Over kanseri hücrelerinde DNA hasari ve golgi stresine yanitta apoptotik mekanizmalarin araştirilmasi

Ovarian cancer has the highest mortality rate among all gynecologic cancers due to its diagnosis at the metastatic stage and developing chemotherapy resistance. Despite surgical removal of the tumor and platinum-based chemotherapy, many ovarian cancer patients succumb to the disease due to cancer recurrence. Therefore, new treatment strategies are essential to improve the prognosis of ovarian cancer patients. Replication stress is a common feature of ovarian cancer, and ATR/CHK1 signaling plays a primary role in protecting cells from replication stress. Although ATR inhibitors have single applications, combination therapeutic applications also show efficacy as specific targets. Although ATR inhibitors activate mitochondrial cell death pathways in combination in many studies in ovarian cancer, studies remain limited. This thesis study aimed to find a new molecular combination therapy that could be effective in ovarian cancer cells, as well as the molecular working mechanisms of this combinatorial application. Using high-throughput small molecule screening analysis, AZD6738 (ATR inhibitor)/Brefeldin A (Golgi stress inducer) was determined as the most effective cell death-inducing combination in ovarian cancer cells. Experimental studies have shown that simultaneous application of AZD6738/Brefeldin A causes apoptotic cell death in SKOV3 (***p<0.001, control vs AZD6738+BFA) and IGROV1 (**p<0.01, control vs AZD6738+BFA) ovarian cancer cells, together with caspase-3 and caspase-9 activation. AZD6738/Brefeldin A exposure also induces cytochrome c translocation to the cytosol, which is a characteristic feature of the mitochondrial cell death pathway. The most important molecular process here is that the combinatorial use of AZD6738/Brefeldin A in SKOV3 and IGROV1 cells leads to a decrease in the expression levels of anti-apoptotic BCL-2 family members BCL-2, BCL-XL and MCL1, while it leads to an increase in the expression levels of pro-apoptotic BCL-2 proteins, especially BIM and PUMA. All these findings suggest that AZD6738/Brefeldin A is a potential therapeutic approach for ovarian cancer.