Expression analysis of caspase-6, caspase-9 and BNIP3 in prostate cancer.

Aims: Altered regulation of cell death is a feature of human cancer. The aim of this study was to explore whether the expression of the proapoptotic proteins caspase-6, caspase-9, and Bcl-2/adenovirus E1B-19kDa-interacting protein3 (BNIP3) is altered in prostate cancers.

Methods: We analyzed the expression of caspase-6, caspase-9, and BNIP3 in 107 prostate adenocarcinoma tissues by immunohistochemistry using a tissue microarray (TMA) method.

Results: Normal glandular cells expressed caspase-6 and BNIP3 proteins in 10 (9.3%) and 9 (8.4%) prostate tissues, respectively. By contrast, the prostate cancers expressed caspase-6 and BNIP3 in 65 (60.7%) and 69 (64.5%) cases, respectively. Prostate intraepithelial neoplasia (PIN) showed caspase-6 and BNIP3 expression in 65% and 65% of cases, respectively. We observed caspase-9 expression in 40 (37.4%) normal, 8 (40%) PIN, and 45 (42.1%) cancer tissues. None of the expression of caspase-6, caspase-9 or BNIP3 was associated with pathological characteristics such as tumor size, patient age, Gleason score, or tumor stage.

Conclusion: Our data showed that prostate cancer and PIN cells display higher expression of the proapoptotic proteins caspase-6 and BNIP3 than normal cells. Neo-expression of these proteins from the PIN stage suggests that apoptosis deregulation might occur in the early stage of prostate carcinogenesis, and that altered expression of proapoptotic proteins may be a feature of prostate cancer.