Androgen plays a critical role in the development and progression of prostate cancer. However, the regulatory role of androgen in the autophagic process and the function of the increased autophagosomes following androgen deprivation remain poorly understood. We found that autophagosomes, which were induced upon serum deprivation in LNCaP cells, can be significantly suppressed by dihydrotestosterone (DHT). Pharmacological inhibition of autophagy by 3-methyladenine led to increased apoptosis of LNCaP cells in serum-free medium compared to the medium with DHT or serum. Additionally, depletion of Beclin 1 to inhibit autophagy by small interfering RNA resulted in a slower proliferation of LNCaP cells in the medium depleted of serum than in the medium with DHT. Altogether, these findings suggested that LNCaP cells can resort to the autophagic pathway to survive under androgen deprivation conditions, which can be a novel mechanism involved in the transition of prostate cancer cells from an androgen-dependent to an androgen-independent cell type.

Abstract. Prostate cancer (PCa) is common in Western populations and the second leading cause of cancer-related mortality among males in North America, with an increasing morbidity in China and other Asian countries. The aim of this study was to evaluate the protein expression of autophagy-related genes Beclin-1 and LC3 in patients with prostate cancer (PCa) and benign prostatic hyperplasia (BPH) and elucidate their association with p53 and Bcl-2. The total protein of 34 PCa and 50 BPH samples was extracted and the expression of Beclin-1 and LC3 was analyzed by western blotting assay. Subsequently, a total of 96 paraffin-embedded BPH tissue samples was subdivided into 2 groups, one group in which patients had received 5α-reductase inhibitor, due to its effect of androgen ablation, and the control group, in which patients had not received the 5α-reductase inhibitor. The samples were randomly collected and examined using immunohistochemical (IHC) analysis. The western blot analysis demonstrated that Beclin-l and LC3 expression was higher in BPH tissues compared to PCa tissues (P<0.001). There was no statistically significant difference between PCas of different Gleason scores (P>0.05). The result of IHC revealed that Beclin-l and LC3 expression in the group of patients who had received the 5α-reductase inhibitor was significantly higher compared to that in the control group; however, the expression of Bcl-2 and p53 was lower (P<0.05). Beclin-1 expression exhibited a negative correlation with Bcl-2 (r=-0.402, P<0.001), whereas LC3 expression exhibited a positive correlation with Beclin-1 (r=0.345, P=0.001) and a negative correlation with Bcl-2 (r=-0.216, P=0.035). It was suggested that autophagy-related genes Beclin-l and LC3 may be involved in the development and progression of PCa. In addition, the expression of these genes was higher in patients with BPH who had received a 5α-reductase inhibitor, due to androgen reduction. As a result, the induced autophagy may reduce the risk of PCa.

Abbreviations & Acronyms 3-MA = 3-methyladenine 5-ARI = 5-α reductase inhibitor AD = androgen deprivation medium BPH = benign prostatic hyperplasia CM = complete medium DAPI = 4, 6-diamidino-2-phenylindole Objective: 5-α Reductase inhibitor can reduce the volume of benign prostatic hyperplasia by lowering benign prostatic hyperplasia level and consequently inducing epithelial cells apoptosis. The present study investigated whether autophagy and apoptosis of benign prostatic hyperplasia epithelial cells are influenced by low benign prostatic hyperplasia levels. Methods: PWR-1E prostate epithelial cells transfected with GFP-LC3 plasmid were subjected to androgen deprivation conditions. Then the autophagic puncta were evaluated by fluorescence microscopy, and the cellular apoptosis rate was detected by 4, 6-diamidino-2-phenylindole staining after blocking of autophagic process by 3-methyladenine. Furthermore, autophagy status was also determined in hyperplasia prostate tissues from 5-α reductase inhibitor-treated patients by immunohistochemistry. Results: In the androgen deprivation medium, autophagic punta increased markedly in PWR-1E cells, and blockage of autophagy by 3-methyladenine significantly promoted PWR-1E cells' apoptosis rate. In vivo, the expression of LC3 protein (an important autophagic marker) in hyperplasia prostate tissue significantly increased after 5-α reductase inhibitor treatment. Meanwhile, the prostate-specific antigen, as an inner control, decreased. Conclusion: 5-α Reductase inhibitor treatment increases autophagy and possibly decreases the apoptosis of prostate epithelial cells.