Abstract
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.
Highlights
The 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 expression is up-regulated in human non-small cell lung cancer (NSCLC) tissues The level of HOTAIR was detected in 42 NSCLC samples and adjacent, histologically normal tissues by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and normalized to glyceraldehyde3-phosphate dehydrogenase (GAPDH)
These findings support the hypothesis that over-expression of HOTAIR may play a key role in NSCLC progression and development
Summary
The 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; 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. The participation of lncRNAs in a wide repertoire of biological processes has been intensely researched, because virtually every step of mRNA biology, from transcription to mRNA splicing, RNA decay and translation can be influenced by these molecules [7,8,9]. Identification of cancer-associated lncRNAs and the interplay between lncRNAs and proteincoding genes are important topics in the field of cancer biology, in which lncRNAs may provide a missing piece of the oncogene and tumor suppressor network puzzle
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