Abstract 3316: The stem cell marker nestin inhibits growth and invasion of malignant melanoma

Abstract

Abstract BACKGROUND: Nestin, a class VI intermediate filament protein, was first described as a neural stem cell/progenitor cell marker. Nestin was detected in various neoplasms, and its expression level has relevance to the poor prognosis in some tumors, including malignant melanomas. Recently, nestin was reported as one of the cancer stem cell markers in melanomas. Furthermore, nestin is expressed in circulating tumor cells of melanoma patients, and its expression was found to be correlated with the prognosis. These reports indicate that nestin plays important roles in melanomas, and has the possibility of becoming a therapeutic target in melanomas. In the present study, we used a silencing strategy of nestin to clarify the effectiveness of nestin-targeting therapy in malignant melanomas. METHODS: We constructed a plasmid vector of short hairpin RNA (shRNA) tageting nestin and scramble vector as a negative control. Human malignant melanoma cells, A375 cells, were stably transfected with these vectors. Using nestin-shRNA-transfected cells, scramble vector-transfected cells, and wild-type cells, we analyzed cell growth, sphere formation, and invasion in vitro. Activation of the AKT/MAPK pathway was analyzed using a phosphorylated protein array. To determine the effect of nestin-knockdown in vivo, we performed tail vein injection of transfected and wild-type A375 cells into nude mice, and analyzed the metastatic tumor formation in 5 weeks. RESULTS: Nestin shRNA transfection suppressed cell growth, invasion, and sphere formation of A375 cells in vitro. In the protein array, the suppression of nestin decreased the phosphorylation of AKT and p53. The incidence of liver metastasis in nude mice was 100% in wild-type cell-injected mice, 75% in scramble vector-transfected cell-injected mice, and 16.7% in nestin-shRNA-transfected cell-injected mice. CONCLUSION: These findings suggest that nestin regulates cell growth, stemness, invasion, and metastasis of melanomas, in part, by alterling the phosphorylation of the MAPK/AKT pathway. Nestin may be a candidate therapeutic target in malignant melanomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3316. doi:1538-7445.AM2012-3316