Background and Aims: Long non-coding RNA (lncRNA) MLK7-AS1 is a newly identified lncRNA that is closely related to the occurrence and development of various tumors. However, the expression and function of lncRNA MLK7-AS1 in colon cancer have not been reported yet. Therefore, this study was conducted to investigate the expression of lncRNA MLK7-AS1 in colon cancer and its effects on the biological behaviors of the colon cancer cells. 
Methods: The lncRNA MLK7-AS1 expressions in the surgical specimens of 21 paired colon cancer tissue and corresponding adjacent normal tissue, as well as in different colon cancer cell lines (SW480, HCT116, SW620, DLD1, HT29 and LOVO) and normal colon epithelial cell line (NCM460) were detected by qRT-PCR. In colon cancer cells after transfection with lncRNA MLK7-AS1 overexpression plasmid, the changes in cell viability, colony forming capacity, cell cycle and the expressions of cell cycle-associated proteins were determined by MTS assay, plate cloning assay, flow cytometry and Western blot assays as well as qRT-PCR, respectively.
Results: The expression levels of lncRNA MLK7-AS1 in colon cancer tissue was significantly higher than that in normal adjacent tissue, and in all studied colon cancer cell lines were significantly higher than that in the normal colonic epithelial cells (all P<0.05). In both SW480 and HCT116 cells that had relatively low lncRNA MLK7-AS1 expressions after transfection with lncRNA MLK7-AS1 overexpression plasmid, the cell viabilities and colony forming capacities were significantly enhanced (both P<0.05); the proportion of cells in G1 phase were significantly decreased and the proportion of cells in S phase were significantly increased (all P<0.05); the expression levels of cyclin D1 and CDK6 were significantly up-regulated (all P<0.05).
Conclusion: LncRNA MLK7-AS1 is highly expressed in colon cancer, which can promote the proliferation and colony formation of colon cancer cells, and the mechanism is probably related to its regulating the cell cycle-associated proteins cyclinD1 and CDK6 expressions.