Upregulated lncRNA CASC2 May Inhibit Malignant Melanoma Development Through Regulating miR-18a-5p/RUNX1

This study aimed to investigate the effect and underlying mechanism of lncRNA CASC2 in malignant melanoma (MM). Expression of CASC2 in MM tissues and cells was detected. A375 cells were transfected with pc-CASC2, si-CASC2, miR-18a-5p inhibitor, or corresponding controls, and then cell proliferation, migration, and invasion were detected using MTT assay, colony formation assay, and Transwell analysis, respectively. The relationship of miR-18a-5p and CASC2 or RUNX1 was detected by luciferase reporter assay. The levels of CASC2 and RUNX1 were significantly reduced in MM tissues compared with normal skin tissues or cells, while the miR-18a-5p level was obviously increased (all p < 0.01). Cell viability, colony number, migration, and invasion were significantly decreased in cells with pc-CASC2 compared with cells transfected with pcDNA3.1 (all p < 0.05). These effects were consistent with the cells transfected with miR-18a-5p inhibitor. The luciferase reporter assay revealed that CASC2 acted as a molecular sponge for miR-18a-5p, and RUNX1 was a target gene of miR-18a-5p. Moreover, CASC2 overexpression promoted the expression of RUNX1, while upregulated miR-18a-5p significantly reversed the effect of CASC2 on the RUNX1 level (all p < 0.05). Upregulated CASC2 may inhibit cell proliferation, migration, and invasion through regulating miR-18a-5p and its target gene RUNX1 in MM.