Loss of heterozygosity of gene THW is frequently found in melanoma metastases.

We have recently described a new member of the PMP22/gas3 family of plasma membrane proteins referred to as THW. This gene is located on chromosome 6q and preliminary data have indicated a possible tumor suppressor gene function. We have therefore investigated LOH for gene THW in a panel of cancer cell lines and in a series of primary human melanomas as well as in melanoma metastases. We have detected LOH for gene THW in cell lines derived from melanoma, breast, pancreas, cervical, prostate and colon carcinoma with different prevalence, whereas the ovary carcinoma cell lines (n = 3) were negative. For melanomas we found a prevalence of LOH for gene THW of 10-20% in primary tumors, whereas in melanoma metastases we found a score of 50%. These data and the fact that the recently identified murine homologue PERP of gene THW mediates cell death in murine fibroblasts support the possible tumor suppressor function of gene THW.