HOTAIR Knockdown Research Articles

ZBTB7A regulates LncRNA HOTAIR-mediated ELAVL1/SOX17 axis to inhibit malignancy and angiogenesis in endometrial carcinoma

BackgroundEndometrial cancer (EC) is the sixth most frequent cancer in women worldwide and has higher fatality rates. The pathophysiology of EC is complex, and there are currently no reliable methods for diagnosing and treating the condition. Long non-coding RNA (lncRNA), according to mounting evidence, is vital to the pathophysiology of EC. HOTAIR is regarded as a significant prognostic indicator of EC. ZBTB7A decreased EC proliferation and migration, according to recent studies, however the underlying mechanism still needs to be clarified.MethodsThe research utilized RT-qPCR to measure HOTAIR expression in clinical EC tissues and various EC cell lines. Kaplan-Meier survival analysis was employed to correlate HOTAIR levels with patient prognosis. Additionally, the study examined the interaction between ZBTB7A and HOTAIR using bioinformatics tools and ChIP assays. The experimental approach also involved manipulating the expression levels of HOTAIR and ZBTB7A in EC cell lines and assessing the impact on various cellular processes and gene expression.ResultsThe study found significantly higher levels of HOTAIR in EC tissues compared to adjacent normal tissues, with high HOTAIR expression correlating with poorer survival rates and advanced cancer characteristics. EC cell lines like HEC-1 A and KLE showed higher HOTAIR levels compared to normal cells. Knockdown of HOTAIR in these cell lines reduced proliferation, angiogenesis, and migration. ZBTB7A was found to be inversely correlated with HOTAIR, and its overexpression led to a decrease in HOTAIR levels and a reduction in malignant cell behaviors. The study also uncovered that HOTAIR interacts with ELAVL1 to regulate SOX17, which in turn activates the Wnt/β-catenin pathway, promoting malignant behaviors in EC cells.ConclusionHOTAIR is a critical regulator in EC, contributing to tumor growth and poor prognosis. Its interaction with ZBTB7A and regulation of SOX17 via the Wnt/β-catenin pathway underlines its potential as a therapeutic target.

HYPOXIA induces lncRNA HOTAIR for recruiting RELA in papillary thyroid cancer cells to upregulate miR-181a and promote angiogenesis.

Papillary thyroid carcinoma (PTC) is one of the most common subtypes of thyroid carcinoma. Exosomal miR-181a plays an important role in the development of PTC. This study examined the regulatory mechanism of miR-181a under conditions of hypoxia and its impact on angiogenesis. A ribonucleoprotein immunoprecipitation (RIP) experiment was conducted to verify the interaction between HOTAIR and RELA. The relationship between RELA and the miR-181a promoter was detected by ChIP-qPCR. Short hairpin (sh) RNA was designed to knock down HOTAIR in TPC cells. The underlying mechanism of miR-181a was verified by use of dual-luciferase assays and rescue experiments. The regulatory effect of GATA6 on angiogenesis was studied using CCK8, EdU, Transwell, and western blot assays. A RIP assay showed that HOTAIR could bind to RELA under hypoxic conditions. ChIP-qPCR and dual luciferase assays showed RELA could interact with the miR181a promoter and upregulate miR-181a. Knockdown of HOTAIR downregulated miR-181a in TPC-1 cells, and the downregulation could be rescued by RELA overexpression. MiR-181a downregulated GATA6 in HUVEC cells. Overexpression of GATA6 inhibited HUVEC proliferation, migration, tube formation, and EGFR expression. Exosomal miR-181a promoted angiogenesis by downregulating GATA6 expression. HOTAIR activated RELA to upregulate miR-181a during hypoxia. Exosomal miR-181a promotes tumor angiogenesis by downregulating GATA6.

Exploring the Functional Roles of lncRNA-HOTAIR in Glioma: Unraveling its Impact on Tumor Progression

Abstract: Gliomas, a heterogeneous class of brain cancers, pose significant challenges as they are considered incurable. They represent the most recurrent primary intracranial cancer and exhibit distinct clinical and biological characteristics. Traditional treatment options for glioma include radiotherapy, chemotherapy, and surgery; however, the emergence of molecular-targeted therapy has provided a new avenue for improved therapeutic responses. One intriguing oncogene type of long noncoding RNAs (lncRNAs) in glioma is the HOX Transcript Antisense RNA, commonly referred to as HOTAIR. HOTAIR is characterized by its overexpression in various cancers and is situated in the intergenic region between HOXC12 and HOXC11 of the HOXC cluster on chromosome 12. Its upregulation in glioma has been found to be associated with tumor grade and plays a significant role in disease progression. HOTAIR exerts vital functions in glioma, including promoting angiogenesis, modulating glutamine catabolism, and influencing sensitivity to temozolomide (TMZ), a commonly used chemotherapy drug. Knockdown of HOTAIR has been shown to suppress cell invasion, migration, and proliferation, while inducing apoptosis, ultimately leading to tumor repression. HOTAIR achieves its biological effects, by targeting specific microRNAs (miRNAs). In this review study, we have summarized several signaling pathways that are intricately linked to HOTAIR in the context of glioma. Understanding the mechanisms and interactions involving HOTAIR and these signaling pathways may provide valuable insights for the development of targeted therapies and improved management strategies for glioma. This review provides a summary of the potential roles of HOTAIR in glioma, encompassing its effects in commercial cell lines, patient-derived cell lines, animal studies, and clinical trials.

The long non-coding RNA HOTAIR contributes to joint-specific gene expression in rheumatoid arthritis

Although patients with rheumatoid arthritis (RA) typically exhibit symmetrical joint involvement, some patients develop alternative disease patterns in response to treatment, suggesting that different molecular mechanism may underlie disease progression depending on joint location. Here, we identify joint-specific changes in RA synovium and synovial fibroblasts (SF) between knee and hand joints. We show that the long non-coding RNA HOTAIR, which is only expressed in knee SF, regulates more than 50% of this site-specific gene expression in SF. HOTAIR is downregulated after stimulation with pro-inflammatory cytokines and is expressed at lower levels in knee samples from patients with RA, compared with osteoarthritis. Knockdown of HOTAIR in knee SF increases PI-Akt signalling and IL-6 production, but reduces Wnt signalling. Silencing HOTAIR inhibits the migratory function of SF, decreases SF-mediated osteoclastogenesis, and increases the recruitment of B cells by SF. We propose that HOTAIR is an important epigenetic factor in joint-specific gene expression in RA.

Dynamic regulation of BDNF gene expression by estradiol and lncRNA HOTAIR

Brain derived neurotrophic factor (BDNF) is a major neurotransmitter that controls growth and maintenance of neurons and its misregulation is linked to neurodegeneration and human diseases. Estradiol (E2) is well-known to regulate the process of differentiation and plasticity of hippocampal neurons. Here we examined the mechanisms of BDNF gene regulation under basal conditions and under stimuli such as E2. Our results demonstrated that BDNF expression is induced by E2 in vitro in HT22 cells (hippocampal neuronal cells) and in vivo (in ovariectomized mouse brain under E2-treatment). Using chromatin immunoprecipitation assay, we demonstrated that estrogen receptors (ERα, ERβ) were enriched at the BDNF promoter in presence of E2. Additionally, ER-coregulators (e.g., CBP/p300, MLL3), histone acetylation, H3K4-trimethylation, and RNA polymerase II levels were also elevated at the BDNF promoter in an E2-dependent manner. Additionally, under the basal conditions (in the absence of E2), the long noncoding RNA HOTAIR and its interacting partners PRC2 and LSD1 complexes binds to the promoter of BDNF and represses its expression. HOTAIR knockdown -relieves the repression resulting in elevation of BDNF expression. Further, levels of HOTAIR-interacting partners, EZH2 and LSD1 were reduced at the BDNF promoter upon HOTAIR-knockdown revealing that HOTAIR plays a regulatory role in BDNF gene expression by modulating promoter histone modifications. Additionally, we showed that E2 induced-BDNF expression is mediated by the displacement of silencing factors, EZH2 and LSD1 at BDNF promoter and subsequent recruitment of active transcription machinery. These results reveal the mechanisms of BDNF gene regulation under the basal condition and in presence of a positive regulator such as E2 in neuronal cells.

Downregulated lncRNA HOTAIR inhibits the proliferation of granulosa cells in endometriosis by upregulating p21.

This study was carried out to elucidate the biological function of HOTAIR in granulosa cells of endometriosis and the underlying mechanism. Granulosa cells were extracted from endometriosis patients and subjects with fallopian tube factor alone who received IVF-ET. Relative levels of HOTAIR and p21 in the extracted granulosa cells were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, HOTAIR level in endometriosis patients in stage I-II or III-IV was determined. Regulatory effects of HOTAIR on the proliferation of KGN cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), 5-Ethynyl-2'- deoxyuridine (EdU) and colony formation assay. Flow cytometry was conducted to evaluate the potential influence of HOTAIR on apoptosis of KGN cells. The interaction between HOTAIR and EZH2, SUV12 was detected by RNA binding protein immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assay. Finally, the potential role of the HOTAIR/p21 axis in mediating cellular behaviors of KGN cells was explored. HOTAIR was downregulated in granulosa cells extracted from endometriosis patients relative to those with fallopian tube factor alone who received IVF-ET. Knockdown of HOTAIR suppressed the proliferative ability and induced apoptosis of KGN cells. RIP and ChIP assay showed that silence of HOTAIR released EZH2 to suppress the DNA methylation of p21. Knockdown of p21 could reverse the regulatory effect of HOTAIR on the proliferative change of KGN cells. Downregulated HOTAIR suppresses the proliferative ability and induces apoptosis of granulosa cells in endometriosis by upregulating p21.

Estrogen promotes the proliferation and migration of endometrial cancer cells by upregulating the expression of lncRNA HOTAIR

Objective Estrogen (E2) is the main contributor to the progression of endometrial cancer (EC). The long noncoding RNA HOX antisense intergenic RNA (HOTAIR) is emerging as a new regulator in several cancer types. This study aimed to investigate the role of HOTAIR in EC development and identify the underlying molecular mechanisms. Methods HOTAIR expression levels in human EC tissues and the corresponding adjacent tissues and human EC Ishikawa cells were determined by quantitative PCR. Ishikawa cells were treated with E2 or estrogen receptor (ER) inhibitor ICI182780, transfected with siHOTAIR oligo, or infected with lentivirus expressing shHOTAIR/shNC, alone or in combinations. The protein expression of polycomb repressive complex 2 (PRC2) was evaluated by western blotting, and cell migration was measured by transwell assays. A xenograft tumorigenic model was established by inoculating control or stable shHOTAIR-infected Ishikawa cells into nude mice and implanting 17β-estradiol release pellets. Results HOTAIR expression was significantly elevated in human EC tissues. E2 exposure markedly increased HOTAIR levels in Ishikawa cells. Notably, E2 increased the protein expression of PRC2 and promoted EC cell migration, which were dependent on HOTAIR expression, as HOTAIR knockdown abolished these effects of E2. Similarly, E2 promoted the in vivo proliferation of grafted Ishikawa cells via upregulated HOTAIR expression in nude mice. Conclusions Human EC tissues highly express HOTAIR, and E2-induced EC progression depends on HOTAIR expression. This work suggests that the E2-HOTAIR axis is a potential therapeutic target in EC therapy.

LncRNA HOTAIR promotes ROS generation and NLRP3 inflammasome activation by inhibiting Nrf2 in diabetic retinopathy.

Diabetic retinopathy (DR) is a microvascular complication associated with damage to the retina due to inflammation induced by high glucose. Activation of the NLRP3 inflammasome plays a critical role in DR and its prevention is beneficial to patients. However, the regulation of long non-coding RNA (lncRNA) in NLRP3 inflammasome activation of DR is incompletely understood. So, this study aimed to uncover the functional and regulatory mechanism of the lncRNA HOTAIR in NLRP3 inflammasome activation in Dr. The vitreous humor was collected from the patients and detected the inflammatory and oxidative stress makers. Human retinal endothelial cells (HRECs) were cultured and stimulated in low D-glucose (5 mmol/L) or high D-glucose (20 mmol/L). Additionally, HRECs were knocked down HOTAIR with a si-RNA. Then, the NLRP3 inflammasome activation was analyzed by western blotting and pyroptosis cell imaging. The ROS was measured by specific probe. The activation of Nrf2 measured by Immunofluorescent staining. The interaction between HOTAIR and Nrf2 was evaluated by co-immunoprecipitation and RNA immunoprecipitation. The expression of HOTAIR was significantly increased in the vitreous of patients with DR and in HRECs stimulated with high glucose. Furthermore, HOTAIR knockdown relieved NLRP3 inflammasome activation. More specifically, HOTAIR knockdown suppressed the expression of NLRP3, pro-caspase-1, and pro-IL-1β, as well as IL-1β maturation and pyroptosis. HOTAIR knockdown also interfered with the ROS generation induced by high glucose. Moreover, HOTAIR promoted the interaction between Nrf2 and Keap1 by binding and inactivating Nrf2. The lncRNA HOTAIR promotes NLRP3 inflammasome activation and ROS generation by inhibiting Nrf2 in Dr.

Dampening HOTAIR sensitizes the gastric cancer cells to oxaliplatin through miR-195-5p and ABCG2 pathway.

Long non-coding RNAs (lncRNA) have an extensive role in the progression and chemoresistance of gastric cancer (GC). Deeply study the regulatory role of lncRNAs could provide potential therapeutic targets. The aim of this study is to explore the regulatory role of HOTAIR in the progression and oxaliplatin resistance of GC. The expression of HOTAIR in GC and cell lines were detected by using qRT-PCR. Cell proliferation and apoptosis were analysed by CCK-8, EdU incorporation and flow cytometry. Luciferase reporter assay was used to identify the interaction between HOTAIR and ABCG2 (ATP-binding cassette (ABC) superfamily G member 2, ABCG2) via miR-195-5p. The regulatory functions were verified by using molecular biology experiments. HOTAIR was significantly overexpressed in GC and associated with poor prognosis. Knock-down of HOTAIR inhibited the GC cells proliferation and oxaliplatin resistance, while overexpression of HOTAIR showed opposite functions. Further studies found that HOTAIR acted as a competing endogenous RNA (ceRNA) to absorb miR-195-5p and elevated the expression of ABCG2, which leads to resistance of GC cells to oxaliplatin. Taken together, our findings demonstrated that HOTAIR regulates ABCG2 induced resistance of GC to oxaliplatin through miR-195-5p signalling and illustrate the great potential of developing new therapeutic targets for GC patients.

Downregulated lncRNA HOTAIR ameliorates polycystic ovaries syndrome via IGF-1 mediated PI3K/Akt pathway

: Objective Polycystic ovarian syndrome (PCOS) is a common disorder that leads to infertility in reproductive-aged females. HOTAIR is highly expressed in various gynecological diseases and is associated with a poor prognosis. We aimed to explore the role of HOTAIR in PCOS. Methods First, PCOS rats were induced using dehydroepiandrosterone and then treated with si-HOTAIR. Next, HOTAIR mRNA expression and serum hormone levels were detected. HE staining was applied to observe estrus cycle, ovarian morphology and count the number of follicles. Apoptosis in the ovary was detected by TUNEL. Thereafter, ovarian granulosa cells (GCs) were isolated from PCOS rats, transfected with si-HOTAIR and treated with LY294002 (Akt inhibitor) or IGF-1. CCK-8 and flow cytometry assays were used to evaluate cell viability and apoptosis. IGF-1, apoptosis- and PI3K/Akt pathway-associated protein expressions in ovary and GCs were also detected. Results In in vivo experiments, si-HOTAIR decreased serum T, E2 and LH levels but increased FSH level, restored estrus cycle, ovarian morphology and inhibited apoptosis of ovary in PCOS rats. Meanwhile, in vitro assays showed that si-HOTAIR upregulated the viability but inhibited the apoptosis of PCOS GCs. Furthermore, both in vivo and in vitro assays revealed that si-HOTAIR increased Bcl-2 expression but suppressed Bax, Bad, IGF-1 expressions and PI3K, AKT phosphorylation. However, the aforementioned effects of si-HOTAIR in vitro were further enhanced by LY294002 and partially reversed by IGF-1. Conclusions HOTAIR knockdown improved PCOS, and the mechanism may relate to IGF-1-mediated PI3K/Akt pathway, indicating HOTAIR may be a novel therapeutic target for PCOS.

Reversal of H2O2-induced cell death by knockdown of HOTAIR in HTR-8/SVneo cells by mediation of miR-106b-5p/ACSL4 axis.

Preeclampsia is a serious threat to the health of pregnant women. Injury of trophoblasts could contribute to the progression of preeclampsia, and H2O2 was able to induce apoptosis in trophoblasts. LncRNAs have been reported to be involved in the progression of preeclampsia. Additionally, lncRNA HOTAIR is upregulated in patients with preeclampsia. However, the function of HOTAIR in H2O2-treated trophoblasts remains unclear. To explore the function of HOTAIR in preeclampsia, HTR-8/SVneo cells were stimulated with H2O2. RT-qPCR was performed to measure HOTAIR expression in HTR-8/SVneo cells. The apoptosis of HTR-8/SVneo cells was measured using TUNEL staining. The mitochondrial membrane potential was measured using JC-1 staining. Western blotting was performed to detect the expression of ACSL4, GPX4, and FTH1 in HTR-8/SVneo cells. The level of HOTAIR in HTR-8/SVneo cells was upregulated by H2O2. In addition, H2O2 notably inhibited the proliferation of HTR-8/SVneo cells, whereas knockdown of HOTAIR reversed this phenomenon. The mitochondrial membrane potential in HTR-8/SVneo cells was significantly inhibited by H2O2 and partially abolished by HOTAIR silencing. Moreover, HOTAIR could bind to miR-106b-5p; ACSL4 was identified as the downstream target of miR-106b-5p. Furthermore, HOTAIR knockdown reversed H2O2-induced ferroptosis in HTR-8/SVneo cells by regulating miR-106b-5p/ACSL4. Collectively, the knockdown of HOTAIR reversed H2O2-induced ferroptosis in HTR-8/SVneo cells by mediating miR-106b-5p/ACSL4. Thus, HOTAIR may serve as a new therapeutic target against preeclampsia.

HOTAIR knockdown impairs metastasis of cervical cancer cells by down-regulating metastasis-related genes

This study investigated the role of LncRNA HOTAIR knockdown in the biological impacts on cervical cancer cells. The HOTAIR gene in two human cervical cancer cell lines was silenced with small interfering (si) RNA siHOTAIR. Proliferation, apoptosis, migration and invasion of cells were assessed following the knockdown. The expressions of Notch1, EpCAM, E-cadherin, vimentin and STAT3 were assessed using qRT-PCR and Western blotting analysis. Compared with controls, HOTAIR levels were reduced significantly, the OD values of cells were significantly decreased in proliferation assays, cell apoptosis was significantly increased, cell migration and invasion were significantly reduced after HOTAIR knockdown. Molecular analysis showed that Notch1, EpCAM, vimentin and STAT3 expressions were decreased significantly, while the expression of E-cadherin was significantly increased after HOTAIR knockdown. Rescue experiments further confirmed that Notch1 and STAT3 were involved in siHOTAIR-mediated reduction of migration and invasion of cervical cancer cells. IMPACT STATEMENT What is already known on this subject? Long non-coding RNAs including HOTAIR, is implicated in occurrence and development of cancer and have been explored to develop new therapeutic options for cancer. What do the results of this study add? HOTAIR silencing significantly reduces the viability and migration ability of cells and induces cell apoptosis, adding experimental data supporting the potential use of HOTAIR specific-siRNA as a therapeutic avenue for the cancer. What are the implications of these findings for clinical practice and/or further research? The finding from this study would help develop clinically applicable therapeutic avenues for the cancer and identify new treatment targets in the relevant pathways leading to new drugs or treatments.

Retracted: Long Chain Non-Coding RNA (lncRNA) HOTAIR Knockdown Increases miR-454-3p to Suppress Gastric Cancer Growth by Targeting STAT3/Cyclin D1.

This publication has been retracted by the Editor due to the identification of non-original figure images and manuscript content that raise concerns regarding the credibility and originality of the study and the manuscript. Reference: Jiang, He Li, Heping Xiang, Ming Gao, Chunlin Yin, Haiping Wang, Yuansong Sun, Maoming Xiong. Long Chain Non-Coding RNA (lncRNA) HOTAIR Knockdown Increases miR-454-3p to Suppress Gastric Cancer Growth by Targeting STAT3/Cyclin D1. Med Sci Monit, 2019; 25: 1537-1548. DOI: 10.12659/MSM.913087.

LncRNA HOTAIR enhances RCC2 to accelerate cervical cancer progression by sponging miR-331-3p.

Long noncoding RNAs (lncRNAs) have been gradually regarded as influential indicators of various cancers. The present study aimed to identify the effects of lncRNA HOTAIR on cervical cancer progression. RNA and protein expressions were quantified by RT-qPCR and western blot assays. Fluorescence in situ hybridization (FISH) assay was carried out to examine the intracellular location of HOTAIR. Cancer cell viability and mobility were detected by CCK-8, colony formation, transwell and wound healing assays. Binding relationships between miR-331-3p and HOTAIR/RCC2 were validated by luciferase reporter assay. RT-qPCR assays showed that HOTAIR levels were notably upregulated in cervical cancer tissues and cell lines. Furthermore, a fluorescence in situ hybridization (FISH) assay suggested that HOTAIR was mostly located in the cytoplasm of cancer cells, indicating a sponging function. CCK-8, colony formation, Transwell and wound-healing assays indicated that knockdown of HOTAIR in HeLa and SiHa cells significantly reduced cell growth, migration and invasion. Subsequently, miR-331-3p was proven to be the target molecule of HOTAIR. In addition, results from Pearson's correlation analysis indicated negative correlation between HOTAIR and miR-331-3p in cervical cancer tissues. HOTAIR negatively modulated miR-331-3p expression. Ultimately, the target gene of miR-331-3p was verified to be RCC2, and miR-331-3p negatively modulated RCC2 expression. In addition, analysis on clinical cervical cancer tissues confirmed the negative correlation between miR-331-3p and RCC2. HOTAIR and RCC2 showed oncogenic functions in HeLa and SiHa cells, while miR-331-3p exerted the reverse effect. HOTAIR plays a carcinogenic role in cervical cancer by targeting the miR-331-3p/RCC2 axis. Moreover, clinical cervical cancer tissues confirmed the negative correlation between miR-331-3p with lncRNA HOTAIR and RCC2. These data suggested an underlying therapeutic target for cervical cancer.

Clinical Value of Long Non-Coding RNA HOTAIR in Carotid Artery Stenosis and Its Role in Vascular Smooth Muscle Cell Proliferation.

This study investigated the clinical role of HOTAIR in patients with carotid artery stenosis (CAS) and its mechanism in vascular smooth muscle cells (VSMCs). Patients with CAS were collected. The expression of HOTAIR was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The clinical importance of HOTAIR was revealed by the receiver operating characteristic curve. Overexpression and knockdown of HOTAIR were achieved by transfecting pCDNA3.1-HOTAIR plasmid and si-HOTAIR respectively. CCK-8 assay or Transwell assay were used to analyze the changes in cell viability or migration after transfection treatments. Double luciferase reporter gene assay confirmed the targeted relationship between HOTAIR and miR-148b-3p. The levels of miR-148b-3p in VSMCs and patients were detected by qRT-PCR. Pearson analysis was used to analyze the relationship between HOTAIR and miR-148b-3p in patients with CAS. The expression of HOTAIR in patients with CAS was significantly higher than that in healthy individuals. HOTAIR appeared to discriminate CAS patients from healthy people. The overexpression of HOTAIR increased the viability and migration of VSMCs. Silenced HOTAIR restricted the abnormal viability and migration of VSMCs. A double luciferase reporter revealed a region of complementary binding between HOTAIR and miR-148b-3p. The expression of miR-148b-3p in VSMCs was regulated by the levels of HOTAIR. Reduction of miR-148b-3p expression was substantiated in CAS patients. Pearson analysis exhibited that the expression of HOTAIR was negatively relative to the levels of miR-148b-3p. The long noncoding RNA HOTAIR might be a diagnostic biomarker for CAS patients, and it was involved in the activity of vascular smooth muscle cells.

Expression Profiles, Prognosis, and ceRNA Regulation of SRY-Related HMG-Box Genes in Stomach Adenocarcinoma.

Aberrant expression of the SRY-related HMG-box (SOX) genes contributes to tumor development and progression. This research aimed to identify the regulation of the SOX genes in stomach adenocarcinoma (STAD). Expression profiles downloaded from The Cancer Genome Atlas (TCGA) were conducted to analyze the expression and function of the SOX genes. A competing endogenous RNAs (ceRNA) network mediated by the SOX genes was effectively constructed consisting of 64 lncRNAs, 29 miRNAs, and 11 SOX genes based on predicted miRNAs shared by lncRNAs and mRNAs using miRDB, TargetScan, miRTarBase, miRcode, and starBase v2.0. SOX9 was identified as a prognostic signature, which showed the usefulness of diagnosis and prognosis of STAD by the receiver operating characteristic (ROC) and Kaplan-Meier curves. SOX9 was also shown specifically in STAD and identified as highly expressed in the gastrointestinal tract. Gene Ontology (GO) enrichment analysis showed that SOX9 might influence the genes related to the pattern specification process, sodium ion homeostasis, and potassium ion transport, mainly including FEZF1, HOXC13, HOXC10, HOXC9, HOXA11, DPP6, ATP4B, CASQ2, KCNA1, ATP4A, and SFRP1. Furthermore, HOTAIR knockdown, miR-206-mimic transfection, the Cell Count Kit-8 (CCK-8) assay were performed to verify the function of HOTAIR/miR-206/SOX9 axis, which was identified in the ceRNA network analysis. HOTAIR could induce proliferation potentially by competitively binding miR-206/SOX9 axis in STAD. These findings provide new clues with prognostic and therapeutic implications in STAD and suggest that HOTAIR/miR-206/SOX9 might be a potential new strategy for therapeutic targeting of gastric cancer.

LncRNA HOTAIR Enhances Epithelial-to-mesenchymal Transition to Promote the Migration and Invasion of Liver Cancer by Regulating NUAK1 via Epigenetic Inhibition miR-145-5p Expression.

LncRNA HOTAIR play important roles in the epigenetic regulation of carcinogenesis and progression in liver cancer. Previous studies suggest that the overexpression of HOTAIR predicts poor prognosis. In this study, through transcriptome sequencing data and in vitro experiments, we found that HOTAIR were more highly expressed and there is significantly positive relationship between HOTAIR and NUAK1 in liver cancer tissues and cell lines. miR-145-5p was downregulated and showed negative correlation with HOTAIR and NUAK1. Transfect Sh-HOTAIR, LZRS-HOTAIR, miR-145 mimic, miR-145 inhibitor to change the expression of HOTAIR and miR-145-5p. The addition of HTH-01-015 inhibits the expression of NUAK1. HOTAIR knockdown, miR-145-5p upregulation and NUAK1 inhibition all repressed migration, invasion and metastasis and reversed the epithelial-to-mesenchymal transition in SNU-387 and HepG2 cells. We also showed that HOTAIR recruiting and binding PRC2 (EZH2) epigenetically represses miR-145-5p, which controls the target NUAK1, thus contributing to liver cancer cell-EMT process and accelerating tumor metastasis. Moreover, it is demonstrated that HOTAIR crosstalk with miR-145-5p/NUAK1 during epigenetic regulation. Our findings indicate that HOTAIR/miR-145-5p/NUAK1 axis acts as an EMT regulator and may be candidate prognostic biomarker and targets for new therapies in liver cancer.

Inhibitory effect of calycosin on breast cancer cell progression through downregulating lncRNA HOTAIR and downstream targets: HuR and IGF2BP1.

Breast cancer is the most commonly diagnosed cancer worldwide. Previously, we reported that calycosin, a typical isoflavone phytoestrogen, triggers apoptosis and is associated with lncRNA HOTAIR in the estrogen receptor (ER)-positive breast cancer MCF-7-cell line. In the present study, we aim to uncover the mechanism of lncRNA HOTAIR in the inhibitory effect induced by calycosin in both ER-positive and ER-negative breast cancer cell lines. Results show that calycosin significantly inhibits proliferation and triggers apoptosis in both ER-positive (MCF-7 and T47D) and ER-negative (MDA-MB-231 and SK-BR-3) breast cancer cell lines, accompanied by downregulation of lncRNA HOTAIR expression. Accordingly, knockdown of lncRNA HOTAIR promotes the anti-tumor effect of calycosin, while overexpression of lncRNA HOTAIR attenuates this effect. Meanwhile, the expression levels of HuR and IGF2BP1 are also reduced by calycosin. More importantly, calycosin facilitates the downregulation of HuR and IGF2BP1 caused by decreasing lncRNA HOTAIR expression, and the upregulation of HuR and IGF2BP1 caused by overexpression of lncRNA HOTAIR is weakened by calycosin. These results demonstrate that downregulating HuR and IGF2BP1 by suppressing lncRNA HOTAIR results in inhibited growth of breast cancer cells by calycosin. In addition, the binding of HuR and IGF2BP1 to lncRNA HOTAIR is detected by RIP assay, implying an interaction between these two proteins and lncRNA HOTAIR. Together, lncRNA HOTAIR may play a carcinogenic role in breast cancer development and has the potential to be a novel therapeutic target for breast cancer in the future, especially in isoflavone phytoestrogen therapy.

LncRNA HOTAIR impairs the prognosis of papillary thyroid cancer via regulating cellular malignancy and epigenetically suppressing DLX1.

Papillary thyroid cancer (PTC) is the most common endocrine malignancy with a fast-growing incidence in recent decades. HOTAIR as a long non-coding RNA has been shown to be highly expressed in papillary thyroid cancer tissues with only a limited understanding of its functional roles and downstream regulatory mechanisms in papillary thyroid cancer cells. We applied three thyroid cancer cell lines (MDA-T32, MDA-T41 and K1) to investigate the phenotypic influence after gain or loss of HOTAIR. The Cancer Genome Atlas (TCGA) database were utilised to select candidate genes possibly regulated by HOTAIR with validation in the cellular system and immunohistochemical (IHC) staining of PTC tissues. We observed HOTAIR was highly expressed in MDA-T32 cells but presents significantly decreased levels in MDA-T41 and K1 cells. HOTAIR knockdown in MDA-T32 cells significantly suppressed proliferation, colony formation, migration with cell cycle retardation at G1 phase. On the contrary, HOTAIR overexpression in MDA-T41 cells dramatically enhanced proliferation, colony formation, migration with cell cycle driven toward S and G2/M phases. Similar phenotypic effects were also observed as overexpressing HOTAIR in K1 cells. To explore novel HOTAIR downstream mechanisms, we analyzed TCGA transcriptome in PTC tissues and found DLX1 negatively correlated to HOTAIR, and its lower expression associated with reduced progression free survival. We further validated DLX1 gene was epigenetically suppressed by HOTAIR via performing chromatin immunoprecipitation. Moreover, IHC staining shows a significantly stepwise decrease of DLX1 protein from normal thyroid tissues to stage III PTC tissues. Our study pointed out that HOTAIR is a key regulator of cellular malignancy and its epigenetic suppression on DLX1 serves as a novel biomarker to evaluate the PTC disease progression.

LncRNA HOTAIR regulates cell invasion and migration in endometriosis through miR-519b-3p/PRRG4 pathway.

Endometriosis is a common benign disease in gynecology and has malignant biological behaviors, such as hyperplasia, invasion, metastasis, and recurrence. However, the pathogenesis of endometriosis remains unclear. The present study aimed to investigate whether LncRNA HOTAIR regulates cell invasion and migration in endometriosis by regulating the miR-519b-3p/PRRG4 pathway. The qRT-PCR results showed that the average relative expression of LncRNA HOTAIR was much higher in ectopic endometrial tissues than in eutopic endometrial tissues. Scratch and transwell assays showed that the cell migration and invasion ability of LncRNA HOTAIR overexpression group was significantly higher than those in the control group. Conversely, the LncRNA HOTAIR knockdown group showed the opposite results. Bioinformatics analysis suggested that the downstream target genes of LncRNA HOTAIR were miR-519b-3p and Prrg4. Knockdown of LncRNA HOTAIR can reduce the up-regulation of Prrg4 by miR-519b-3p and then inhibit the invasion and migration ability of endometrial stromal cells. In Conclusion, LncRNA HOTAIR can regulate the ability of invasion and migration of endometrial stromal cells, and its mechanism is proved by regulating the miR-519b-3p/PRRG4 pathway.