LncRNA ROR1-AS1 promotes colon cancer cell proliferation by suppressing the expression of DUSP5/CDKN1A.

OBJECTIVE: The purpose of this study was to explore the possible role of ROR1AS1 in the pathogenesis of colon cancer and the underlying mechanism. PATIENTS AND METHODS: The expression levels of ROR1-AS1 in 75 colon cancer tissue samples and adjacent ones, as well as in cell lines were examined by quantitative Polymerase Chain Reaction (qPCR). Then, ROR1-AS1 over-expression plasmid and siRNA were transfected into colon cancer cells using liposome method. After that, Cell Counting Kit-8 (CCK-8) and plate colony formation assays were conducted to analyze cell proliferation, while flow cytometry was applied for the analysis of cell cycle and apoptosis. At last, the mechanism of action of ROR1-AS1 was further explored by nuclear separation, RNA binding protein immunoprecipitation (RIP) and chromatin immunoprecipitation (CHIP) assays. RESULTS: ROR1-AS1 level in colon cancer tissues was remarkably higher than that in normal tissues. and the expression in tumors of stage III and IV was remarkably higher than those of stage I and II. Meanwhile, tumors with diameters more than 5 cm had a higher ROR1-AS1 expression than those less than 5 cm. After transfection with ROR1-AS1 overexpression plasmid, the cell proliferation ability was enhanced, the G0/G1 phase time of cell cycle was shortened, and the apoptosis was suppressed. However, the opposite result was observed after ROR1-AS1 was downregulated. Furthermore, RIP showed that ROR1-AS1 can bind to enhancer of zeste homolog 2 (EZH2) and inhibit the expression of DUSP5. and thus be engaged in the proliferation and apoptosis of colon cancer cells. CONCLUSIONS: ROR1-AS1 is highly expressed either in colon cancer tissues or in cell lines. which is able to enhance cell proliferation, accelerate cell cycle, and inhibit cell apoptosis. The mechanism of ROR1-AS1 to participate in the development of colon cancer may be the down-regulation of DUSP5 via combination with EZH2.