HOTAIR promotes osteosarcoma development by sponging miR-217 and targeting ZEB1

Osteosarcoma in a ceRNET perspective

Osteosarcoma (OS) is the most prevalent and fatal type of bone tumor. It is characterized by great heterogeneity of genomic aberrations, mutated genes, and cell types contribution, making therapy and patients management particularly challenging. A unifying picture of molecular mechanisms underlying the disease could help to transform those challenges into opportunities.This review deeply explores the occurrence in OS of large-scale RNA regulatory networks, denominated "competing endogenous RNA network" (ceRNET), wherein different RNA biotypes, such as long non-coding RNAs, circular RNAs and mRNAs can functionally interact each other by competitively binding to shared microRNAs. Here, we discuss how the unbalancing of any network component can derail the entire circuit, driving OS onset and progression by impacting on cell proliferation, migration, invasion, tumor growth and metastasis, and even chemotherapeutic resistance, as distilled from many studies. Intriguingly, the aberrant expression of the networks components in OS cells can be triggered also by the surroundings, through cytokines and vesicles, with their bioactive cargo of proteins and non-coding RNAs, highlighting the relevance of tumor microenvironment. A comprehensive picture of RNA regulatory networks underlying OS could pave the way for the development of innovative RNA-targeted and RNA-based therapies and new diagnostic tools, also in the perspective of precision oncology.

Extracellular vesicles in endometriosis: role and potential

Endometriosis is a chronic inflammatory gynecological disease, which profoundly jeopardizes women's quality of life and places a significant medical burden on society. The pathogenesis of endometriosis remains unclear, posing major clinical challenges in diagnosis and treatment. There is an urgent demand for the development of innovative non-invasive diagnostic techniques and the identification of therapeutic targets. Extracellular vesicles, recognized for transporting a diverse array of signaling molecules, have garnered extensive attention as a novel mode of intercellular communication. A burgeoning body of research indicates that extracellular vesicles play a pivotal role in the pathogenesis of endometriosis, which may provide possibility and prospect for both diagnosis and treatment. In light of this context, this article focuses on the involvement of extracellular vesicles in the pathogenesis of endometriosis, which deliver information among endometrial stromal cells, macrophages, mesenchymal stem cells, and other cells, and explores their potential applications in the diagnosis and treatment, conducing to the emergence of new strategies for clinical diagnosis and treatment.

Emerging roles of long non-coding RNAs in osteosarcoma

Osteosarcoma (OS) is a highly aggressive and lethal malignant bone tumor that primarily afflicts children, adolescents, and young adults. However, the molecular mechanisms underlying OS pathogenesis remain obscure. Mounting evidence implicates dysregulated long non-coding RNAs (lncRNAs) in tumorigenesis and progression. These lncRNAs play a pivotal role in modulating gene expression at diverse epigenetic, transcriptional, and post-transcriptional levels. Uncovering the roles of aberrant lncRNAs would provide new insights into OS pathogenesis and novel tools for its early diagnosis and treatment. In this review, we summarize the significance of lncRNAs in controlling signaling pathways implicated in OS development, including the Wnt/β-catenin, PI3K/AKT/mTOR, NF-κB, Notch, Hippo, and HIF-1α. Moreover, we discuss the multifaceted contributions of lncRNAs to drug resistance in OS, as well as their potential to serve as biomarkers and therapeutic targets. This review aims to encourage further research into lncRNA field and the development of more effective therapeutic strategies for patients with OS.

Long intergenic non-coding RNA DIO3OS promotes osteosarcoma metastasis via activation of the TGF-β signaling pathway: a potential diagnostic and immunotherapeutic target for osteosarcoma

BACKGROUND

The aim of this study was to determine the underlying potential mechanisms and function of DIO3OS, a lincRNA in osteosarcoma and clarify that DIO3OS can be used as a potential diagnostic biomarker and immunotherapeutic target.

METHODS

The expression matrix data and clinical information were obtained from XENA platform of UCSC and GEO database as the test cohorts. The external validation cohort was collected from our hospital. Bioinformatics analysis was used to annotate the biological function of DIO3OS. Immune infiltration and immune checkpoint analysis were applied to evaluate whether DIO3OS can be used as an immunotherapeutic target. ROC curves and AUC were established to assess the diagnostic value of DIO3OS for differentiating patients from other subtypes sarcoma. The expression analysis was detected by qRT-PCR, western blot, and immunohistochemical. Wound healing assay and Transwell assay were applied to determine the migration and invasion function of DIO3OS in osteosarcoma cell lines. The tail vein injection osteosarcoma cells metastases model was used in this research.

RESULTS

High expression of DIO3OS was identified as a risk lincRNA for predicting overall survival of osteosarcoma in test cohort. The outcomes of experiments in vitro and in vivo showed that low expression of DIO3OS limited osteosarcoma tumor metastasis with inhibiting TGF-β signaling pathway. Immune checkpoint genes (CD200 and TNFRSF25) expressions were inhibited in the low DIO3OS expression group. The DIO3OS expression can be applied to reliably distinguish osteosarcoma from lipomatous neoplasms, myomatous neoplasms, nerve sheath tumors, and synovial-like neoplasms. This result was further validated in the validation cohort.

CONCLUSIONS

In conclusion, our outcomes indicated that DIO3OS is a potential diagnostic and prognostic biomarker of osteosarcoma, emphasizing its potential as a target of immunotherapy to improve the treatment of osteosarcoma through TGF-β signaling pathway.

TRIAL REGISTRATION NUMBER

The present retrospectively study was approved by the Ethics Committee of The Second Affiliated Hospital of Nanchang University [Review (2020) No. (115)].

Noncoding RNA as an influential epigenetic modulator with promising roles in cancer therapeutics

The epigenetic landscape has an important role in cellular homeostasis and its deregulation leads to cancer. Noncoding (nc)RNA networks function as major regulators of cellular epigenetic hallmarks via regulation of vital processes, such as histone modification and DNA methylation. They are integral intracellular components affecting multiple oncogenic pathways. Thus, it is important to elucidate the effects of ncRNA networks on epigenetic programming that lead to the initiation and progression of cancer. In this review, we summarize the effects of epigenetic modification influenced by ncRNA networks and crosstalk between diverse classes of ncRNA, which could aid the development of patient-specific cancer therapeutics targeting ncRNAs, thereby altering cellular epigenetics.

Oncogenic Long Noncoding RNAs in Prostate Cancer, Osteosarcoma, and Metastasis

Prostate cancer (PC) is a common malignancy and is one of the leading causes of cancer-related death in men worldwide. Osteosarcoma (OS) is the most common bone cancer, representing 20-40% of all bone malignancy cases. Cancer metastasis is a process by which malignant tumor cells detach from the primary tumor site via a cascade of processes and migrate to secondary sites through the blood circulation or lymphatic system to colonize and form secondary tumors. PC has a specific affinity to the bone based on the "seed and soil" theory; once PC reach the bone, it becomes incurable. Several studies have identified long noncoding RNAs (lncRNAs) as potential targets for cancer therapy or as diagnostic and prognostic biomarkers. The dysregulation of various lncRNAs has been found in various cancer types, including PC, OS, and metastasis. However, the mechanisms underlying lncRNA oncogenic activity in tumor progression and metastasis are extremely complex and remain incompletely understood. Therefore, understanding oncogenic lncRNAs and their role in OS, PC, and metastasis and the underlying mechanism may help better manage and treat this malignancy. The aim of this review is to summarize current knowledge of oncogenic lncRNAs and their involvement in PC, OS, and bone metastasis.

Hox transcript antisense RNA knockdown inhibits osteosarcoma progression by regulating the phosphoinositide 3-kinase/AKT pathway through the microRNA miR-6888-3p/spleen tyrosine kinase axis

Long non-coding RNA HOX transcript antisense RNA (lncRNA HOTAIR) is thought to be a key regulator of the occurrence and development of osteosarcoma (OS). The expression of HOTAIR, microRNA miR-6888-3p, spleen tyrosine kinase (SYK), and phosphoinositide 3-kinase/AKT (PI3K/AKT) pathway-related proteins in OS was detected by quantitative reverse transcription-PCR (qRT-PCR) and western blotting. Changes in the proliferation and migration of OS cells were detected by Cell Counting Kit-8 (CCK-8) and transwell assays after the knockdown of HOTAIR, miR-6888-3p, or SYK. Luciferase assays, RNA immunoprecipitation (RIP), and RNA pull-down assays were used to detect the relationship between miR-6888-3p and HOTAIR or SYK. We found that HOTAIR and SYK were highly expressed in OS, whereas miR-6888-3p expression was low. In addition, downregulation of HOTAIR or SYK significantly inhibited the growth and migration of OS cells and the PI3K/AKT pathway, both in vitro and in vivo. Additionally, downregulation of miR-6888-3p promoted the proliferation and migration of OS cells and activated the PI3K/AKT pathway. Mechanistically, these results suggest that the HOTAIR sponge, miR-6888-3p, regulates SYK expression. To summarize, HOTAIR regulates SYK by acting on miR-6888-3p, thereby promoting the proliferation and migration of OS cells.

Exosomal lncRNA HOTAIR Promotes the Progression and Angiogenesis of Endometriosis via the miR-761/HDAC1 Axis and Activation of STAT3-Mediated Inflammation

Background

Long non-coding RNA (lncRNA) and exosomes are implicated in endometriosis development. We measured the expression of an exosomal lncRNA, homeobox transcript antisense RNA (HOTAIR), and explored its molecular mechanism in endometriosis progression.

Methods

Expression of HOTAIR and microRNA (miR)-761 in different endometrial tissues was measured. Exosomes were isolated from a culture medium of endometrial stromal cells (ESCs). RT-qPCR was used to measure HOTAIR expression in different exosome types. CCK-8, Edu, wound healing, transwell assays, flow cytometry and tube formation were used to detect the role of exosomal HOTAIR on ESCs and human umbilical vein endothelial cells (HUVECs). The relationship among miR-761, HOTAIR, and histone deacetylase 1 (HDAC1) was verified by dual-luciferase reporter assay. ESCs were transfected with miR-761 mimics or HDAC1 small interfering RNA (si-RNA) to ascertain if alterations in expression of miR-761 or HDAC1 could reverse the effect of exosomal HOTAIR. Then, we detected the effect of the HOTAIR/miR-761/HDAC1 axis on signal transducer and activator of transcription 3 (STAT3)-mediated inflammation. In vivo experiments were conducted to verify in vitro results.

Results

HOTAIR expression was upregulated and miR-761 expression was downregulated in ectopic endometrium tissues. HOTAIR was packaged into exosomes and transported from ESCs to surrounding cells. Exosomal HOTAIR promoted the proliferation, migration, and invasion, and inhibited the apoptosis of ESCs. Angiogenesis of HUVECs was enhanced after cultured with exosomal HOTAIR. HOTAIR acted as a competing endogenous RNA to downregulate miR-761 and increase HDAC1 expression. miR-761 overexpression or HDAC1 knockdown reversed the role of exosomal HOTAIR on ESCs and HUVECs. The HOTAIR/miR-761/HDAC1 axis could activate STAT3-related proinflammatory cytokines and stattic (inhibitor of phosphorylated-STAT3) could reverse the effect of HOTAIR on ESCs and HUVECs. In vivo experiments suggested that exosomal HOTAIR promoted the growth of endometrial lesions in vivo.

Conclusion

Exosomal HOTAIR promoted the progression and angiogenesis of endometriosis by regulating the miR-761/HDAC1 axis and activating STAT3-mediated inflammation in vitro and in vivo, which may provide promising treatment for endometriosis.

Progress of HOTAIR-microRNA in hepatocellular carcinoma

The Hox transcript antisense intergenic RNA (HOTAIR) has been identified as a tumor gene, and its expression in HCC is significantly increased. HOTAIR is associated with the proliferation, invasion, metastasis and poor prognosis of HCC. In addition, HOTAIR can also regulate the expression and function of microRNA by recruiting the polycomb repressive complex 2 (PRC2) and competitive adsorption, thus promoting the occurrence and development of HCC. In this review, we discussed the two mechanisms of HOTAIR regulating miRNA through direct binding miRNA and indirect regulation, and emphasized the role of HOTAIR in HCC through miRNA, explained the regulatory pathway of HOTAIR-miRNA-mRNA and introduced the role of this pathway in HCC proliferation, drug resistance, invasion and metastasis.

The Role of lncRNAs in Rare Tumors with a Focus on HOX Transcript Antisense RNA (HOTAIR)

Rare cancers are identified as those with an annual incidence of fewer than 6 per 100,000 persons and includes both epithelial and stromal tumors from different anatomical areas. The advancement of analytical methods has produced an accurate molecular characterization of most human cancers, suggesting a “molecular classification” that has allowed the establishment of increasingly personalized therapeutic strategies. However, the limited availability of rare cancer samples has resulted in very few therapeutic options for these tumors, often leading to poor prognosis. Long non coding RNAs (lncRNAs) are a class of non-coding RNAs mostly involved in tumor progression and drug response. In particular, the lncRNA HOX transcript antisense RNA (HOTAIR) represents an emergent diagnostic, prognostic and predictive biomarker in many human cancers. The aim of this review is to highlight the role of HOTAIR in rare cancers, proposing it as a new biomarker usable in the management of these tumors.

Oncogenic functions of ZEB1 in pediatric solid cancers: interplays with microRNAs and long noncoding RNAs

The transcription factor Zinc finger E-box binding 1 (ZEB1) displays a range of regulatory activities in cell function and embryonic development, including driving epithelial-mesenchymal transition. Several aspects of ZEB1 function can be regulated by its functional interactions with noncoding RNA types, namely microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). Increasing evidence indicates that ZEB1 importantly influences cancer initiation, tumor progression, metastasis, and resistance to treatment. Cancer is the main disease-related cause of death in children and adolescents. Although the role of ZEB1 in pediatric cancer is still poorly understood, emerging findings have shown that it is expressed and regulates childhood solid tumors including osteosarcoma, retinoblastoma, neuroblastoma, and central nervous system tumors. Here, we review the evidence supporting a role for ZEB1, and its interplays with miRNAs and lncRNAs, in pediatric cancers.

LncRNA HOTAIR: A Potential Prognostic Factor and Therapeutic Target in Human Cancers

Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of gene expression and physiological processes. LncRNAs are a class of ncRNAs of 200 nucleotides in length. HOX transcript antisense RNA (HOTAIR), a trans-acting lncRNA with regulatory function on transcription, can repress gene expression by recruiting chromatin modifiers. HOTAIR is an oncogenic lncRNA, and numerous studies have determined that HOTAIR is highly upregulated in a wide variety of human cancers. In this review, we briefly summarize the impact of lncRNA HOTAIR expression and functions on different human solid tumors, and emphasize the potential of HOTAIR on tumor prognosis and therapy. Here, we review the recent studies that highlight the prognostic potential of HOTAIR in drug resistance and survival, and the progress of therapies developed to target HOTAIR to date. Furthermore, targeting HOTAIR results in the suppression of HOTAIR expression or function. Thus, HOTAIR knockdown exhibits great therapeutic potential in various cancers, indicating that targeting lncRNA HOTAIR may serve as a promising strategy for cancer therapy. We also propose that preclinical studies involving HOTAIR are required to provide a better understanding of the exact molecular mechanisms underlying the dysregulation of its expression and function in different human cancers and to explore effective methods of targeting HOTAIR and engineering efficient and targeted drug delivery methods in vivo.

HOPMCLDA: predicting lncRNA-disease associations based on high-order proximity and matrix completion

In recent years, emerging evidence has shown that long noncoding RNAs (lncRNAs) have important roles in the biological processes of complex diseases. However, experiments to determine the associations between diseases and lncRNAs are time consuming and costly. Therefore, there is a need to develop effective computational methods for exploring potential lncRNA-disease associations. In this study, we present a computational prediction method based on high-order proximity and matrix completion to predict lncRNA-disease associations (HOPMCLDA). HOPMCLDA integrates explicit similarity and high-order proximity information on lncRNAs and diseases and constructs a heterogeneous disease-lncRNA network to utilize similarity information. Finally, nuclear norm regularization is carried out on the heterogeneous network for the recovery of a lncRNA-disease association matrix. By implementing leave-one-out cross validation (LOOCV) and five-fold cross validation (5-fold CV), we compare HOPMCLDA with five other methods. HOPMCLDA outperforms the other methods, with area under the receiver operating characteristic curve values of 0.8755 and 0.8353 ± 0.0045 using LOOCV and 5-fold CV, respectively. Furthermore, case studies of three human diseases (gastric cancer, osteosarcoma, and hepatocellular carcinoma) confirm the reliable predictive performance of HOPMCLDA.

Development of a Novel Immune Infiltration-Related ceRNA Network and Prognostic Model for Sarcoma

Due to the rarity and heterogeneity, it is challenging to explore and develop new therapeutic targets for patients with sarcoma. Recently, immune cell infiltration in the tumor microenvironment (TME) was widely studied, which provided a novel potential approach for cancer treatment. The competing endogenous RNA (ceRNA) regulatory network has been reported as a critical molecular mechanism of tumor development. However, the role of the ceRNA regulatory network in the TME of sarcoma remains unclear. In this study, gene expression data and clinical information were obtained from The Cancer Genome Atlas (TCGA) sarcoma datasets, and an immune infiltration-related ceRNA network was constructed, which comprised 14 lncRNAs, 13 miRNAs, and 23 mRNAs. Afterward, we constructed an immune infiltration-related risk score model based on the expression of IRF1, MFNG, hsa-miR-940, and hsa-miR-378a-5p, presenting a promising performance in predicting the prognosis of patients with sarcoma.

LncRNA HOTAIR contributes Taxol-resistance of hepatocellular carcinoma cells via activating AKT phosphorylation by down-regulating miR-34a

Drug resistance of Taxol leads to the treatment failure in hepatocellular carcinoma (HCC). LncRNA HOTAIR have drawn increasing attention in various diseases; its function and mechanism in Taxol-resistance in HCC remain unclear. In the present study, the two Taxol resistant HCC cell lines (HepG2/Taxol and SMMC7721/Taxol) were induced. The qRT-PCR data exhibited that over-expressed HOTAIR as well as low-expressed miR-34a were founded in HepG2/Taxol and SMMC7721/Taxol cells. HOTAIR knockdown suppresses proliferation, invasion and promotes apoptosis of in HepG2/Taxol and SMMC7721/Taxol cells through up-regulating miR-34a by MTT assay, transwell invasion assays and flow cytometry, while down-regulation of miR-34a had an opposite effect on reversing Taxol resistance. Cleaved caspase-3 and Bax were significantly up-regulated by si-HOTAIR transfection, while Bcl-2 level exhibited opposite trend. Besides, HOTAIR knockdown impaired Taxol-resistance in HCC by accommodating Akt phosphorylation and Wnt/β-catenin signaling via interacting with miR-34a. The present study may afford a valuable target for treating Taxol-resistance in HCC.

Functional Interaction among lncRNA HOTAIR and MicroRNAs in Cancer and Other Human Diseases

Simple Summary

This review aimed to describe the contribution of functional interaction between the lncRNA HOTAIR and microRNAs in human diseases, including cancer. HOTAIR/miRNAs complexes interfere with different cellular processes during carcinogenesis, mainly deregulating a series of oncogenic signaling pathways. A great number of ncRNAs-related databases have been established, supported by bioinformatics technologies, to identify the ncRNA-mediated sponge regulatory network. These approaches need experimental validation through cells and animal models studies. The optimization of systems to interfere with HOTAIR/miRNAs interplay could represent a new tool for the definition of diagnostic therapeutics in cancer patients.

Abstract

LncRNAs are a class of non-coding RNAs mostly involved in regulation of cancer initiation, metastatic progression, and drug resistance, through participation in post-transcription regulatory processes by interacting with different miRNAs. LncRNAs are able to compete with endogenous RNAs by binding and sequestering miRNAs and thereby regulating the expression of their target genes, often represented by oncogenes. The lncRNA HOX transcript antisense RNA (HOTAIR) represents a diagnostic, prognostic, and predictive biomarker in many human cancers, and its functional interaction with miRNAs has been described as crucial in the modulation of different cellular processes during cancer development. The aim of this review is to highlight the relation between lncRNA HOTAIR and different microRNAs in human diseases, discussing the contribution of these functional interactions, especially in cancer development and progression.

The lncRNA LINC00691Functions as a ceRNA for miRNA-1256 to Suppress Osteosarcoma by Regulating the Expression of ST5

Introduction

Osteosarcoma is the most common primary malignant tumor in children and young patients. Although neoadjuvant chemotherapy and surgery could improve the prognosis of these patients, treatment outcomes are poor because of its low early diagnosis rate and high degree of malignancy as well as its tendency for early metastasis. In the field of osteosarcoma, lncRNAs have become a hot spot for studying the molecular mechanisms driving malignant biological characteristics and exploring effective treatment methods. An lncRNA is a long noncoding RNA lacking protein-encoding ability, and in its RNA form, it regulates various gene expression processes, such as epigenetic regulation, transcriptional regulation, and posttranscriptional regulation. LncRNAs play an important role in tumorigenesis and metastasis.

Methods

We used bioinformatics software to analyze the data in geo database. CCK-8 and Transwell were used to detect the effect of lncRNA LINC00691 on the proliferation and migration of osteosarcoma cells. The target gene of LINC00691 was detected by bioinformatics analysis and RNA pull down.

Results

In this study, we identified the lncRNA LINC00691 and confirmed its expression in osteosarcoma cells through GEO database analysis. Expression analysis showed that the levels of lncRNA LINC00691 in osteosarcoma cells were decreased compared to those of control cells. Overexpression of LINC00691 could inhibit the proliferation, migration, invasion, and induction of G1 cell cycle arrest in osteosarcoma cells, which was shown through in vitro and in vivo studies. Using bioinformatics analysis, RNA pull down experiments and luciferase reporter gene detection assays, we found that LINC00691 regulated ST5 expression by binding miR-1256. LINC00691 overexpression inhibited EMT by promoting the expression of E-cadherin and increasing the expression of ZEB1, Snail, and Fibronectin.

Conclusion

These results suggested that overexpressed LINC00691 promoted the expression of ST5 by regulating the function of miR-1256 through a ceRNA mechanism. The LINC00691/miR-1256/ST5 pathway plays an important role in the progression and metastasis of osteosarcoma and represents a good therapeutic target.

Long non-coding RNA HOTAIR regulates myeloid differentiation through the upregulation of p21 via miR-17-5p in acute myeloid leukaemia

Long non-coding RNA HOTAIR has been reported to play a key role in regulating various biological processes in various cancers. However, the roles and mechanisms of HOTAIR in acute myeloid leukaemia (AML) are still unclear and need to be investigated. In this study, we induced differentiation of four AML cell lines by all-trans retinoic acid (ATRA) and found HOTAIR was significantly upregulated in the process. Chromatin immunoprecipitation (ChIP) assays indicated that C/EBPβ upregulated HOTAIR during ATRA induced differentiation in HL-60 cells. By gain- and loss-of-function analysis, we then observed that HOTAIR expression was positively correlated with ATRA-induced differentiation and negatively regulated G1 phase arrest in HL-60 cells. In addition, we found that HOTAIR promoted ATRA-induced differentiation via the regulation of the cell cycle regulator p21 via miR-17-5p. Moreover, we detected the expression of HOTAIR in 84 de novo AML patients, HOTAIR was found significantly downregulated in the AML patients compared to the iron deficiency anaemia (IDA) control group, negatively correlated with the platelet level in M2 patients. In all, our data suggest that HOTAIR may be subtype-specific in AML-M2 patients, also HOTAIR regulates AML differentiation by C/EBPBβ/HOTAIR/miR-17-5p/p21 pathway. The findings of the present study provide a novel insight into the mechanism of lncRNA-mediated differentiation and indicate that HOTAIR may be a promising therapeutic target for leukaemia, especially for AML with M2 type.Abbreviation: AML: acute myeloid leukaemia; APL: acute promyelocytic leukaemia; ATRA: all-trans retinoic acid; CCK8: cell Counting Kit-8; CDKs: cyclin-dependent kinases ; CeRNA: competing endogenous RNAs; ChIP: chromatin immunoprecipitation; CHX: cycloheximide; FAB: French-American-British; FCM: flow cytometry; HOTAIR: HOX transcript antisense RNA; IDA: iron-deficiency anemia; lncRNA: long non-coding RNA; 3'UTR: 3'untranslated region; MT: Mutation type; WT: Wild type; qRT-PCR: Quantitative real-time PCR.

MicroRNA-217: A regulator of human cancer

As highly conserved non-coding RNAs of approximately 18-24 nucleotides, microRNAs (miRNAs) regulate the expression of target genes. Multiple studies have demonstrated that miRNAs participate in the regulation of human cancer. MircoRNA-217 (miR-217) participates in the regulation of various tumors by specifically binding target genes and post-transcriptional regulation. In recent years, there have been numerous reports about miR-217 in tumor progression. MiR-217 is known mainly as a tumor suppressor, although some studies have shown that it functions as an oncomiR. Here, we review the current research related to miR-217, including its role in tumor progression and the molecular mechanisms.

The landscape of long non-coding RNAs in tumor stroma

AIMS

Long non-coding RNAs (lncRNAs) are associated with cancer development, while their relationship with the cancer-associated stromal components remains poorly understood. In this review, we performed a broad description of the functional landscape of stroma-associated lncRNAs in various cancers and their roles in regulating the tumor-stroma crosstalk.

MATERIALS AND METHODS

We carried out a systematic literature review of PubMed, Scopus, Medline, Bentham, and EMBASE (Elsevier) databases by using the keywords "LncRNAs in cancer," "LncRNAs in tumor stroma," "stroma," "cancer-associated stroma," "stroma in the tumor microenvironment," "tumor-stroma crosstalk," "drug resistance of stroma," and "stroma in immunosuppression" till July 2020. We collected the latest articles addressing the biological functions of stroma-associated lncRNAs in cancer.

KEY FINDINGS

These articles reported that dysregulated stroma-associated lncRNAs play significant roles in modulating the tumor microenvironment (TME) by the regulation of tumor-stroma crosstalk, epithelial to mesenchymal transition (EMT), endothelial to mesenchymal transition (EndMT), extracellular matrix (ECM) turnover, and tumor immunity.

SIGNIFICANCE

The tumor stroma is a substantial portion of the TME, and the dysregulation of tumor stroma-associated lncRNAs significantly contributes to cancer initiation, progression, angiogenesis, immune evasion, metastasis, and drug resistance. Thus, stroma-associated lncRNAs could be potentially useful targets for cancer therapy.

Integrated Analysis of Competing Endogenous RNAs Network Reveals Potential Signatures in Osteosarcoma Development

The purpose of this work was to extract key players such as mRNAs and long non-coding RNA (lncRNAs) in the etiopathogenesis of osteosarcoma (OS). The sequencing analyses (mRNAs and lncRNAs) of OS were conducted followed by differentially expressed mRNAs and lncRNAs (DEmRNAs and DElncRNAs) identification between U-2OS cells with has-miR-590-5p overexpression and negative control cells. Following this, the co-expression and functional enrichment analyses of DEmRNAs and DElncRNAs were carried out. Also, the miRNAs-DElncRNAs-DEmRNAs regulatory network was constructed with DElncRNAs-miRNAs and DElncRNAs-DEmRNAs pairs after the target gene analysis of miRNA. In addition, the ceRNA-has-miR-590-5p was further extracted based on the has-miR-590-5p-DElncRNAs and DElncRNAs-DEmRNAs interactions. Finally, the results of the bioinformatics analysis was verified by reverse-transcription polymerase chain reaction (RT-PCR). Totally, 980 DEmRNAs (539 up-regulated DEmRNAs and 441 down-regulated DEmRNAs) and 682 DElncRNAs (352 up-regulated DElncRNAs and 330 down-regulated DElncRNAs) were extracted between cells with hsa-miR-590-5p overexpression and normal cells. The functional analyses suggested that up-regulated genes were significantly enriched in several GO terms such as signal transduction and cytokine-cytokine receptor interaction pathway while down-regulated genes (SCUBE3, HIST1H4E and EDIL3) were associated with calcium ion binding, cell surface function and nucleosome assembly. Additionally, the miRNAs-DEmRNAs-DEmRNAs network represented 220 pairs among 41 miRNAs, 38 DElncRNAs and 61 DEmRNAs. Furthermore, the ceRNA-hsa-miR-590-5p network consisted of 70 interaction pairs including hsa-miR-590-5p-SCUBE3-CTB-113D17.1, hsa-miR-590-5p-EDIL3-CTB-113D17.1 and hsa-miR-590-5p-HIST1H4E-CTB-113D17.1) among hsa-miR-590-5p, 30 DEmRNAs and 4 down-regulated DElncRNAs. Meanwhile, the RT-PCR results incidated that compared with the blank (KB) and negative control (NC) group, the mRNA expression of SCUBE3, HIST1H4E, and EDIL3 were significantly descreased in mimics group (P value <0.05). The lncRNA CTB-113D17.1 might implicate with OS development probably via serving as a hsa-miR-590-5p sponge to regulate gene targets (SCUBE3, EDIL3 and HIST1H4E), which will facilitate the deep understandings of OS progression.

LncRNA-ROR/microRNA-185-3p/YAP1 axis exerts function in biological characteristics of osteosarcoma cells

AIM

The co-expression network of long non-coding RNA ROR (lncRNA-ROR) and microRNA-185-3p (miR-185-3p) has not been focused on osteosarcoma. Therein, this work was initiated to uncover lncRNA-ROR and miR-185-3p functions in osteosarcoma.

METHODS

LncRNA-ROR, miR-185-3p and Yes-associated protein 1 (YAP1) expression in osteosarcoma tissues and cells were detected. The screened cells (MG63 and U2OS) were transfected with decreased and/or increased lncRNA-ROR and miR-185-3p to explore osteosarcoma progression. Tumor growth was detected by tumor xenografts in mice.

RESULTS

Up-regulated lncRNA-ROR and YAP1 and down-regulated miR-185-3p were found in osteosarcoma. LncRNA ROR knockdown or miR-185-3p overexpression inhibited osteosarcoma cell progression while lncRNA ROR elevation or miR-185-3p inhibition presented the opposite effects. Function of lncRNA ROR was rescued by miR-185-3p and regulated the growth and metastasis of osteosarcoma cells via modulating YAP1, the target gene of miR-185-3p.

CONCLUSION

This work illustrates that lncRNA-ROR down-regulation or miR-185-3p up-regulation inhibits osteosarcoma progression via YAP1 repression.

MicroRNAs and Their Influence on the ZEB Family: Mechanistic Aspects and Therapeutic Applications in Cancer Therapy

Molecular signaling pathways involved in cancer have been intensively studied due to their crucial role in cancer cell growth and dissemination. Among them, zinc finger E-box binding homeobox-1 (ZEB1) and -2 (ZEB2) are molecules that play vital roles in signaling pathways to ensure the survival of tumor cells, particularly through enhancing cell proliferation, promoting cell migration and invasion, and triggering drug resistance. Importantly, ZEB proteins are regulated by microRNAs (miRs). In this review, we demonstrate the impact that miRs have on cancer therapy, through their targeting of ZEB proteins. MiRs are able to act as onco-suppressor factors and inhibit the malignancy of tumor cells through ZEB1/2 down-regulation. This can lead to an inhibition of epithelial-mesenchymal transition (EMT) mechanism, therefore reducing metastasis. Additionally, miRs are able to inhibit ZEB1/2-mediated drug resistance and immunosuppression. Additionally, we explore the upstream modulators of miRs such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as these regulators can influence the inhibitory effect of miRs on ZEB proteins and cancer progression.

circRNA_100859 functions as an oncogene in colon cancer by sponging the miR-217-HIF-1α pathway

Circular RNAs (circRNAs) play an important role in cancer development and progression by regulating gene expression. The present study aimed to investigate the function of circRNA_100859 in colon cancer. circRNA expression profiles from a human circRNAs chip were analyzed. The effects of circRNA_100859 on cell proliferation and apoptosis were assessed in vitro and interactions between circRNA_100859 and its micro (mi)RNA and target genes were analyzed. The diagnostic and prognostic significance of circRNA_100859 was also investigated. It was identified that circRNA_100859 was overexpressed in colon cancer tissues and promoted cell proliferation and inhibited cell apoptosis. Additionally, bioinformatics and a dual-luciferase reporter assay confirmed that circRNA_100859 acted as a miR-217 sponge, and miR-217 directly targeted hypoxia-inducible factor (HIF)-1α. Rescue assays demonstrated that HIF-1α protein and mRNA expression levels and cell proliferation were regulated by the circRNA_100859/miR-217 axis (P<0.05). Furthermore, statistical analysis showed that the circRNA_100859-miR-217-HIF-1α axis was associated with Tumor-Node-Metastasis (TNM) stage, histological grade, and KRAS mutations, and also showed high diagnostic and prognostic value for patients with colon cancer (P<0.05). Therefore, it was concluded that circRNA_100859 functions as an oncogene in colon cancer by sponging the miR-217-HIF-1α pathway. In addition, the circRNA_100859-miR-217-HIF-1α axis may serve as a novel diagnostic and prognostic biomarker for patients with colon cancer.

Long Noncoding RNA HOTAIR Contributes to Progression in Hepatocellular Carcinoma by Sponging miR-217-5p

Background: Hepatocellular carcinoma (HCC) is an aggressive primary hepatic cancer with high malignancy and poor prognosis. Long noncoding RNA HOTAIR has been classified as an oncogene to accelerate cell proliferation, migration, and invasion in many cancer types by interacting with the miRNA. Therefore, we assumed that HOTAIR might participate in HCC cell progression by interacting with miR-217-5p expression. Materials and Methods: The expression of HOTAIR and miR-217-5p in 35 HCC patients and HCC cells was measured by quantitative real-time polymerase chain reaction. Cell transfection was conducted using Lipofectamine 2000 transfection reagent. CCK8 and flow cytometry was applied for the measurement of cell proliferation and apoptosis. Cell migration and invasion capacities were carried out by transwell assay. Xenograft mice were constructed by subcutaneously injecting of stably transfected Huh-7 cells in mice. The interaction between HOTAIR and miR-217-5p was determined by luciferase reporter system. Protein expression of P13K, p-P13K, AKT, p-AKT, MMP-2, and MMP-9 was analyzed using Western blot assay. Results: The expression of HOTAIR was upregulated, whereas miR-217-5p was downregulated in HCC tumor tissues and cell lines (Hep3B and Huh-7) compared with normal tissues and human normal liver cell line MIHA. In addition, HOTAIR expression was negatively correlated with miR-217-5p expression in HCC (r² = 0.1867, p = 0.0171). More importantly, HOTAIR knockdown induced apoptosis and inhibited cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT). In vivo experiments revealed that the interference of HOTAIR inhibited tumor growth. Subsequently, luciferase reporter system confirmed the interaction between HOTAIR and miR-217-5p. The rescue experiments clarified that miR-217-5p inhibitor attenuated the suppression of HOTAIR silencing on HCC cell proliferation, migration, invasion, and EMT. Furthermore, miR-217-5p inhibitor restored the inhibition of HOTAIR silencing mediated p-PI3K/p-AKT/MMP-2/9 protein expression. Conclusions: HOTAIR contributes to cell progression in HCC by sponging miR-217-5p, representing promising biomarkers for HCC treatment.

Circular RNA ADAM9 facilitates the malignant behaviours of pancreatic cancer by sponging miR-217 and upregulating PRSS3 expression

Pancreatic cancer (PC) is a highly lethal human cancer. We previously found that Serine protease 3 (PRSS3), as an oncogene, is significantly upregulated in PC. In this study, we aimed to investigate the potential mechanism of PRSS3 dysregulation in PC. In this research, low miR-217 and high circ-ADAM9 expression were found in PC tissues and cell lines, which was closely associated with advanced clinical stage and lymph node metastasis. Patients with low miR-217 or high circ-ADAM9 expression had shorter survival time than those with high miR-217 or low circ-ADAM9 expression. Functionally, manipulation of miR-217 and circ-ADAM9 expression showed opposite effects on cell proliferation, migration and invasion. Stepwise mechanism studies indicated that circ-ADAM9 alleviated the inhibitory effect of miR-217 on PRSS3 by directly sponging miR-217 to increase the expression level of PRSS3, resulting in the activation of ERK/VEGF signalling pathway. In vivo, circ-ADAM9 silencing or miR-217 overexpression evidently retarded the growth of tumour, and the combination of them exhibited an additive inhibitory effect on tumourigenicity. Briefly, the ceRNA regulatory network of circ-ADAM9/miR-217/PRSS3 plays a pivotal role in PC progression by the regulation of ERK/VEGF signalling pathway.

Long non-coding RNA HOTAIR in cervical cancer: Molecular marker, mechanistic insight, and therapeutic target

Cervical cancer is a common gynecologic malignant tumor with high mortality. HOX transcript antisense RNA (HOTAIR), a trans-acting long non-coding RNA (lncRNA) containing six exons in humans, is transcribed from the antisense strand of homeobox gene C cluster. This lncRNA serves as a modular scaffold for gene silencing and protein ubiquitination. In patients with cervical cancer, elevated HOTAIR levels are significantly associated with poor prognosis. HOTAIR plays an oncogenic role in cervical cancer by promoting cell proliferation, migration, invasion and autophagy, inhibiting cell apoptosis, stimulating angiogenesis, accelerating cell cycle progression, and inducing epithelial-mesenchymal transition. Moreover, blockade of HOTAIR by artesunate or propofol shows promise for further development of this lncRNA as a potential therapeutic target in cervical cancer. In this review, we summarized the latest advances regarding the role of HOTAIR in cervical cancer with an emphasis on its diagnostic and prognostic values.

CircRNA_100367 regulated the radiation sensitivity of esophageal squamous cell carcinomas through miR-217/Wnt3 pathway

Background: Circular RNAs (circRNAs) play important roles in regulating the radioresistance of esophageal squamous cell carcinoma (ESCC). This study aimed to determine the role of hsa_circRNA_100367 in regulating radioresistance of ESCC.

Results: Higher expression and potency of endothelial to mesenchymal transformation (EMT) was found in radioresistant ESCC cells (KYSE-150R) than in ESCC cells (KYSE-150). Silencing circRNA_100367 inhibited the proliferation and migration of KYSE-150R cells, and decreased the expression of β-catenin (an important molecule in Wnt pathway) in KYSE-150R cells. Additionally, circRNA_100367 bound to miR-217, and miR-217 targeted Wnt3. Low Wnt3 expression was associated with the short survival time in patients with ESCC and Wnt3 knockdown inhibited the proliferation and migration of KYSE-150R cells. CircRNA_100367 enhanced the radioresistance of KYSE-150R cells through miR-217/Wnt3 pathway. In vivo, circRNA_100367 silence reduced the growth of KYSE-150R cells under radiation.

Conclusion: Our results revealed that circRNA_100367 attenuated radioresistance of ESCC through miR-217/Wnt3 pathway.

Methods: CircRNAs related with the radioresistance of ESCC were analyzed by hierarchical cluster analysis. The relationship between circRNA_100367 and miR-217, Wnt3 was detected by RNA immunoprecipitation (RIP), RNA pull-down and luciferase reporte assays. The proliferation and migration ESCC cells were detected by MTT, Transwell and colony formation assays.

Long non-coding RNA HOTAIR functions as a competitive endogenous RNA to regulate PRAF2 expression by sponging miR-326 in cutaneous squamous cell carcinoma

Background

LncRNAs may exert a regulatory effect in tumorigenesis. Although the expression of lncRNA HOTAIR has been confirmed to be notably elevated in the tissues of CSCC, its biological mechanism in CSCC is still unknown.

Methods

HOTAIR expression level in CSCC cell lines was monitored via qRT-PCR. Then CCK-8 assay, Transwell assay and EdU assay were adopted to detect cell migration and proliferation. Meanwhile, through bioinformatics analysis and luciferase reporter gene detection, a new target of HOTAIR was identified. Additionally, Western blotting and RIP analysis were adopted to discuss the possible mechanism.

Results

HOTAIR expression in CSCC cell lines exhibited an obvious elevation. Cell function analysis revealed that HOTAIR overexpression remarkably facilitated CSCC cell migration, proliferation and EMT process, which were impeded by down-regulation of HOTAIR. Furthermore, HOTAIR competitively bound to miR-326, so as to positively modulate miR-326 expression.

Conclusions

These results present that HOTAIR, as a ceRNA, regulates PRAF2 expression by competitive binding to miR-326 during CSCC.

Deregulated Expression of Long Non-coding RNA HOX Transcript Antisense RNA (HOTAIR) in Egyptian Patients with Multiple Myeloma

Increasing evidence of involvement of non-coding RNAs, especially long non-coding RNAs (lncRNAs), in the molecular biology of various malignancies have been recently reported. Their utilization as markers for diagnosis, prognosis and evaluation of treatment response was widely investigated. As the impact of lncRNA HOTAIR on multiple myeloma (MM) was not properly highlighted, we aimed to explore the expression levels of HOTAIR in three groups of MM patients and to analyze its relationship to different patients' characteristics. Plasma samples were withdrawn from 24 newly diagnosed MM patients, 23 post-therapy patients in complete response (CR) or very good partial response (VGPR) and 15 patients who had either progressive disease (PD) or relapse. The expression of lncRNA HOTAIR in MM patients and 20 healthy controls was analyzed by quantitative reverse transcription polymerase chain reactions. HOTAIR was significantly upregulated in newly diagnosed and PD/relapse categories in comparison with controls and MM patients who had achieved CR or VGPR (P < 0.001). Furthermore; HOTAIR expression levels correlated with the percentage of malignant plasma cells in bone marrow (P = 0.006) and disease stage (ISS stage) (P = 0.031). HOTAIR may be employed as  prognostic molecular marker and novel therapeutic tool for newly diagnosed MM patients.

Non-Coding RNAs in Pediatric Solid Tumors

Pediatric solid tumors are a diverse group of extracranial solid tumors representing approximately 40% of childhood cancers. Pediatric solid tumors are believed to arise as a result of disruptions in the developmental process of precursor cells which lead them to accumulate cancerous phenotypes. In contrast to many adult tumors, pediatric tumors typically feature a low number of genetic mutations in protein-coding genes which could explain the emergence of these phenotypes. It is likely that oncogenesis occurs after a failure at many different levels of regulation. Non-coding RNAs (ncRNAs) comprise a group of functional RNA molecules that lack protein coding potential but are essential in the regulation and maintenance of many epigenetic and post-translational mechanisms. Indeed, research has accumulated a large body of evidence implicating many ncRNAs in the regulation of well-established oncogenic networks. In this review we cover a range of extracranial solid tumors which represent some of the rarer and enigmatic childhood cancers known. We focus on two major classes of ncRNAs, microRNAs and long non-coding RNAs, which are likely to play a key role in the development of these cancers and emphasize their functional contributions and molecular interactions during tumor formation.

lncRNA ZEB1-AS1 promotes pulmonary fibrosis through ZEB1-mediated epithelial-mesenchymal transition by competitively binding miR-141-3p

Long non-coding RNAs (lncRNAs) have been reported to be involved in various pathophysiological processes in many diseases. However, the role and mechanism of lncRNAs in pulmonary fibrosis have not been explicitly delineated. In the present study, we found that lncRNA ZEB1 antisense RNA 1 (ZEB1-AS1) is upregulated in the lungs of BLM-induced rats and TGF-β1-induced RLE-6TN cells, and positively correlated with the levels of ZEB1, an epithelial-mesenchymal transition (EMT) master regulator. Knockdown of ZEB1-AS1 alleviated BLM-induced fibrogenesis, in vivo, via inhibiting EMT progress. Mechanistically, we identified that ZEB1-AS1 promoted fibrogenesis in RLE-6TN cells and ZEB1-AS1 silencing inhibited TGF-β1-induced fibrogenesis through modulation of miR-141-3p. Further experiments revealed that ZEB1-AS1 acted as competing endogenous RNA (ceRNA) of miR-141-3p: forced expression of ZEB1-AS1 reduced the expression of miR-141-3p to activate Zinc-finger Ebox Binding Homeobox 1 (ZEB1) in RLE-6TN cells. In addition, we found that upregulation of miR-141-3p prevented fibrogenesis by targeting ZEB1. Therefore, our finding suggested lncRNA ZEB1-AS1 as a new profibrotic molecule that acts as a regulator of miR-141-3p/ZEB1 axis during lung fibrosis and demonstrated ZEB1-AS1 as a potential therapeutic target for the prevention and treatment of pulmonary fibrosis.

Epitranscriptomic Signatures in lncRNAs and Their Possible Roles in Cancer

In contrast to the amazing exponential growth in knowledge related to long non-coding RNAs (lncRNAs) involved in cell homeostasis or dysregulated pathological states, little is known so far about the links between the chemical modifications occurring in lncRNAs and their function. Generally, ncRNAs are post-transcriptional regulators of gene expression, but RNA modifications occurring in lncRNAs generate an additional layer of gene expression control. Chemical modifications that have been reported in correlation with lncRNAs include m⁶A, m⁵C and pseudouridylation. Up to date, several chemically modified long non-coding transcripts have been identified and associated with different pathologies, including cancers. This review presents the current level of knowledge on the most studied cancer-related lncRNAs, such as the metastasis associated lung adenocarcinoma transcript 1 (MALAT1), the Hox transcript antisense intergenic RNA (HOTAIR), or the X-inactive specific transcript (XIST), as well as more recently discovered forms, and their potential roles in different types of cancer. Understanding how these RNA modifications occur, and the correlation between lncRNA changes in structure and function, may open up new therapeutic possibilities in cancer.

Retracted Article: Long noncoding RNA HOTAIR promotes cell apoptosis by sponging miR-221 in Parkinson's disease

Parkinson's disease (PD) is a common neurological disorder that is detrimental to the health of older people worldwide. Long noncoding RNAs (lncRNAs) have been reported to play essential roles in the pathogenesis and therapeutics of PD. LncRNA homeobox transcript antisense intergenic RNA (HOTAIR) is expressed in PD samples; however, the exact roles of HOTAIR and its mechanism remain largely unclear. Herein, the neurotoxins 1-methyl-4-phenylpyridine (MPP⁺) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were used to establish PD models in vitro and in vivo. The expressions of HOTAIR and microRNA-221 (miR-221) were measured by the quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and apoptosis were detected by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and western blot or flow cytometry, respectively. The interaction between HOTAIR and miR-221 was explored by luciferase activity and RNA immunoprecipitation (RIP). The tyrosine hydroxylase (TH)-positive cells in MPTP-treated-mouse midbrains were analyzed by immunohistochemistry. The HOTAIR expression was up-regulated and that of miR-221 was down-regulated in the serum of PD patients and MPP⁺-treated SH-SY5Y cells. Overexpression of HOTAIR inhibited cell viability and promoted apoptosis in MPP⁺-treated SH-SY5Y cells. However, the down-regulation of HOTAIR showed an opposite effect. Moreover, miR-221 was validated to be bound to HOTAIR, and its addition reversed the regulatory effect of HOTAIR on cell viability and apoptosis in MPP⁺-treated SH-SY5Y cells. Moreover, the knockdown of HOTAIR attenuated the degree of PD and cell apoptosis by regulating miR-221 in MPTP-treated mice. In conclusion, HOTAIR contributed to cell apoptosis by sponging miR-221 in PD. This study elucidates a new mechanism for understanding the pathogenesis of PD and provides a promising target for the treatment of PD.

Parkinson's disease (PD) is a common neurological disorder that is detrimental to the health of older people worldwide.