Molecular classification of cutaneous malignant melanoma by gene expression profiling

The most common human cancers are malignant neoplasms of the skin. Incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease. Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular or immunohistochemical marker defines subsets of this neoplasm. Accordingly, though melanoma is thought to present with different 'taxonomic' forms, these are considered part of a continuous spectrum rather than discrete entities. Here we report the discovery of a subset of melanomas identified by mathematical analysis of gene expression in a series of samples. Remarkably, many genes underlying the classification of this subset are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas. Global transcript analysis can identify unrecognized subtypes of cutaneous melanoma and predict experimentally verifiable phenotypic characteristics that may be of importance to disease progression

Comparison of the in vitro and in vivo effects of retinoids either alone or in combination with cisplatin and 5-fluorouracil on tumor development and metastasis of melanoma.

Purpose: Retinoids have previously been reported to inhibit proliferation of melanoma cell lines in vitro. However, the relative antimetastatic efficacy of various retinoids on melanoma in vivo is unknown. Therefore, we investigated the effects of different retinoids on the invasion and metastasis of murine melanoma B16-F10 cells in vitro and in vivo. Based on the findings, the antitumor effects of a selected retinoid either alone or in combination with cisplatin were also investigated in a preclinical mouse melanoma model. Methods: Cell proliferation and invasion analyses of murine melanoma B16-F10 cells were assessed in the presence of different retinoids, either alone or in combination with cisplatin (CDDP) or 5-fluorouracil (5-FU). Experimental lung metastasis assay was performed in this study to investigate the antimetastatic efficacy of retinoids. Additionally, a mouse melanoma model was used to assess the antitumor efficacy of a selected retinoid in combination with cisplatin. Results: Retinoids showed significant antiproliferation and anti-invasion effects on murine melanoma B16-F10 cells. Pretreatment with retinoids increased the sensitivity to CDDP but not to 5-FU in in-vitro. Moreover, the number of metastatic colonies formed in the lungs of mice injected intravenously with B16-F10 cells was significantly reduced by injecting the respective retinoid once a day for 10 days. Treatment with a combination of cisplatin and 13-cis-retinoic acid resulted in a significant reduction in primary tumor size and the number of lung metastatic nodules in melanoma-bearing mice. Conclusion: These results suggest that retinoids not only exhibit antimetastatic effect, but also enhance the antitumor activity of cisplatin in vivo