Chemopreventive effects of Rubus coreanus Miquel on prostate cancer.

The growing incidence of prostate cancer and the traditional use of Rubus coreanus Miquel (RCM) for prostate health led us to compare RCM extracts and to test their efficacy in inhibiting the growth of prostate cancer cells differing in androgen dependency. Ethanol extracts of unripe RCM (EUR) were more effective in reducing cell viability than water extracts or ripe RCM. EUR-induced growth inhibition, as indicated by significant reductions in numbers of proliferating cells and decreases in the protein levels of proliferating cell nuclear antigen (PCNA), cyclin D1 and CDK4, was greater in the androgen-dependent LNCaP cells than in the androgen-independent DU145 cells. EUR also induced mitochondrial-mediated apoptosis in prostate cancer cells by reducing Bcl-2 and Bcl-(X)L levels, but increased Bax levels. Nevertheless, the LNCaP cells were more sensitive to EUR-induced apoptosis and displayed sub-G1 and late apoptotic cell populations, whereas the DU145 cells did not. Our findings suggest that EUR suppresses the growth of prostate cancer cells by anti-proliferative and/or pro-apoptotic effects, and that these effects are stronger in androgen-dependent cells.