Long non-coding RNA HOTAIR is targeted and regulated by miR-141 in human cancer cells

The Underlying Mechanisms of Noncoding RNAs in the Chemoresistance of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal human malignancies. Chemotherapeutic agents, such as sorafenib and lenvatinib, can improve the outcomes of HCC patients. Nevertheless, chemoresistance has become a major hurdle in the effective treatment of HCC. Noncoding RNAs (ncRNAs), including mircoRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), have been demonstrated to participate in the onset and progression of HCC. Moreover, multiple lines of evidence have indicated that ncRNAs also play a pivotal role in HCC drug resistance. ncRNAs can regulate drug efflux and metabolism, glucose metabolism, cellular death pathways, and malignant characteristics in HCC. A deeper understanding of the molecular mechanisms responsible for ncRNA-mediated drug resistance in HCC will provide new opportunities for improving the treatment of HCC. In this review, we summarize recent findings on the molecular mechanisms by which ncRNAs regulate HCC chemoresistance, as well as their potential clinical implications in overcoming HCC chemoresistance.

The emerging role of the long non-coding RNA HOTAIR in breast cancer development and treatment

Despite considering vast majority of the transcribed molecules as merely noise RNA in the last decades, recent advances in the field of molecular biology revealed the mysterious role of long non-coding RNAs (lncRNAs), as a massive part of functional non-protein-coding RNAs. As a crucial lncRNA, HOX antisense intergenic RNA (HOTAIR) has been shown to participate in different processes of normal cell development. Aberrant overexpression of this lncRNA contributes to breast cancer progression, through different molecular mechanisms. In this review, we briefly discuss the structure of HOTAIR in the context of genome and impact of this lncRNA on normal human development. We subsequently summarize the potential role of HOTAIR overexpression on different processes of breast cancer development. Ultimately, the relationship of this lncRNA with different therapeutic approaches is discussed.

The multifaceted roles of long noncoding RNAs in pancreatic cancer: an update on what we know

Pancreatic cancer (PC) is one of the leading causes of cancer-related deaths worldwide. Due to the shortage of effective biomarkers for predicting survival and diagnosing PC, the underlying mechanism is still intensively investigated but poorly understood. Long noncoding RNAs (lncRNAs) provide biological functional diversity and complexity in protein regulatory networks. Scientific studies have revealed the emerging functions and regulatory roles of lncRNAs in PC behaviors. It is worth noting that some in-depth studies have revealed that lncRNAs are significantly associated with the initiation and progression of PC. As lncRNAs have good properties for both diagnostic and prognostic prediction due to their translation potential, we herein address the current understanding of the multifaceted roles of lncRNAs as regulators in the molecular mechanism of PC. We also discuss the possibility of using lncRNAs as survival biomarkers and their contributions to the development of targeted therapies based on the literature. The present review, based on what we know about current research findings, may help us better understand the roles of lncRNAs in PC.

Genistein Represses HOTAIR/Chromatin Remodeling Pathways to Suppress Kidney Cancer

BACKGROUND/AIMS

Genistein, a soy isoflavone, has been shown to have anti-cancer effects in various cancers including renal cancer. Long non-coding RNA, HOX transcript antisense RNA (HOTAIR), is involved in cancer progression and metastasis, such as renal cancer. Our aim was to investigate the effects of genistein on HOTAIR chromatin remodeling functions.

METHODS

We used MTS assays and Transwell migration assays to study the effects of genistein on cell proliferation and migration respectively in human renal cell carcinoma (RCC) cell lines. We used Western blots to analyze SNAIL and ZO-1 expression. We performed chromatin immunoprecipitation (ChIP) assays to study recruitment of the polycomb repressive complex 2 (PRC2) to the ZO-1 promoter. We performed RNA immunoprecipitation (RIP) assays to study interaction between HOTAIR and PRC2, SMARCB1 or ARID1A. We also performed transfection experiments to overexpress EED, HOTAIR and knockdown SMARCB1.

RESULTS

Genistein reduced cell proliferation and migration of human renal cell carcinoma cell lines. ChIP assays indicated that genistein reduces recruitment of the PRC2 to the ZO-1 promoter and increased its expression. RIP assays showed that genistein inhibits HOTAIR interaction with PRC2, leading to tumor suppression. Immunoprecipitation also revealed that genistein reduced EED levels in PRC2, suggesting that decreased EED levels suppress HOTAIR interaction with PRC2. EED overexpression in the presence of genistein restored PRC2 interaction with HOTAIR and reduced ZO-1 transcription, suggesting genistein activates ZO-1 by inhibiting HOTAIR/PRC2 functions. RIP assays also showed that HOTAIR interacts with SMARCB1 and ARID1A, subunits of the human SWI/SNF chromatin remodeling complex and genistein reduces this interaction. Combination of HOTAIR overexpression and SMARCB1 knockdown in the presence of genistein revealed that genistein inhibits SNAIL transcription via the HOTAIR/SMARCB1 pathway.

CONCLUSION

Genistein suppresses EED levels in PRC2 and inhibits HOTAIR/PRC2 interaction. Genistein suppresses HOTAIR/PRC2 recruitment to the ZO-1 promoter and enhances ZO-1 transcription. Genistein also inhibits SNAIL transcription via reducing HOTAIR/SMARCB1 interaction. We demonstrate that the reduction of HOTAIR interaction with chromatin remodeling factors by genistein represses HOTAIR/chromatin remodeling pathways to suppress RCC malignancy.

Cantharidin suppresses gastric cancer cell migration/invasion by inhibiting the PI3K/Akt signaling pathway via CCAT1

Cantharidin (CTD) is a traditional Chinese medicine that shows an anticancer effects in multiple types of cancer cells. However, the mechanism of CTD anti-cancer function in gastric cancer (GC) is still unclear. The aim of the present study was to investigate the underlying mechanism that CTD inhibits proliferation and migration through suppression of the PI3K/Akt signaling. CTD induced GC cell apoptosis and inhibited metastasis measured by CCK8 assays as well as wound healing assays and transwell assays. Mechanistic investigations suggested that CTD modulated the PI3K/Akt signaling via western-blot and quantitative q-PCR. In addition, we identified and confirmed CCAT1 as a novel direct target of CTD inhibited PI3K/AKt signaling expression. In conclusion, our results provide new point into the critical role of CTD in suppressing PI3K/Akt signaling via down-regulation of CCAT1, resulting in suppression GC cell growth and migration/invasion.

A Comparative Study of HOTAIR Expression in Breast Cancer Patient Tissues and Cell Lines

Objective

Recent data suggest that increased levels of the HOTAIR long non-coding RNA (lncRNA) are involved in the development of various types of malignancy, including breast cancer. The aim of present study was to investigate HOTAIR lncRNA expression profile in breast cancer (BC) patients and cell lines.

Materials and Methods

In this experimental study, expression level of HOTAIR lncRNA was evaluated in BC and normal tissues of 15 patients as well as MDA-MB-231, MCF-7 and MCF-10A cell lines, using quantitative reverse- transcription polymerase chain reaction (qRT-PCR). HOTAIR lncRNA expression levels were estimated using 2^-ΔΔCt method. Further, receiver operating characteristic (ROC) curve analysis was done to evaluate the selected lncRNA diagnostic potential. The Cox’s proportional hazards regression model was performed to evaluate the predictive value of this lncRNA level in BC patients.

Results

The results of present study demonstrated no significant difference in the expression of HOTAIR lncRNA in MCF7 and MDA-MB-231 cancer cell lines compared to MCF-10A as normal cell line (P>0.05). However, we observed a significantly increase in the expression of HOTAIR in BC patients compared to normal tissues (P<0.001). Significant associations were found between gene expression and tumour size and margin. We found 91.1% sensitivity and 95.7% specificity of circulating HOTAIR with an area under the ROC curve of 0.969. The Kaplan-Meier analysis indicated significant correlation between HOTAIR expression and overall survival.

Conclusion

This study demonstrated that expression of HOTAIR is increased in BC and might be associated with its progression. According to these findings, HOTAIR expression could be proposed as biomarkers for BC early diagnosis and prognosis.

MiR-21-3p Centric Regulatory Network in Dairy Cow Mammary Epithelial Cell Proliferation

MicroRNA-mediated gene regulation is important for the development of the mammary gland and the lactating process. A previous study has shown that the expression of microRNA-21 (miR-21) is different in the dry and early lactation period of the dairy cow mammary gland, but the molecular mechanisms underlying the lactation cycle are not fully understood. Here, the function of miR-21-3p on bovine mammary gland epithelial cells (BMECs) was detected by MTT assay and flow cytometry analysis, which showed that miR-21-3p significantly promoted the cell viability and proliferation. Then, the regulating mechanism of miR-21-3p on cell viability and proliferation was elucidated. Dual luciferase assay, RT-qPCR, and Western blot results revealed that IGFBP5 was a target gene of miR-21-3p. It was known that lncRNA could act as a competing endogenous RNA to sequester miRNAs and reduce the regulatory effect of miRNA-targeted genes. Based on our previous lncRNA-seq data and bioinformatics analysis, lncRNA NONBTAT017009.2 was potentially associated with miR-21-3p, and its expression was specifically inhibited with the transfection of miR-21-3p mimic into BMECs. Inversely, the overexpression of NONBTAT017009.2 significantly decreased the expression level of miR-21-3p in BMECs, while the expression of IGFBP5, the target gene of miR-21-3p, was significantly upregulated. In addition, the promoter region of miR-21 contained two STAT3 binding sites, and the dual luciferase reporter assays revealed that the overexpression of STAT3 significantly reduced the promoter activity of miR-21, implying that the transcription factor STAT3 may act as an upstream regulator affecting the regulation process of miR-21-3p. The overexpression of STAT3 significantly inhibited the expression of miR-21-3p, while the mRNA expression of IGFBP5 was significantly increased compared with the control group. Besides, there are no STAT3 binding sites in the promoter region of IGFBP5 as we predicted by gene-regulation and JASPAR software. Therefore, it could infer that STAT3 might regulate the expression of IGFBP5 by miR-21-3p. Taken together, these results established a regulatory network of miR-21-3p to illustrate the regulating mechanism on promoting cow mammary epithelial cell proliferation.

miR-200c overexpression inhibits the invasion and tumorigenicity of epithelial ovarian cancer cells by suppressing lncRNA HOTAIR in mice

Epithelial ovarian cancer (EOC) is a common ovarian cancer in gynecological cancers today. It has been found that microRNAs and long-chain noncoding RNA (lncRNA) regulate the gene transcriptional expression in cells. However, it is not well understood that the upstream and downstream regulatory molecules of lncRNA HOX antisense intergenic RNA (HOTAIR). The effects of miR-200c overexpression on the invasion and nude mouse tumorigenicity, as well as lncRNA HOTAIR and snail expression of EOC SKOV3 cells, should be further explored. The expression of miR-200c and lncRNA HOTAIR was detected by reverse transcription PCR (RT-PCR) in EOC SKOV3 cells. The whole miR-200c gene fragment was cloned into a lentiviral plasmid vector. The miR-200c expression in transducted SKOV3 cells with reconstructed miR-200c lentivirus was significantly higher than the negative control (P < .01). The lentivirus-miR-200c-SKOV3 cells show that the invasion ability was significantly decreased compared with the negative control (P < .01). The nude mouse tumorigenicity was significantly decreased compared with that of the control group (P < .01). The snail protein expression in lentivirus-miR-200c-SKOV3 xenograft tumor was significantly decreased compared with the negative control lentivirus-SKOV3 group (P < .05). The miR-200c overexpression significantly decreased the expressions of lncRNA HOTAIR and snail, but increased E-cadherin expression in the lentivirus-miR-200c transducted SKOV3 cells of xenograft tumor, compared with the negative control (P < .05). The miR-200c overexpression in SKOV3 cells with transducted lentivirus-miR-200c can inhibit lncRNA HOTAIR expression, decrease snail, increase E-cadherin and significantly reduce the invasion and tumorigenicity of EOC SKOV3 cells. These results suggest that the miR-200c and lncRNA HOTAIR could be effective therapeutic targets for human epithelial ovarian cancer treatment.

Long non‑coding RNA nuclear paraspeckle assembly transcript 1 interacts with microRNA‑107 to modulate breast cancer growth and metastasis by targeting carnitine palmitoyltransferase‑1

Previous studies revealed that the long non‑coding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) exhibits abnormal expression in numerous cancer types, including breast cancer (BC); however, the regulatory mechanism of NEAT1 in BC remains unclear. In the present study, the effect of NEAT1 on the progression of BC and its regulation mechanism was investigated. The expression levels of NEAT1 and microRNA‑107 (miR‑107) in BC cells were analyzed using the reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). NEAT1 was knocked down in BC cells, and mimics‑miR‑107 or inhibitor‑miR‑107 were transfected into BC cells. Subsequently, cell proliferation, invasion and migration, apoptosis and cell cycle distribution were determined. The regulatory mechanism of NEAT1, miR‑107 and carnitine palmitoyltransferase‑1 (CPT1A) was analyzed using a luciferase reporter assay system, western blotting and RT‑qPCR. NEAT1 expression was increased in BC cells, whereas miR‑107 expression was decreased, compared with normal mammary gland cells. NEAT1 promoted the progression of BC cells through inhibiting apoptosis‑associated genes and promoting cell cycle‑ and invasion‑associated gene expression, whereas miR‑107 served the opposite function. Furthermore, NEAT1 promoted the expression of CPT1A, which was mediated by miR‑107. The results of the present study indicate that NEAT1 promotes the expression of CPT1A by inhibiting miR‑107 to improve the progression of BC cells; therefore, NEAT1 is a potential therapeutic target of BC.

MALAT1 accelerates the development and progression of renal cell carcinoma by decreasing the expression of miR-203 and promoting the expression of BIRC5

OBJECTIVE

We aimed to investigate the roles of the lncRNA MALAT1 in renal cell carcinoma (RCC) progression.

METHODS

qRT-PCR was used for the assessment of BIRC5, miRNA-203 and MALAT1 expression. Furthermore, the targeted relationships between miR-203 and BIRC5, as well as MALAT1 and miR-203, were predicted by the miRanda/starBase database and verified by dual-luciferase reporter gene assay. The effects of MALAT1, miRNA-203 and BIRC5 on cell proliferation, cell cycle, cell apoptosis, cell invasion and cell migration were studied by using CCK-8, flow cytometry, transwell and wound healing assays, respectively. In addition, the effects of MALAT1 on RCC tumorigenesis were evaluated in vivo by nude mouse tumorigenesis.

RESULTS

The expression levels of BIRC5 and MALAT1 were higher in RCC tissues and cell lines than in adjacent normal tissues and a normal renal cortex proximal tubule epithelial cell line. In contrast, the expression of miRNA-203 in RCC tissues and cell lines was higher than that in adjacent normal tissues and a normal renal cortex proximal tubule epithelial cell line. BIRC5 and MALAT1 promoted cell proliferation yet decreased the percentage of RCC cells at G0/G1 phase.

CONCLUSIONS

Our study demonstrated that MALAT1 functions as a miR-203 decoy to increase BIRC5 expression in RCC.

Phytochemicals as Modulators of Long Non-Coding RNAs and Inhibitors of Cancer-Related Carbonic Anhydrases

Long non-coding RNAs (lncRNAs) are classified as a group of transcripts which regulate various biological processes, such as RNA processing, epigenetic control, and signaling pathways. According to recent studies, lncRNAs are dysregulated in cancer and play an important role in cancer incidence and spreading. There is also an association between lncRNAs and the overexpression of some tumor-associated proteins, including carbonic anhydrases II, IX, and XII (CA II, CA IX, and CA XII). Therefore, not only CA inhibition, but also lncRNA modulation, could represent an attractive strategy for cancer prevention and therapy. Experimental studies have suggested that herbal compounds regulate the expression of many lncRNAs involved in cancer, such as HOTAIR (HOX transcript antisense RNA), H19, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), PCGEM1 (Prostate cancer gene expression marker 1), PVT1, etc. These plant-derived drugs or phytochemicals include resveratrol, curcumin, genistein, quercetin, epigallocatechin-3-galate, camptothcin, and 3,3'-diindolylmethane. More comprehensive information about lncRNA modulation via phytochemicals would be helpful for the administration of new herbal derivatives in cancer therapy. In this review, we describe the state-of-the-art and potential of phytochemicals as modulators of lncRNAs in different types of cancers.

Rosiglitazone Inhibits Activation of Hepatic Stellate Cells via Up-Regulating Micro-RNA-124-3p to Alleviate Hepatic Fibrosis

BACKGROUND

The activation of hepatic stellate cells (HSCs) is involved in hepatic fibrogenesis and is regulated by the decreased expression of peroxisome proliferator-activated receptor γ (PPARγ). Rosiglitazone (RGZ) is a highly potent agonist of PPARγ.

AIMS

To clarify molecular regulatory mechanism of RGZ in the activation of HSCs in hepatic fibrosis.

METHODS

A mouse model of hepatic fibrosis was established by carbon tetrachloride with or without RGZ intervention. A vector carrying pcDNA-HOTAIR was constructed and injected into a mouse model. HSCs were isolated from liver tissue and activated by transforming growth factor-β. The expression of miR-124-3p, HOTAIR, Col1A1, α-SMA, and PPARγ mRNAs was measured by quantitative real-time PCR. The level of PPARγ was measured by Western blotting. The interaction between HOTAIR and PPARγ was assessed by RNA immunoprecipitation (RIP) and RNA pull-down. The target gene of miR-124-3p was determined by luciferase reporter assay and RNA interference approaches.

RESULTS

The expression of Col1A1 and α-SMA was reduced after RGZ intervention. Different expressions of HOTAIR and miR-124-3p were observed in liver tissue and HSCs. The luciferase reporter assay and RNA interference approaches indicated that miR-124-3p negatively regulated HOTAIR expression. RIP and RNA pull-down results revealed that PPARγ was interacted by HOTAIR. The therapeutic effect of RGZ on hepatic fibrosis was reversed by overexpression of HOTAIR.

CONCLUSIONS

RGZ inhibits the activation of HSCs by up-regulating miR-124-3p. The silencing of HOTAIR by miR-124-3p in HSC activation provided the foundation to understand interactions of ncRNAs and potential treatment target in hepatic fibrosis.

[ARTICLE WITHDRAWN] Long Noncoding RNA LINC01296 Harbors miR-21a to Regulate Colon Carcinoma Proliferation and Invasion

THIS ARTICLE WAS WITHDRAWN BY THE PUBLISHERS IN NOVEMBER 2020.

Long non-coding RNAs are emerging targets of phytochemicals for cancer and other chronic diseases

The long non-coding RNAs (lncRNAs) are the crucial regulators of human chronic diseases. Therefore, approaches such as antisense oligonucleotides, RNAi technology, and small molecule inhibitors have been used for the therapeutic targeting of lncRNAs. During the last decade, phytochemicals and nutraceuticals have been explored for their potential against lncRNAs. The common lncRNAs known to be modulated by phytochemicals include ROR, PVT1, HOTAIR, MALAT1, H19, MEG3, PCAT29, PANDAR, NEAT1, and GAS5. The phytochemicals such as curcumin, resveratrol, sulforaphane, berberine, EGCG, and gambogic acid have been examined against lncRNAs. In some cases, formulation of phytochemicals has also been used. The disease models where phytochemicals have been demonstrated to modulate lncRNAs expression include cancer, rheumatoid arthritis, osteoarthritis, and nonalcoholic fatty liver disease. The regulation of lncRNAs by phytochemicals can affect multi-steps of tumor development. When administered in combination with the conventional drugs, phytochemicals can also produce synergistic effects on lncRNAs leading to the sensitization of cancer cells. Phytochemicals target lncRNAs either directly or indirectly by affecting a wide variety of upstream molecules. However, the potential of phytochemicals against lncRNAs has been demonstrated mostly by preclinical studies in cancer models. How the modulation of lncRNAs by phytochemicals produce therapeutic effects on cancer and other chronic diseases is discussed in this review.

Molecular Mechanisms in Clear Cell Renal Cell Carcinoma: Role of miRNAs and Hypermethylated miRNA Genes in Crucial Oncogenic Pathways and Processes

Clear cell renal cell carcinoma (ccRCC) is the third most common urological cancer, and it has the highest mortality rate. The increasing drug resistance of metastatic ccRCC has resulted in the search for new biomarkers. Epigenetic regulatory mechanisms, such as genome-wide DNA methylation and inhibition of protein translation by interaction of microRNA (miRNA) with its target messenger RNA (mRNA), are deeply involved in the pathogenesis of human cancers, including ccRCC, and may be used in its diagnosis and prognosis. Here, we review oncogenic and oncosuppressive miRNAs, their putative target genes, and the crucial pathways they are involved in. The contradictory behavior of a number of miRNAs, such as suppressive and anti-metastatic miRNAs with oncogenic potential (for example, miR-99a, miR-106a, miR-125b, miR-144, miR-203, miR-378), is examined. miRNAs that contribute mostly to important pathways and processes in ccRCC, for instance, PI3K/AKT/mTOR, Wnt-β, histone modification, and chromatin remodeling, are discussed in detail. We also separately consider their participation in crucial oncogenic processes, such as hypoxia and angiogenesis, metastasis, and epithelial-mesenchymal transition (EMT). The review also considers the interactions of long non-coding RNAs (lncRNAs) and miRNAs of significance in ccRCC. Recent advances in the understanding of the role of hypermethylated miRNA genes in ccRCC and their usefulness as biomarkers are reviewed based on our own data and those available in the literature. Finally, new data and perspectives concerning the clinical applications of miRNAs in the diagnosis, prognosis, and treatment of ccRCC are discussed.

Long noncoding RNA EGFR-AS1 promotes cell growth and metastasis via affecting HuR mediated mRNA stability of EGFR in renal cancer

Long noncoding RNAs (lncRNAs) are implicated in renal cell carcinoma (RCC), but remain largely unclear. Using publicly available transcriptome sequencing data from renal cancer (n = 703) and integrating bioinformatics analyses, we screened and identified a valuable lncRNA, EGFR-AS1. In our validation cohort (n = 204), EGFR-AS1 was significantly upregulated in RCC tissues (P < 0.001). Gain-of-function and loss-of-function studies showed that EGFR-AS1 promoted cell proliferation and invasion in vitro and in vivo. Based on previous studies and sequence complementarity of EGFR with EGFR-AS1, we demonstrated that EGFR-AS1 directly bound to EGFR mRNA and inhibited its degradation. Furthermore, RNA pull-down and mass spectrometry analyses showed that EGFR-AS1 interacted with HuR, which was responsible for the mRNA stability of EGFR. Multivariate analysis suggested that higher EGFR-AS1 expression predicted a poor prognosis in RCC patients (high vs low: P = 0.018, HR = 2.204, 95% CI: 1.145-4.241). In conclusion, EGFR-AS1 enhances the malignant phenotype of RCC cells by enhancing HuR-mediated mRNA stability of EGFR. Our data also provide biological rationales for EGFR-AS1 as a prognostic biomarker and a potential therapeutic target for RCC.

Linc00662 Promotes Tumorigenesis and Progression by Regulating miR-497-5p/AVL9 Axis in Colorectal Cancer

BACKGROUND

Recently, multiple lines of evidence have demonstrated that linc00662 serves as an oncogene in various cancers. However, the exact mechanism of oncogenesis mediated by linc00662 in colorectal cancer (CRC) remains unknown. In this study, we aimed to explore the biological role of linc00662 in the regulation of CRC progression.

METHODS

Both gene expression omnibus (GEO) and the cancer genome atlas (TCGA) datasets were used to evaluate the expression of linc00662. RT-qPCR was used to analyze the expression of linc00662, miR-497-5p, and AVL9 in CRC clinical samples and cell lines. Cell Counting Kit-8 (CCK-8), flow cytometry, transwell assay, and xenograft model were used to investigate the effect of linc00662 on CRC cell proliferation, cell cycle, and metastasis. Western blot analysis was used to analyze the expression of the epithelial-mesenchymal transition (EMT)-associated markers. Furthermore, bioinformatics analysis and mechanism assays were used to elucidate the underlying mechanism. Dual-luciferase reporter assays were used to analyze the regulatory relationships among linc00662, miR-497-5p, and AVL9.

RESULTS

In this study, we found that the expression of linc00662 was significantly upregulated in CRC tissues compared to normal tissues and positively correlated with tissue differentiation, T stage, and lymphatic metastasis. Further, our data showed that the expression of linc00662 was positively associated with lymph node metastasis, TMN stage, and poor-moderate differentiation. Patients with higher linc00662 expression level were more likely to have poorer overall survival. Knockdown of linc00662 inhibited CRC cell growth, induced cell apoptosis, triggered cell cycle arrest at G2/M phase, and suppressed cell migration and invasion through regulating the EMT pathway. Further, mechanistic studies revealed that knockdown of linc00662 significantly reduced the expression of AVL9, a direct target of miR-497-5p.

CONCLUSIONS

Linc00662 was significantly upregulated in CRC, and mediated CRC progression and metastasis by competing with miR-497-5p to modulate the expression of AVL9. Therefore, our result sheds light on the potential application of linc00662 in CRC diagnosis and therapy.

Long non-coding RNA H19 promotes tumorigenesis of ovarian cancer by sponging miR-675

BACKGROUND

Ovarian cancer is one of the six most common women's cancers in the world, and is found among the top three female genital tumors, which is lower than the rate of endometrial cancer and cervical cancer.

METHODS

This study utilized miR-675 mimics and siRNA transfection to construct miR-675 overexpression and lower-expression model to investigate the effect of miR-675 on the regulation of ovarian cancer. Western blotting and RT-qPCR were applied for the quantitative testing of mRNA and protein expression. Apoptosis of podocytes was detected by TUNEL staining.

RESULTS

H19 expression was also up-regulated. In vitro, H19 silencing after transfection with si-H19 could suppress proliferation and invasion. Luciferase reporter assay revealed a close link between miR-675 and H19 3'-UTR. Furthermore, combining experiments of miR-675 and H19 indicated that miR-675 could reverse the function of H19 on ovarian cancer.

CONCLUSION

Our study reveals the overexpression of H19 in ovarian cancer tissue and cells, and discovers an oncogenic role in ovarian cancer via sponging miR-675, providing a potential biomarker for early detection and prognosis of ovarian cancer.

[ARTICLE WITHDRAWN] Long Noncoding RNA TUNAR Represses Growth, Migration, and Invasion of Human Glioma Cells Through Regulating miR-200a and Rac1

THIS ARTICLE WAS WITHDRAWN BY THE PUBLISHERS IN NOVEMBER 2020.

Long non-coding RNA PVT1 promotes glioma cell proliferation and invasion by targeting miR-200a

Glioma is a type of malignant tumor accounting for 80% of all brain cancer morbidity. The long non-coding RNA (lncRNA) PVT1 has been demonstrated to be an oncogenic lncRNA in other types of cancer. However, the role of PVT1 in glioma is still unknown. The aim of the present study was to investigate the role of PVT1 in glioma, and its potential association with microRNA (miR)-200a. miR-200a mimics and small interfering (si)RNA transfection were utilized to construct miR-200a overexpression and knockdown models to investigate the effect of miR-200a on glioma cells. Slow-virus infection was used to transfect cells. Western blotting and reverse transcription-quantitative polymerase chain reaction were applied for the quantitative analysis of mRNA and protein expression. Apoptosis of podocytes was detected by terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling staining. PVT1 expression in glioma was upregulated. In vitro, PVT1 silencing via transfection with si-PVT1 suppressed proliferation and invasion and induced G0/G1 phase arrest. Luciferase reporter assay revealed the association between miR-200a and the PVT1 3'-untranslated region. Furthermore, experiments examining both miR-200a and PVT1 indicated that miR-200a could reverse the effects of PVT1 on glioma cell phenotypes. The present study reveals the overexpression of PVT1 in glioma tissue and cells and the oncogenic role of PVT1 in gliomagenesis via sponging miR-200a, thus providing a potential biomarker for the early detection of glioma and prognosis prediction.

LncRNAs on guard

Long noncoding RNAs (lncRNAs) are emerging as crucial regulators of gene expression in immune system. It has been reported that lncRNAs participate in regulation of immune responses through both transcriptional and post-transcriptional mechanisms. In this review, we summarize the molecular functions of lncRNAs and discuss their binding to DNA, RNA and protein targets. We focus on the regulatory function of lncRNAs in both innate and adaptive immunity, as well as in autoimmunity and cancer immunology. In addition, we point out the limitation in current knowledge and future directions for the study of lncRNAs in the immune system.

Long non-coding RNA HOTAIR promotes tumorigenesis and forecasts a poor prognosis in cholangiocarcinoma

Cholangiocarcinoma (CCA) arising from the neoplastic transformation of cholangiocytes with increasing incidence in the worldwide. Unfortunately, a large amount of CCA patients lost their chance for surgery because it is hard to diagnose in the early stages. Long non-coding RNAs (lncRNAs) is closely associated with development and progression of various malignant tumors. Hox transcript antisense intergenic (HOTAIR), a negative prognostic factor for patients with gastric, liver and pancreatic carcinoma. Its transcription levels and functional roles in CCA is still unknown. Therefore, we aimed to explore the effect of HOTAIR in CCA including cell proliferation, apoptosis, migration, invasion and epithelial-to-mesenchymal transition (EMT). The results showed that HOTAIR was highly expressed both in CCA tissue samples and cell lines compared with corresponding normal bile duct tissues and Human intrahepatic biliary epithelial cells (HIBEC). Its overexpression was closely correlated with Tumor size, TNM stage and postoperative recurrence in CCA patients. Moreover, up-regulation of HOTAIR has correlation with prognosis in CCA patients. Knockdown of HOTAIR by siRNAs significantly decreased the migration and invasion but increased apoptosis of CCA cells in vitro. Overall, our study revealed that HOTAIR may play as a new potential therapeutic target and forecast poor prognosis for this fatal disease.

A non-canonical tumor suppressive role for the long non-coding RNA MALAT1 in colon and breast cancers

Long noncoding RNAs (lncRNAs) constitute one of the largest classes of transcripts and have been widely implicated in various diseases such as cancer. Increasing evidence suggests that several lncRNAs are dysregulated and play critical roles in tumorigenesis. LncRNAs can be regulated by key oncogenes and tumor suppressors, adding complexity to the intricate crosstalk between protein coding genes and the noncoding transcriptome. In our study, we investigated the effect that dysregulation of the key tumor suppressor PTEN has on the noncoding transcriptome. We identified the lncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) as a target of PTEN and find that this regulation is conserved in both human and mouse as well as with both chronic and acute PTEN dysregulation. We show that this regulation is at least in part microRNA (miRNA)-dependent, and characterize the miRNAs that may be mediating this crosstalk. In summary, we establish and characterize a non-canonical PTEN-microRNA-MALAT1 axis that regulates tumorigenesis and describe for the first time that the MALAT1 lncRNA possesses novel tumor suppressive properties in colon and breast cancers.

HOTAIR gene polymorphisms contribute to increased neuroblastoma susceptibility in Chinese children

BACKGROUND

Neuroblastoma is the most frequently diagnosed extracranial solid tumor in children. Previous studies have shown that single-nucleotide polymorphisms in some genes are associated with the risk of multiple cancers, including neuroblastoma. Although Hox transcript antisense intergenic RNA (HOTAIR) gene polymorphisms have been investigated in a variety of cancers, to the authors' knowledge the relationships between HOTAIR gene polymorphisms and neuroblastoma susceptibility have not been reported to date. The objective of the current study was to evaluate the correlation between HOTAIR gene polymorphisms and neuroblastoma risk in Chinese children.

METHODS

The authors genotyped 6 polymorphisms (rs920778 A>G, rs12826786 C>T, rs4759314 A>G, rs7958904 G>C, rs874945 C>T, and rs1899663 C>A) of the HOTAIR gene in 2 Chinese populations including 393 neuroblastoma cases and 812 healthy controls. The strength of the associations was evaluated using odds ratios and 95% confidence intervals. Further stratification analyses were conducted to explore the association between the HOTAIR gene polymorphisms rs12826786 C>T, rs874945 C>T, and rs1899663 C>A with neuroblastoma susceptibility in terms of age, sex, clinical stage of disease, and sites of origin.

RESULTS

The authors found that the rs12826786 C>T (P =.013), rs874945 C>T (P =.020), and rs1899663 C>A (P =.029) polymorphisms were significantly associated with increased neuroblastoma risk. In stratification analyses, these associations were more predominant in females and among patients with tumor in the retroperitoneal region or mediastinum. The remaining 3 polymorphisms were not found to be related to neuroblastoma susceptibility.

CONCLUSIONS

The results of the current study verified that HOTAIR gene polymorphisms are associated with increased neuroblastoma risk and suggest that HOTAIR gene polymorphisms might be a potential biomarker for neuroblastoma susceptibility. Cancer 2018;124:2599-606. © 2018 American Cancer Society.

Long non-coding RNA expression profiles reveals AK098783 is a biomarker to predict poor prognosis in patients with colorectal cancer

Background

Long non-coding RNAs (lncRNAs) have essential regulatory function, yet their roles in colorectal cancer (CRC) are not well understood.

Materials and methods

Microarray was applied to detect lncRNAs expression profiles in tumor tissues, liver metastasis and paired adjacent normal tissues of CRC. And using RT-PCR to verify chip results.

Results

A total of 10 680 lncRNAs demonstrated differential expressions (fold change ≥2) between tumor tissues and adjacent normal tissues; furthermore there were 2970 lncRNAs, which showed different expression level between CRC tissues with liver metastasis and adjacent normal tissues. Especially, lncRNA-AK098783 expression level was frequently higher in cancerous tissues than corresponding noncancerous tissue. Higher AK098783 expression was significantly correlated with shortened overall survival (P < 0.001) and distant metastasis (P < 0.001).

Conclusions

Our results suggest that AK098783 is involved in distant metastasis and dramatically associated with poor prognosis in patients with CRC.

LincRNA 1700020I14Rik alleviates cell proliferation and fibrosis in diabetic nephropathy via miR-34a-5p/Sirt1/HIF-1α signaling

Long intergenic noncoding RNAs (lincRNAs) have been gradually identified to be functional in a variety of different mechanisms associating with development and epigenetic regulation of cellular homeostasis. However, the study of lincRNAs in diabetic nephropathy (DN) is still in its infancy. Here, we have found dysexpressed long noncoding RNAs (lncRNAs) in renal tissues of db/db DN mice compared with db/m mice by RNA sequencing. In this study, 5 lincRNAs were confirmed to express in a consistent trend among these DN-related lncRNAs both in vivo and in vitro. Particularly, 1700020I14Rik was the downregulated one. Moreover, our data showed overexpression or knockdown of 1700020I14Rik could regulate cell proliferation and fibrosis in mouse mesangial cells (MCs). Furthermore, 1700020I14Rik was found to interact with miR-34a-5p via both the directly targeting way by bioinformatic investigation and luciferase assay and the Ago2-dependent manner by RIP assay. Results also displayed that overexpression of 1700020I14Rik inhibited cell proliferation and expressions of renal fibrosis markers through miR-34a-5p/Sirt1/HIF-1α pathway in MCs under high glucose condition, while knockdown of 1700020I14Rik could increase cell proliferation and expressions of renal fibrosis markers. In conclusion, these results provide new insights into the regulation between 1700020I14Rik and miR-34a-5p/Sirt1/HIF-1α signaling pathway during the progression of DN.

MicroRNA-203 Inhibits Long Noncoding RNA HOTAIR and Regulates Tumorigenesis through Epithelial-to-mesenchymal Transition Pathway in Renal Cell Carcinoma

This study aims to investigate the role of miR-203-HOTAIR interaction in the suppression of renal cell carcinoma (RCC). We employed series of in vitro assays such as proliferation, invasion, migration, and colony formation along with in vivo tumor xenograft model. Profiling of miR-203 and HOTAIR expression revealed that miR-203 was significantly underexpressed, whereas HOTAIR was overexpressed in RCC cell lines and clinical specimens compared with normal cell line and tissue. Both miR-203 and HOTAIR expression significantly distinguished malignant from normal tissues and significantly correlated with clinicopathologic characteristics of patients. Overexpression of miR-203 significantly inhibited proliferation, migration, and invasion with an induction of apoptosis and cell-cycle arrest. However, HOTAIR suppression resulted in the similar functional effects in the same RCC cell lines. In silico, RNA-22 algorithm showed a binding site for miR-203 in HOTAIR. We observed a direct interaction between miR-203 and HOTAIR by RNA-immunoprecipitation (RIP) and luciferase reporter assays. We show that miR-203-HOTAIR interaction resulted in the inhibition of epithelial-to-mesenchymal transition (EMT) and metastatic genes as indicated by induction of key metastasis-suppressing proteins E-cadherin, claudin (epithelial markers), and PTEN along with induction of tumor suppressor genes p21 and p27. A significant decrease in vimentin (mesenchymal marker), KLF4, and Nanog (stemness markers) was also observed. This is the first report demonstrating miR-203-mediated regulation of HOTAIR induces tumor suppressor effects in RCC by regulating EMT and metastatic pathway genes. Thus, the study suggests that therapeutic regulation of HOTAIR by miR-203 overexpression may provide an opportunity to regulate RCC growth and metastasis. Mol Cancer Ther; 17(5); 1061-9. ©2018 AACR.

Long non-coding RNAs in renal cell carcinoma: A systematic review and clinical implications

Renal cell carcinoma is one of the most common malignancy in adults, its prognosis is poor in an advanced stage and early detection is difficult due to the lack of molecular biomarkers. The identification of novel biomarkers for RCC is an urgent and meaningful project. Long non-coding RNA (lncRNA) is transcribed from genomic regions with a minimum length of 200 bases and limited protein-coding potential. Recently, lncRNAs have been greatly studied in a variety of cancer types. They participate in a wide variety of biological processes including cancer biology. In this review, we provide a new insight of the profiling of lncRNAs in RCC and their roles in renal carcinogenesis, with an emphasize on their potential in diagnosis, prognosis and potential roles in RCC therapy.

Non-coding RNAs: long non-coding RNAs and microRNAs in endocrine-related cancers

The human genome is 'pervasively transcribed' leading to a complex array of non-coding RNAs (ncRNAs) that far outnumber coding mRNAs. ncRNAs have regulatory roles in transcription and post-transcriptional processes as well numerous cellular functions that remain to be fully described. Best characterized of the 'expanding universe' of ncRNAs are the ~22 nucleotide microRNAs (miRNAs) that base-pair to target mRNA's 3' untranslated region within the RNA-induced silencing complex (RISC) and block translation and may stimulate mRNA transcript degradation. Long non-coding RNAs (lncRNAs) are classified as >200 nucleotides in length, but range up to several kb and are heterogeneous in genomic origin and function. lncRNAs fold into structures that interact with DNA, RNA and proteins to regulate chromatin dynamics, protein complex assembly, transcription, telomere biology and splicing. Some lncRNAs act as sponges for miRNAs and decoys for proteins. Nuclear-encoded lncRNAs can be taken up by mitochondria and lncRNAs are transcribed from mtDNA. Both miRNAs and lncRNAs are dysregulated in endocrine cancers. This review provides an overview on the current understanding of the regulation and function of selected lncRNAs and miRNAs, and their interaction, in endocrine-related cancers: breast, prostate, endometrial and thyroid.

Hepatitis B Virus-Associated Hepatocellular Carcinoma and Hepatic Cancer Stem Cells

Chronic Hepatitis B Virus (HBV) infection is linked to hepatocellular carcinoma (HCC) pathogenesis. Despite the availability of a HBV vaccine, current treatments for HCC are inadequate. Globally, 257 million people are chronic HBV carriers, and children born from HBV-infected mothers become chronic carriers, destined to develop liver cancer. Thus, new therapeutic approaches are needed to target essential pathways involved in HCC pathogenesis. Accumulating evidence supports existence of hepatic cancer stem cells (hCSCs), which contribute to chemotherapy resistance and cancer recurrence after treatment or surgery. Understanding how hCSCs form will enable development of therapeutic strategies to prevent their formation. Recent studies have identified an epigenetic mechanism involving the downregulation of the chromatin modifying Polycomb Repressive Complex 2 (PRC2) during HBV infection, which results in re-expression of hCSC marker genes in infected hepatocytes and HBV-associated liver tumors. However, the genesis of hCSCs requires, in addition to the expression of hCSC markers cellular changes, rewiring of metabolism, cell survival, escape from programmed cell death, and immune evasion. How these changes occur in chronically HBV-infected hepatocytes is not yet understood. In this review, we will present the basics about HBV infection and hepatocarcinogenesis. Next, we will discuss studies describing the mutational landscape of liver cancers and how epigenetic mechanisms likely orchestrate cellular reprograming of hepatocytes to enable formation of hCSCs.

LncRNA HOTAIR influences cell growth, migration, invasion, and apoptosis via the miR-20a-5p/HMGA2 axis in breast cancer

To study the regulatory effect of lncRNA HOTAIR/miR-20a-5p/HMGA2 axis on breast cancer (BC) cell growth, cell mobility, invasiveness, and apoptosis. The microarray data of lncRNAs and mRNAs with differential expression in BC tissues were analyzed in the Cancer Genome Atlas (TCGA) database. LncRNA HOX transcript antisense RNA (lncRNA HOTAIR) expression in BC was assessed by qRT-PCR. Cell viability was confirmed using MTT and colony formation assay. Cell apoptosis was analyzed by TdT-mediated dUTP nick-end labeling (TUNEL) assay. Cell mobility and invasiveness were testified by transwell assay. RNA pull-down and dual luciferase assay were used for analysis of the correlation between lncRNA HOTAIR and miR-20a-5p, as well as relationship of miR-20a-5p with high mobility group AT-hook 2 (HMGA2). Tumor xenograft study was applied to confirm the correlation of lncRNA HOTAIR/miR-20a-5p/HMGA2 axis on BC development in vivo. The expression levels of the lncRNA HOTAIR were upregulated in BC tissues and cells. Knockdown lncRNA HOTAIR inhibited cell propagation and metastasis and facilitated cell apoptosis. MiR-20a-5p was a target of lncRNA HOTAIR and had a negative correlation with lncRNA HOTAIR. MiR-20a-5p overexpression in BC suppressed cell growth, mobility, and invasiveness and facilitated apoptosis. HMGA2 was a target of miR-20a-5p, which significantly induced carcinogenesis of BC. BC cells progression was mediated by lncRNA HOTAIR via affecting miR-20a-5p/HMGA2 in vivo. LncRNA HOTAIR affected cell growth, metastasis, and apoptosis via the miR-20a-5p/HMGA2 axis in breast cancer.

Long noncoding RNAs in gastric cancer carcinogenesis and metastasis

Recent studies of the human transcriptome, most prominently by the ENCyclopedia Of DNA Elements project, have revealed an unexpected number of noncoding RNAs (ncRNAs). Long noncoding RNAs (lncRNAs) are typically referred to a heterogeneous group of polyadenylated long ncRNAs, with a length of > 200 nt. LncRNAs constitute an integral part of tumor biology, with many lncRNAs discovered to be aberrantly expressed in various cancer types. They are involved in many aspects of cancer pathogenesis from its initiation to progression, metastasis and treatment response. Gastric cancer (GC) is the third leading cause of cancer death worldwide. Despite the current improvements of life expectancy and survival rate, most of the patients are diagnosed when their cancer has been progressed to advanced stages. Therefore, unraveling the molecular mechanisms of GC to find early-stage biomarkers is urgent. As the list of lncRNAs with deregulated expression in GC is steadily expanding, these molecules offer a source for developing GC-specific biomarkers. In this review, we will present and discuss those lncRNAs whose expression has been shown to be deregulated in GC.

LncRNAs in pancreatic cancer

Pancreatic cancer (PC) is one of the most common causes of cancer-related death. The underlying mechanism of PC is not completely understood at present. Studies in recent years have demonstrated that long non-coding RNAs (lncRNAs) have multiple biological functions in cell growth, differentiation and proliferation. Notably, expressions of some lncRNAs undergo significant changes in the initiation and progression of cancers. In addition, lncRNAs are reported to be involved in various steps of PC development and have a potential value in the diagnosis, treatment and prognostic prediction of PC. In this review, we highlight recent evidence related to the molecular mechanism of lncRNAs in growth, survival, invasion, metastasis, angiogenesis and apoptosis of PC cells, and discuss the potential clinical application of lncRNAs to the diagnosis, treatment and prognostic prediction of PC.

Association between the HOTAIR polymorphisms and cancer risk: an updated meta-analysis

Purpose

LncRNA HOTAIR plays an important role in many cancer. Several studies have shown that some HOTAIR SNPs might be associated with tumor risk in case-control studies, but the results are inconsistent and inconclusive. Therefore, it is necessary to better evaluate association between the HOTAIR SNPs and the risk of cancer.

Results

rs920778, rs7958904 and rs874945 but not rs4759314 and rs1899663 loci were significantly related to cancer risk, among of which rs920778 and rs874945 increased and rs7958904 decreased cancer risk, respectively. Moreover, rs920778 is significantly susceptible in both Asian population and digestive cancer risks.

Materials and Methods

Data were collected from PubMed, Embase and Web of Science. A total of 11 case-control studies were selected for the quantitative analysis. Software Stata (Version 12) was used to calculate Odds ratios (ORs) and 95% confidence intervals (CIs) to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and publication bias were also performed. Five HOTAIR SNPs were finally enrolled in the study.

Conclusions

HOTAIR SNP rs920778, rs7958904 and rs874945 are susceptible to cancer risk. SNP rs920778 is also a useful risk factor in evaluation of Asian population and digestive cancer. In addition, the cancer risk SNP rs874945 is first reported in the meta-analysis.

SPION-mediated miR-141 promotes the differentiation of HuAESCs into dopaminergic neuron-like cells via suppressing lncRNA-HOTAIR

In this study, a bioinformatics analysis and luciferase reporter assay revealed that microRNA‐141 could silence the expression of lncRNA‐HOTAIR by binding to specific sites on lncRNA‐HOTAIR. We used superparamagnetic iron oxide nanoparticles (SPIONs) to mediate the high expression of microRNA‐141 (SPIONs@miR‐141) in human amniotic epithelial stem cells (HuAESCs), which was followed by the induction of the differentiation of HuAESCs into dopaminergic neuron‐like cells (iDNLCs). qPCR, western blot, immunofluorescence staining and HPLC all suggested that SPION‐mediated overexpression of miR‐141 could promote an increased expression of brain‐derived neurotrophic factor (BDNF), DAT and 5‐TH in HuAESC‐derived iDNLCs. The RIP and ChIP assay also showed that overexpression of miR‐141 could significantly inhibit the recruitment and binding of lncRNA‐HOTAIR to EZH2 on BDNF gene promoter. cDNA microarray analysis revealed that the expression levels of 190 genes were much higher in iDNLCs than in HuAESCs. Finally, a protein interaction network analysis and identification showed that in the iDNLC group with SPIONs@miR‐141, factors that interact with BDNF, such as FGF8, SHH, NTRK3 and CREB1, all showed significantly higher expression levels compared with those in the SPIONs@miR‐Mut. Therefore, this study confirmed that the highly efficient expression of microRNA‐141 mediated by SPIONs could improve the efficiency of HuAESCs differentiation into dopaminergic neuron‐like cells.

Epigenetics and MicroRNAs in Cancer

The ability to reprogram the transcriptional circuitry by remodeling the three-dimensional structure of the genome is exploited by cancer cells to promote tumorigenesis. This reprogramming occurs because of hereditable chromatin chemical modifications and the consequent formation of RNA-protein-DNA complexes that represent the principal actors of the epigenetic phenomena. In this regard, the deregulation of a transcribed non-coding RNA may be both cause and consequence of a cancer-related epigenetic alteration. This review summarizes recent findings that implicate microRNAs in the aberrant epigenetic regulation of cancer cells.

Interaction and cross-talk between non-coding RNAs

Non-coding RNA (ncRNA) has been shown to regulate diverse cellular processes and functions through controlling gene expression. Long non-coding RNAs (lncRNAs) act as a competing endogenous RNAs (ceRNAs) where microRNAs (miRNAs) and lncRNAs regulate each other through their biding sites. Interactions of miRNAs and lncRNAs have been reported to trigger decay of the targeted lncRNAs and have important roles in target gene regulation. These interactions form complicated and intertwined networks. Certain lncRNAs encode miRNAs and small nucleolar RNAs (snoRNAs), and may regulate expression of these small RNAs as precursors. SnoRNAs have also been reported to be precursors for PIWI-interacting RNAs (piRNAs) and thus may regulate the piRNAs as a precursor. These miRNAs and piRNAs target messenger RNAs (mRNAs) and regulate gene expression. In this review, we will present and discuss these interactions, cross-talk, and co-regulation of ncRNAs and gene regulation due to these interactions.

Targetable long non-coding RNAs in cancer treatments

Aberrant expression of many long non-coding RNAs has been observed in various types of cancer, implicating their crucial roles in tumorigenesis and cancer progression. Emerging knowledge with regard to the critical physiological and pathological roles of long non-coding RNAs in cancers makes them potential targets in cancer treatments. In this review, we present a summary of the relatively well studied long non-coding RNAs that are involved in oncogenesis and outline their functions and functional mechanisms. Recent findings that may be utilized in therapeutic intervention are also highlighted. With the fast development in nucleic acid-based therapeutic reagents that can target disease associated RNAs, lncRNAs should be explored as potential targets in cancer treatments.

The long non-coding RNA HOTAIR increases tumour growth and invasion in cervical cancer by targeting the Notch pathway

Evidence suggests that the long non-coding RNA (lncRNA), HOTAIR, is involved in cervical cancer pathogenesis. We examined serum HOTAIR expression levels in cervical cancer patients and determined the relationships between HOTAIR expression and several clinicopathological factors, including survival. We also examined the functional consequences of HOTAIR overexpression both in vitro and in vivo. Compared with control patients, HOTAIR expression was significantly greater in the serum of cervical cancer patients (P < 0.001). The results indicated that this increase was significantly associated with tumour size (P = 0.030), lymphovascular space invasion (P = 0.037), and lymph node metastasis (P = 0.043). Univariate analysis revealed that disease-free survival and overall survival times were significantly shorter in cervical cancer patients with high HOTAIR expression (hazard ratio [HR] = 4.27, 4.68 and P = 0.039, 0.031, respectively). Cell proliferation and invasion in vitro increased as a result of lentiviral-mediated HOTAIR overexpression in cervical cancer cell lines. HOTAIR knockdown inhibited these properties and increased apoptosis. In vivo xenograft experiments using the HOTAIR-overexpressing SiHa cell line revealed that HOTAIR was a strong inducer of tumour growth and modulated the expression of epithelial-mesenchymal transition and Notch-Wnt signalling pathway-related genes. This result suggested that HOTAIR overexpression promoted cell proliferation and invasion. In conclusion, increased HOTAIR expression was associated with decreased patient survival times. HOTAIR may be a useful target for treatment of cervical cancer patients.

Impact of HOTAIR Gene Polymorphism and Environmental Risk on Oral Cancer

Genetic and acquired factors are thought to be interrelated and imperative to estimate the risk and prognosis of oral squamous cell carcinoma (OSCC). HOX transcript antisense intergenic RNA ( HOTAIR) plays crucial roles in gene regulation and is regulated in a variety of cancers. Polymorphisms in HOTAIR have been recently linked to the predisposition to diverse malignancies. In the present study, we aimed to evaluate the influences of HOTAIR gene polymorphisms, combined with environmental triggers, on the susceptibility to oral tumorigenesis. Four single-nucleotide polymorphisms of the HOTAIR gene— rs920778, rs1899663, rs4759314, and rs12427129—were tested in 1,200 control participants and 907 patients with OSCC. We detected a significant association of rs1899663 with the risk of OSCC (adjusted odds ratio, 2.227; 95% confidence interval [95% CI], 1.197 to 4.146; P = 0.012) after adjustment for 3 potential confounders: smoking, betel quid chewing, and alcohol consumption. In further analyses where habitual exposure to each of 3 environmental factors was excluded, we found that, in addition to rs1899663, non–betel quid users who carried the polymorphic allele of rs920778 were more prone to develop OSCC than were those homozygous for wild-type allele (TC: odds ratio [OR], 1.472; 95% CI, 1.069 to 2.029; P = 0.018; TC+CC: OR, 1.448; 95% CI, 1.060 to 1.977; P = 0.020). Moreover, in exploring the relationship between HOTAIR gene polymorphisms and the clinical status of only patients with OSCC who were non–betel quid chewers (excluding the advanced clinical stage), we found that rs920778 and rs4759314 were correlated with the development of large-size tumors (OR, 1.891; 95% CI, 1.027 to 3.484; P = 0.04) and increased lymph node metastasis (OR, 4.140; 95% CI, 1.785 to 9.602; P = 0.001), respectively. Further functional assessments link rs920778 to the regulation of HOTAIR expression and epigenetic status. Our results reveal an interactive effect of HOTAIR gene polymorphisms and betel quid chewing on the development and progression of oral cancer.

PIWIL3/OIP5-AS1/miR-367-3p/CEBPA feedback loop regulates the biological behavior of glioma cells

Rationale: PIWI-interacting RNAs (piRNAs), a class of newly discovered small RNA molecules that function by binding to the Argonaute protein family (i.e., the PIWIL protein subfamily), and long noncoding RNAs (lncRNA) are implicated in several cancers. However, the detailed roles of ncRNAs in glioma remain unclear.

Methods: The expression of PIWIL3, piR-30188, OIP5-AS1, miR-367, CEBPA and TRAF4 were measured in glioma tissues and cells. The role of PIWIL3/OIP5-AS1/miR-367-3p/CEBPA feedback loop was evaluated in cell and animal models. The association of the above molecules was analyzed.

Results: Over-expression of PIWIL3, piR-30188 and miR-367-3p or knockdown of OIP5-AS1 resulted in inhibition of glioma cells progression. Binding sites between piR-30188 and OIP5-AS1 as well as between OIP5-AS1 and miR-367-3p were confirmed by RNA immunoprecipitation and luciferase assays. OIP5-AS1 knockdown or miR-367-3p over-expression contributed to a decrease in CEBPA (CCAAT/enhancer binding protein alpha) protein. Furthermore, CEBPA was detected as a target of miR-367-3p and played an oncogenic role in glioma. Treatment with CEBPA and miR-367-3p resulted in the modulation of downstream TRAF4 (TNF receptor-associated factor 4). PIWIL3 was also a target of CEBPA, forming a positive feedback loop in the growth regulation of glioma cells. Significantly, knockdown of OIP5-AS1 combined with over-expression of PIWIL3 and miR-367-3p resulted in tumor regression and extended survival in vivo.

Conclusion: These results identified a novel molecular pathway in glioma cells that may provide a potential innovative approach for tumor therapy.

HOTAIR Long Non-coding RNA: Characterizing the Locus Features by the In Silico Approaches

HOTAIR is an lncRNA that has been known to have an oncogenic role in different cancers. There is limited knowledge of genetic and epigenetic elements and their interactions for the gene encoding HOTAIR. Therefore, understanding the molecular mechanism and its regulation remains to be challenging. We used different in silico analyses to find genetic and epigenetic elements of HOTAIR gene to gain insight into its regulation. We reported different regulatory elements including canonical promoters, transcription start sites, CpGIs as well as epigenetic marks that are potentially involved in the regulation of HOTAIR gene expression. We identified repeat sequences and single nucleotide polymorphisms that are located within or next to the CpGIs of HOTAIR. Our analyses may help to find potential interactions between genetic and epigenetic elements of HOTAIR gene in the human tissues and show opportunities and limitations for researches on HOTAIR gene in future studies.

Epigenetic modification of miR-141 regulates SKA2 by an endogenous 'sponge' HOTAIR in glioma

Aberrant expression of miR-141 has recently implicated in the occurrence and development of various types of malignant tumors. However whether the involvement of miR-141 in the pathogenesis of glioma remains unknown. Here, we showed that miR-141 was markedly downregulated in glioma tissues and cell lines compared with normal brain tissues, and its expression correlated with the pathological grading. Enforced expression of miR-141 in glioma cells significantly inhibited cell proliferation, migration and invasion, whereas knockdown of miR-141 exerted opposite effect. Mechanistic investigations revealed that HOTAIR might act as an endogenous 'sponge' of miR-141, thereby regulating the derepression of SKA2. Further, we explored the molecular mechanism by which miR-141 expression was regulated, and found that the miR-141 promoter was hypermethylated and that promoter methylation of miR-141 was mediated by DNMT1 in glioma cells. Finally, both overexpression of miR-141 and knockdown of HOTAIR in a mouse model of human glioma resulted in significant reduction of tumor growth in vivo. Collectively, these results suggest that epigenetic modification of miR-141 and the interaction of ceRNA regulatory network will provide a new approach for therapeutics against glioma.

Negative regulation of lncRNA GAS5 by miR-196a inhibits esophageal squamous cell carcinoma growth

MiR-196a could play important roles in carcinogenesis by targeting many protein coding genes. However, little is known about whether miR-196a can target any long non-coding RNAs (lncRNAs). In the present study, we screen lncRNAs which are regulated by miRNA-196a in human esophageal squamous cell carcinoma (ESCC). We found that miR-196a could suppress the expression of lncRNA growth arrest-specific 5(GAS5). GAS5 is frequently down-regulated in 86 paired human ESCC tissues. Importantly, there was lower GAS5 expression in the late stage of ESCC patients. The reduced expression of GAS5 in ESCC may not be related to DNA methylation but related to the high expression of miR-196a. In vitro and in vivo studies indicated that GAS5 could inhibit the growth of ESCC cells. Using Chromatin Isolation by RNA Purification-qPCR, we found that miR-196a could bind to GAS5. The Luciferase Reporter Assay indicated that miR-196a could bind to the seventh exon of GAS5. Additionally, both GAS5 and miR-196a could bind to Ago2 which is a key component of the RNA-induced silencing complex (RISC). Together, these results suggest that GAS5 functions as a tumor suppressor gene in ESCC and is regulated by miR-196a involved in RISC.