Expression of nm23‐Hl and nm23‐H2 Proteins in Prostate Carcinoma

The nm23 gene products/nucleoside diphosphate (NDP) kinase expression in prostate carcinomas and benign hyperplasias was evaluated immunohistochemically. Monoclonal antibodies against nm23‐H1 and nm23‐H2 proteins were prepared using the corresponding proteins fused with glutathione S‐transferase as immunogens. Of the 80 cases of nonmetastatic prostate carcinoma examined, 74% (59/80) and 60% (48/80) were immunoreactive for nm23‐H1 or nm23‐H2 protein, respectively. Negative staining for nm23‐H1 occurred in 83% of metastatic lesions, while 34% were negative for nm23‐H2. All primary tumors corresponding to the metastases examined showed positive immunostaining for nm23‐H1, indicating an inverse relationship between expression of this protein and metastatic status. nm23‐H2 protein was detected in 83% of primary tumors and its expression appeared to he significantly correlated to the degree of histological differentiation. In contrast, all cases of benign prostatic hyperplasia showed elevated levels of both nm23‐H1 and nm23‐H2 expression. These data suggest that the nm23/NDP kinase may play a role in suppressing the expression of malignant potential in prostate carcinomas.