Investigating The Alteration in DNA Double-Stranded Break Accumulation in Murine Ovarian Cancer Cells; after Anti-Cancer Drug Treatment, Individually and in Combination

Neeraj, Bhavani A B (2023) Investigating The Alteration in DNA Double-Stranded Break Accumulation in Murine Ovarian Cancer Cells; after Anti-Cancer Drug Treatment, Individually and in Combination. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Neeraj Bhavani A B (18MS013)) Thesis_18MS013.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Over three lakh women are diagnosed with Ovarian cancer, OC, yearly worldwide, and the disease has a mortality rate of 66%. The five-year survival rate of the disease is less than 50%, and we are in dire need of new improvised therapies to combat the disease and its reoccurrence. One of the main reasons for the ineffectiveness of traditional therapies- radiotherapy followed by chemotherapy, is the DNA damage repair system in our cells. Combination therapy and phytomedicines are new and promising approaches in cancer research. Here, in this study, we have compared two cell lines, ID8 and ID8-VEGF. The ID8 cell is an ovarian surface epithelial cancer cell that accumulated spontaneous mutations and became cancerous, while ID8-VEGF cells are ID8 cells transfected with vascular endothelial growth factor, VEGF, to overexpress it. They represent the early and late stages of ovarian cancer, respectively, in terms of the DNA damage, DSBs accumulated and repaired by them when a radiomimetic is added. This study observed that in the late stages of cancer, where VEGF is overexpressed, the DSBs accumulated are less, indicating that VEGF has a role in the prevention of DNA damage or in the enhancement of the repair of the damage caused. This is especially relevant considering the lack of effectiveness of conventional therapies at later stages of cancer. We have studied the combinations of drugs and phytomedicine, methanolic neem bark extract, MNBE, that may effectively inhibit the repair of radiomimetic induced DNA damage. The conventional treatments cause high nephrotoxicity and impose high cytotoxicity on normal cells. Through combination therapy, we can cut down the therapeutic dose of the drugs, thus reducing the chance of multi-drug resistance and the associated nephrotoxicity. We have observed that the combinations of Cisplatin (IC12.5) and MNBE (IC12.5) are the most effective in inhibiting the repair of the DSBs induced as a consequence of anti-cancer therapy. This opens new possibilities for using MNBE in combination with new or established anti-cancer drugs for treating OC. From the apoptosis assay, we see that in an 11-hour period (3-hour Bleomycin treatment followed by 8 hours of drug treatment), the sequential combination of Bleomycin (IC10) and Rucaparib (IC12.5), Cisplatin (IC12.5) + Rucaparib (IC12.5), and Cisplatin (IC12.5)+ MNBE (IC12.5) led to the most fraction of cells being in the late apoptotic stage. The most fraction of cell death was observed when Cisplatin (IC12.5)+ Rucaparib (IC12.5) was sequentially treated after Bleomycin treatment.

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