Long non-coding RNA PVT1 promotes osteosarcoma development by acting as a molecular sponge to regulate miR-195

Long Noncoding RNA PVT1 Acts as a "Sponge" to Inhibit microRNA-152 in Gastric Cancer Cells

BACKGROUND

PVT1 was up-regulated in patients with gastric cancer (GC) and might be as a novel biomarker for predicting GC. However, the exact mechanism of PVT1 exerting functions in GC was still poorly understood. Emerging evidence suggests that long noncoding RNAs may act as endogenous microRNA (miRNA) sponges to bind to miRNAs and regulate their function.

AIM

This study aimed to determine the function of PVT1 on miR-152 expression in GC cells.

METHODS

The levels of PVT1 and miR-152 were determined in GC tissues by quantitative real-time PCR. The expression of miR-152 was detected in GC cells transfected with PVT1 plasmid or siPVT1. Luciferase assay was performed to verify the regulation of miR-152 to CD151 or FGF2 expression and PVT1 to miR-152 expression. The effects of PVT1 on the expression of CD151 and FGF2 were evaluated by Western blot.

RESULTS

PVT1 was up-regulated in GC tissues than that in the matched normal tissues, and mRNA level of miR-152 was decreased. MiR-152 was negatively associated with PVT1 expression in GC tissues. Based on the in silico analysis, we found that PVT1 have three binding sequences for miR-152. Moreover, PVT1 might inhibit the expression of miR-152 and increased the expression of CD151 and FGF2 through regulating miR-152. PVT1 was positively associated with CD151 and FGF2 expression in GC tissues.

CONCLUSIONS

PVT1 might act as a "sponge" to inhibit miR-152 in gastric cancer cells. PVT1 is a promising molecular target to improve the diagnosis and therapy of GC.

Knockdown of Long Non-Coding RNA NEAT1 Inhibits Proliferation and Invasion and Induces Apoptosis of Osteosarcoma by Inhibiting miR-194 Expression

PURPOSE

Long non-coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (NEAT1) has been implicated as an oncogene in the development and progression of osteosarcoma. This study aims to explore the mechanism of NEAT1 in osteosarcoma.

MATERIALS AND METHODS

Expressions of NEAT1 and miR-194 in osteosarcoma tissues and cells were detected by quantitative real-time PCR. The effects of NEAT1 knockdown or miR-194 overexpression on cell proliferation, invasion, and apoptosis were determined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay, transwell invasive assay, and flow cytometry analysis, respectively. Luciferase reporter assay was performed to observe the possible interaction between NEAT1 and miR-194.

RESULTS

NEAT1 was upregulated and miR-194 was downregulated in osteosarcoma tissues and cells. Knockdown of NEAT1 or overexpression of miR-194 suppressed proliferation and invasion and induced apoptosis of osteosarcoma cells in vitro. Luciferase reporter assay validated that NEAT1 could interact with miR-194 and negatively modulated its expression. Furthermore, inhibition of miR-194 reversed the suppression of proliferation and invasion and the promotion of apoptosis induced by NEAT1 depletion in osteosarcoma cells.

CONCLUSION

Knockdown of NEAT1 suppressed proliferation and invasion and induced apoptosis in osteosarcoma cells by inhibiting miR-194 expression.

Long non-coding RNA ZFAS1 sponges miR-486 to promote osteosarcoma cells progression and metastasis in vitro and vivo

Long noncoding RNAs (lncRNAs) have been wildly demonstrated to participate in the osteosarcoma tumorigenesis. ZFAS1 is a novel identified lncRNA, however, its role in osteosarcoma is still unclear. In present study, we utilize lncRNA microarray assay to screen the lncRNA expression profile in osteosarcoma tissue, and investigate the regulatory function of ZFAS1 in osteosarcoma. LncRNA microarray assay revealed that lncRNA ZFAS1 was significantly up-regulated in 3 pairs of osteosarcoma and adjacent non-tumor tissue, which was confirmed by RT-PCR. Furthermore, in 53 pairs of osteosarcoma patient samples, the up-regulated expression of ZFAS1 was closely related to poor prognosis. In vitro, loss-of-function experiments showed that ZFAS1 knockdown significantly suppressed the proliferation, induced cycle arrest at G0/G1 phase and enhance apoptosis. In vivo, ZFAS1 knockdown inhibited the tumor growth. Bioinformatics online programs predicted that ZFAS1 sponge miR-486 at 3’-UTR with complementary binding sites, which was validated using luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Rescue experiments confirmed that miR-486 could reverse the functions of ZFAS1 on osteosarcoma genesis. In conclusion, our results demonstrate that ZFAS1 act as competing endogenous RNA (ceRNA) for miR-486, and act as oncogene in osteosarcoma tumorigenesis, and discover the functional regulatory pathway of ZFAS1 sponging miR-486.

Upregulation of long noncoding RNA Xist promotes proliferation of osteosarcoma by epigenetic silencing of P21

Recent studies show that lncRNAs involve in the initiation and progression of various cancers including osteosarcoma (OS). IncRNA Xist has been verified as an oncogene in several human cancers, and its abnormal expression was closely associated with tumor initiation and progression. Nevertheless, the role of Xist in OS remains unclear. Here, we revealed the Xist expression level was up-regulated in OS tissues and discovered that Xist knockdown significantly repressed OS cell proliferation. Additionally, mechanistic analysis revealed that Xist can repress P21 expression to regulate OS cell cycle and proliferation by binding to EZH2. Taking all into account, Xist may function in promoting OS cell proliferation and may potentially serve as a novel biomarker and therapeutic target for OS.

Long non-coding RNAs for osteosarcoma in the mouse: a meta-analysis

Osteosarcoma, one of the most common primary bone malignances, is a leading cause of cancer death among children and adolescents. Recently, growing studies have found that long non-coding RNAs (lncRNAs) can interfere with the expression of various genes, and participate in the occurrence and development of malignancies. The purpose of this study is to evaluate the potential functions of lncRNAs as diagnostic biomarkers and therapeutic targets for osteosarcoma in mice, thus to direct the strict design for the future preclinical experiments and clinical trials. We systematically searched PubMed, Web of Science, Embase, China Knowledge Resource Integrated Database, VIP, Chinese BioMedical and Wan Fang Database from their initiation date to June 20, 2017. Two researchers independently screened the literatures and withdrew the data, which used the tumor volume and tumor weight as the outcome measures. A total of 10 studies were included, and the results of this meta-analysis revealed that lncRNAs could serve as the diagnostic biomarkers and therapeutic targets for osteosarcoma; and progression of osteosarcoma in mice could be inhibited via rescuing the abnormally expressed lncRNAs. It is necessary to carry out more rigorous basic experiments before lncRNAs can be further investigated in the clinical trials and used in future clinical practices.

LncRNA ODRUL Contributes to Osteosarcoma Progression through the miR-3182/MMP2 Axis

Recent findings have shown that lncRNA dysregulation is involved in many cancers, including osteosarcoma (OS). In a previous study, we reported a novel lncRNA, ODRUL, that could promote doxorubicin resistance in OS. We now report the function and underlying mechanism of ODRUL in regulating OS progression. We show that ODRUL is upregulated in OS tissues and cell lines and correlates with poor prognosis. ODRUL knockdown significantly inhibits OS cell proliferation, migration, invasion, and tumor growth in vitro and in vivo by decreasing matrix metalloproteinase (MMP) expression. A microarray screen combined with online database analysis showed that miR-3182 is upregulated and MMP2 is downregulated in sh-ODRUL-expressing MG63 cells and that miR-3182 harbors potential binding sites for ODRUL and the 3' UTR of MMP2 mRNA. In addition, miR-3182 expression and function are inversely correlated with ODRUL expression in vitro and in vivo. A luciferase reporter assay demonstrated that ODRUL could directly interact with miR-3182 and upregulate MMP2 expression via its competing endogenous RNA activity on miR-3182 at the posttranscriptional level. Taken together, our study has elucidated the role of oncogenic ODRUL in OS progression and may provide a new target in OS therapy.

Increased circular RNA UBAP2 acts as a sponge of miR-143 to promote osteosarcoma progression

Deregulated expression of circular RNA (circRNA) has been determined to be important in carcinogenesis and progression; however, in the most common type of primary malignant bone tumor osteosarcoma, the roles of circRNA in cancer development still remain to be elucidated. Here, we found that circRNA UBAP2 (circUBAP2) expression is significantly increased in human osteosarcoma tissues as compared to those in matched controls. Increased circUBAP2 expression was significantly correlated with human osteosarcoma progression and prognosis. Furthermore, increased circUBAP2 could promote osteosarcoma growth and inhibit apoptosis both in vitro and in vivo. Mechanistically, circUBAP2 was found to inhibit the expression of microRNA-143 (miR-143), thus enhancing the expression and function of anti-apoptotic Bcl-2, which is a direct target of miR-143. Together, our results suggest the roles of circUBAP2 in osteosarcoma development and implicate its potential in prognosis prediction and cancer therapy.

LncRNA PVT1 Regulates Chondrocyte Apoptosis in Osteoarthritis by Acting as a Sponge for miR-488-3p

Long noncoding RNAs (lncRNAs) have been known to be involved in multiple diverse diseases, including osteoarthritis (OA). The present study aims at exploring the biological role of lncRNA plasmacytoma variant translocation 1 (PVT1) in OA and the underlying mechanism. Results showed that the expression of PVT1 was upregulated in OA chondrocytes compared with normal chondrocytes, silencing PVT1 inhibited the apoptosis of OA chondrocytes, and overexpression of PVT1 promoted the apoptosis of normal chondrocytes. To further investigate the underlying mechanism, miR-488-3p was predicted to be a targeted microRNA of PVT1. Different methods, including MS2 RNA immunoprecipitation (RIP), luciferase activity, and anti-AGO2 RIP, were performed to detect the interaction between PVT1 and miR-488-3p, which suggested that PVT1 negatively regulated miR-488-3p in OA chondrocytes. Moreover, PVT1 promoted the apoptosis of OA and normal chondrocytes through miR-488-3p. Collectively, this study revealed that lncRNA PVT1 regulated the apoptosis of chondrocytes by acting as a sponge for miR-488-3p in OA. PVT1 may be considered a new therapeutic target for the treatment of OA.

LncRNA FENDRR sensitizes doxorubicin-resistance of osteosarcoma cells through down-regulating ABCB1 and ABCC1

Long noncoding RNAs (LncRNAs) act as crucial regulators in various cancers including osteosarcoma (OS), yet their potential roles and molecular mechanisms in OS chemoresistance remain unclear. In the present study, we investigated the role and potential regulatory mechanism of the most down-regulated expressed lncRNA, FENDRR screened by our previous lncRNA microarray analysis between the paired doxorubicin-resistant and sensitive human osteosarcoma cell lines (MG63/DXR vs MG63). FENDRR expression was down-regulated in the doxorubicin-resistant OS cell lines and tissues and negatively correlated to the poor prognosis of OS patients. Overexpression of FENDRR suppressed doxorubicin-resistance, G2/M phase of cell cycle, and promoted cell apoptosis of osteosarcoma cells in vitro and tumor growth in vivo whereas FENDRR knockdown had the opposite effects. In addition, we found that FENDRR was mainly located in the cytoplasm and could regulate the drug resistance of osteosarcoma cells by negatively affecting posttranscriptional expression of ABCB1 and ABCC1. Together, our study demonstrated that lncRNA FENDRR may act as an inhibitory molecule of doxorubicin-resistance through down-regulating the expression of ABCB1 and ABCC1 genes in osteosarcoma cells. These findings may extend the function of FENDRR in tumor progression and provide a novel target for reversing OS chemoresistance.

Decrease of miR-195 Promotes Chondrocytes Proliferation and Maintenance of Chondrogenic Phenotype via Targeting FGF-18 Pathway

Slow growth and rapid loss of chondrogenic phenotypes are the major problems affecting chronic cartilage lesions. The role of microRNA-195 (miR-195) and its detailed working mechanism in the fore-mentioned process remains unknown. Fibroblastic growth factor 18 (FGF-18) plays a key role in cartilage homeostasis; whether miR-195 could regulate FGF-18 and its downstream signal pathway in chondrocyte proliferation and maintenance of chondrogenic phenotypes still remains unclear. The present research shows elevated miR-195 but depressed FGF-18 expressed in joint fluid specimens of 20 patients with chronic cartilage lesions and in CH1M and CH3M chondrocytes when compared with that in joint fluid specimens without cartilage lesions and in CH1W and CH2W chondrocytes, respectively. The following loss of function test revealed that downregulation of miR-195 by transfection of miR-195 inhibitors promoted chondrocyte proliferation and expression of a type II collagen α I chain (Col2a1)/aggrecan. Through the online informatics analysis we theoretically predicted that miR-195 could bind to a FGF-18 3' untranslated region (3'UTR), also, we verified that a miR-195 could regulate the FGF-18 and its downstream pathway. The constructed dual luciferase assay further confirmed that FGF-18 was a direct target of miR-195. The executed anti-sense experiment displayed that miR-195 could regulate chondrocyte proliferation and Col2a1/aggrecan expression via the FGF-18 pathway. Finally, through an in vivo anterior cruciate ligament transection (ACLT) model, downregulation of miR-195 presented a significantly protective effect on chronic cartilage lesions. Evaluating all of the outcomes of the current research revealed that a decrease of miR-195 protected chronic cartilage lesions by promoting chondrocyte proliferation and maintenance of chondrogenic phenotypes via the targeting of the FGF-18 pathway and that the miR-195/FGF-18 axis could be a potential target in the treatment of cartilage lesions.

Potentials of Long Noncoding RNAs (LncRNAs) in Sarcoma: From Biomarkers to Therapeutic Targets

Sarcoma includes some of the most heterogeneous tumors, which make the diagnosis, prognosis and treatment of these rare yet diverse neoplasms especially challenging. Long noncoding RNAs (lncRNAs) are important regulators of cancer initiation and progression, which implies their potential as neoteric prognostic and diagnostic markers in cancer, including sarcoma. A relationship between lncRNAs and sarcoma pathogenesis and progression is emerging. Recent studies demonstrate that lncRNAs influence sarcoma cell proliferation, metastasis, and drug resistance. Additionally, lncRNA expression profiles are predictive of sarcoma prognosis. In this review, we summarize contemporary advances in the research of lncRNA biogenesis and functions in sarcoma. We also highlight the potential for lncRNAs to become innovative diagnostic and prognostic biomarkers as well as therapeutic targets in sarcoma.