The purpose of this study was to determine the aberrant expression of the long noncoding RNA (lncRNA) colon cancer-associated transcript 1 (CCAT1) in 5-fluorouracil-resistant colonic neoplasm cells and to elucidate its effects on the 5-fluorouracil sensitivity of human colonic neoplasm cells. The aberrant expression of lncRNAs in normal tissues and colonic neoplasm tissues was detected by microarray assay. qRT-PCR analysis was performed to assess CCAT1 expression levels in colonic neoplasm cell lines and corresponding normal tissues. After constructing the 5-FU-resistant cell lines and validating the resistance by measuring the IC50 value, the CCAT1 expression levels in parental and artificially resistant cell lines were determined by qRT-PCR. Transfection was used to modulate the expression of CCAT1. Cell proliferation and apoptosis were then detected by CCK-8 and flow cytometry, respectively. CCAT1 in colon cancer tissues was higher than that in noncancer tissues, and the levels of CCAT1 in HCT 116, SW1417, HT-29, and KM12 cell lines were higher than those in the human normal colon epithelial NCM460 cell line. Moreover, the expression levels of CCAT1 were high in HCT 116/5-FU and HT-29/5-FU cell lines, whose apoptosis rates induced by 5-FU were lower than those in corresponding parental cells. The results of qRT-PCR and CCK-8 assay showed that enhancement of lncRNA CCAT1 expression levels in HCT 116 and HT-29 cell lines increased their IC50 of 5-FU and decreased their apoptosis rates. Meanwhile, siRNA-CCAT1 effectively inhibited the expression of CCAT1 and enhanced the 5-FU-sensitivity of HCT 116/5-FU and HT-29/5-FU, in which apoptosis rates were increased at the same time. Downregulation of CCAT1 effectively reversed the resistance of HCT 116/5-FU and HT-29/5-FU cells to 5-FU chemotherapeutic, opening a new avenue in colon cancer therapy.

中文翻译：

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lncRNA CCAT1的下调增强了人类结肠癌细胞中的5-氟尿嘧啶敏感性

这项研究的目的是确定耐5-氟尿嘧啶的结肠肿瘤细胞中长非编码RNA（lncRNA）结肠癌相关转录本1（CCAT1）的异常表达，并阐明其对人类5-氟尿嘧啶敏感性的影响结肠肿瘤细胞。通过微阵列检测法检测到lncRNA在正常组织和结肠肿瘤组织中的异常表达。进行qRT-PCR分析以评估结肠肿瘤细胞系和相应的正常组织中的CCAT1表达水平。构建5-FU耐药细胞系并通过测量IC50值验证耐药性后，通过qRT-PCR确定亲本和人工耐药细胞系中CCAT1表达水平。转染用于调节CCAT1的表达。然后分别通过CCK-8和流式细胞术检测细胞增殖和凋亡。结肠癌组织中的CCAT1高于非癌组织，HCT 116，SW1417，HT-29和KM12细胞系中的CCAT1水平高于人正常结肠上皮NCM460细胞系。此外，在HCT 116 / 5-FU和HT-29 / 5-FU细胞系中，CCAT1的表达水平较高，由5-FU诱导的细胞凋亡率低于相应的亲代细胞。qRT-PCR和CCK-8分析的结果表明，HCT 116和HT-29细胞系中lncRNA CCAT1表达水平的提高增加了5-FU的IC50，并降低了其凋亡率。同时，siRNA-CCAT1有效抑制了CCAT1的表达，增强了HCT 116 / 5-FU和HT-29 / 5-FU的5-FU敏感性，同时凋亡率增加。CCAT1的下调有效地逆转了HCT 116 / 5-FU和HT-29 / 5-FU细胞对5-FU化疗的耐药性，为结肠癌治疗开辟了一条新途径。