Zonal variation of apoptosis and proliferation in the normal prostate and in benign prostatic hyperplasia.

OBJECTIVE: To determine whether benign prostatic hyperplasia (BPH) results from an imbalance between cell proliferation and apoptosis, and the extent to which the rates of these opposing processes are altered with the expression of the anti-death oncoprotein bcl-2. MATERIALS AND METHODS: Ten prostate glands from normal men (mean age 43.7 years) were sampled according to McNeal's zonal anatomy, in addition to 30 prostate adenomas obtained from prostatectomy specimens from symptomatic patients (mean age 61.4 years). Tissue samples were fixed in formalin and embedded in paraffin. Proliferation and bcl-2 expression were assessed by immunostaining using Mib-1 and anti-bcl-2 antibodies, while apoptotic bodies were specifically stained using in situ nick translation. The percentage of positive cells was determined by optical microscopy. RESULTS: In normal epithelium, the rates of proliferation and apoptosis were increased in the peripheral zone (Mib-1 1.7%, apoptotic bodies 3.3%) compared with the central (0.2% vs 1.4%) and transition (0.1% vs 1.8%) zones. Proliferation was significantly greater in BPH than in normal prostate tissue (3.7%), contrasting with a stable rate of apoptosis (1.4%). In the normal prostate, bcl-2 was expressed by glandular and basal cells in the peripheral zone. In the central zone, bcl-2 was overexpressed in basal cells and in most glandular cells of the intraluminal ridges. Bcl-2 expression in the transition zone was limited to dispersed basal cells. In BPH, bcl-2 was strongly expressed by basal cells in mature glandular formations and in most cells of young small nodules. CONCLUSION: BPH may result from both an increase of proliferation within the basal compartment and a failure of apoptosis to counterbalance basal cell proliferation. Increased expression of bcl-2 may participate in this process by blocking apoptosis.

Expression of human chorionic gonadotropin beta subunit genes in superficial and invasive bladder carcinomas.

Increased serum levels of human chorionic gonadotropin beta subunit (hCG beta) were described previously in patients with bladder cancer. To obtain insight into such production of hCG beta, the expression of hCG beta 7, 8, 5, and 3 genes in bladder carcinomas and normal urothelia was investigated by reverse transcription PCR. Surprisingly, hCG beta mRNAs were detected in both normal urothelial and carcinomatous cells. However, tumor progression was characterized by different patterns of transcription of the hCG beta genes; the beta 7 gene was the only gene transcribed in normal urothelia and Ta tumors included in this study, whereas in addition to beta 7, genes beta 5, 8, and 3 were transcribed in T1 to T4 tumors. Moreover, transcription levels of the latter three genes increased with the stage of the disease. These observations showed that dramatic modifications in the expression of hCG beta genes accompany progression of bladder carcinomas.