EXPRESSION OF KAI1 IN PARAFFIN-EMBEDDED NORMAL, HYPERPLASTIC AND NEOPLASTIC PROSTATE AND PROSTATE CARCINOMA CELL-LINES

Expression of KAI1, a tumor metastasis suppressor gene, was studied wi th different fixatives in frozen and paraffin-embedded sections of hum an and rat prostate carcinoma cell lines and human prostate lesions by immunohistochemistry. Immunoreactivity of the membrane antigen in cel l lines was associated with known expression levels in these lines and the fixative used. Formalin and paraformaldehyde helped maintain the immunoreactivity of cells. in human prostate, frozen sections revealed diffuse reactivity of the antigen in normal and neoplastic tissues wh ile paraffin-embedded tissues usually showed focal reactivity, althoug h more than 50% of cases with normal epithelium and adenocarcinomas we re reactive. in some cases, pretreatment with trypsin enhanced immunor eactivity. Benign prostatic hyperplasia (BPH) showed the most intense diffuse immunoreactivity, which suggested enhanced expression. Prostat ic intraepithelial neoplasia (PIN) also often expressed high levels of KAI1. Three of five metastases were reactive but two primaries and th eir metastases were not. Lymphocytes in primary carcinomas and lymphoc ytes and germinal center cells in lymph nodes were immunoreactive, whi le adjacent primary or metastatic prostate adenocarcinoma epithelium w as not immunoreactive. Although paraffin-embedded human tissues were n ot optimal for determining revels of expression of KAI1, they did show immunoreactivity that could have prognostic value and showed the spec ific cytoplasmic localization of the protein in cells.