Objective: To investigate the effects of various carotenoids on the proliferation, cell cycle, apoptosis and expression of bcl-2 gene in breast cancer cell MCF-7.
Methods: Time and dose effects of individual carotenoids were detected using the MTT assay. The effects of individual carotenoids on cell cycle and the apoptosis were observed by flow cytometry. The expression of bcl-2 mRNA gene was detected using the RT-PCR method.
Results: All 4 carotenoids tested inhibited the proliferation of MCF-7 cell line, but with different potencies. beta-carotene and lycopene were the most active inhibitors (inhibition rate 88.2% and 87.8%, respectively) followed by zeaxanthin and astaxanthin. All 4 carotenoids did not induce cell apoptosis. Cell cycle progression was blocked at G(2)/M phase with 60 micromol/L lycopene and at G(0)/G(1) phase with 60 micromol/L zeaxanthin dipalmitate. Carotenoids down regulated bcl-2 gene expression.
Conclusion: Carotenoids could inhibit the proliferation of human beast cancer MCF-7 cell line in vitro and the action of carotenoids may be worked through different pathways.