Effect of epigallocatechin gallate and 5-fluorouracil (5-FU) on notch signaling pathway receptors, transcription factors, caspase3/7 in HT-29 cell line

Epigallocatechin gallate (EGCG) and 5-fluorouracil (5-FU) increase chemosensitivity. Recent studies have shown that cotreatment with epigallocatechin gallate (EGCG) increases the sensitivity of colorectal cancer cells to 5-fluorouracil (5-FU), and HT29 cells were treated with a mixture of 5-FU, EGCG, and equimolar EGCG. We determined the cell viability by using both substances, and 5-FU showed an apparent efficacy, while EGCG alone did not show any effectiveness. However, EGCG showed a strong effect when cells were treated with 5-FU and EGCG. Previously, the result of EGCG on the NOTCH pathway was shown on NOTCH 1,2,3 but not on NOTCH 4, HES/HEY, caspases, and SOX9 in HT-29 cells. HES1 and SOX9 may be novel therapeutic targets in the treatment of colorectal cancer. There are studies evaluating SOX9 expression in colorectal cancer. In vitro experiments suggest that increased SOX9 expression is vital in tumorigenesis. It is also noted that more experimental data are needed to decipher the molecular mechanisms of SOX9 in colon cancer. Caspase-3/7 is the primary mediator of apoptosis activated by cytotoxic drugs, radiotherapy, or cellular exposure. It is often used as a marker for the efficacy of cancer treatment. Therefore, the role of caspase-3/7 in tumor progression remains to be clearly defined. It was observed that the combination of EGCG and 5-Fu decreased the mRNA levels of Notch signaling receptors. In this study, Notch3 was also examined, showing that EGCG administration alone inhibited receptor activity. However, when 100 µM EGCG was co-administered with 5-Fu, gene expression was inhibited only after 72 hours of treatment. In contrast, when 200 µM EGCG was co-administered with 5-FU, gene expression was increased after 72 hours. The emergence of an unknown dose-dependent mechanism for Notch3 may explain this. When the expression status of transcription factors was examined, it was observed that combining 100 µM EGCG with 5-FU generally decreased the expression of transcription factors in parallel with other gene expressions studied in the present study. Co-administration of epigallocatechin gallate and 5-Fluorouracil reduced the expression of Notch1, Sox9, and Hes1 as novel therapeutic targets in the HT-29 cell line. This study will allow rapid screening for the use of identified target genes in novel therapeutic approaches.