Identification by differential display of annexin-VI, a gene differentially expressed during melanoma progression

To identify genes involved in the melanocyte to malignant melanoma conversion, we have applied differential display to the comparison of syngeneic murine B16F10 (metastatic melanoma) and Melan-a-immortalized melanocyte cell lines. Approximately 7000 bands were analyzed, revealing approximately 80 to be differentially displayed. Reverse Northern blotting and subsequent Northern blotting confirmed the reproducible differential expression of four transcripts. Three B16F10-specific bands encode novel genes or partially sequenced cDNAs of unknown function. One 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 expression in B16F10 relative to Melan-a. Differential expression was confirmed at the protein level with Western blotting using a rabbit polyclonal 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 in tumor suppression.