Background

Long non-coding RNAs (lncRNAs) play important roles in regulation of gene expression and are involved in pathogenesis of different diseases including cancer. Recent studies suggested the lncRNA Colon cancer associated transcript-1 (CCAT1) to act as putative oncogene. In this study, to elucidate the role of this lncRNA in endometrial cancer, we examined its expression in normal endometrium and type 1 endometrial cancer and knocked down its expression in endometrial cancer cell lines followed by transcriptome and pathway analyses.

Methods

CCAT1 expression was examined in 100 tissue samples of normal endometrium and type 1 endometrial cancer tissues by means of RT-qPCR. Knockdown of CCAT1 expression in HEC-1B and RL95/2 endometrial cancer cells was performed by siRNA transfection. Affymetrix GeneChip arrays were used to elucidate the effect of both lncRNAs on the transcriptome of these cell lines.

Results

Median CCAT1 expression was found to be 9.3-fold higher in endometrial cancer when compared to normal endometrium (p < 0.05). In contrast to premenopausal endometrium and G1, G2 and G3 graded endometrial cancer, CCAT1 expression was nearly absent in postmenopausal tissue. Knockdown of CCAT1 by transient siRNA transfection significantly reduced proliferation of HEC-1B cancer cells in vitro by 35.5 % 6 days after transfection and notably reduced their colony formation ability. Affymetrix microarray and Ingenuity pathway analyses revealed a set of up- or down-regulated genes in transfected ERα-negative HEC-1B cells forming a network controlled by the key regulators TNF and TP53, including genes known to be involved in growth control, providing putative molecular mechanisms underlying the observed growth inhibition of HEC-1B cells. In contrast, CCAT1 knockdown in ERα-positive RL95/2 cells did not significantly affect proliferation, but resulted in down-regulation of a network of ERα target genes.

Conclusions

Given that the lncRNA CCAT1 was found to be overexpressed in endometrial cancer, affected the growth of HEC-1B cells and the expression of growth regulatory genes, our data suggest CCAT1 to exert oncogenic functions in endometrial cancer and encourage further studies to examine to what extent this lncRNA might be a potential therapy target in this cancer entity.

中文翻译：

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长的非编码RNA CCAT1在子宫内膜癌中过表达，并调节子宫内膜腺癌细胞的生长和转录组。

背景

长非编码RNA（lncRNA）在调节基因表达中起重要作用，并参与包括癌症在内的各种疾病的发病机制。最近的研究表明，lncRNA结肠癌相关转录本1（CCAT1）充当推定的癌基因。在这项研究中，为了阐明该lncRNA在子宫内膜癌中的作用，我们检查了其在正常子宫内膜和1型子宫内膜癌中的表达，并敲除了其在子宫内膜癌细胞系中的表达，然后进行了转录组和通路分析。

方法

通过RT-qPCR检测100例正常子宫内膜和1型子宫内膜癌组织中的CCAT1表达。通过siRNA转染敲低HEC-1B和RL95 / 2子宫内膜癌细胞中CCAT1表达。Affymetrix基因芯片用于阐明这两种lncRNA对这些细胞系转录组的影响。

结果

与正常子宫内膜相比，发现子宫内膜癌中位CCAT1表达高9.3倍（p <0.05）。与绝经前子宫内膜和G1，G2和G3分级的子宫内膜癌相比，绝经后组织中几乎不存在CCAT1表达。瞬时siRNA转染抑制CCAT1显着降低体外HEC-1B癌细胞的增殖转染后第6天的35.5％，明显降低了其菌落形成能力。Affymetrix芯片和Ingenuity通路分析揭示了转染的ERα阴性HEC-1B细胞中一组上调或下调的基因，形成了由关键调节剂TNF和TP53控制的网络，包括已知参与生长控制的基因，观察到的HEC-1B细胞生长抑制的分子机制。相比之下，ERα阳性RL95 / 2细胞中的CCAT1敲低并未显着影响增殖，但导致ERα靶基因网络的下调。

结论

鉴于发现lncRNA CCAT1在子宫内膜癌中过表达，影响了HEC-1B细胞的生长和生长调节基因的表达，我们的数据表明CCAT1在子宫内膜癌中发挥致癌作用，并鼓励进一步研究以探讨在何种程度上该lncRNA可能是该癌症实体中潜在的治疗靶标。