Long non-coding RNA XIST exerts oncogenic functions in pancreatic cancer via miR-34a-5p

Reprogramming tendon healing: a guide to novel molecular tools

Tendons are a frequent site of injury, which greatly impairs the movement and locomotion of patients. Regrettably, injuries at the tendon frequently require surgical intervention, which leads to a long path to recovery. Moreover, the healing of tendons often involves the formation of scar tissue at the site of injury with poor mechanical properties and prone to re-injury. Tissue engineering carries the promise of better and more effective solutions to the improper healing of tendons. Lately, the field of regenerative medicine has seen a significant increase in the focus on the potential use of non-coding RNAs (e.g., siRNAs, miRNAs, and lncRNAs) as molecular tools for tendon tissue engineering. This class of molecules is being investigated due to their ability to act as epigenetic regulators of gene expression and protein production. Thus, providing a molecular instrument to fine-tune, reprogram, and modulate the processes of tendon differentiation, healing, and regeneration. This review focuses particularly on the latest advances involving the use of siRNAs, miRNAs, and lncRNAs in tendon tissue engineering applications.

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

LncRNA XIST promotes adjuvant-induced arthritis by increasing the expression of YY1 via miR-34a-5p

Objectives: This study aims to explore the mechanism by which long non-coding ribonucleic acids (lncRNA) X-inactive specific transcript (XIST) affects the progression of adjuvant-induced arthritis (AIA).

Materials and methods: Freund's complete adjuvant was used to induce arthritis in rats. The polyarthritis, spleen and thymus indexes were calculated to evaluate AIA. Hematoxylin-eosin (H&E) staining was used to reveal the pathological changes in the synovium of AIA rats. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the expression of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6 and IL-8 in the synovial fluid of AIA rats. The cell continuing kit (CCK)-8, flow cytometry, and Transwell assays were used to assess the proliferation, apoptosis, migration and invasion of transfected fibroblast-like synoviocytes (FLS) isolated from AIA rats (AIA-FLS). Dual-luciferase reporter assay was performed to verify the binding sites between XIST and miR-34b-5p or between YY1 mRNA and miR-34b-5p.

Results: The XIST and YY1 were highly expressed, and miR-34a-5p was lowly expressed in the synovium of AIA rats and in AIA-FLS. Silencing of XIST impaired the function of AIA-FLS in vitro and inhibited the progression of AIA in vivo. The XIST promoted the expression of YY1 by competitively binding to miR-34a-5p. Inhibition of miR-34a-5p strengthened the function of AIA-FLS by upregulating XIST and YY1.

Conclusion: The XIST controls the function of AIA-FLS and may promote the progression of rheumatoid arthritis via the miR-34a-5p/YY1 axis.

Potential roles of lncRNA-XIST/miRNAs/mRNAs in human cancer cells

Long non-coding RNAs (lncRNAs) are non-coding RNAs that contain more than 200 nucleotides but do not code for proteins. In tumorigenesis, lncRNAs can have both oncogenic and tumor-suppressive properties. X inactive-specific transcript (XIST) is a known lncRNA that has been implicated in X chromosome silencing in female cells. Dysregulation of XIST is associated with an increased risk of various cancers. Therefore, XIST can be a beneficial prognostic biomarker for human malignancies. In this review, we attempt to summarize the emerging roles of XIST in human cancers.

Extracellular vesicle expansion of PMIS-miR-210 expression inhibits colorectal tumour growth via apoptosis and an XIST/NME1 regulatory mechanism

BACKGROUND

Colorectal cancer (CRC) has a high mortality rate, and therapeutic approaches to treat these cancers are varied and depend on the metabolic state of the tumour. Profiles of CRC tumours have identified several biomarkers, including microRNAs. microRNA-210 (miR-210) levels are directly correlated with CRC survival. miR-210 expression is higher in metastatic colon cancer cells versus non-metastatic and normal colon epithelium. Therefore, efficient methods to inhibit miR-210 expression in CRC may provide new advances in treatments.

METHODS

Expression of miRs was determined in several metastatic and non-metastatic cell lines. miR-210 expression was inhibited using PMIS-miR-210 in transduced cells, which were transplanted into xenograft mice. In separate experiments, CRC tumours were allowed to grow in xenograft mice and treated with therapeutic injections of PMIS-miR-210. Molecular and biochemical experiments identified several new pathways targeted by miR-210 inhibition.

RESULTS

miR-210 inhibition can significantly reduce tumour growth of implanted colon cancer cells in xenograft mouse models. The direct administration of PMIS-miR-210 to existing tumours can inhibit tumour growth in both NSG and Foxn1nu/j mouse models and is more efficacious than capecitabine treatments. Tumour cells further transfer the PMIS-miR-210 inhibitor to neighbouring cells by extracellular vesicles to inhibit miR-210 throughout the tumour. miR-210 inhibition activates the cleaved caspase 3 apoptotic pathway to reduce tumour formation. We demonstrate that the long non-coding transcript XIST is regulated by miR-210 correlating with decreased XIST expression in CRC tumours. XIST acts as a competing endogenous RNA for miR-210, which reduces XIST levels and miR-210 inhibition increases XIST transcripts in the nucleus and cytoplasm. The increased expression of NME1 is associated with H3K4me3 and H3K27ac modifications in the NME1 proximal promoter by XIST.

CONCLUSION

Direct application of the PMIS-miR-210 inhibitor to growing tumours may be an effective colorectal cancer therapeutic.

Altered Expressions of NF1 and NF1-Related microRNAs as Biomarkers in the Diagnosis of Undifferentiated Pleomorphic Sarcoma

Objective: Undifferentiated pleomorphic sarcoma (UPS) is a highly malignant, aggressive, and pleomorphic subtype of soft tissue sarcoma in adults. However, UPS is difficult to be diagnosed due to the lack of specific morphological and immunophenotypic features. Here, we aimed to identify new biomarkers for the diagnosis of UPS.

Methods: The mRNA and protein expression of neurofibromin 1 (NF1) in 68 pairs of UPS and adjacent normal tissues were detected by qRT-PCR and immunohistochemistry, and the correlation between the NF1 protein expression and clinicopathological characteristics was analyzed. Then, differentially expressed microRNAs (DE miRNAs) were identified between the UPS tumor tissue and matched adjacent normal tissue using Hisep sequencing, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG). The DE miRNAs of the regulating NF1 gene were also identified using the TargetScan and miRanda databases and validated by qRT-PCR.

Results: Compared with the adjacent normal tissue, both mRNA and protein expressions of NF1 in the UPS tumor tissue were significantly decreased, and the positive rate of NF1 protein was associated with the tumor size, metastasis, and recurrence. A total of 125 known DE miRNAs were identified from the screened miRNAs based on | log₂(Fold Change) ≥5 and p-value < 0.05 (A total of 82 upregulated and 43 downregulated DE miRNAs in the UPS tissue). Target genes regulated by the DE miRNAs were enriched in pathways of metabolisms, RNA degradation, PI3K-Akt, and Rap1 pathway. In total, 11 miRNAs which were predicted to regulate the NF1 gene were screened. After verification, the relative expressions of hsa-miR-199a-3p and hsa-miR-34a-5p were increased and decreased in the UPS tumor tissue compared with those in the adjacent normal tissue, respectively.

Conclusion: NF1 and NF1-related microRNAs including hsa-miR-199a-3p and hsa-miR-34a-5p may be novel biomarkers in the diagnosis of undifferentiated pleomorphic sarcoma (UPS).

Silencing of Long Non-coding RNA LINC01106 Represses Malignant Behaviors of Gastric Cancer Cells by Targeting miR-34a-5p/MYCN Axis

Long non-coding RNA LINC01106 is an lncRNA aberrantly expressed in gastric cancer (GC). However, the accurate function remains unclear. The objective of this investigation is to explore detailed regulatory mechanism of lncRNA LINC01106 in GC. The expression of lncRNA LINC01106, MYCN, and miR-34a-5p was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was examined using MTT assay. Migratory and invasive abilities of GC cells were evaluated by transwell assay. The targeting relation among lncRNA LINC01106, MYCN, and miR-34a-5p was tested by dual-luciferase reporter (DLR) assay. Relative protein expression of MYCN was assessed via western blot. Besides, a xenograft mouse model was established to assess the role of LINC01106 in GC in vivo. LncRNA LINC01106 and MYCN expression were boosted and miR-34a-5p expression was reduced in GC cells and tissues compared to their controls. Functionally, decreased lncRNA LINC01106 or increased miR-34a-5p restrained GC cells in viability, invasion, and migration in vitro. LINC01106 down-regulation suppressed tumor growth of mice in vivo. In terms of mechanism, lncRNA LINC01106 directly targeted miR-34a-5p and was inversely correlated with miR-34a-5p. MYCN was targeted by miR-34a-5p and was inversely correlated with miR-34a-5p. There was a positive correlation between LINC01106 and MYCN. LINC01106 knockdown led to the suppression of cell invasion, migration, and viability, whereas these effects caused by LINC01106 knockdown were reversed by miR-34a-5p down-regulation or MYCN up-regulation in GC cells. Silencing of lncRNA LINC01106 attenuated cell viability, invasion, and migration by sponging miR-34a-5p to target MYCN in GC.

Long non-coding RNA XIST: a novel oncogene in multiple cancers

Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is an important lncRNA derived from the XIST gene in mammals. XIST is abnormally expressed in numerous tumors, in most of which XIST functions as an oncogene. XIST is involved in multiple aspects of carcinogenesis, including tumor onset, progression, and prognosis. In our review, we collected and analyzed the recent studies on the impact of XIST in human tumor development. The multilevel molecular functions of XIST in human tumors are comprehensively reviewed to clarify the pathologic mechanisms and to offer a novel direction for further study.

Long Noncoding Competing Endogenous RNA Networks in Pancreatic Cancer

Pancreatic cancer (PC) is a highly malignant disease characterized by insidious onset, rapid progress, and poor therapeutic effects. The molecular mechanisms associated with PC initiation and progression are largely insufficient, hampering the exploitation of novel diagnostic biomarkers and development of efficient therapeutic strategies. Emerging evidence recently reveals that noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs) and microRNAs (miRNAs), extensively participate in PC pathogenesis. Specifically, lncRNAs can function as competing endogenous RNAs (ceRNAs), competitively sequestering miRNAs, therefore modulating the expression levels of their downstream target genes. Such complex lncRNA/miRNA/mRNA networks, namely, ceRNA networks, play crucial roles in the biological processes of PC by regulating cell growth and survival, epithelial-mesenchymal transition and metastasis, cancer stem cell maintenance, metabolism, autophagy, chemoresistance, and angiogenesis. In this review, the emerging knowledge on the lncRNA-associated ceRNA networks involved in PC initiation and progression will be summarized, and the potentials of the competitive crosstalk as diagnostic, prognostic, and therapeutic targets will be comprehensively discussed.

LncRNA XIST Prevents Tendon Adhesion and Promotes Tendon Repair Through the miR-26a-5p/COX2 Pathway

Tendon adhesion is the biggest obstacle to repair of tendon injury. Long-chain non-coding RNA X-inactive specific transcript (lncRNA XIST) is highly expressed in populations at high risk of tendon injury. However, whether XIST participates in tendon injury and the specific mechanism remain unknown. Here, we aimed to explore the effects and underlying mechanism of XIST in tendon injury. A mouse model of tendon injury was constructed by the transection method in vivo. XIST and COX2 were highly expressed in tendon tissues of mice with tendon injury, while miR-26a-5p was lowly expressed. Fibroblasts were isolated from tendon injury mice. Overexpression of XIST promoted fibroblast proliferation and upregulated α-SMA and Collagen I protein expression, while silencing XIST indicated the opposite effects. Further dual-luciferase reporter gene assay and RIP assay verified a targeting relationship between XIST and miR-26a-5p, as well as miR-26a-5p and COX2, and XIST targeted miR-26a-5p to act on COX2 expression. miR-26a-5p inhibition and COX2 overexpression reversed the decrease in fibroblast proliferation and the downregulation of α-SMA and Collagen I expression caused by XIST silencing, while interference with si-COX2 eliminated the effects of miR-26a-5p inhibitor. This study revealed that XIST promoted fibroblast proliferation and the formation of tendon adhesion through miR-26a-5p/COX2 pathway, suggesting that XIST/miR-26a-5p/COX2 may be a potential target for the treatment of tendon injury.

Research updates on the clinical implication of long noncoding RNA in digestive system cancers and chemoresistance

Long noncoding RNAs (lncRNAs) are implicated in various biological processes, such as cell proliferation, differentiation, apoptosis, migration, and invasion. They are also key players in various biological pathways. LncRNA was considered as 'translational noise' before 1980s. It has been reported that lncRNAs are aberrantly expressed in different cancers, either as oncogene or tumor suppressor gene. Therefore, more and more lncRNAs are recognized as potential diagnostic biomarkers and/or therapeutic targets. As competitive endogenous RNA, lncRNAs can interact with microRNA to alter the expression of target genes, which may have extensive clinical implications in cancers, including diagnosis, treatment, prognosis, and chemoresistance. This review comprehensively summarizes the functions and clinical relevance of lncRNAs in digestive system cancers, especially as a potential tool to overcome chemoresistance.

X-Inactive-Specific Transcript: Review of Its Functions in the Carcinogenesis

X-inactive-specific transcript (XIST) is one of the firstly discovered long non-coding RNAs with prominent roles in the process of X inactivation. Moreover, this transcript contributes in the carcinogenic process in different tissues. In addition to interacting with chromatin modifying molecules, XIST can be served as a molecular sponge for miRNAs to modulate expression of miRNA targets. Most of the studies have indicated an oncogenic role for XIST. However, in prostate cancer, a single study has indicated a tumor suppressor role for this lncRNA. Similar result has been reported for XIST in oral squamous cell carcinoma. In hepatocellular carcinoma, breast cancer, ovarian cancer, osteosarcoma, and renal cell carcinoma, different studies have reported inconsistent results. In the present manuscript, we review function of XIST in the carcinogenesis.

Biological Function of Long Non-coding RNA (LncRNA) Xist

Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (Furlan and Rougeulle, 2016; Maduro et al., 2016). These RNAs are believed to be transcribed by the approximately 98-99% non-coding regions of the human genome (Derrien et al., 2012; Fu, 2014; Montalbano et al., 2017; Slack and Chinnaiyan, 2019), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (Ma et al., 2013; Devaux et al., 2015; St Laurent et al., 2015; Chen, 2016; Quinn and Chang, 2016; Richard and Eichhorn, 2018; Connerty et al., 2020). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (Cao et al., 2018). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (Jiang W. et al., 2018; Zhou et al., 2019a). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000-20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (Brown et al., 1992; Debrand et al., 1998; Kay, 1998; Lee et al., 2013; da Rocha and Heard, 2017; Yang Z. et al., 2018; Brockdorff, 2019). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (Liu et al., 2018b; Deng et al., 2019; Dinescu et al., 2019; Mutzel and Schulz, 2020; Patrat et al., 2020; Wang et al., 2020a). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in Table 1. It was also believed that lncRNA Xist (Chaligne and Heard, 2014; Yang Z. et al., 2018) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in Table 2. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.

Long noncoding RNAs: role and contribution in pancreatic cancer

Noncoding RNAs are proclaimed to be expressed in various cancer types and one such type is found to be pancreatic ductal adenocarcinoma (PDAC). The long noncoding RNAs (LncRNAs) affect the migration, invasion, and growth of tumor cells by playing important roles in the process of epigenesis, post-transcription, and transcriptional regulation along with the maintenance of apoptosis and cell cycle. It is quite subtle whether the alterations in lncRNAs would impact PDAC progression and development. This review throws a spotlight on the lncRNAs associated with tumor functions: MALAT-1, HOTAIR, HOXA13, H19, LINC01559, LINC00460, SNHG14, SNHG16, DLX6-AS1, MSC-AS1, ABHD11-AS1, DUXAP8, DANCR, XIST, DLEU2, etc. are upregulated lncRNAs whereas GAS5, HMlincRNA717, MIAT, LINC01111, lncRNA KCNK15-AS1, etc. are downregulated lncRNAs inhibiting the invasion and progression of PDAC. These data provided helps in the assessment of lncRNAs in the development, metastasis, and occurrence of PDAC and also play a vital role in the evolution of biomarkers and therapeutic agents for the treatment of PDAC.

The comprehensive landscape of miR-34a in cancer research

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

LncRNA XIST promotes the progression of laryngeal squamous cell carcinoma via sponging miR-125b-5p to modulate TRIB2

Objective: X inactivate-specific transcript (XIST) is an attractive long noncoding RNA (lncRNA) functioning as an indicator of various human tumors, including laryngeal squamous cell carcinoma (LSCC). The present study was conducted to explore a novel regulatory network of lncRNA XIST in LSCC cells.

Materials and methods: Quantitative real-time polymerase chain reaction (QRT-PCR) was used to detect the expression levels of XIST, miR-125b-5p and TRIB2 in LSCC cells and tissues. Cell proliferation, apoptosis, migration and invasion were detected by Cell Counting Kit-8 (CCK-8), flow cytometry and Transwell assays, separately. The relationship among XIST, miR-125b-5p and tribbles homolog 2 (TRIB2) was predicted by starBase v2.0 or TargetScan and confirmed by Dual-luciferase reporter assay. The TRIB2 protein expression was quantified by Western blot assay. Murine xenograft model was utilized to validate the role of XIST in vivo.

Results: XIST was notably up-regulated in LSCC tissues and cells, and the high level of XIST was associated with the low survival rate of LSCC patients. XIST knockdown markedly repressed cell proliferation, migration and invasion and promoted the apoptosis of LSCC cells and the effects were antagonized by loss of miR-125b-5p. MiR-125b-5p was a target of XIST in LSCC cells, and it could bind to TRIB2 as well. Moreover, XIST-loss-induced down-regulation of TRIB2 could be significantly reversed by miR-125b-5p knockdown. XIST promoted the growth of LSCC tumor in vivo.

Conclusion: LncRNA XIST promoted the malignance of LSCC cells partly through competitively binding to miR-125b-5p, which in turn increased TRIB2 expression.

The function of lncRNAs in the pathogenesis of osteoarthritis

Osteoarthritis (OA), one of the most common motor system disorders, is a degenerative disease involving progressive joint destruction caused by a variety of factors. At present, OA has become the fourth most common cause of disability in the world. However, the pathogenesis of OA is complex and has not yet been clarified. Long non-coding RNA (lncRNA) refers to a group of RNAs more than 200 nucleotides in length with limited protein-coding potential, which have a wide range of biological functions including regulating transcriptional patterns and protein activity, as well as binding to form endogenous small interference RNAs (siRNAs) and natural microRNA (miRNA) molecular sponges. In recent years, a large number of lncRNAs have been found to be differentially expressed in a variety of pathological processes of OA, including extracellular matrix (ECM) degradation, synovial inflammation, chondrocyte apoptosis, and angiogenesis. Obviously, lncRNAs play important roles in regulating gene expression, maintaining the phenotype of cartilage and synovial cells, and the stability of the intra-articular environment. This article reviews the results of the latest research into the role of lncRNAs in a variety of pathological processes of OA, in order to provide a new direction for the study of OA pathogenesis and a new target for prevention and treatment. Cite this article: Bone Joint Res 2021;10(2):122-133.

Prognostic value of low microRNA-34a expression in human gastrointestinal cancer: a systematic review and meta-analysis

Background

Mounting evidence shows that microRNA-34a (miR-34a) is involved in cancer prognosis. Therefore, we summarize the predictive role of miR-34a for survival in patients with gastrointestinal cancers (GICs).

Methods

All eligible studies were found by searching PubMed, Web of Science and EMBASE, and survival results were extracted. Then, the hazard ratio (HR) with the corresponding 95% confidence interval (CI) was calculated to evaluate the prognostic role of miR-34a in GICs. The association between miR-34a expression and clinicopathological characteristics was estimated by odds ratios (ORs) and 95% CIs.

Results

A total of 20 studies were included in this meta-analysis. For overall survival (OS), lower miR-34a expression could probably predict poorer outcome in GICs, with a pooled HR of 1.86 (95% CI: 1.52–2.28, P < 0.01). For disease-free survival (DFS), progression-free survival (PFS), and recurrence-free survival (RFS), lower miR-34a expression was related to worse DFS/PFS/RFS with a pooled HR of 1.86 (95% CI: 1.31–2.63, P  <  0.01). A significant relation of differentiation/TNM stage/lymphatic metastasis and the expression level of miR-34a was identified.

Conclusion

This meta-analysis revealed that lower miR-34a expression is significantly connected with worse OS and DFS/PFS/RFS in GIC patients. In addition, the miR-34a expression level is relatively lower in patients with lymph node metastasis than in patients without lymph node metastasis, and decreased miR-34a expression levels are linked to poor tumour differentiation and late TNM stage. MiR-34a may become a new factor for the prognosis prediction and progression of GICs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07751-y.

LncRNA XIST Inhibits the Progression of Oral Squamous Cell Carcinoma via Sponging miR-455-3p/BTG2 Axis

Objective

Oral squamous cell carcinoma (OSCC) is one of the most common cancers, accounting for over 90% of malignant lesions in the oral cavity. Long non-coding RNAs play an important role in the development of OSCC. This study aimed to investigate the effects of lncRNA XIST on the malignant behaviors of OSCC cells and its possible molecular mechanisms.

Methods

Real-time quantitative PCR and Western blot were used to detect the RNA and protein level, respectively. CAL27 and SCC25 cells with the lowest expression level of XIST were used for further study. MTT, transwell assay, colony formation, and xenograft model were applied to examine the effect of XIST on the progression of OSCC. FISH assay was performed to investigate the co-location of XIST and miR-455-3p in OSCC cells. The bioinformatics analysis, luciferase, and RNA pull down assay were utilized to predict and verify the target genes of miR-455-3p.

Results

XIST was downregulated in OSCC tissues and cell lines. Overexpression of XIST inhibited the proliferation, migration, and invasion ability of OSCC cells. Bioinformatics analysis and luciferase reporter assay confirmed XIST could bind to miR-455-3p. Besides, miR-455-3p directly targeted BTG2 in OSCC cells. Rescue experiments further confirmed the positive interaction between miR-455-3p and XIST as well as between miR-455-3p and BTG2.

Conclusion

XIST was down-regulated in OSCC. XIST regulated the expression of BTG2 via sponging miR-455-3p. XIST/miR-455-3p/BTG2 signal axis inhibited the malignant progression of OSCC.

Long non‑coding RNA TP73‑AS1 accelerates the progression and cisplatin resistance of non‑small cell lung cancer by upregulating the expression of TRIM29 via competitively targeting microRNA‑34a‑5p

Non-small cell lung cancer (NSCLC) is a leading subtype of lung cancer, with high mortality rates. Recently, long non-coding RNAs (lncRNAs) have been associated with NSCLC. The present study aimed to examine the role of the TP73 antisense RNA 1 (TP73-AS1) lncRNA in NSCLC. TP73-AS1 and microRNA(miR)-34a-5p expression levels were measured using reverse transcription-quantitative PCR (RT-qPCR) and chromogenic in situ hybridization (CISH). Cell proliferation, apoptosis, migration and invasion was determined using Cell Counting Kit-8 (CCK-8), flow cytometry, Transwell and Matrigel assays, respectively. The median inhibitory concentration (IC₅₀) value of cisplatin (cis-diamminedichloroplatinum; DDP) was assessed using a CCK-8 assay. The interaction between miR-34a-5p and TP73-AS1 or tripartite motif-containing 29 (TRIM29) was predicted using microRNA.org and Starbase, then verified using a dual-luciferase reporter assay. The expression of TRIM29 was quantified at the mRNA and protein level using RT-qPCR and western blot analysis, respectively. TP73-AS1 was significantly upregulated, while miR-34a-5p was downregulated in NSCLC tissues and cells. Functionally, TP73-AS1 knockdown inhibited proliferation, migration, invasion and DDP resistance, whilst inducing apoptosis in NSCLC cells. miR-34a-5p was identified as a target for TP73-AS1, and its inhibition reversed the effects of TP73-AS1 knockdown on NSCLC cells. In addition, TRIM29 was targeted by miR-34a-5p, and its overexpression reversed the effects of miR-34a-5p. Moreover, TP73-AS1 acted as a molecular sponge for miR-34a-5p, increasing the expression of TRIM29. In conclusion, TP73-AS1 contributed to proliferation, migration and DDP resistance but inhibited apoptosis of NSCLC cells by upregulating TRIM29 and sponging miR-34a-5p.

The Ambivalent Role of lncRNA Xist in Carcinogenesis

Long non-coding RNA (lncRNA) Xist has emerged as a key modulator in dosage compensation by randomly inactivating one of the X chromosomes in mammals during embryonic development. Dysregulation of X chromosome inactivation (XCI) due to deletion of Xist has been proven to induce hematologic cancer in mice. However, this phenomenon is not consistent in humans as growing evidence suggests Xist can suppress or promote cancer growth in different organs of the human body. In this review, we discuss recent advances of XCI in human embryonic stem cells and provide an explanation for the seemingly contradictory roles of Xist in development of human cancer.

Prognostic value of microRNAs in pancreatic cancer: a meta-analysis

BACKGROUND

The prognostic impact of microRNA (miRNA) expression levels in pancreatic cancer (PC) has been estimated for years, but the outcomes are controversial and heterogeneous. Therefore, we comprehensively reviewed the evidence collected on miRNA expression in PC to determine this effect.

RESULTS

PC patients with high miR-21 (HR=2.61, 95%CI=1.68-4.04), miR-451a (HR=2.23, 95%CI=1.23-4.04) or miR-1290 (HR=1.43, 95%CI=1.04-1.95) levels in blood had significantly poorer OS (P<0.05). Furthermore, PC patients with high miR-10b (HR=1.73, 95%CI=1.09-2.76), miR-17-5p (HR=1.91, 95%CI=1.30-2.80), miR-21 (HR=1.90, 95%CI=1.61-2.25), miR-23a (HR=2.18, 95%CI=1.52-3.13), miR-155 (HR=2.22, 95%CI=1.27-3.88), miR-203 (HR=1.65, 95%CI=1.14-2.40), miR-221 (HR=1.72, 95%CI=1.08-2.74), miR-222 levels (HR=1.72, 95%CI=1.02-2.91) or low miR-29c (HR=1.39, 95%CI=1.08-1.79), miR-126 (HR=1.55, 95%CI=1.23-1.95), miR-218 (HR=2.62, 95%CI=1.41-4.88) levels in tissues had significantly shorter OS (P<0.05).

CONCLUSIONS

In summary, blood miR-21, miR-451a, miR-1290 and tissue miR-10b, miR-17-5p, miR-21, miR-23a, miR-29c, miR-126, miR-155, miR-203, miR-218, miR-221, miR-222 had significant prognostic value.

METHODS

We searched PubMed, EMBASE, Web of Science and Cochrane Database of Systematic Reviews to recognize eligible studies, and 57 studies comprising 5445 PC patients and 15 miRNAs were included to evaluate the associations between miRNA expression levels and overall survival (OS) up to June 1, 2019. Summary hazard ratios (HR) with 95% confidence intervals (CI) were calculated to assess the effect.

A Systemic Review on the Regulatory Roles of miR-34a in Gastrointestinal Cancer

MicroRNAs (miRNAs) are a class of endogenous non-coding single-stranded small-molecule RNAs that regulate gene expression by repressing target messenger RNA (mRNA) translation or degrading mRNA. miR-34a is one of the most important miRNAs participating in various physiological and pathological processes. miR-34a is abnormally expressed in a variety of tumors. The roles of miR-34a in gastrointestinal cancer (GIC) draw lots of attention. Numerous studies have demonstrated that dysregulated miR-34a is closely related to the proliferation, differentiation, migration, and invasion of tumor cells, as well as the diagnosis, prognosis, treatment, and chemo-resistance of tumors. Thus, we systematically reviewed the abnormal expression and regulatory roles of miR-34a in GICs including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), and gallbladder cancer (GBC). It may provide a profile of versatile roles of miR-34a in GICs.

LncRNA XIST acts as a ceRNA sponging miR-185-5p to modulate pancreatic cancer cell proliferation via targeting CCND2

BACKGROUND

Long non-coding RNAs (lncRNAs) have been proved to be involved in the occurrence and progression of various tumors including pancreatic cancer (PC). Growing evidence shows that lncRNA X inactive-specific transcript (XIST) functions as an oncogene in multiple tumorigenesis. However, the underlying mechanism of lncRNA XIST in the progression of PC remains elusive.

METHODS

Expression levels of XIST and miR-185-5p both in PC tissues or PC cells were determined using real-time quantitative PCR (qRT-PCR). Gain and loss-of-function of XIST or miR-185-5p was performed for further exploration. Moreover, colony formation assay was performed to assess cell proliferation. Flow cytometry analysis was performed to measure cell cycle and apoptosis. Dual-luciferase reporter assay was conducted to verify the correlation between XIST, miR-185-5p and CCND2, respectively. Additionally, western blot analysis was conducted to determine the expression pattern of apoptosis-related proteins and cell cycle-associated proteins.

RESULTS

Herein, we found that XIST expression was up-regulated while miR-185-5p was down-regulated both in PC tissues and cell lines, compared with that of controls. Moreover, there was a negative correlation between XIST and miR-185-5p. Following that, functional experiments displayed that knockdown of XIST or overexpression of miR-185-5p inhibited cell proliferation, induced cell cycle arrest and promoted apoptosis in PC cells. Furthermore, mechanistic experiments displayed that XIST could negatively regulate miR-185-5p via direct binding. In addition, CCND2 was shown to be a downstream target of miR-185-5p. Importantly, overexpression or knockdown of XIST significantly increased or decreased the expression of CCND2, while these effects were reversed by miR-185-5p.

CONCLUSIONS

Taken together, our study demonstrated that lncRNA XIST functions as an oncogene and exerts its regulation via miR-185-5p/CCND2 axis, promoting proliferation and inhibiting apoptosis in PC.

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.

Long noncoding RNA 00976 promotes pancreatic cancer progression through OTUD7B by sponging miR-137 involving EGFR/MAPK pathway

BACKGROUND

Accumulation evidence indicates the vital role of long non-coding RNAs (lncRNAs) in tumorigenesis and the progression of malignant tumors, including pancreatic cancer (PC). However, the role and the molecular mechanism of long non-coding RNA 00976 is unclear in pancreatic cancer.

METHODS

In situ hybridization (ISH) and qRT-PCR was performed to investigate the association between linc00976 expression and the clinicopathological characteristics and prognosis of patients with PC. Subsequently, linc00976 over-expression vector and shRNAs were transfected into PC cells to up-regulate or down-regulate linc00976 expression. Loss- and gain-of function assays were performed to investigate the role of linc00976 in proliferation and metastasis in vitro and vivo. ITRAQ, bioinformatic analysis and rescue assay were used to illustrate the ceRNA mechanism network of linc00976/miR-137/OTUD7B and its downstream EGFR/MAPK signaling pathway.

RESULTS

linc00976 expression was overexpressed in PC tissues and cell lines and was positively associated with poorer survival in patients with PC. Function studies revealed that linc00976 knockdown significantly suppressed cell proliferation, migration and invasion in vivo and in vitro, whereas its overexpression reversed these effects. Based on Itraq results and online database prediction, Ovarian tumor proteases OTUD7B was found as a downstream gene of linc00976, which deubiquitinated EGFR mediates MAPK signaling activation. Furthermore, Bioinformatics analysis and luciferase assays and rescue experiments revealed that linc00976/miR137/OTUD7B established the ceRNA network modulating PC cell proliferation and tumor growth.

CONCLUSION

The present study demonstrates that linc00976 enhances the proliferation and invasion ability of PC cells by upregulating OTUD7B expression, which was a target of miR-137. Ultimately, OTUD7B mediates EGFR and MAPK signaling pathway, suggesting that linc00976/miR-137/OTUD7B/EGFR axis may act as a potential biomarker and therapeutic target for PC.

The Emerging Role of Major Regulatory RNAs in Cancer Control

Alterations and personal variations of RNA interactions have been mechanistically coupled with disease etiology and phenotypical variations. RNA biomarkers, RNA mimics, and RNA antagonists have been developed for diagnostic, prognostic, and therapeutic uses. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are two major types of RNA molecules with regulatory roles, deregulation of which has been implicated in the initiation and progression of many human malignancies. Accumulating evidence indicated the clinical roles of regulatory RNAs in cancer control, stimulating a surge in exploring the functionalities of regulatory RNAs for improved understanding on disease pathogenesis and management. In this review, we highlight the critical roles of lncRNAs and miRNAs played in tumorigenesis, scrutinize their potential functionalities as diagnostic/prognostic biomarkers and/or therapeutic targets in clinics, outline opportunities that ncRNAs may bring to complement current clinical practice for improved cancer management and identify challenges faced by translating frontier knowledge on non-coding RNAs (ncRNAs) to bedside clinics as well as possible solutions.

Long non-coding RNA PXN-AS1 suppresses pancreatic cancer progression by acting as a competing endogenous RNA of miR-3064 to upregulate PIP4K2B expression

BACKGROUND

Dysregulation of microRNAs (miRNAs) play critical roles in cancerous processes. Although miR-3064 was reported to be an important tumor suppressor in ovarian cancer, the cellular impact of miR-3064 on pancreatic cancer (PC) progression, its downstream target genes and upstream mechanisms that control the expression of miR-3064 remain to be fully clarified.

METHODS

We compared miRNA expression profiles between PC tissues compared with normal tissues using a miRNA microarray analysis of clinical samples, and screened the identified miRNAs for their influence on cell proliferation. We measured the expression of miR-3064 in PC tissues and PC cell lines using quantitative real-time PCR assays. Gain- and loss-of-function experiments were conducted to explore the biologic significance of miR-3064 in PC progression both in vitro and in vivo. The interactions between miR-3064 and long noncoding RNA (lncRNA) PXN-AS1 was verified using the luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

We showed that miR-3064 was significantly overexpressed in PC tissues compared to normal tissues. High miR-3064 was associated with worse prognosis in patients with PC. Functionally, ectopic expression of miR-3064 promoted the proliferation, invasion, clone formation and sphere formation of PC cells in vitro and stimulated PC growth in vivo, while specific knockdown of miR-3064 or CRISPR/Cas9-mediated knockout of miR-3064 resulted in opposite phenotypes. Further investigation revealed that miR-3064 directly targeted PIP4K2B, which was reduced in PC tissues and attenuated PC cell proliferation, invasion and sphere formation induced by miR-3064. Importantly, lncRNA PXN-AS1 expression was downregulated in PC samples, and it directly interacted with miR-3064 and suppressed its levels in PC cells. Enforced expression of PXN-AS1 remarkably decreased cell proliferation, invasion and sphere formation, while re-expression of miR-3064 abrogated these effects of PXN-AS1.

CONCLUSIONS

MiR-3064, a key oncogenic miRNA, could promote PC cell growth, invasion and sphere formation via downregulating the levels of tumor suppressor PIP4K2B. PXN-AS1 functioned as a sponge to suppress the expression of miR-3064. These observations offer fresh insight into the mechanisms through which miR-3064 modulates the development of PC.

LncRNA XIST depletion prevents cancer progression in invasive pituitary neuroendocrine tumor by inhibiting bFGF via upregulation of microRNA-424-5p

Background

Long noncoding RNAs (lncRNAs) are vital mediators in human cancers including pituitary neuroendocrine tumor (PitNET) and could function as competing endogenous RNAs (ceRNAs) of microRNAs (miRNAs). The main objective of this study is to identify effect of lncRNA X-inactive specific transcript (XIST) and microRNA-424-5p (miR-424-5p) on PitNET.

Methods

Microarray analysis was employed to identify the PitNET-related differentially expressed lncRNAs. PitNET tissues, including both invasive and non-invasive subtypes in parallel with normal pituitary tissues were collected for the determination of the expression of XIST, miR-424-5p and basic fibroblast growth factor (bFGF) and the interaction among them. Subsequently, the expression of XIST, miR-424-5p and bFGF in PitNET cells was altered to elucidate their biological significance in the aspects of proliferation, migration, invasion, and the apoptosis.

Results

Both XIST and bFGF exhibited high expression, but miR-424-5p had a low expression in invasive PitNET tissues as compared to non-invasive PitNET normal pituitary tissues. Additionally, XIST competitively bound to miR-424-5p to elevate the expression of bFGF. Furthermore, depleted XIST or bFGF, or elevated miR-424-5p was revealed to suppress the proliferation, migration, invasion, and promote cell cycle arrest and apoptosis of invasive PitNET cells. miR-424-5p repressed the proliferation, migration, invasion of invasive PitNET cells by targeting bFGF.

Conclusion

In conclusion, the fundamental findings of the present study suggested that the functional suppression of XIST downregulated bFGF to inhibit the development of PitNET by increasing miR-424-5p expression, proposing XIST as a novel therapeutic target for PitNET.

Long non-coding RNA XIST promotes cell proliferation and migration through targeting miR-133a in bladder cancer

The long non-coding RNA (lncRNA) X inactive specific transcript (XIST) has recently been reported to promote the malignant progression of bladder cancer through regulating several microRNAs (miRs), including miR-124, miR-139-5p and miR-200c. However, whether other miRs are also involved in this process has remained to be determined. The present study demonstrated that XIST was significantly upregulated in bladder cancer tissues compared with that in adjacent normal tissues. Furthermore, its expression was reduced in several common bladder cancer cell lines. High expression of XIST was significantly associated with tumour progression and poor prognosis of patients with bladder cancer. An in vitro experiment indicated that knockdown of XIST significantly reduced the proliferation and migration of bladder cancer cells. A luciferase assay suggested that XIST binds to its predicted binding site in miR-133a. In addition, it was identified that miR-133a was significantly downregulated in bladder cancer, and its expression levels were inversely correlated with those of XIST in bladder cancer tissues. Furthermore, loss- and gain-of-function experiments indicated that miR-133a acted as a downstream effector in XIST-mediated bladder cancer cell proliferation and migration. In conclusion, the present study demonstrates that XIST promotes bladder cancer cell proliferation and migration via targeting miR-133a and thus suggests that XIST may be used as a potential therapeutic target for bladder cancer.

Long non-coding RNA XIST promotes extracellular matrix degradation by functioning as a competing endogenous RNA of miR-1277-5p in osteoarthritis

Osteoarthritis (OA) is a common and troublesome disease among the elderly, and is characterized by extracellular matrix (ECM) degradation. The function of the long non‑coding RNA X‑inactive‑specific transcript (XIST) and its working mechanism in ECM degradation remains unclear. In the present study, XIST was revealed to be upregulated in OA specimens and in articular chondrocytes (ACs) derived from OA tissue (AC/OA) and interleukin‑1β (IL‑1β)‑treated ACs. Loss‑of‑function experiments demonstrated that downregulation of XIST suppressed the degradation of the ECM in AC/OA and AC/IL‑1β‑5.0 cells. Furthermore, XIST, matrix metalloproteinase 13 (MMP‑13) and ADAM metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS5) were identified as targets of microRNA (miR)‑1277‑5p, and the reciprocal inhibitive effect between XIST and miR‑1277‑5p was elucidated. Furthermore, the role of XIST in ECM degradation was confirmed to be functioning as a competing endogenous RNA (ceRNA) of miR‑1277‑5p. Finally, the protective effect of the downregulation of XIST on ECM degradation was verified in an OA rat model. In conclusion, the present study suggests that XIST promotes MMP‑13 and ADAMTS5 expression, indicating ECM degradation, by functioning as a ceRNA of miR‑1277‑5p in OA. The present study proposed a novel potential target with a new working mechanism in molecular treating of OA.

Up-regulated lncRNA XIST contributes to progression of cervical cancer via regulating miR-140-5p and ORC1

Background

The study purpose was to make investigation into the influence of XIST on cervical cancer progression and what’s more its potential mechanism.

Methods

The cervical cancer data sets (lncRNA, miRNA, and mRNA) obtained from TCGA were analyzed with the “mixOmics” R package. Then, the expression of XIST, miR-140-5p, and ORC1 were detected using qRT-PCR and western blot in both tissues and cervical cancer cell lines (Hela and C33A) to verify the bioinformatics analyses results. CCK-8 assay, 5-ethynyl-2′-deoxyuridine (EdU) assays, cell cycle assay and cell apoptosis assay were practiced. Besides, immunohistochemistry staining was operated for the detection of the Ki-67, E-cadherin and vimentin expression in cervical cancer tissues and the apoptosis-related proteins expression (c-caspase3, Bcl-2, total PARP and cleaved PARP) was verified through western blot. And in vivo experiments were implemented.

Results

MiR-140-5p was down-regulated but XIST and ORC1 were up-regulated in cervical cancer tissues and cell lines. Knocking down of the XIST or ORC1 memorably suppressed cell proliferation, blocked cell cycle, decreased the expression of Bcl-2 while increased the apoptosis rate and the expression of c-caspase3 and cleaved PARP in HeLa and C33A cells. Besides, the results of immunohistochemistry staining showed knocking down the expression of XIST improved the expression levels of E-cadherin and decreased Ki-67 and vimentin expression. And overexpression of miR-140-5p also could inhibit the progression and reverse the influence of XIST and ORC1 in HeLa and C33A cells.

Conclusion

Our study indicated the effects of XIST/miR-140-5p/ORC1 axis on the progression of cervical cancer which will shed new light on epigenetic diagnostics and therapeutics in cervical cancer.

Long non-coding RNA XIST serves an oncogenic role in osteosarcoma by sponging miR-137

The long non-coding RNA X inactive-specific transcript (XIST) has been implicated in certain human cancers, including osteosarcoma (OS), but the molecular mechanism of XIST underlying OS progression remains to be fully uncovered. In the present study, reverse transcription-quantitative polymerase chain reaction data demonstrated that XIST was significantly upregulated in OS tissues and cell lines (Saos-2, U2OS, HOS and MG63) compared with adjacent non-tumour tissues and normal human osteoblast cell line HFOB1.19. Bioinformatics analysis and luciferase reporter gene assay data demonstrated that XIST could directly target microRNA (miR)-137 and negatively regulate the expression of miR-137 in Saos-2 and U2OS cells. Furthermore, miR-137 was markedly downregulated in OS tissues and cell lines. An inverse association between XIST and miR-137 expression was observed in OS tissues. Knockdown of XIST caused a significant reduction in cell proliferation and invasion and suppressed matrix metalloproteinase (MMP2) and MMP9 protein levels in Saos-2 and U2OS cells. Furthermore, inhibition of miR-137 expression abolished the effects of XIST downregulation on the proliferation and invasion of OS cells. In summary, the present study suggests that XIST promotes OS cell proliferation and invasion by inhibition of miR-137 expression. Thus, XIST may be a potential therapeutic target for the treatment of OS.

Long noncoding RNA XIST promotes proliferation and invasion by targeting miR-141 in papillary thyroid carcinoma

Background

The long noncoding RNA X-inactive specific transcript (XIST) was reported to play vital roles in tumor progression. In the present study, we determined the regulatory function of XIST in papillary thyroid carcinoma (PTC).

Materials and methods

XIST expression was determined in PTC tissues and cell lines by quantitative real-time polymerase chain reaction (PCR) (qRT-PCR). Cellular proliferation, migration, and invasion were measured using the Cell Counting Kit-8 (CCK-8) assay, wound-healing assay, and transwell invasion assay, respectively. Western blotting was used to determine protein expression. The downstream target miRNAs for XIST were identified by luciferase reporter assay and qRT-PCR.

Results

Relative expression of XIST was upregulated in PTC tissues and cell lines. High XIST expression was positively correlated with TNM stage and lymph node metastasis. Function assay demonstrated that knockdown of XIST significantly decreased cell proliferation, migration, and invasion in PTC cells. Moreover, we showed that the effects of XIST on PTC cell progression were mediated by miR-141.

Conclusion

Our results demonstrated that XIST functioned as an oncogene in PTC progression by regulating miR-141, suggesting that XIST might be a promising therapeutic target for PTC treatment.