Nm23 and breast cancer metastasis

Summary The majority of breast cancer patients succumb to metastatic disease. We summarize published and recent research concerning thenm23 gene in breast cancer metastasis. In a murine developmental study, nm23 expression increased with the functional differentiation of the mammary gland in nulliparous and pregnant animals. In human breast cancer, five studies have now demonstrated a significant association between reduced nm23 expression, at the RNA or protein levels, and aggressive tumor behavior. Nm23-negative tumor cells have been observed in comedo ductal carcinoma in situ lesions in two independent studies, indicating that decreases innm23 expression begin prior to actual histologically identifiable invasion. Transfection studies, in which humannm23-H1 cDNA was expressed in the metastatic human MDA-MB-435 breast carcinoma cell line, indicate thatnm23-H1 suppresses in vivo metastatic potential by 50-90%. Finally, our data in melanoma and breast carcinoma transfection systems suggest that the biochemical mechanism of nm23 suppressive activity is likely not due to its nucleoside diphosphate kinase activity, association with GAP proteins, or secretion from cells.Supported by an educational grant from CIBA-GEIGY Corp., at the San Antonio Breast Cancer Symposium, Dec. 8, 1992.