Ethyl Acetate Fraction of Caesalpinia sappan L. Enhances Cisplatin’s Cytotoxicity on HeLa Cells via G1 and S Arrest through p53 Expression

Cisplatin (cisp) is the first line chemotherapeutic agent for several cancer diseases which can cause significant side effects and cellular resistance. Combination-chemotherapy treatment (co-chemotherapy) was reported to be able to reduce cisp effects. Therefore, this study was carried out to investigate the cytotoxic activity of ethyl acetate fraction of C. sappan (EFC) in combination with cisp by observing apoptosis induction and cell cycle profile. Cytotoxic activity was evaluated by MTT assay. Cell cycle and apoptosis analysis were performed using flow cytometry and p53 expression was analyzed using immunocytochemistry. EFC performed cytotoxic effect on HeLa cells by showing morphological changes such as cell shrinkage, rounding and decreasing of cells viability in concentration dependent manner, giving IC50 value of 65 μg/mL. Combination of EFC and cisp in low concentration decreased cell viability into 36.86%. Further assay indicated that this combination caused redistribution of cell cycle arrest in G1 and S phases through p53 stabilization in nucleus. However, that mechanism was not followed by apoptosis. These results provide evidence to support EFC development as the enhancer of cisp effect, by improving its cytotoxicity on HeLa cells. EFC increases HeLa cells sensitivity to cisp through G1 and S cells’ arrest depending on p53 expression. Key words: co-chemotherapy, EFC, cervix cancer HeLa cells, p53, G1 and S arrest