Dietary isoflavone daidzein synergizes centchroman action via induction of apoptosis and inhibition of PI3K/Akt pathway in MCF-7/MDA MB-231 human breast cancer cells.

BACKGROUND: Despite advancements in the prognosis and management of breast cancer, it remains a major cause of mortality in women worldwide. Centchroman (CC), an oral contraceptive has been found to exhibit anti-cancer potential against a wide range of cancer including breast cancer.

PURPOSE: The present study is intended to evaluate the ability of soy isoflavone Daidzein (DZ) in enhancing the efficacy of CC in Human Breast Cancer Cells (HBCCs).

METHODS/STUDY DESIGN: Sulforhodamine B assay was employed to determine the cytotoxicity induced by 10 µM CC & 50 µM DZ separately and together in MCF-7/MDA MB-231 HBCCs and non-tumorigenic Human Mammary Epithelial Cells (HMECs) MCF-10A as a control. Combination Index (CI) analysis was executed using CompuSyn software. Further, apoptosis was assessed using Annexin V/PI, AO/PI staining and tunel assay. Cell cycle, reactive oxygen species generation and mitochondrial membrane potential alteration was determined using flow cytometry. Western blot analysis was performed to check the expression of respective proteins.

RESULTS: The results suggest that the combination exerts elevated toxicity as compared to control and each drug per se without affecting HMECs MCF-10A. This therefore implies cancer cell specific action of CC plus DZ administered together. Additionally, combination index analysis suggests synergistic action of CC and DZ combination in HBCCs. Cell cycle analysis, Annexin V/PI staining, tunel assay and western blot analysis confirms the induction of apoptosis by combination in HBCCs. Interestingly, western blot analysis also revealed that the combination down-regulated the expression of proteins involved in cell survival i.e. PI3K, Akt and mTOR, suggesting inhibition of cell survival pathway.

CONCLUSION: The results overall demonstrate that CC plus DZ has higher anticancer efficacy as compared to either drug alone. Hence, the combination of CC plus DZ may offer a novel strategy for the management of breast cancer.