LncRNA XIST Promotes Pancreatic Cancer Proliferation Through miR-133a/EGFR

Knockdown of long non-coding RNA XIST suppresses nasopharyngeal carcinoma progression by activating miR-491-5p

Dysregulated long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) play key roles in the development and progression of human cancers. X-inactive specific transcript (XIST), an lncRNA, is known as an oncogene in multiple tumors. However, the roles of XIST and its related miRNAs in nasopharyngeal carcinoma (NPC) are poorly understood. In this study, we found that XIST expression was significantly upregulated in NPC tissues and cell lines. Knockdown of XIST inhibited NPC cell proliferation and invasion and induced apoptosis in vitro, as well as suppressed NPC tumor growth in vivo. Further analysis revealed that XIST and miR-491-5p interact with and repress each other. XIST may function as an endogenous miR-491-5p sponge to regulate the target gene of miR-491-5p. Taken together, these results provide a comprehensive view of the XIST/miR-491-5p axis in human NPC cells and may provide a new therapeutic target for treating NPC.

Long non-coding RNA XIST as a potential prognostic biomarker in human cancers: a meta-analysis

Growing studies have confirmed that long non-coding RNAs (lncRNAs) involve in the occurrence and development of various cancers. XIST, as a lncRNA, was dysregulated in different cancers. This meta-analysis was performed to evaluate the prognostic potential of XIST in malignant tumors. Eight databases of PubMed, Web of Science, Embase, Cochrane library, CNKI, VIP, SinoMed and Wang Fang were comprehensively searched from their initiation date to August 15, 2017. A total of nine studies with 853 cancer patients met the including criteria were finally included in this meta-analysis after independently screening the literatures by two researchers. Any discrepancies were resolved by a consensus. Hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) for the primary endpoints were extracted and pooled for meta-analysis. Our results showed that expression level of XIST was markedly associated with overall survival (function as oncogene, HR = 0.53, 95% CI: 0.42-0.68, p < 0.00001; function as tumor suppressor, HR = 2.25, 95% CI: 1.15-4.37, p = 0.02), disease free survival (DFS)(HR = 0.45; 95% CI: 0.31-0.67, p < 0.0001), tumor type (digestive system carcinoma, HR = 0.50; 95% CI: 0.37-0.69, p < 0.00001; non-digestive system carcinoma, HR = 0.58; 95% CI: 0.39-0.87, p = 0.008), lymph node metastasis (OR = 0.32, 95% CI: 0.20-0.52, p < 0.00001), distant metastasis (OR = 0.36, 95% CI: 0.22-0.60, p < 0.0001) and tumor stage (OR = 0.43, 95% CI: 0.31-0.60, p < 0.00001). In conclusion, the pooled results in our current work suggest that XIST is an important prognostic biomarker in cancer patients.

The lncRNA XIST interacts with miR-140/miR-124/iASPP axis to promote pancreatic carcinoma growth

Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is involved in the development and progression of many tumors. In this study, XIST was specifically upregulated in pancreatic carcinoma tissues and cell lines; a higher XIST expression was correlated to poorer clinicopathologic features. After XIST knockdown, the proliferation of PC cell lines was suppressed and cell cycle stagnated in G1 phase; XIST knockdown also reduced the protein levels of inhibitor of apoptosis-stimulating protein of p53 (iASPP) and Cyclin-dependent kinase 1 (CDK1), increased the protein level of P21, a potent CDK inhibitor. In PC cell lines, XIST and miR-140/miR-124, two tumor-associated miRNAs, could inversely regulate each other, respectively; miR-140/miR-124 could bind to XIST and the 3’UTR of PPP1R13L, respectively. XIST and miR-140/miR-124 exerted opposite effects on iASPP, CDK1, P21 and P27 proteins; whereas the effects of LV-sh-XIST on the indicated protein levels could be partially reversed by miR-140 and/or miR-124 inhibitor. In PC tissues, miR-140 and miR-124 expression was down-regulated, iASPP and CDK1 mRNA expression was up-regulated. XIST positively correlated with iASPP and CDK1, inversely correlated with miR-140 and miR-124, respectively. Taken together, our data indicated that XIST might be an oncogenic lncRNA that promoted proliferation of PC cell line through inhibiting miR-140/miR-124 expression and promoting cell cycle-related factor expression, and could be regarded as a therapeutic target in human pancreatic carcinoma.

Long non-coding RNA XIST promotes cell growth and metastasis through regulating miR-139-5p mediated Wnt/β-catenin signaling pathway in bladder cancer

Bladder cancer is one of the most common urological malignancy all over the world. Recently, long non-coding RNA (lncRNA) XIST has been identified as an oncogenic gene in several type of cancers. However, the expression level and functional role of XIST in bladder cancer remain largely unknown. In the present study, we found that XIST was significantly up-regulated in bladder cancer tissues and cell lines, and was correlated with poor prognosis of bladder cancer patients. Furthermore, XIST knockdown significantly inhibited bladder cancer cell growth and metastasis in vitro and tumor growth in vivo. We also demonstrated that XIST acted as a competing endogenous RNA for miR-139-5p and repression of miR-139-5p could restore the inhibitory effects on bladder cancer cells induced by XIST shRNA. In addition, we identified that Wnt1 was a direct target of miR-139-5p, and XIST played the oncogenic role in bladder cancer by activating the Wnt/β-catenin signaling pathway. Taken together, our study suggested that lncRNA XIST may serve as a prognostic biomarker and a potential therapeutic target for bladder cancer.

LncRNA XIST acts as a tumor suppressor in prostate cancer through sponging miR-23a to modulate RKIP expression

Accumulating evidences have indicated that aberrant expression of long non-coding RNAs (LncRNAs) is tightly associated with cancer development. Previous studies have reported that lncRNA XIST regulates tumor malignancies in several cancers. However, the underlying mechanism of XIST in prostate cancer remains unclear. In the current study, we found that XIST was down-regulated in prostate cancer specimens and cell lines. Low expression of XIST was correlated with poor prognosis and advanced tumor stage in prostate cancer patients. In gain and loss of function assays, we confirmed that XIST suppressed cellular proliferation and metastasis in prostate cancer both in vitro and in vivo. Furthermore, we found that XIST negatively regulates the expression of miR-23a and subsequently promotes RKIP expression at post-transcriptional level. Consequently, we investigated the correlation between XIST and miR-23a, and identified miR-23a as a direct target of XIST. In addition, over-expression of miR-23a efficiently abrogated the up-regulation of RKIP induced by XIST, suggesting that XIST positively regulates the expression of RKIP by competitively binding to miR-23a. Taken together, our study indicated that lncRNA XIST acts as a tumor suppressor in prostate cancer, and this regulatory effect of XIST will shed new light on epigenetic diagnostics and therapeutics in prostate cancer.

Meta-analysis of the clinical value of abnormally expressed long non-coding RNAs for pancreatic cancer

Pancreatic cancer (PC) is one of the most lethal malignant neoplasms of the digestive system. Long non-coding RNAs (lncRNAs) are a novel type of non-protein coding transcripts that play an important role in pancreatic carcinogenesis. We herein aimed to meta-analyze the diagnostic and prognostic significance of lncRNA expression profiles in PC. A comprehensive retrieval of eligible studies was performed based on the online databases. Quantitative meta-analyses of the pooled diagnostic parameters and hazard ratios (HRs) were enabled by using standard statistical methods. A total of 16 studies comprising 1386 PC patients were included. The pooled effect sizes exhibited that lncRNA expression profile achieved a combined sensitivity of 0.82 (95% CI: 0.72-0.89), specificity of 0.77 (95% CI: 0.65-0.86) and AUC (area under curve) of 0.87 (95% CI: 0.83-0.89) in distinguishing patients with PC from noncancerous controls. Notably, abnormally expressed lncRNAs were markedly associated with unfavorable overall survival (OS) in PC (univariate analysis: HR = 1.52, 95% CI: 1.04-2.22, P = 0.031; multivariate analysis: HR = 1.55, 95% CI: 1.19-2.02, P = 0.001). Statistical significance was also observed in our stratified analyses grouped by clinicopathologic features. In conclusion, abnormal lncRNA expression profiles could be rated as promising biomarker(s) to enable diagnosis and predict the prognosis of PC.

Long noncoding RNA XIST expedites metastasis and modulates epithelial-mesenchymal transition in colorectal cancer

Tumor progression and metastasis is the main cause of death in colorectal cancer (CRC). Long noncoding RNAs (lncRNAs) are critical regulators in various diseases including human cancer. In this study, we found that lncRNA XIST was overexpressed in CRC cell lines and tissues. High expression of lncRNA XIST was associated with adverse overall survival in CRC patients. Knockdown of lncRNA XIST remarkably inhibited CRC cell proliferation, invasion, epithelial–mesenchymal transition (EMT) and CRC stem cell formation in vitro as well as tumor growth and metastasis in vivo. Further study indicated that knockdown of lncRNA XIST markedly increased the expression of microRNA-200b-3p (miR-200b-3p) that has been found to be downregulated in CRC tissues and cell lines, and luciferase activity assay indicated that lncRNA XIST could bind directly with miR-200b-3p. Moreover, knockdown of lncRNA XIST significantly reduced the expression of ZEB1, which was the direct target of miR-200b-3p, and the tumor suppressive effects caused by knockdown of lncRNA XIST could be rescued by re-expression of ZEB1 in CRC cells. Overall, our study demonstrated how lncRNA XIST regulates CRC progression and metastasis by competing for miR-200b-3p to modulate the expression of ZEB1. lncRNA XIST may be used as a biomarker to predict prognosis in CRC patients.

Long Non-Coding RNA (LncRNA) HOXA11-AS Promotes Breast Cancer Invasion and Metastasis by Regulating Epithelial-Mesenchymal Transition

BACKGROUND To detect the expression of lncRNA HOXA11-AS and its biological effect in breast cancer. MATERIAL AND METHODS In this study, fluorescent quantitative real-time PCR (qRT-PCR), MTT assay and clone formation assay, flow cytometry, Transwell assay and wound healing assay, immunofluorescence, and Western blot analysis were conducted to detect the expression of lncRNA HOXA11-AS, cell proliferation activity, cell apoptosis rate and cell cycle distribution, the changes of cell invasion and metastasis capacity, and the expressions of molecular markers of epithelial-mesenchymal transition (EMT), respectively. Additionally, a nude mouse metastatic tumor model was established to study the influence of lncRNA HOXA11-AS on invasion and metastasis capacity of breast cancer cells. RESULTS The qRT-PCR experiment results showed that HOXA11-AS expression in breast cancer tissue of 50 patients was relatively higher than that in tissue adjacent to cancer. MTT assay suggested that tumor cell proliferation capacity was suppressed followed by the knockdown of lncRNA HOXA11-AS expression in MDA-MB-231 and MCF-7 cells; flow cytometry results demonstrated that interfering in lncRNA HOXA11-AS could induce tumor cell apoptosis and promote cell cycle progression to be arrested in G1/G0 stage; experiments in vivo/vitro manifested that interfering in lncRNA HOXA11-AS could inhibit tumor cell invasion and migration capacity by affecting the expressions of EMT-related molecular markers (E-cadherin, N-cadherin, Vimentin). CONCLUSIONS High expression of lncRNA HOXA11-AS promotes breast cancer invasion and metastasis by affecting EMT, and interfering in lncRAN HOXA11-AS expression provides a theoretical basis and important molecular target for inhibiting the distant metastasis of breast cancer in clinical practice.