Immunohistochemical expression of caspase-1 and -9, uncleaved caspase-3 and -6, cleaved caspase-3 and -6 as well as Bcl-2 in benign epithelium and cancer of the prostate.

Activation of caspases is an essential prerequisite for induction of apoptosis. In many tumors caspases are down-regulated, while anti-apoptotic Bcl-2 is up-regulated. To elucidate their putative role in prostate cancer (PCa) we determined the expression of different caspases and Bcl-2 in benign prostate epithelium (BPE) and PCa. Paraffin-embedded prostate whole mounts were cut (4 μm) and investigated immunohistochemically using monoclonal antibodies against caspase-1 and -9, uncleaved caspase-3 and -6, cleaved caspase-3 and -6, and Bcl-2. In BPE all caspases were localized to the cytoplasm of glandular cells. In PCa we found a statistically significant reduction in cleaved caspase-3 and -6 compared to the levels in BPE. The Bcl-2 protein was detected in the basal compartment of epithelial gland cells, but no immunostaining was noted in PCa. The decreased immunoreactivity of activated caspases probably indicates an alteration in post-translational cleavage that may play an important role during PCa progression.