Abstract
The present study investigated the molecular mechanism of apoptosis and autophagy in prostate epithelial cells under androgen deprivation (AD). BPH-1 cells were divided into four groups as follows: Control (Cont), AD, autophagy inhibition (AI) and AD + AI groups. Cells in the four groups were treated accordingly, and the level of apoptosis was subsequently measured via flow cytometry. The expression of the microtubule-associated proteins 1A/1B light chain 3 (LC3), caspase-3, poly (ADP-ribose) polymerase 1 (PARP-1) and Beclin-1 proteins of BPH-1 cells was detected at different time points following culture in androgen-deprived medium. Western blotting revealed that the basal levels of the LC3-II protein were detected at 0 h. At 4 h, LC3-II was significantly increased compared with 0 h (P<0.05). Beginning at 20 h, the expression level of the LC3-II protein decreased significantly (P<0.05). Western blotting revealed that beginning at 24 h, the expression level of the PARP-1 protein decreased significantly (P<0.001) and the cleavage fragments of the PARP-1 protein appeared. These results further imply that autophagy serves a cell protective function by mutual inhibition with apoptosis in BPH-1 cells in the removal of androgen conditions. Furthermore, the fragments of the cleaved Beclin-1 protein appeared as 35 and 37 kDa bands. Flow cytometry analysis demonstrated that the rate of cell apoptosis in the AD, AI and AD + AI groups was significantly increased compared with the Cont group (P<0.01). Compared with the AD or the AI groups individually, the rate of cell apoptosis in the AD + AI group was significantly increased (P<0.001). These findings suggest that in the early stage of AD, autophagy has a compensatory function in the cell, whereas in the whole process, autophagy and apoptosis share a mutual antagonism. The Beclin-1-C protein fragment contributed positive feedback to the process of apoptosis, which may be a potential mechanism of AD therapy. Therefore, AD and AI exhibit a synergistic effect to further improve the level of apoptosis.