Small molecule inhibitor of tyrosine kinase activity, compound SU11274, was reported to have antitumorigenic and antimetastatic effect in melanoma.,In this study, we evaluated, whether similar effect could be achieved also in other melanoma cells including highly tumorigenic and hypermetastatic variant.,The effect of SU11274 was evaluated in adherent and non-adherent melanosphere cultures of human melanoma cells M14, M4Beu, A375 and EGFP-A375/Rel3.,Tumorigenicity of SU11274-treated cells was tested by limiting dilution assay in xenograft model in vivo.,Here we show that SU11274 enriched for melanoma-initiating cells in vivo.,SU11274 substantially decreased number of cells in adherent and spheroid cultures, but increased their tumorigenic potential as determined by higher frequency of tumor-initiating cells in vivo.,SU11274 treatment was not associated with any significant alteration in the expression of stem cell markers, but the inhibitor stimulated higher level of pluripotent markers.,SU11274-treated melanoma cells exhibited higher ATP content and lactate release indicative of increased glycolysis.,Our data suggest that the SU11274 altered bioenergetic state of the cells.,Indeed, pharmacological intervention with a glycolytic inhibitor dichloroacetate significantly reduced SU11274-promoted increase in melanoma-initiating cells and decreased their tumorigenicity.,Our data suggest critical role of glycolysis regulation in melanoma-initiating cells.,Moreover, these data unravel substantial plasticity of melanoma cells and their adoptive mechanisms, which result in ambivalent response to therapeutic targeting.
MicroRNAs (miRNAs) are a group endogenous small non-coding RNAs that inhibit protein translation through binding to specific target mRNAs.,Recent studies have demonstrated that miRNAs are implicated in the development of cancer.,However, the role of miR-144 in uveal melanoma metastasis remains largely unknown.,MiR-144 was downregulated in both uveal melanoma cells and tissues.,Transfection of miR-144 mimic into uveal melanoma cells led to a decrease in cell growth and invasion.,After identification of two putative miR-144 binding sites within the 3' UTR of the human c-Met mRNA, miR-144 was proved to inhibit the luciferase activity inMUM-2B cells with a luciferase reporter construct containing the binding sites.,In addition, the expression of c-Met protein was inhibited by miR-144.,Furthermore, c-Met-mediated cell proliferation and invasion were inhibited by restoration of miR-144 in uveal melanoma cells.,In conclusion, miR-144 acts as a tumor suppressor in uveal melanoma, through inhibiting cell proliferation and migration. miR-144 might serve as a potential therapeutic target in uveal melanoma patients.