HOX Transcript Antisense Intergenic RNA Knockdown Research Articles

LncRNA HOTAIR promotes DNA damage repair and radioresistance by targeting ATR in colorectal cancer.

Long non-coding RNAs (lncRNAs) have been implicated in cancer progression and drug resistance development. Moreover, there is evidence that lncRNA HOX transcript antisense intergenic RNA (HOTAIR) is involved in colorectal cancer (CRC) progression. The present study aimed to examine the functional role of lncRNA HOTAIR in conferring radiotherapy resistance in CRC cells, as well as the underlying mechanism. The relative expression levels of HOTAIR were examined in 70 pairs of CRC tumor and para-cancerous tissues, as well as in radiosensitive and radioresistant samples. The correlations between HOTAIR expression levels and clinical features of patients with CRC were assessed using the Chi-square test. Functional assays such as cell proliferation, colony formation and apoptosis assays were conducted to determine the radiosensitivity in CRC cells with HOTAIR silencing after treatment with different doses of radiation. RNA pull-down assay and fluorescence in situ hybridization (FISH) were used to determine the interaction between HOTAIR and DNA damage response mediator ataxia-telangiectasia mutated- and Rad3-related (ATR). HOTAIR was significantly upregulated in CRC tumor tissues, especially in radioresistant tumor samples. The elevated expression of HOTAIR was correlated with more advanced histological grades, distance metastasis and the poor prognosis in patients with CRC. Silencing HOTAIR suppressed the proliferation and promoted apoptosis and radiosensitivity in CRC cells. HOTAIR knockdown also inhibited the tumorigenesis of CRC cells and enhanced the sensitivity to radiotherapy in a mouse xenograft model. Moreover, the data showed that HOTAIR could interact with ATR to regulate the DNA damage repair signaling pathway. Silencing HOTAIR impaired the ATR-ATR interacting protein (ATRIP) complex and signaling in cell cycle progression. Collectively, the present results indicate that lncRNA HOTAIR facilitates the DNA damage response pathway and promotes radioresistance in CRC cells by targeting ATR.

LncRNA HOTAIR promotes the proliferation and invasion/metastasis of breast cancer cells by targeting the miR-130a-3p/Suv39H1 axis

Long noncoding RNAs (lncRNAs) are a group of transcripts, more than 200 bp in size and regulate cell proliferation, differentiation and apoptosis. LncRNA HOX Transcript Antisense Intergenic RNA (HOTAIR) promotes tumor progression and increases cancer susceptibility by regulating microRNA expression and function. HOTAIR regulates miR-130a-3p expression in hepatocellular carcinoma cells. Bioinformatics analysis revealed that Suv39H1 contained a putative binding site for miR-130a-3p. We speculate that LncRNA HOTAIR promotes the proliferation and invasion/metastasis of breast cancer (BC) cells by targeting the miR-130a-3p/Suv39H1 axis. High HOTAIR expression facilitated BC cell growth and metastasis. HOTAIR functioned as a ceRNA by sponging miR-130a-3p and subsequently promoted Suv39H1-mediated AKT/mTOR signaling. Suv39H1 restoration abolished the effects of HOTAIR knockdown on BC cell growth and metastasis. HOTAIR facilitated the Suv39H1-mediated AKT/mTOR pathway by acting as a molecular sponge of miR-130a-3p.Our results provide a better understanding of the interactions of HOTAIR and miR-103a-3p/Suv39H1 in BC and a potential prognostic biomarker and therapeutic target for BC.

Knockdown of long non-coding RNA HOTAIR promotes bone marrow mesenchymal stem cell differentiation by sponging microRNA miR-378g that inhibits nicotinamide N-methyltransferase

ABSTRACT Osteoporosis (OP) is associated with a serious social and economic burden. Recent studies have shown that the differential expression of long non-coding RNAs (lncRNAs) is closely related to OP. However, the specific molecular mechanism of HOX transcript antisense intergenic RNA (HOTAIR) remains to be elucidated. The expression of HOTAIR and miR-378g in OP patients was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured, and osteogenic differentiation was induced. Alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2) were detected by qRT-PCR, ELISA, and Western blotting. Calcium deposition was measured using Alizarin red s (ARS) staining. Molecular interactions between HOTAIR, miR-378g, and nicotinamide N-methyltransferase (NNMT) were detected using a dual-luciferase reporter assay. HOTAIR expression was upregulated and miR-378g level was downregulated in OP patients. HOTAIR expression decreased during the osteogenic differentiation of BMSCs. Silencing HOTAIR or NNMT reduced ALP and RUNX2 levels and promoted calcium deposition. The overexpression of HOTAIR or interference with miR-378g inhibited the osteogenic differentiation of BMSCs. HOTAIR negatively regulates miR-378g by targeting NNMT. HOTAIR is an miR-378g sponge that targets NNMT, inhibits the osteogenic differentiation of BMSCs, and provides a valuable target for the treatment of OP.

LncRNA HOTAIR mediates OGD/R-induced cell injury and angiogenesis in a EZH2-dependent manner.

Long non-coding RNAs (lncRNA) serve an important role in neonatal hypoxic-ischemic encephalopathy (HIE) have been reported to regulate the activity of HIE-associated proteins. The present study aimed to elucidate the role of Hox transcript antisense intergenic RNA (HOTAIR) in oxygen-glucose deprivation/reperfusion (OGD/R)-induced injury in human brain microvascular endothelial cells (hBMVECs). The levels of HOTAIR were evaluated in the serum of neonatal patients with HIE, and the effects of HOTAIR were evaluated using in vitro assays, such as reverse transcription-quantitative PCR to detect lncRNA and mRNA levels and western blot analysis to determine protein levels. Moreover, RNA immunoprecipitation assays were used to evaluate the association between HOTAIR and enhancer of zeste homolog 2 (EZH2), Cell Counting Kit-8 was used to detect cell viability, an endothelial monolayer cell permeability assay was used to analyze cell viability, TUNEL staining was used to detect the levels of apoptosis, a Transwell assay was used to evaluate cell invasion and a tube formation assay was used to analyze tube formation ability. In addition, the effects of HOTAIR and EZH2 on cell apoptosis and the invasive and tube formation abilities of hBMVECs were investigated using TUNEL, Transwell and tube formation assays, respectively. The results showed that the expression levels of HOTAIR were markedly increased both in neonatal HIE patients and in the OGD/R injury in vitro model. HOTAIR knockdown reduced hBMVEC viability, enhanced cell permeability and apoptosis, in addition to decreasing the expression levels of tight junction-related proteins, such as zonula occludens-1, occluden, Claudin5 and vascular endothelial-cadherin. However, EZH2 overexpression reversed the effects of HOTAIR silencing on hBMVECs. Additionally, HOTAIR knockdown enhanced the migratory and tube formation abilities of OGD/R-induced hBMVECs, which were also reversed by EZH2 overexpression. Overall, the present study revealed an association between the HOTAIR/EZH2 axis and brain microvascular endothelial cell injury and angiogenesis, which provides a novel insight into the molecular mechanism underlying stroke or the development of new pharmacotherapies.

Long noncoding RNA HOTAIR functions as ceRNA to regulate MMP2 in paraquat induced lung epithelial-mesenchymal transition

Paraquat (PQ) poisoning induces epithelial-mesenchymal transition (EMT) in the lungs, resulting in pulmonary fibrosis with a poor prognosis. Although competitive endogenous RNA (ceRNA) networks are known to exert post-transcriptional regulatory effects, the roles of such networks in PQ-induced EMT remain unknown. We explored the potential ceRNA network involved in PQ-induced pulmonary EMT. The male BALB/c mice were injected with 10 mg/kg PQ intraperitoneally and the lungs were harvested at 21st day. The A549 cells were treated with 60 μmol/L PQ for 6 days. We determined the expression level of epithelia cadherin (E-cadherin) and α-smooth muscle actin (α-SMA) in the lungs and A549 cells after PQ exposure. We also detected the expression level of the long noncoding RNA (lncRNA) HOX transcript antisense intergenic RNA (HOTAIR), microRNA-17-5p (miR-17-5p), and matrix metalloproteinase 2 (MMP2). We used specific siRNA to determine the influence of HOTAIR on MMP2. We also transfected a mimic or inhibitor of miR-17-5p to explore its role. Moreover, we used the luciferase reporter gene assay to confirm the relationship between miR-17-5p and HOTAIR or MMP2. In this study, we found that MMP2 and HOTAIR were upregulated and miR-17-5p was downregulated in PQ-induced EMT. The knockdown of HOTAIR decreased the expression of MMP2, and the upregulation of miR-17-5p suppressed HOTAIR and MMP2. Apparently, the downregulation of miR-17-5p increased the expression of HOTAIR and MMP2. The expression of α-SMA was negatively regulated by miR-17-5p after PQ exposure. In addition, the luciferase reporter gene assay confirmed that HOTAIR and MMP2 had direct binding sites with miR-17-5p. In conclusion, this study showed that the HOTAIR could act as a ceRNA for miR-17-5p to regulate MMP2 expression in PQ-induced pulmonary EMT.

Long non-coding RNA HOTAIR promotes hepatocellular carcinoma progression by regulating miR-526b-3p/DHX33 axis.

Hepatocellular carcinoma (HCC) is one of the most common human cancers. Long non-coding RNAs (lncRNAs) play pivotal roles in progression of various cancers, including HCC. We aimed to explore the exact role and underlying mechanism of lncRNA HOX transcript antisense intergenic RNA (HOTAIR) in HCC. Quantitative real time polymerase chain reaction (qRT-PCR) was carried out to determine the levels of HOTAIR, DEAH-box helicase 33 (DHX33) and miR-526b-3p. Western blot assay was used to detect the protein level of DHX33. Besides, cell proliferation and apoptosis were assessed by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Cell migration and invasion were detected by transwell assay. The interaction between miR-526b-3p and HOTAIR or DHX33 was predicted by starbase and confirmed by the dual-luciferase reporter assay. Murine xenograft model was established through injecting Huh7 cells transfected with sh-NC or sh-HOTAIR. The levels of HOTAIR and DHX33 were increased in HCC tissues and cells. Knockdown of either HOTAIR or DHX33 suppressed proliferation, migration and invasion but increased apoptosis in HCC cells. Moreover, DHX33 overexpression reversed the suppressive effect of HOTAIR knockdown on progression of HCC cells. Interestingly, miR-526b-3p could directly bind to HOTAIR, and DHX33 was a direct target of miR-526b-3p. Additionally, interference of HOTAIR restrained the tumor growth by upregulating miR-526b-3p and downregulating DHX33 in vivo. HOTAIR knockdown suppressed cell proliferation, migration and invasion, and promoted apoptosis via regulating miR-526b-3p/DHX33 axis in HCC cells, providing a potential avenue for treatment of HCC.

LncRNA HOTAIR recruits SNAIL to inhibit the transcription of HNF4α and promote the viability, migration, invasion and EMT of colorectal cancer

Colorectal cancer causes severe burdensome on the health by its high fatality and poor prognosis. Hox transcript antisense intergenic RNA (HOTAIR) was believed closely related with the genesis and development of colorectal cancer, but the regulatory mechanism is still to be investigated. The expression of HOTAIR was analyzed in colorectal cancer using both qRT-PCR and ISH assay. The cell viability, migration, invasion and apoptosis rate were evaluated using MTT, BrdU,Transwell and flow cytometryexperiments. The interaction between HOTAIR and SNAIL was detected using RIP and RNA pull-down. The binding of SNAIL to HNF4α promoter was assessed by ChIP. The cell lines that knock down HOTAIR, SNAIL or overexpress HNF4α were constructed using retroviral vector system. The tumorigenic and metastatic capacity of colorectal cancer cells after knocking down HOTAIR were evaluated based on xenograft assay and liver metastases model. HOTAIR was highly expressed in both tissue and cell lines of colorectal cancer, indicated a regulatory function in colorectal cancer. Knock-down of HOTAIR suppressed cell viability, migration, invasion and epithelial-mesenchymal transition (EMT) of colorectal cancer cells in vitro, and inhibited the growth and metastasis of colorectal tumor in nude mice. We further found that HOTAIR suppressed HNF4α via recruiting SNAIL, and the overexpression of HNF4α inhibited cell viability, migration, invasion and EMT of colorectal cancer cells. We demonstrated that HOTAIR regulates the level of HNF4α via recruiting SNAIL, knocking down HOTAIR repressed the cell viability and metestasis of colorectal cancer cell line in vitro, and suppressed the tomorgenesis and migration/invasion of colorectal cancer in vivo.

HOTAIR Induces Methylation of PCDH10, a Tumor Suppressor Gene, by Regulating DNMT1 and Sponging with miR-148b in Gastric Adenocarcinoma.

PurposeHOX transcript antisense intergenic RNA (HOTAIR), as a long non-coding RNA, has been reported to regulate carcinogenesis by epigenetic mechanism in various cancers. Protocadherin 10 (PCDH10) is one of the well-known tumor suppressor genes, and is frequently methylated in gastric cancers (GC). We aimed to investigate the detailed pathway of how HOTAIR contributes to the target gene in gastric carcinogenesis.Materials and MethodsWe investigated the mechanism of HOTAIR on carcinogenesis and metastasis of GC. Methylation-specific PCR was performed to identify the interaction between HOTAIR and PCDH10. In addition, we investigated the interaction between miR-148b and HOTAIR by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.ResultsThe expression of HOTAIR was significantly upregulated in GC tissues (p<0.05) and GC cell lines (p<0.01), while PCDH10 was downregulated in GC tissues (p<0.05). The knockdown of HOTAIR (si-HOTAIR1 and 2) significantly upregulated the mRNA/protein expression of PCDH10 and reduced the methylation of PCDH10 compared to the control in MKN 28 and MKN 74. Si-HOTAIR1 and 2 significantly reduced DNA methyltransferase 1 (DNMT1) expression, and overexpression of HOTAIR increased DNMT1 expression. In RIP, we found that miR-148b interacted with HOTAIR. Si-HOTAIRs increased miR-148b expression, and miR-148b mimic inversely reduced HOTAIR expression. Si-HOTAIRs and miR-148b mimic reduced DNMT1 expression and increased PCDH10 expression compared to the control.ConclusionThis study demonstrated that HOTAIR interacts with miR-148b and DNMT1, eventually leading to PCDH10 methylation, which contributes to the progression of GC. Our findings provide a better understanding for detailed pathway of HOTAIR in epigenetic mechanism of GC.

LncRNA HOTAIR promotes breast cancer progression through regulating the miR-129-5p/FZD7 axis.

Breast cancer is the most common malignancies worldwide. LncRNA HOX transcript antisense intergenic RNA (HOTAIR) has been shown to promote progression and metastasis of various cancers, including breast cancer. This reasearch aimed to investigate the downstream regulatory pathways of HOTAIR in breast cancer. The levels of HOTAIR and miR-129-5p were examined in breast cancer tissues and SKBR3 and MCF7 cells by quantitative real-time PCR (qRT-PCR). Cell proliferation was examined by Cell Counting Kit-8 (CCK-8) assay. Cell migration and invasion were estimated by transwell assay. Epithelial-to-mesenchymal transition (EMT)-related markers (E-cadherin, N-cadherin and Vimentin) were measured by Western blot assay. The expression of Frizzled 7 (FZD7) was detected using qRT-PCR or Western blot assay. Bioinformatics analysis, luciferase reporter assay or RNA Immunoprecipitation (RIP) assay was performed to explore the molecular mechanism of HOTAIR in breast cancer. Xenograft analysis was utilized to evaluate the tumor growth in vivo. HOTAIR and FZD7 were upregulated, while miR-129-5p was down-regulated in breast cancer tissues and cells. Knockdown of miR-129-5p reversed the effect of HOTAIR knockdown on cell proliferation, migration, invasion and EMT. FZD7 restored the inhibition of miR-129-5p on breast cancer progression. Furthermore, HOTAIR was a sponge of miR-129-5p and FZD7 was a target of miR-129-5p. Knockdown of HOTAIR inhibited the tumor growth in vivo. HOTAIR facilitated breast cancer progression by regulating the miR-129-5p/FZD7 axis, indicating that HOTAIR may be a potential biomarker and therapeutic target for breast cancer.

Exosome-Mediated Transfer of Long Noncoding RNA HOTAIR Regulates Temozolomide Resistance by miR-519a-3p/RRM1 Axis in Glioblastoma.

Background: Chemoresistance obstructs the treatment of glioblastoma (GB). Exosome-mediated transfer of long noncoding RNAs (lncRNAs) was reported to regulate chemoresistance in diverse cancers. The authors aimed to investigate the underlying mechanism of lncRNA HOX transcript antisense intergenic RNA (HOTAIR) in regulating temozolomide (TMZ) resistance in GB. Materials and Methods: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to check TMZ resistance and cell proliferation. The abilities of cell migration and invasion were evaluated by transwell assay. The protein levels of E-cadherin, N-cadherin, Vimentin, CD63, CD81, and ribonucleoside-diphosphate reductase subunit M1 (RRM1) were measured by western blot. Quantitative real-time polymerase chain reaction was conducted to detect the levels of HOTAIR, microRNA (miR)-519a-3p, and RRM1. The starBase was hired to predict the target sites between miR-519a-3p and HOTAIR or RRM1 and the dual-luciferase reporter assay was performed to verify the interaction. Xenograft tumor model was established to investigate the biological role of HOTAIR in vivo. Results: The high abilities of cell viability and metastasis were observed in TMZ-resistant GB cells. LncRNA HOTAIR was significantly upregulated in TMZ-resistant GB cells and its downregulation inhibited proliferation, migration, invasion, and epithelial/mesenchymal transition in TMZ-resistant GB cells. Further analysis indicated that exosomal lncRNA HOTAIR induced TMZ resistance and modulated TMZ resistance through miR-519a-3p/RRM1 axis. Besides, serum exosomal lncRNA HOTAIR was stable and had diagnostic value. Moreover, knockdown of lncRNA HOTAIR reduced TMZ resistance in vivo. Conclusions: Exosomal lncRNA HOTAIR mediated TMZ resistance through miR-519a-3p/RRM1 axis in GB.

LncRNA HOTAIR Contributes to Sorafenib Resistance through Suppressing miR-217 in Hepatic Carcinoma.

Background Sorafenib is a multi-target kinase inhibitor that has been approved as a unique target drug for the treatment of advanced hepatocellular carcinoma (HCC). However, due to the frequent occurrence of drug resistance, its treatment efficacy is often limited. The aim of this study was to explore the function of HOX transcript antisense intergenic RNA (HOTAIR) for the treatment of HCC with sorafenib, and its underlying mechanism. Methods A cell counting kit-8 (CCK-8) assay and Edu assay were used to examine the viability and proliferation of HCC cells. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of HOTAIR and miR-217 in HCC cells. Small interfering (si) RNA was transfected to knockdown HOTAIR to explore its biological function. A Western blot and immunofluorescence were performed to detect the level of E-cadherin and Vimentin expression. Results Sorafenib resistance was increased in HCC cells with high HOTAIR expression. Moreover, a knockdown of HOTAIR could improve the therapeutic effect of sorafenib on HCC via increasing E-cadherin and decreasing Vimentin expression. Additionally, a HOTAIR knockdown could increase the sensitivity of sorafenib for HCC treatment by up-regulating miR-217. Conclusions Lnc HOTAIR could increase sorafenib resistance in HCC by inhibiting miR-217. Our research attempts to elucidate a more effective treatment and provides novel insight into potential clinical treatment for HCC.

Long-chain non-coding RNA HOTAIR promotes the progression of osteoarthritis via sponging miR-20b/PTEN axis

AimsCumulative evidence suggests that long-chain non-coding RNA (lncRNA) is involved in the pathogenesis of osteoarthritis (OA). The present study aimed to explore the regulatory role and related mechanisms of HOX transcript antisense intergenic RNA (HOTAIR) in OA. Material and methodsThe OA mouse model was constructed by the medial meniscus (DMM) method, and Interleukin (IL)-1β-induced chondrocytes were used to simulate OA in vitro. Key findingsResults found that HOTAIR was significantly up-regulated in articular cartilage tissues of OA mice and IL-1β-induced chondrocytes, accompanied by down-regulation of miR-20b and increased expression of the phosphatase and tensin homolog (PTEN). HOTAIR silencing improved cartilage tissue damage in OA mice, and promoted the expression of collagen II and aggrecan in cartilage tissue, while inhibited the expression of matrix metalloproteinases (MMP)-13 and ADAMTS-5. Overexpression of HOTAIR inhibited the proliferation of IL-1β-induced chondrocytes and promoted apoptosis and extracellular matrix (ECM) degradation, whereas the effect of HOTAIR knockdown was reversed. Bioinformatics software and luciferase reporter experiments confirmed that HOTAIR could negatively regulate miR-20b, and PTEN was a target gene of miR-20b. An increase in PTEN expression induced by HOTAIR overexpression could be reversed by the introduction of miR-20b mimic. HOTAIR overexpression significantly reversed miR-20 mimic-mediated inhibition of apoptosis and ECM degradation in IL-1β-induced chondrocytes, whereas the introduction of si-HOTAIR eliminated anti-miR-20b-mediated apoptosis and ECM degradation. SignificanceHOTAIR can participate in OA by promoting chondrocyte apoptosis and ECM degradation, which may be related to its targeted regulation of miR-20b/PTEN axis.

HOTAIR regulates lipopolysaccharide-induced inflammatory response in hepatocytes.

It has been widely accepted that long-noncoding RNA (lncRNA) HOX transcript antisense intergenic RNA (HOTAIR) emerges as a crucial mediator in inflammation. Here, we first detected HOTAIR in lipopolysaccharide (LPS)-treated normal human liver cell line (L02) and hepatocellular carcinoma cell lines (C3A, HepG2, and SMMC-7721). Further, we explored the biological function of HOTAIR in LPS-induced hepatocytes (L02 and C3A) lesions and investigated the molecular mechanisms. Besides, we focused on inflammatory signaling crosstalk. The inflammatory insults were assayed by cell counting kit-8 (CCK-8), cell cycle and apoptosis analysis kit, and immunoblotting assay. HOTAIR level was examined by reverse-transcription polymerase chain reaction. To determine the effect of HOTAIR silence or overexpression in inflammation, we applied quantitative reverse-transcription polymerase chain reaction, immunoblotting assay, and enzyme-linked immuno sorbent assay. Regulator inhibitors of Janus kinase/signal transducer and activator of transcription (JAK2/STAT3; AG490) and nuclear factor κB (NF-κB; BAY-11-7082) were applied to treat cells. Our results suggested that LPS induced the overexpression of HOTAIR in L02, C3A, HepG2, and SMMC-7721 cells. LPS repressed viability, induced apoptosis, and facilitated the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in L02 and C3A cells. IL-1β, IL-6, and TNF-α were upregulated by HOTAIR overexpression while downregulated by HOTAIR knockdown in LPS-treated cells. We further observed that HOTAIR overexpression accelerated LPS-induced phosphorylation whereas HOTAIR silence blocked this progress. Inhibition of JAK/STAT and NF-κB contributed to the suppression of cytokines which was evoked by LPS. Collectively, our findings indicated that HOTAIR exerted a crucial role in cytokines expression by activating JAK/STAT and NF-κB.

Knockdown of long noncoding RNA HOTAIR inhibits cell growth of human lymphoma cells by upregulation of miR-148b.

Lymphoma is a common cause of cancer worldwide with an increasing incidence in recent years. A large number of studies have shown that HOX transcript antisense intergenic RNA (HOTAIR) exerts as an oncogene in various neoplasms. However, the function of HOTAIR in lymphoma still remains unclear. The present study aimed to investigate the function of HOTAIR in lymphoma and its underlying mechanisms. The expressions of HOTAIR, miR-148b, and BMI1 in lymphoma samples and cells (AHH-1, Raji, and U937) were quantified by quantitative reverse polymerase chain reaction (qRT-PCR). Cell viability was measured by trypan blue assay. The efficiency of transfection was verified by qRT-PCR or Western blot analysis. Apoptotic cells and cell cycle progression were both detected by flow cytometry assay. Furthermore, Western blot analysis was performed to assess the expression of mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathway-related core factors. We found that HOTAIR knockdown reduced cell viability but increased apoptotic cells and inhibited cell cycle progression in Raji and U937 cells. miR-148b expression was upregulated by HOTAIR inhibition. Meanwhile, miR-148b inhibitor abolished the modulation of HOTAIR silence on cell growth, as evidenced by increased cell viability, reduced apoptotic cells, and decreased the rate of G1 phase cells. Furthermore, miR-148b negatively regulated the expression of BMI1 by targeting its 3'-untranslated region (3'-UTR), and BMI1 overexpression blocked the effect of miR-148b mimic on cell growth. In addition, BMI1 promoted the activation of MAPK and ERK in Raji and U937 cells. In conclusion, the present study demonstrated that HOTAIR knockdown inhibited the cell growth and promoted apoptosis of lymphoma cells via upregulation of miR-148b and miR-148b further regulated the expression of BMI1 via MAPK and ERK signaling pathways.

Long non-coding RNA HOTAIR mediates the switching of histone H3 lysine 27 acetylation to methylation to promote epithelial-to-mesenchymal transition in gastric cancer

HOX transcript antisense intergenic RNA (HOTAIR), a well-known long non-coding RNA, plays an important role in the regulation of epithelial-to-mesenchymal transition (EMT). In this study, we propose a novel mechanism through which HOTAIR promotes EMT by switching histone H3 lysine 27 acetylation to methylation at the E-cadherin promoter, which induces the transcriptional inhibition of E-cadherin. HOTAIR recruits polycomb repressive complex 2 (PRC2) to catalyze H3K27me3; however, whether HOTAIR is associated with the acetylation of histone H3 lysine 27, a marker of transcriptional activation, and the mechanisms through which HOTAIR triggers the metastasis of gastric cancer (GC) by epigenetic regulation remain largely unknown. In this study, HOTAIR knockdown significantly reversed EMT by increasing the expression of E-cadherin in GC cells. Additionally, the loss of PRC2 activity induced by HOTAIR knockdown resulted in a global decrease in H3K27 methylation and an increase in H3K27 acetylation. Furthermore, HOTAIR recruits PRC2 (which consists of H3K27 methyltransferase EZH2, SUZ12 and EED), which may inhibit the reaction between the acetyltransferase CBP and H3K27 acetylation. On the whole, the findings of this study suggested that the HOTAIR-mediated acetylation to methylation switch was associated with the transcriptional inhibition of E-cadherin. HOTAIR can promote the development of GC through the epigenetic regulation of E-cadherin, switching the state of the E-cadherin promoter from the transcriptionally active to the transcriptionally repressive state.

Long Non-coding RNA–mRNA Correlation Analysis Reveals the Potential Role of HOTAIR in Pathogenesis of Sporadic Thoracic Aortic Aneurysm

Long non-coding RNA (lncRNA) play important roles in many diseases. However, their roles in sporadic thoracic aortic aneurysm (STAA) are unclear. Therefore, the objective of this study was to construct an lncRNA–mRNA network and dissect lncRNAs that might contribute to the pathogenesis of STAA. Differentially expressed lncRNAs and mRNAs between four ascending aortic specimens derived from STAA and four controls from patients who had undergone coronary artery bypass graft (CABG) were identified by microarray analysis. Gene Ontology (GO) enrichment and lncRNA–mRNA correlation analysis were implemented with differentially expressed genes. An lncRNA in the correlation network HOX transcript antisense intergenic RNA (HOTAIR) was selected as a candidate. HOTAIR expression was examined by quantitative real time polymerase chain reaction in STAA (n = 24) and controls (n = 24 [CABG, n = 22; heart transplant donors, n = 2]). HOTAIR expression was knocked down with siRNA in order to evaluate its role in apoptosis, cell proliferation, and expression of collagen types I and III. Five percent of lncRNAs were significantly differentially expressed in STAA patient samples compared with controls. GO enrichment analysis suggested differentially expressed genes were significantly enriched in the process of extracellular matrix organisation and leukocyte migration. lncRNA–mRNA interaction network revealed HOTAIR was associated with genes involved in extracellular matrix organisation. Moreover, HOTAIR expression was significantly decreased in STAA specimens and it negatively correlated with aortic diameter. HOTAIR knockdown induced early and late apoptosis and reduced cell proliferation. Furthermore, both mRNA and protein levels of collagen types I and III expression were suppressed after HOTAIR knockdown. Transcriptomic and lncRNA–mRNA correlation analysis revealed HOTAIR was downregulated in STAA and associated with genes involved in extracellular matrix remodelling. In vitro experiments confirmed that knockdown of HOTAIR could induce apoptosis and suppress collagen types I and III expression in human aortic smooth muscle cells.

HOX transcript antisense intergenic RNA represses E-cadherin expression by binding to EZH2 in gastric cancer.

AIMTo clarify the mechanisms of HOX transcript antisense intergenic RNA (HOTAIR) in gastric cancer (GC) migration and invasion.METHODSQuantitative real-time polymerase chain reaction (qPCR) was used to detect the expression level of HOTAIR in GC tissues. The correlation of its expression with clinicopathological features was analyzed. Area under receiver operating characteristic curve (AUCROC) was constructed to evaluate the diagnostic value of HOTAIR. Wound-healing assay and Transwell assay were performed to detect the biological effects of HOTAIR in GC cells. qPCR, western blot and immunohistochemistry were used to evaluate the mRNA and protein expression of E-cadherin. RNA-binding protein immunoprecipitation was used for the analysis of EZH2 interactions with HOTAIR. Chromatin immunoprecipitation assay was performed to investigate direct interactions between EZH2 and E-cadherin.RESULTSThe expression of HOTAIR was up-regulated in GC tumorous tissues compared with the para-tumorous tissues (P < 0.001). Its over-expression was correlated with tumor-node-metastasis (TNM) stage (P = 0.024), tumor invasion (P = 0.018), lymph node metastasis (P = 0.023), and poor prognosis (P < 0.001). Multivariate Cox regression analysis confirmed expression of HOTAIR as an independent predictor of overall survival (P = 0.033), together with TNM stage (P = 0.002) and lymph node metastasis (P = 0.002). The AUCROC was up to 0.709 (95%CI: 0.623-0.785, P < 0.001). Knockdown of HOTAIR by siRNA in GC cells suppressed the migration and invasion of GC cells. Significantly negative correlation between HOTAIR and E-cadherin was found in GC tissues and cell lines, and HOTAIR contributed to the regulation of E-cadherin through binding to EZH2 with the E-cadherin promoter.CONCLUSIONHOTAIR may play a pivotal role in tumor cell migration and invasion. It can be used as a potential diagnostic and prognostic biomarker for GC.

Long Non-coding RNA–mRNA Correlation Analysis Reveals the Potential Role of HOTAIR in Pathogenesis of Sporadic Thoracic Aortic Aneurysm

Long non-coding RNA (lncRNA) play important roles in many diseases. However, their roles in sporadic thoracic aortic aneurysm (STAA) are unclear. Therefore, the objective of this study was to construct an lncRNA-mRNA network and dissect lncRNAs that might contribute to the pathogenesis of STAA. Differentially expressed lncRNAs and mRNAs between four ascending aortic specimens derived from STAA and four controls from patients who had undergone coronary artery bypass graft (CABG) were identified by microarray analysis. Gene Ontology (GO) enrichment and lncRNA-mRNA correlation analysis were implemented with differentially expressed genes. An lncRNA in the correlation network HOX transcript antisense intergenic RNA (HOTAIR) was selected as a candidate. HOTAIR expression was examined by quantitative real time polymerase chain reaction in STAA (n=24) and controls (n=24 [CABG, n=22; heart transplant donors, n=2]). HOTAIR expression was knocked down with siRNA in order to evaluate its role in apoptosis, cell proliferation, and expression of collagen types I and III. Five percent of lncRNAs were significantly differentially expressed in STAA patient samples compared with controls. GO enrichment analysis suggested differentially expressed genes were significantly enriched in the process of extracellular matrix organisation and leukocyte migration. lncRNA-mRNA interaction network revealed HOTAIR was associated with genes involved in extracellular matrix organisation. Moreover, HOTAIR expression was significantly decreased in STAA specimens and it negatively correlated with aortic diameter. HOTAIR knockdown induced early and late apoptosis and reduced cell proliferation. Furthermore, both mRNA and protein levels of collagen types I and III expression were suppressed after HOTAIR knockdown. Transcriptomic and lncRNA-mRNA correlation analysis revealed HOTAIR was downregulated in STAA and associated with genes involved in extracellular matrix remodelling. Invitro experiments confirmed that knockdown of HOTAIR could induce apoptosis and suppress collagen types I and III expression in human aortic smooth muscle cells.

The long noncoding RNA HOTAIR promotes Parkinson’s disease by upregulating LRRK2 expression

Long noncoding RNAs (lncRNAs) have emerged recently as a new class of genes that regulate cellular processes. HOTAIR (Hox transcript antisense intergenic RNA), an approximately 2.2 kb long noncoding RNA transcribed from the HOXC locus, is upregulated in various diseases. However, the role of HOTAIR in Parkinson's disease (PD) remains unclear. A mouse model of PD was developed by intraperitoneal injection of MPTP. The expression of HOTAIR and LRRK2 were detected in the PD mice and in human neuroblastoma cell lines SH-SY5Y pretreated with MPP+. The effect of HOTAIR on the expression of LRRK2 was examined in SH-SY5Y cells through overexpressing or knockdown of HOTAIR. MTT and flow cytometry assay were performed to measure the cell viability and apoptosis of SH-SY5Y cells. We found that HOTAIR was up-regulated in midbrain tissue of MTPT induced PD mice and in SH-SY5Y cells exposed to MPP+. With the presence of HOTAIR overexpression in SH-SY5Y cells, the expression of LRRK2 was increased compared with that in the control. HOTAIR knockdown showed a protective effect on the cell viability of SH-SY5Y cells pretreated with MPP+. HOTAIR knockdown provided protection against MPP+-induced DA neuronal apoptosis by repressing caspase 3 activity. The finding that HOTAIR promoted PD induced by MPTP could add our understanding of the molecular mechanisms in PD. These findings suggested that inhibition of HOTAIR levels is an effective disease-modifying strategy in PD.

RNA helicase DEAD box protein 5 regulates Polycomb repressive complex 2/Hox transcript antisense intergenic RNA function in hepatitis B virus infection and hepatocarcinogenesis.

Chronic hepatitis B virus (HBV) infection is a major factor in hepatocellular carcinoma (HCC) pathogenesis by a mechanism not yet understood. Elucidating mechanisms of HBV‐mediated hepatocarcinogenesis is needed to gain insights into classification and treatment of HCC. In HBV replicating cells, including virus‐associated HCCs, suppressor of zeste 12 homolog (SUZ12), a core subunit of Polycomb repressive complex2 (PRC2), undergoes proteasomal degradation. This process requires the long noncoding RNA, Hox transcript antisense intergenic RNA (HOTAIR). Intriguingly, HOTAIR interacts with PRC2 and also binds RNA‐binding E3 ligases, serving as a ubiquitination scaffold. Herein, we identified the RNA helicase, DEAD box protein 5 (DDX5), as a regulator of SUZ12 stability and PRC2‐mediated gene repression, acting by regulating RNA‐protein complexes formed with HOTAIR. Specifically, knockdown of DDX5 and/or HOTAIR enabled reexpression of PRC2‐repressed genes epithelial cell adhesion molecule (EpCAM) and pluripotency genes. Also, knockdown of DDX5 enhanced transcription from the HBV minichromosome. The helicase activity of DDX5 stabilized SUZ12‐ and PRC2‐mediated gene silencing, by displacing the RNA‐binding E3 ligase, Mex‐3 RNA‐binding family member B (Mex3b), from HOTAIR. Conversely, ectopic expression of Mex3b ubiquitinated SUZ12, displaced DDX5 from HOTAIR, and induced SUZ12 down‐regulation. In G2 phase of cells expressing the HBV X protein (HBx), SUZ12 preferentially associated with Mex3b, but not DDX5, resulting in de‐repression of PRC2 targets, including EpCAM and pluripotency genes. Significantly, liver tumors from HBx/c‐myc bitransgenic mice and chronically HBV‐infected patients exhibited a strong negative correlation between DDX5 messenger RNA levels, pluripotency gene expression, and liver tumor differentiation. Notably, chronically infected HBV patients with HCC expressing reduced DDX5 exhibited poor prognosis after tumor resection, identifying DDX5 as an important player in poor prognosis HCC. Conclusion: The RNA helicase DDX5, and E3 ligase Mex3b, are important cellular targets for the design of novel, epigenetic therapies to combat HBV infection and poor prognosis HBV‐associated liver cancer. (Hepatology 2016;64:1033‐1048)