expression analysis showed upregulation of FAS (1.67-fold; P<0.001), FASL (1.28 fold; P=0.005), BAX (2.34 fold; P<0.001), BAK (1.29 fold; P=0.004), and BIM (1.4 fold; P<0.001) and downregulation of BCL-2 (0.44 fold; P<0.001), BCL-XL (0.47 fold; P<0.001), PI3K (P<0.001), AKT (P<0.001), and MTOR (P<0.001). Vipera raddei kurdistanica venom may exert selective cytotoxic effects against gastric cancer cells and may induce apoptosis through both intrinsic and extrinsic pathways, potentially via inhibition of the PI3K/AKT/mTOR signalling axis.