The expression of corticotropin-releasing hormone in melanoma.

We previously demonstrated that advanced melanoma cells express high amounts of proopiomelanocortin (POMC) that correlate with tumor progression. We now investigated whether the high expression of POMC derives from increased expression of corticotropin-releasing hormone (CRH) and the possible role of CRH as a melanoma growth factor. Forty-five cases of melanoma [25 primary malignant melanoma; 20 metastatic melanoma (MetM)] were immunohistochemically analysed for coexpression of POMC and CRH peptides. The ability of CRH to induce POMC expression in cultured melanoma cells was examined using CRH and a CRH antagonist. In CRH positive melanomas, seven out of nine cases (78%) of primary melanoma, and 7 out of 12 cases (58%) of MetM showed colocalization of CRH and POMC peptides. CRH induced POMC mRNA expression, an effect that was inhibited by a CRH antagonist. These results provide evidence for the existence of the CRH/POMC axis in pigmented lesions.