NUCLEOSIDE DIPHOSPHATE KINASE NM23 EXPRESSION IN BREAST-CANCER - LACK OF CORRELATION WITH LYMPH-NODE METASTASIS

The product of the nm23-H1 gene, reported to be a metastatic suppressor gene, was recently identified as the nucleoside diphosphate (NDP) kinase A, and was found to be over-expressed in several types of malignant tumors as compared with normal tissues. In order to determine whether NDP-kinase expression serves as a marker for metastatic potential and whether hyperproliferation of neoplastic cells would correlate with expression, we analyzed NDP-kinase levels and activity by immunohistochemical staining and by an enzymatic assay in 13 benign and 98 malignant breast-tissue specimens. Our results confirm that NDP-kinase expression increases in malignant cells of breast carcinomas, but cannot be considered as a biological marker of metastatic dissemination. No correlation was found between NDP-kinase activity and S phase, taken as an index of cell proliferation. Moreover, no correlation was observed between NDP-kinase activity and tumor size, histoprognostic index, estrogen receptors or progesterone receptors. The mechanism of over-expression of NDP in malignant cells and its role in tumor progression remain to be determined.