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Long noncoding RNA CCAT1 acts as an oncogene and promotes chemoresistance in docetaxel-resistant lung adenocarcinoma cells.

ABSTRACT: Chemoresistance remains one of the major obstacles in clinical treatment of lung adenocarcinoma (LAD). Indeed, docetaxel-resistant LAD cells present chemoresistance and epithelial-to-mesenchymal transition phenotypes. Long non-coding RNAs (lncRNAs) are known to promote tumorigenesis in many cancer types. Here, we showed that the lncRNA colon cancer-associated transcript-1 (CCAT1) was upregulated in docetaxel-resistant LAD cells. Furthermore, downregulation of CCAT1 decreased chemoresistance, inhibited proliferation, enhanced apoptosis and reversed the epithelial-to-mesenchymal transition phenotype of docetaxel-resistant LAD cells. We also found that the oncogenic function of CCAT1 in docetaxel-resistant LAD cells depended on the sponging of let-7c. In turn, the sponging of let-7c by CCAT1 released Bcl-xl (a let-7c target), thereby promoting the acquisition of chemoresistance and epithelial-to-mesenchymal transition phenotypes in docetaxel-resistant LAD cells. Our data reveal a novel pathway underlying chemoresistance and the epithelial-to-mesenchymal transition in docetaxel-resistant LAD cells.

SUBMITTER: Chen J

PROVIDER: S-EPMC5308740 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Long noncoding RNA CCAT1 acts as an oncogene and promotes chemoresistance in docetaxel-resistant lung adenocarcinoma cells.

Chen Jing J Zhang Kai K Song Haizhu H Wang Rui R Chu Xiaoyuan X Chen Longbang L

Oncotarget 20160901 38

Chemoresistance remains one of the major obstacles in clinical treatment of lung adenocarcinoma (LAD). Indeed, docetaxel-resistant LAD cells present chemoresistance and epithelial-to-mesenchymal transition phenotypes. Long non-coding RNAs (lncRNAs) are known to promote tumorigenesis in many cancer types. Here, we showed that the lncRNA colon cancer-associated transcript-1 (CCAT1) was upregulated in docetaxel-resistant LAD cells. Furthermore, downregulation of CCAT1 decreased chemoresistance, inh ...[more]

PMID: 27566568

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Project description:BackgroundAll cell types express long non-coding RNAs (lncRNAs), which have the potential to play a role in carcinogenesis by altering the levels of their expression. Squamous cell carcinoma of the esophagus (ESCC) is a deadly disease with a poor prognosis and a high frequency of lymphatic metastases. Understanding the functional role and signaling pathways of two neighboring lncRNAs, CCAT1 and PVT1, in this oncogene's pathogenesis may help us determine ESCC. Furthermore, it is still unclear whether these lncRNAs are linked to the clinicopathological characteristics of patients with ESCC.MethodsFor this study, we used biopsy from the Imam Khomeini Cancer Institute's tumor bank in Tehran, Iran to obtain 40 ESCC tumor samples and their normal margin counterparts. The expression levels of the CCAT1, PVT1, and c-MYC genes were assessed using quantitative Real-Time RT-PCR. Additionally, demographic data and clinical-pathologic characteristics, such as tumor grade, tumor stage, lymph node, and metastasis, were taken into consideration. Graphpad prism version 8 was used for bioinformatics analyses.ResultsComparing ESCC tissues to non-tumor tissues, we found significant upregulation of PVT1, CCAT1, and c-MYC. Patients with ESCC who had increased PVT1 expression also had higher rates of advanced stage and lymph node metastasis, whereas increased CCAT1 expression was only linked to advanced stage and wasn't associated with lymph node metastasis. In predicting ESCC, CCAT1 (p < 0.05) was found to be an important factor. Overall survival was reduced by c-MYC and PVT1 overexpression (p < 0.001), according to Kaplan-Meier analysis. PVT1, CCAT1, and c-MYC were found to interact with 23 miRNAs with high and medium score classes, as shown in a bioinformatics study. We summarized the experimentally proven interactions between c-MYC, PVT1, and CCAT1 and other miRNAs, lncRNAs, and proteins.ConclusionThis is the first report that CCAT1, PVT1 and c-MYC have been found to be up-regulated simultaneously in ESCC. It is possible that these genes may be involved in ESCC as a result of these findings. Therefore, as consequence, more research is needed to determine whether or not these lncRNAs play an oncogenic role in ESCC development and progression, as well as the regulatory mechanisms that control them.

Project description:BACKGROUND:Colorectal cancer (CRC) is one of the most common cancers and causes of cancer-related death worldwide. In patients with CRC, metastasis is a crucial problem that leads to treatment failure and is the primary cause of the lethality of colon cancer. Long noncoding RNAs (lncRNAs) have recently emerged as critical molecules in the development, cell growth, apoptosis, and metastasis of CRC. METHOD:We investigated the transcriptome profiles of human lncRNAs in the primary tumor tissues and in the corresponding normal mucosa of two patients with CRC by using a microarray approach. The expression levels of lncRNAs were verified in colon cancer by real-time PCR. Using bioinformatics approach to illustrate putative biological function of Linc00659 in colon cancer. The effects of Linc00659 on cell growth, proliferation, cell cycle and apoptosis were studies by in vitro assays. RESULTS:Our data revealed that compared with adjacent normal tissues, 201 lncRNAs were deregulated (fold change ??4 or ??0.25) in CRC tissues. Among them, the expression levels of Linc00659 were significantly increased in colon cancer, and high expression levels were correlated with poor survival in patients with CRC. Bioinformatics analysis results indicated that Linc00659 was significantly coexpressed with cycle-related genes in CRC. Linc00659 expression knockdown could significantly suppress colon cancer cell growth by impairing cell cycle progression. In addition, our results showed that Linc00659 expression knockdown could accelerate cell apoptosis in colon cancer cells treated with chemotherapy drugs. Meanwhile, our results also demonstrated that silencing of Linc00659 expression leads to cell growth inhibition and induced apoptosis, possibly by suppressing PI3K-AKT signaling in colon cancer. CONCLUSION:Linc00659 is a novel oncogenic lncRNA involved in colon cancer cell growth by modulating the cell cycle. Our findings give an insight into lncRNA regulation and provide an application for colon cancer therapy.

Dataset Information

Long noncoding RNA CCAT1 acts as an oncogene and promotes chemoresistance in docetaxel-resistant lung adenocarcinoma cells.

Publications

Long noncoding RNA CCAT1 acts as an oncogene and promotes chemoresistance in docetaxel-resistant lung adenocarcinoma cells.

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