Endothelin-3 (ET-3) is aberrantly expressed in both metastatic melanoma tissues and cultured melanoma cells.Our previous work showed that ET-3 could promote survival of metastatic melanoma cells via its altered expression.In this study,we investigated the mechanisms responsible for these gene-induced phenotypes in melanoma cells.An ET-3 gene sequence-specific shRNA vector pLVTHM-ET3-RNAi was constructed and transfected into human malignant melanoma cells A375 and MMRU,and the resultant molecular events and cellular changes were examined.As compared with the empty-vector group,cell proliferation was slowed down,and the growth inhibition rates were 38.9% in A375 cells and 38.4% in MMRU cells after transfection.In addition,cell invasion capability was also inhibited,with a reduction of 62.2% in A375 cells and 54.3% in MMRU cells.The percentage of apoptotic cells was found to increase.Meanwhile,in both cell lines,secreted protein acidic and rich in cysteine (SPARC) levels were down-regulated together with inhibition of its upstream signaling molecule,NF-κB.Thus,the current results suggested that down-regulated expression of ET3 attenuates the malignant behaviors of human melanoma cells partially by decreasing the expression of SPARC and NF-κB.
