IDENTIFICATION BY DIFFERENTIAL DISPLAY OF ANNEXIN-VI, A GENE DIFFERENTIALLY EXPRESSED DURING MELANOMA PROGRESSION

To identify genes involved in the melanocyte to malignant melanoma con version, we have applied differential display to the comparison of syn geneic murine B16F10 (metastatic melanoma) and Melan-a-immortalized me lanocyte cell lines, Approximately 7000 bands were analyzed, revealing approximately 80 to be differentially displayed. Reverse Northern blo tting and subsequent Northern blotting confirmed the reproducible diff erential expression of four transcripts. Three B16F10-specific bands e ncode novel genes or partially sequenced cDNAs of unknown function. On e Melan-a-specific band was found to be identical to the 3' end region of the mouse Annexin VI mRNA and shown to have a reduced message expr ession in B16F10 relative to Melan-a. Differential expression was conf irmed at the protein level with Western blotting using a rabbit polycl onal antiserum. Immunohistochemistry of human melanoma specimens with this antiserum revealed a decrease or loss of Annexin VI expression as melanomas progressed from a benign to a more malignant phenotype. Our results provide further evidence for a potential role of Annexin VI i n tumor suppression.