Effect of a Fibrinolytic Enzyme (BK-17) from Bacillus subtilis on Apoptosis Induction in AGS and T24 Human Carcinoma Cells

To investigate the effects of a fibrinolytic enzyme, BK-17, on the growth of human cancer cells, we performed various biochemical experiments, including cell proliferation and viability, and investigated subsequent morphological changes and apoptosis induction. BK-17 treatment of AGS human gastric and T24 human bladder carcinoma cells decreased the viability and the proliferation of the cells in a concentration-dependent manner. Microscopic studies indicated that the antiproliferative effects of the BK-17 treatment were associated with morphological changes, such as membrane shrinking, cell rounding up, and the formation of apoptotic bodies, indicating that BK-17 induced apoptosis in the cell lines. Of note, RT-PCR and Western blotting data indicated that the BK-17 treatment induced the down-regulation of antiapoptotic Bcl-2 members, Bcl-2 and , and the up-regulation of proapoptotic Bax members, Bax and Bad, in the AGS cells. BK-17-induced apoptosis of AGS cells was involved in the proteolytic activation of caspase-3, caspase-8, and caspase-9. Taken together, these findings suggest that BK-17 is associated with the induction of apoptotic cell death.