Gene Expression Signatures for Tumor Progression, Tumor Subtype, and Tumor Thickness in Laser-Microdissected Melanoma Tissues

PURPOSE: To better understand the molecular mechanisms of malignant melanoma progression and metastasis, gene expression profiling was done of primary melanomas and melanoma metastases. EXPERIMENTAL DESIGN: Tumor cell-specific gene expression in 19 primary melanomas and 22 melanoma metastases was analyzed using oligonucleotide microarrays after laser-capture microdissection of melanoma cells. Statistical analysis was done by random permutation analysis and support vector machines. Microarray data were further validated by immunohistochemistry and immunoblotting. RESULTS: Overall, 308 genes were identified that showed significant differential expression between primary melanomas and melanoma metastases (false discovery rate85% correct classifications for primary melanomas and metastases was reached. Further analysis showed that subtypes of primary melanomas displayed characteristic gene expression patterns, as do thin tumors (2.0 mm Breslow thickness). CONCLUSIONS: Taken together, this large-scale gene expression study of malignant melanoma identified molecular signatures related to metastasis, melanoma subtypes, and tumor thickness. These findings not only provide deeper insights into the pathogenesis of melanoma progression but may also guide future research on innovative treatments.