Analysis of protooncogene c-erbB-2 in benign and malignant human prostate

In this report, we characterized the c-erbB-2 gene and its product in prostatic cancer cells. Three prostatic cancer cell lines (PC3, DU145 and TSU-Pr1), one primary prostatic cancer and four benign prostatic hyperplasias (BPH) were studied. In reverse transcribed polymerase chain reaction, c-erbB-2 mRNA was demonstrated in all three cell lines and prostatic cancer tissues as well as BPH. The c-erbB-2 protein was expressed higher in prostatic cancer cells and tissues as compared with benign tissue by enzyme immunoassay, but it was not statistically significant. Immunohistochemical study, with the monoclonal antibody SV2-61gamma that recognizes the extracellular domain of c-erbB-2, showed that all the prostatic tissues and cells had reactivity. Antigenicity was mainly in the cytoplasm. Analysis of genomic DNA failed to disclose gene amplifications or rearrangements of c-erbB-2 in both prostatic cancer and BPH. The sequence of amplified c-erbB-2, which corresponds to transmembrane domain, disclosed wild type in all prostatic cancer cells. These results demonstrate that although the number is limited, c-erbB-2 gene and protein are expressed in prostatic cancers and benign prostates. In the previous studies on c-erbB-2 expression in prostatic tissue, mainly conducted by immunohistochemistry, its frequency varies among each study, ranging from less than 0% to 100%. Therefore, to evaluate the c-erbB-2 in prostatic tissue precisely, it is also necessary to detect mRNA of c-erbB-2 as demonstrated in our study.