Evaluation of the expressions pattern of miR-10b, 21, 200c, 373 and 520c to find the correlation between epithelial-to-mesenchymal transition and melanoma stem cell potential in isolated cancer stem cells.

: Small non-coding RNAs named microRNAs (miRNAs) modulate some functions and signaling pathways in skin epithelial cells and melanocytes. They also function as oncogenes or tumor suppressors in malignancies and tumor metastasis. We investigated the expression patterns of miRNAs, including miR-10b, 21, 200c, 373 and 520c, which regulate epithelial-to-mesenchymal transition (EMT) and metastasis in isolated cancer stem cells (CSCs) and non- CSCs. Six melanoma cell lines were tested for the expressions of stem cell markers. Melanoma stem cells were enriched via fluorescence-activated cell sorting (FACS) using the CD133 cell surface marker or spheroid culture. They were then characterized based on colony and sphere formation, and the expressions of stemness and EMT regulator genes and their invasion potential were assessed using real-time qRT-PCR and invasion assay. Our results indicate that cells enriched via sphere formation expressed all the stemness-related genes and had an enhanced number of colonies, spheres and invaded cells compared to cells enriched using the CD133 cell surface marker. Moreover, miRNAs controlling metastasis increased in the melanospheres. This may be related to the involvement of CSCs in the metastatic process. However, this must be further confirmed through the application of knockdown experiments. The results show that sphere formation is a useful method for enriching melanoma stem cells. Melanospheres were found to upregulate miR-10b, 21, 200c, 373 and 520c, so we suggest that they may control both metastasis and stemness potential.