Identification of melanoma inhibitory activity and other differentially expressed messenger RNAs in human melanoma cell lines with different metastatic capacity by messenger RNA differential display.

The differential display technique was used to identify mRNAs differentially expressed in human melanoma cell lines with different metastatic capacity. We report the isolation of nine different clones, of which four were uniquely expressed in the highly metastatic human melanoma cell line MV3, whereas the other five clones were uniquely expressed in the poorly metastatic human melanoma cell line 530. The differences in expression identified by differential mRNA display were confirmed by Northern blot analyses. DNA sequencing followed by computer search analyses indicated that of the nine differentially expressed clones, five represented novel gene products. The other four were histocompatibility antigen HLA-DR, laminin B2, melanoma inhibitory activity (MIA), and tissue inhibitor of metalloproteinases 3. MIA was also identified in RNA from human melanoma metastasis lesions in a comparison by differential display with pooled human nevi. Northern blot analysis confirmed MIA mRNA expression in nonmetastasizing melanoma cell lines and in melanoma metastasis lesions, while expression was absent in highly metastasizing cell lines and pretumor stages. In the 11 metastasis lesions examined, MIA mRNA expression was apparently inversely correlated with pigmentation.