Activation of caspases-3, -6, and -9 during finasteride treatment of benign prostatic hyperplasia.
Benign prostatic hyperplasia (BPH) results from an increase in both epithelial and stromal compartments of the human prostate. Although inhibitors of 5alpha-reductase such as finasteride have been shown to reduce the size of BPH tissues by inducing apoptosis, their mechanisms of action still remain unknown. The present study supports that such a process triggered by finasteride is caspase dependent with a possible involvement of two effector caspases (caspase-3 and 6) and two initiator caspases (caspase-8 and 9). Indeed, by using tissues from patients affected by BPH and treated by finasteride (5 mg/d) for 2-3, 6-8, or 27-32 d, we observed that the 5alpha-reductase inhibitor induced apoptosis in epithelial cells (evaluated through cell number positive for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling) as early as 2-3 d of treatment, with a maximal activity (250-fold increase, P < 0.0001) at 6-8 d of treatment. However, after 27-32 d of treatment, the number of apoptotic cells was reduced and was close to control. Caspases-3, -6, -8, and -9 were immunolocalized to (basal and secretory) epithelial cells and to a lesser extent to stromal cells. Activated caspase-3 immunoexpression was restricted to epithelial secretory cells, and its immunostaining intensity appeared to be higher in BPH tissues from patients treated for 2-3 or 6-8 d. Consistently, in Western blotting analyses, activated caspases-3 and -6 were detected as early as 2-3 d of treatment in BPH tissues, and their levels were increased after 6-8 d of treatment. In real time quantitative PCR experiments, caspase-3 and -6 mRNA levels were found to be unchanged after finasteride treatment. Activated caspase-8 was not detected in the different conditions tested, whereas activated caspase-9 protein levels were maximally enhanced after 2-3 d of finasteride treatment. In conclusion, we report here that finasteride treatment of BPH tissues induced a caspase-dependent apoptotic process restricted to epithelial cells by activating effector caspases-3 and -6 and exhibited a transient action because the apoptotic process was no longer observed after 27-32 d of treatment.
Bozec
Aline
A
Institut National de la Santé et de la Recherche Médicale U 407, Faculté de Médecine Lyon-Sud, BP 12, 69921 Oullins Cedex, France.
Ruffion
Alain
A
Decaussin
Myriam
M
Andre
Jean
J
Devonec
Marian
M
Benahmed
Mohamed
M
Mauduit
Claire
C
D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases / Q000032:analysis* / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018120:Finasteride / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011470:Prostatic Hyperplasia / Q000188:drug therapy* / Q000201:enzymology; D012333:RNA, Messenger / Q000032:analysis; D012189:Retrospective Studies
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D018120:Finasteride; C505407:CASP3 protein, human; C505514:CASP6 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases