Abstract A12: Increased expression of STEAP1 gene as potential poor prognostic marker of prostate cancer

Abstract

A12 Prostate cancer is a public health problem due to its high incidence and mortality rates. STEAP1 and STEAP2 genes (six-transmembrane epithelial antigen of prostate 1 e 2) are mapped at 7q21.13 region, where we have previously described genomic gains by array comparative genomic hybridization (aCGH) of primary prostate adenocarcinomas (PCa). The involvement of these genes in PCa development and progression remains to be clarified. They express tumor antigens and are putative molecular markers. The objective of this study was to determine STEAP1 and STEAP2 genes expressions by real time quantitative PCR (qPCR) and STEAP1protein expression by immunohistochemistry in samples of PCa, in surrounding non-neoplastic tissues, and in prostate nodular hyperplasia. Patients were classified in three groups of recurrence risk depending on serum PSA levels, Gleason scores, and tumor stages for qPCR analysis. Increased STEAP1 and STEAP2 genes expressions were registered in 16% and 21% of the 55 samples, respectively; both genes presented simultaneous increased expression in three high-risk cases. Similar pattern of expression of these genes were detected in the majority of PCa and in surrounding non-neoplastic tissues. Compared to surrounding non-neoplastic tissues, there was significant increase of STEAP1 expression in tumor samples with Gleason scores ≥ 7(4+3) and in cases with vascular invasion. There was a trend for increased STEAP1 expression in high-risk cases when compared to the moderate-risk group. In accordance with gene expression, higher levels of STEAP1 protein were expressed in PCa compared to surrounding non-neoplastic tissues. Our data suggest that increased STEAP1 expression is related to clinical and pathological parameters of PCa patients and it use as a poor prognostic marker should be considered. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A12.