Abstract 1175: PCR array-based gene expression profiling identifies CD70 and CD74 as molecular markers and potential therapeutic targets for human melanoma

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Melanoma is one of the most prevalent cancers. While early detection and surgical excision can cure melanoma, patients with advanced disseminated disease have a very poor prognosis due to its extremely aggressive growth characteristics and high resistance to chemotherapy and radiation. Improvement of our understanding of the mechanisms that lead to progression of metastatic melanoma, as well as development of novel therapeutic strategies are urgently required for patients. In our study, we applied PCR arrays and bioinformatics analysis to evaluate gene expression of metastatic melanoma cells and normal skin cells. We used the Human Inflammatory Cytokine and Receptors RT2 Profiler™ PCR Array to analyze the differential expression of genes in metastatic melanoma cell lines (A375) and primary normal epidermal melanocytes (NHEM), which are the precursor cell of melanoma. We found the 43 genes were highly expressed in A375 which were upregulated by more than 20 fold in comparison to NHEM. We next selected the top-ten differentially expressed genes (CD70, IL-1β, MGLL, SERPINA3, MDK, IL13RA2, CD74, VEGFA, CXCL1, and IL8), whose expression levels in A375 cells were > 250-fold higher than in the primary normal NHEM, for further validation. The results from our RT-PCR, immunoblot, immunocytochemistry (ICC) and tissue microarray (TMA) analysis showed that CD70, SERPINA3, IL13RA2 and CD74 genes were highly expressed at mRNA and protein levels in various melanoma cell lines and metastatic melanoma tumor tissues. A much lower level of expression of each gene was detected in normal human skin cell lines and normal skin tissues. These results thus demonstrated that the four genes identified by our PCR array are likely of molecular markers and should be pursued as therapeutic targets for melanoma treatment. To further verify their potentials as potential melanoma therapeutic targets, we also evaluated the effects of siRNAs targeting CD70 and CD74 genes and the monoclonal antibodies against CD70 and CD74 proteins for regulation of melanoma growth. Treatment with CD70 or CD74-specific siRNAs and also monoclonal antibodies dramatically inhibited cell growth in various melanoma cell lines, indicating that CD70 and CD74 are also attractive molecular targets in the treatment of human metastatic melanoma. Our findings have important implications in understanding the metastatic process of melanoma and discovering novel therapeutic strategies for melanoma treatment. The molecular markers and therapeutic targets developed in this study will have a direct and immediate translational application. If successful, our study will represent a significant advance in the diagnosis and treatment of melanoma. (This study was partially supported by the grant from the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation and the Melanoma SPORE grant from the NCI, P50, CA093459). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1175.