EPIGALLOCATECHIN GALLATE SENSITIZES PANCREATIC CANCER CELLS TO GEMCITABINE BY MODULATING MICRORNA EXPRESSION PROFILE

Abstract

Pancreatic cancer is a leading cause of cancer-related deaths in developed countries, with a 5-year average survival rate of less than 5%, making it a malignant disease. Gemcitabine (GEM), an FDA-approved pyrimidine antimetabolite, is widely used in pancreatic cancer treatment. However, due to its targeting of all dividing cells, severe side effects are frequently observed in patients undergoing GEM treatment for pancreatic cancer. Consequently, meta-analyses have shown that the combination of GEM with other active compounds significantly improves the 1-year survival rate of pancreatic cancer patients. Epigallocatechin- 3-gallate (EGCG), an active compound found in green tea (Camellia sinensis), has proven anticancer activity in pancreatic cancer. Subsequent studies have demonstrated that EGCG enhances the sensitivity of pancreatic cancer cells to GEM. However, among the studies conducted to date, the impact of the combination of EGCG and GEM on the expression of critical microRNAs, which act as key epigenetic regulators in pancreatic cancer pathology, has not been investigated. This study aims to determine the cytotoxic and apoptotic effects of the combination of GEM and EGCG on PANC1 cells and to examine its effectiveness on the expression levels of microRNAs involved in cancer progression. Material and Method Cytotoxicity of GEM and EGCG in PANC1 cells was assessed using the WST-1 assay, and combination effects were analyzed using isobologram analysis. Apoptosis analysis was performed using the Annexin V method. miRNA isolation was conducted with the miRNeasy Kit, followed by cDNA synthesis using the miScript II Reverse Transcription Kit. Changes in the expression of miRNAs involved in cancer cell proliferation, apoptosis, and metastasis were examined using real-time qRT-PCR analysis. Results The IC50 values for GEM at 24, 48, and 72 hours were determined as 72.85 μM, 26.55 μM, and 9.38 μM, respectively. EGCG's IC50 values at 24, 48, and 72 hours were determined as 64.36 μM, 48.34 μM, and 19.73 μM, respectively. When combined at a 2:3 ratio (GEM: EGCG) at 24 and 72 hours, a synergistic effect was observed, while at 48 hours, a strong synergistic drug interaction was observed. At a concentration of only 26.55 μM, the group treated with GEM showed a 4.2-fold increase in apoptosis compared to the control group receiving fresh medium. In contrast, the combination treatment (EGCG: 4.71 μM, GEM: 3.14 μM) resulted in a remarkable 12.04-fold increase in apoptosis. After combination treatment, the expression of tumor suppressor miRNAs, miR-137, and miR-130a-3p, increased, while the expression of oncogenic miRNAs, including miR-27a-3p, miR-425- 5p, miR-183-5p, miR-187-3p, miR-21-5p, miR-324-5p, and miR-486-5p, decreased. Conclusion EGCG can sensitize pancreatic cancer to GEM through epigenetic mechanisms, shedding light on novel therapeutic approaches.