Antitumor mechanisms of S-allyl mercaptocysteine for breast cancer therapy.

BACKGROUND: S-allyl mercaptocysteine (SAMC), a water-soluble component derived from garlic, has been found to exert multi-antitumor activities. This study was to investigate the responsible molecular mechanisms of SAMC in human breast cancer cell lines. METHODS: Sulforhodamine B assay was used to determine cell viability, flow cytometry was applied for the analysis of cell cycle and cell apoptosis, the change of protein was detected by Western blot. RESULTS: It was found that SAMC exhibited an effective cell growth inhibition of human breast cancer cell lines MCF-7 (ER positive) and MDA-MB-231 (ER negative) in a dose- and time-dependent manner by inducing cell cycle arrested in G0/G1 phase, the block of cell cycle was associated with the up-regulation of p53 and p21. Furthermore, the SAMC-mediated cell cycle arrest was accompanied with promotion of apoptosis, as indicated by the changes in the nuclear morphology and expressions of apoptosis-related proteins. SAMC clearly triggered the mitochondrial apoptotic pathway as indicated by activation of Bax, decreased expression of Bcl-2 and Bcl-XL, and subsequent activation of caspase-9 and caspase-3. CONCLUSION: These results highlight the value of a continued investigation into the use of SAMC as a potential antitumor candidate for breast cancer.