A steroid fraction of chloroform extract from bee pollen of Brassica campestris induces apoptosis in human prostate cancer PC-3 cells.

Bee pollen of Brassica campestris L. is widely used in China as a natural food supplement and an herbal medicine in strengthening the body's resistance against diseases including cancer. The present study was carried out to investigate the effect of a steroid fraction of chloroform extract from bee pollen of Brassica campestris L. on human cancer cell viability. Our studies show that among nine cancer cell lines of different origin (PC-3, LNCaP, MCF-7, Hela, BEL-7402, BCG-823, KB, A549 and HO8910), this steroid fraction displayed the strongest cytotoxicity in human prostate cancer PC-3 cells. The mode of cell death appeared to be apoptosis in PC-3 cells, as shown by flow-cytometric analysis and fluorescence microscopes. Caspase-3 activity was obviously enhanced after the cells were treated with the fraction. A time-dependent decrease in the expression of anti-apoptotic protein Bcl-2 was also observed by Western blot analysis. It is suggested that the steroid fraction could induce cytotoxicity in prostate cancer PC-3 cells by triggering apoptosis. The studies indicate that the steroid fraction of chloroform extract from bee pollen of Brassica campestris L. may be a promising candidate for the treatment of advanced prostate cancer.