Combination of Ethanolic Extract of Citrus aurantifolia Peels with Doxorubicin Modulate Cell Cycle and Increase Apoptosis Induction on MCF-7 Cells

New approach of breast cancer therapy is developed toward combination therapy with agents that have a specific molecular target. Our previous study showed that Citrus aurantifolia lime peels ethanolic extract (CPE) increased the sensitivity of MCF-7 cells againts doxorubicin. This study aims to observe the mechanism of combination CPE and doxorubicin in cell cycle modulation and apoptosis on MCF-7 cells. The assays were performed in the study were cell cycle assay, apoptosis induction, and immunocytochemistry of MCF-7 cells. The effect on the modulation of cell cycle and apoptosis were observed by flowcytometry assay in both single dose of CPE and its combination with Doxorubicin. Cell cycle distribution were observed with flowcytometer FACS-Calibur and its data was analyzed by Cell Quest program. Apoptotic induction in MCF-7 cells was examined using acrydine orange-ethidium bromide (AO-EtBr) double staining. Immunocytochemistry assay was done to observe the expression of apoptotic regulation protein p53 and Bcl-2. The result showed that CPE 6 mu g/mL induced apoptosis and cell accumulation at G1 phase, while CPE 15 mu g/mL induced apoptosis and cell accumulation at G2/M phase. The combination of doxorubicin 200 nM with CPE 6 mu g/mL increased apoptosis induction than their single treatment, and cell accumulation at G2/M phase. Evidence of apoptosis and protein expression of p53 and Bcl-2 indicated that both single applications and combinations of CPE and doxorubicin are able to increase apoptotic bodies of MCF-7 cells by increasing the proteins expression. This result suggested that CPE could perform as co-chemotherapeutic agent with doxorubicin on breast cancer cells.