EXPRESSION OF GP185(HER-2) IN HUMAN CUTANEOUS MELANOMA - IMPLICATIONSFOR EXPERIMENTAL IMMUNOTHERAPEUTICS

Over-expression of the HER-2 oncogene correlates with poor prognosis i n breast and ovarian carcinomas. Using a sensitive immunohistochemical assay, we have detected row levers of gp185(HER-2) in intradermal nev i (78%) and in primary (75%) and metastatic melanomas (58%). The HER-2 gene product expressed by cultured melanoma cells had the expected mo lecular weight, but no levels of tyrosine phosphorylation could be det ected. Consistently, we were unable to inhibit in vitro growth of mela noma cells with an anti-gp185(HER-2) MAb, in conditions in which the g rowth of SKBr-3 breast-carcinoma cells was severely impaired. However, immunotoxins to gp185(HER-2) were able to kill gp185(HER-2)-positive melanoma cells. These data indicate that low levels of gp185(HER-2) ar e expressed by the melanocyte lineage, with no correlation with transf ormation or tumor progression. Nevertheless, gp185(HER-2) appears a Su itable target for immunotherapy of cutaneous melanoma. (C) 1994 Wiley- Liss, Inc.