Caspase-3 protease activation during the process of genistein-induced apoptosis in TM4 testicular cells

The role of caspase-3 (CPP32) protease in the molecular pathways of genistein-induced cell death in TM4 cells was investigated. Fluorescence microscopy with Hoechst-33258-PI nuclear stain was used to distinguish between apoptosis and necrosis pathways of cell death. The viability of the test cells was assessed with both the trypan blue exclusion and MTT tetrazolium (3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenylte tralzolium bromide, 2.5 mg/mL) assays. Caspase-5 enzymatic activity was determined using CasPASE Apoptosis Assay Kit. The overall results from all the data demonstrated that: i) genistein exerts dose- and time-dependent effects on TM4 testis cells; ii) apoptosis is induced by lower concentrations of genistein and necrosis induced by higher concentrations of genistein; iii) genistein induced activation caspase-3 enzymatic activity; iv) genistein-induction of apoptosis and necrosis was significantly inhibited by the caspase-3 inhibitor, z-DEV-FMK; v) sodium azide induced necrosis without activation of CPP32 enzymatic activity, and induction of apoptosis; and vi) genistein-induced apoptosis was associated with activation of CPP32 enzymatic activity in the cells. The overall results indicate a strong evidence of caspase3 (CPP332) mediation in the molecular pathways of genistein-induced apoptosis in testicular cells. Apoptosis is the physiologoically programmed cell death in which intrinsic mechanisms participate in the death of the cell, in contrast to necrosis, which induces inflammatory response in the affected cell. The fact that the chemopreventive role of several cancer drugs is due to induction of apoptosis augments the biotherapeutic potential of genistein for the treatment of malignant diseases including prostate and testicular cancers. It is therefore inevitable that identification of the apoptotic pathways and the points at which regulation occurs could be instrumental in the design of genistein biotherapy for such diseases. (C) 2000 Editions scientifiques et medicales Elsevier SAS.