Chai Jie, Dong Wei, Xie Chao, Wang Lin, Han Da-Li, Wang Shan, Guo Hong-Liang, Zhang Zong-Li
Department of General Surgery, Shandong Cancer Hospital and Institute, Jinan, China.
IUBMB Life. 2015 Mar;67(3):191-201. doi: 10.1002/iub.1361. Epub 2015 Apr 15.
Chemoresistance of colon cancer cells to the chemotherapeutics is still a main obstacle in treatment of this malignancy. The microRNA (miRNA) mediated chemosensitivity regulation in colon cancer cells is still largely unknown. Here we constructed a fluorouracil (5-Fu) resistant SW480 cell line (SW480/5-Fu) and discovered that miRNA miR-494 was down-regulated in the drug resistant cells compared with the parental cells. miR-494 level was found to be correlated with 5-Fu sensitivity in colon cancer cells, and artificial alteration of miR-494 affects the sensitivity of colon cancer cell lines to 5-Fu. miR-494 also promoted apoptosis of colon cancer cells at present of 5-Fu. Importantly, as a regulatory enzyme in the 5-Fu catabolic pathway, DPYD was confirmed to be a direct target of miR-494 through the interaction of miR-494 and its binding site within DPYD 3' untranslated region (3'UTR). miR-494 also negatively regulated endogenous DPYD expression in SW480 cells. Overexpression or knockdown of DPYD could attenuate miR-494 mediated 5-Fu sensitivity regulation, suggesting the dependence of DPYD regulation in miR-494 activity. miR-494 inhibited SW480/5-Fu derived xenograft tumors growth in vivo at present of 5-Fu. Thus, we concluded that in colon cancer cells, tumor suppressor miR-494 enhanced 5-Fu sensitivity via regulation of DPYD expression.
结肠癌细胞对化疗药物的耐药性仍是治疗这种恶性肿瘤的主要障碍。微小RNA（miRNA）介导的结肠癌细胞化疗敏感性调控在很大程度上仍不清楚。在此，我们构建了一种对氟尿嘧啶（5-Fu）耐药的SW480细胞系（SW480/5-Fu），并发现与亲代细胞相比，耐药细胞中miRNA miR-494表达下调。发现miR-494水平与结肠癌细胞对5-Fu的敏感性相关，人工改变miR-494会影响结肠癌细胞系对5-Fu的敏感性。在有5-Fu存在的情况下，miR-494还可促进结肠癌细胞凋亡。重要的是，作为5-Fu分解代谢途径中的一种调节酶，通过miR-494与其在二氢嘧啶脱氢酶（DPYD）3'非翻译区（3'UTR）内的结合位点相互作用，证实DPYD是miR-494的直接靶点。miR-494还可负向调节SW480细胞中内源性DPYD的表达。过表达或敲低DPYD可减弱miR-494介导的5-Fu敏感性调控，提示DPYD调控对miR-494活性的依赖性。在有5-Fu存在的情况下，miR-494可抑制SW480/5-Fu来源的异种移植瘤在体内的生长。因此，我们得出结论，在结肠癌细胞中，抑癌性miR-494通过调控DPYD表达增强了5-Fu敏感性。
