Overexpression of Bax sensitizes prostate cancer cells to TGF-beta induced apoptosis.

NRP-154 is a tumorigenic epithelial cell line derived from the preneoplastic dorsal-lateral prostate of rats. These cells are exquisitely sensitive to TGF-beta induced apoptosis. In contrast, we find that NRP-154 cells can sustain overexpression of exogenous Bax protein, which is different from non-tumor cells where Bax functions as a ubiquitous stimulator of apoptosis. NRP-154 cells stably overexpressing Bax show increased sensitivity to TGF-beta induced apoptosis. The degree of TGF-beta induced apoptosis displays high correlation with cleavage of Bax at the amino-terminus. Our data indicate that prostate cancer cells can host high levels of latent Bax which can be activated through post-translational modification.