Investigation of effect of catechin on apoptotic pathaways in HeLa cell line

Nowadays, cancer is one of the most serious health problems of human. The cancer treatment is limited by the side effects of radiation and chemotherapeutic agents and also resistance to cancer treatment of cancer cells. For this reason, it has been investigated that the selective treatment methods on cancer cells. There were many researches showed that the effects of phytochemicals flavonoids on cancer cells. In this thesis, it was aimed to investigate the cytotoxic and apoptotic effects of Epicatechin (EC) and Epicatechin gallate (ECG), which are one of the most important groups of flavonoids, on HeLa cells, which have human cervical adenocarcinoma cell line. The cytotoxic effects of 100 ppm, 10 ppm, 1 ppm, 100 ppb, 10 ppb and 1 ppb doses of EC and ECG on HeLa cells were determined by MTT test. The IC50 value, which is the inhibition concentration at which show 50% viability of cells, was calculated as 48.91 ppm (168,5 µM) for EC, and 4.47 ppm (10.10 µM) for ECG after 72 hours of catechin exposure. In order to determine the effects of EC and ECG on apoptotic pathways in HeLa cells, the expression of important apoptotic proteins Bcl-2, Bax and Caspase-3 was investigated ELISA method. For the ELISA test, HeLa cells were incubated with doses of 1/10 and 1/100 of the determined IC50 values of both catechins for 72 hours. These doses were calculated as 4.89 and 0.489 ppm for EC, and 0.447 and 0.0447 ppm for ECG, respectively. It was found that both catechins increased the expression of Bcl-2 protein, which inhibits apoptosis, compared to the control group. A decrease in apoptosis-inducing bax expression was observed at the 4.89 ppm dose of EC and an increase at the 0.489 ppm dose. It was stated that both doses of ECG increased bax expression. In the expression of caspase-3, which is one of the most important proteins in the formation of apoptosis, a decrease was observed in the 4.89 ppm dose of EC compared to the control, while an insignificant increase was found in the 0.489 ppm dose and in both doses of ECG. As a result, it was determined that the ratio of bax/bcl-2 and caspase-3 expression, EC did not induce apoptosis in HeLa cells but ECG slightly were. It was dedicated that EC and ECG showed efficient cytotoxicity on HeLa cells when the detected IC50 values were compared with other cell lines in the literature.