EXPRESSION OF NM23 IN HUMAN-MELANOMA PROGRESSION AND METASTASIS

NM23 is a putative metastasis-suppressor gene for some human cancers. Here we have studied NM23 expression during melanoma progression using Northern blotting and immunocytochemistry. There was no significant d ifference in the average amounts of NM23 mRNA between cell lines deriv ed from metastatic and primary melanomas. The level of NM23 mRNA was a lso determined for three pairs of poorly metastatic parental (P) and t heir highly metastatic variant (M) cell lines; the ratios for M/P were 1.2, 0.98 and 0.80. Next we used immunocytochemistry to study NM23 pr otein in normal skin, benign naevi and primary and metastatic melanoma s. Melanocytes in all normal skin and benign samples were positive for NM23; however most primary melanomas (7/11) were not stained by the a ntibody. All metastatic melanoma samples (5/5) were positively stained . Findings were similar with an antiserum reactive with both forms of NM23 (H1 and H2), and with an antibody specific for NM23-H1. No relati onship was apparent between NM23 immunoreactivity in primary tumours a nd their aggressiveness or prognosis. Hence, in contrast to the situat ion described for murine melanoma, the amount of NM23 mRNA or protein in human melanoma did not correlate inversely with metastasis.