HOX Transcript Antisense Intergenic RNA Research Articles

The long non-coding RNA HOTAIR indicates a poor prognosis and promotes metastasis in non-small cell lung cancer

BackgroundThe identification of cancer-associated long non-coding RNAs and the investigation of their molecular and biological functions are important for understanding the molecular biology and progression of cancer. HOTAIR (HOX transcript antisense intergenic RNA) has been implicated in several cancers; however, its role in non-small cell lung cancer (NSCLC) is unknown. The aim of the present study was to examine the expression pattern of HOTAIR in NSCLC and to evaluate its biological role and clinical significance in tumor progression.MethodsExpression of HOTAIR was analyzed in 42 NSCLC tissues and four NSCLC cell lines by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Over-expression and RNA interference (RNAi) approaches were used to investigate the biological functions of HOTAIR. The effect of HOTAIR on proliferation was evaluated by MTT and colony formation assays, and cell migration and invasion were evaluated by transwell assays. Tail vein injection of cells was used to study metastasis in nude mice. Protein levels of HOTAIR targets were determined by western blot analysis. Differences between groups were tested for significance using Student’s t-test (two-tailed).ResultsHOTAIR was highly expressed both in NSCLC samples and cell lines compared with corresponding normal counterparts. HOTAIR upregulation was correlated with NSCLC advanced pathological stage and lymph-node metastasis. Moreover, patients with high levels of HOTAIR expression had a relatively poor prognosis. Inhibition of HOTAIR by RNAi decreased the migration and invasion of NSCLC cells in vitro and impeded cell metastasis in vivo. HOXA5 levels were affected by HOTAIR knockdown or over-expression in vitro.ConclusionsOur findings indicate that HOTAIR is significantly up-regulated in NSCLC tissues, and regulates NSCLC cell invasion and metastasis, partially via the down-regulation of HOXA5. Thus, HOTAIR may represent a new marker of poor prognosis and is a potential therapeutic target for NSCLC intervention.

Abstract 5189: The transcriptional regulation of the long non-coding RNA HOTAIR in ovarian cancer.

Abstract The Polycomb Group (PcG) Repressive Complexes 1 and 2 (PRC1 and PRC2) maintain gene expression patterns by epigenetically modifying chromatin. PRC2 suppresses transcription by catalyzing the trimethylation of histone H3 at lysine 27 (H3K27me3), a hallmark of repressed chromatin. Although overexpression of PRC2 components has been implicated in cancer initiation, progression and metastasis how PRC2 is recruited to its target genes remains poorly understood. Recent work suggests the interaction of PRC2 with the long-non coding (lnc) RNA HOX transcript antisense intergenic RNA (HOTAIR) could serve as a potential guide to silence target genes, but the mechanism has yet to be defined. In this study, we performed whole transcriptome RNA-seq analysis of isogenic cisplatin- sensitive and -resistant A2780 ovarian cancer (OC) cell lines. Of the lncRNA examined, HOTAIR was markedly induced in the cisplatin resistant cells (5-fold upregulation compared to the cisplatin-sensitve A2780 parental line). shRNA depletion of HOTAIR resensitized the drug-resistant cells to cisplatin. Based on analysis of the HOTAIR promoter using luciferase assays, we identified two putative NF-κB binding sites and three E-box binding sites. To further investigate whether these sites contributed to HOTAIR expression, platinum-sensitive cells were treated with different growth factors and cytokines (0 to 48hrs) and analyzed for changes in HOTAIR expression. Treatment with TNF-α, a well-known inflammatory cytokine and established activator of NF-κB, resulted in 16 fold-induction of HOTAIR. In accord with these results, we observed significant enrichment of both NF-κB and cMYC on the HOTAIR promoter using ChIP assay. Pharmacological inhibition of cMYC and NF-κB reduced HOTAIR expression by 2-fold, and siRNA depletion of the NF-κB p65 subunit or cMYC similarly reduced (P<0.01) HOTAIR expression. Based on these results, we hypothesize a positive feedback loop for HOTAIR transcriptional regulation: HOTAIR inhibits Iκ-Bα (an inhibitor of NF-κB) allowing the lncRNA to enter the nucleus and activate not only its own expression but also cMYC expression to further drive HOTAIR expression as well as cMYC-inducible genes. We are currently testing this hypothesis. We believe this novel pathway, whose components have been implicated in numerous other cancers, may be involved in cisplatin-resistant OC. Citation Format: Ali R. Ozes, Dave Miller, Cong Guo, Anurag Bhattrai, Yunlong Liu, Kenneth P. Nephew. The transcriptional regulation of the long non-coding RNA HOTAIR in ovarian cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5189. doi:10.1158/1538-7445.AM2013-5189

Abstract 2364: Long non-coding RNA HOTAIR is expressed in small cell lung cancer and relevant to cellular proliferation, invasiveness and clinical relapse - analyses based on tumor tissues and cell lines.

Abstract Small cell lung cancer (SCLC) is a subtype of lung cancer with poor prognosis, showing early relapse after initial fair response to chemotherapy. A long non-coding RNA, Hox transcript antisense intergenic RNA (HOTAIR) has been reported to be involved in breast and colon cancer metastasis. Here we revealed, using 35 surgical SCLC cases, that HOTAIR was expressed highly in pure, rather than combined, SCLC (p=0.012) and that a subset of SCLC with its higher expression tended to relapse earlier (p=0.086). Also, knock down of HOTAIR by siRNA transfection in an SCLC cell line, SBC-3, led to the reduced proliferation activity and invasiveness, due to changes of expression of cell adhesion-related genes. These findings suggest that the HOTAIR expression changes gene expression in relation to cell adhesion and subsequently alters proliferation activity and invasiveness of tumor cells, resulting in early relapse of SCLC. Our results imply that HOTAIR could be a prognostic biomarker and a therapeutic target of SCLC. Citation Format: Hiroshi Ono, Eisaku Miyauchi, Noriko Motoi, Masaru Ushijima, Masaaki Matsuura, Sakae Okumura, Makoto Nishio, Tetsuro Hirose, Satoru Itou, Mutsunori Fujiwara, Naohiko Inase, Yuichi Ishikawa. Long non-coding RNA HOTAIR is expressed in small cell lung cancer and relevant to cellular proliferation, invasiveness and clinical relapse - analyses based on tumor tissues and cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2364. doi:10.1158/1538-7445.AM2013-2364

Long Noncoding RNA HOTAIR Regulates Polycomb-Dependent Chromatin Modification and Is Associated with Poor Prognosis in Colorectal Cancers

The functional impact of recently discovered long noncoding RNAs (ncRNAs) in human cancer remains to be clarified. One long ncRNA which has attracted attention is the Hox transcript antisense intergenic RNA termed HOTAIR, a long ncRNA expressed from the developmental HOXC locus located on chromosome 12q13.13. In cooperation with Polycomb complex PRC2, the HOTAIR long ncRNA is reported to reprogram chromatin organization and promote breast cancer metastasis. In this study, we examined the status and function of HOTAIR in patients with stage IV colorectal cancer (CRC) who have liver metastases and a poor prognosis. HOTAIR expression levels were higher in cancerous tissues than in corresponding noncancerous tissues and high HOTAIR expression correlated tightly with the presence of liver metastasis. Moreover, patients with high HOTAIR expression had a relatively poorer prognosis. In a subset of 32 CRC specimens, gene set enrichment analysis using cDNA array data revealed a close correlation between expression of HOTAIR and members of the PRC2 complex (SUZ12, EZH2, and H3K27me3). Our findings suggest that HOTAIR expression is associated with a genome-wide reprogramming of PRC2 function not only in breast cancer but also in CRC, where upregulation of this long ncRNA may be a critical element in metastatic progression.