Background and Objective: Breast cancer is claimed to be a common cancer amongst women. Estrogen receptors are over-expressed in breast cancer and susceptible to anti-estrogenic effects of tamoxifen. Tamoxifen resistance is a major problem in breast cancer treatment. It has been shown that allicin is an organosulfur compound that is effective in apoptosis induction and cell death in various tumor cell lines. Methylsulfonylmethane (MSM) is non-toxic to the human body whose effect on several cancer lines has been studied. In this study, we assessed the allicin, methylsulfonylmethane and their combined effects on breast cancer cell line (MCF7).

Materials and Methods: Breast cancer cell lines were cultivated in RPMI-1640 and CD44^± cells were separated using magnetic activated cell sorting (MACS). Then, the effect of different concentrations of allicin, methylsulfonylmethane and their combination were investigated on the isolated cells using MTT, clonogenic assay and Acridine orange/ Ethidium bromide staininig methods.

Results: Allicin had cytotoxicitic consequence on breast cancer cells and its combination with methylsulfonylmethane increased the cytotoxicity and number of apoptotic cells compared to the other groups. Lower colonies were seen in CD44^- treated cells in MSM/allicin group compared to CD44⁺ Cells which implies that sensitivity of CD44^-cells was higher compared to the CD44⁺ cells.

Conclusion: In this study, we found that allicin and MSM have anticancer effect inhibiting the growth of breast cancer; but combination of low concentrations of allicin with MSM may be more effective in the treatment of breast cancer cells. So, allicin and MSM, as natural products, can be used for medical purposes due to their cytotoxic effect and their availability.