The Role And Mechanism Of MiR-655in Biological Behavior Of Melanoma

Purpose:MicroRNAs (miRNAs), a class of small non-coding RNAs, that are involoved in the regulationg of multiple cellular processes. Abnormalities in miRNA activity also contribute to the development and progression of cancer diseases. Aberrant expression of miR-655has been found in some types of cancer and cell lines, but it is still unknown about its expression and effect on melanoma cell lines.Methods:The level of miR-655expression in human pigmented nevi samples and melanoma cell lines was quantified by quantitative real-time PCR (qRT-PCR), the student’s t test was used in the comparison of expression levels. Up-regualtion of miR-655by transfecting miR-655mimics was carried out in melanoma celll lines to evaluate the effects of miR-655expression on the cell proliferation and colony formation. Flow cytometry assay was used to assess its effect on cell apoptosis, and the invasiveness of melanoma cells was evaluating by trans well assays. The effect of transfecting miRNA mimics and ZEB1siRNA on ZEB1expression were detected by qRT-PCR and western blot, ZEB1expression was evaluated by a qRT-PCR assay in pigmented nevi tissues and melanoma cells. Subsequent transfectiong ZEB1siRNA was used to assess the effect of ZEB1on colony formation, cell proliferation, apoptosis and cell invasion. Results:The expression level of miR-655in3cell lines was significantly lower than human pigmented nevi. Cell proliferation and invasion were significantly inhibited for melanoma cells transfected with miR-655mimics, and overexpression of miR-655also induced apoptosis. Further qRT-PCR and western blot assays revealed that miR-655mimics reduced the expression of ZEB1in melanoma cells. The expression of ZEB1was lower than human pigmented nevi tissues, and it was negatively correlated with miR-655expression levels. Down-reguation of ZEB1with RNAi inhibited cell proliferation and invasion, also induced apoptosis of melanom cells. These biological effects were consistent with the effects of miR-655in up-regulation.Conclusions:Up-regulation of miR-655can inhibit melanoma cells proliferation and invasion by decreasing ZEB1expression in mRNA and protein levels, also can induce apoptosis, and play an negative regulatory role in the development and progression of melanoma. Our finding suggest that ZEB1may act as a major target of miR-655. Regulation the expression of miR-655may promote the development of novel targeted therapies for melanoma.