Exosomes promote hFOB1.19 proliferation and differentiation via LINC00520

BACKGROUND

Osteoporosis remains a significant clinical challenge worldwide. Recent studies have shown that exosomes stimulate bone regeneration. Thus, it is worthwhile to explore whether exosomes could be a useful therapeutic strategy for osteoporosis. The purpose of this study was to investigate the effects of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs) on osteoblast proliferation and differentiation.

METHODS

Exosomes were isolated from hucMSCs. Bioinformatics analysis was performed to identify the differentially expressed lncRNAs in myeloma-derived mesenchymal stem cells. Plasmids encoding LINC00520 or short hairpin RNA of LINC00520 were transfected into hucMSCs and then exosomes were isolated. After human osteoblasts hFOB1.19 were exposed to the obtained exosomes, cell survival, cell cycle, apoptosis and calcium deposits of hFOB1.19 cell were detected by MTT, 7-aminoactinomycin D, Annexin V-FITC/propidium iodide and Alizarin red staining, respectively.

RESULTS

In hFOB1.19 cells, 10 × 10⁹/mL hucMSC-derived exosomes inhibited cell proliferation, arrested cell cycle, and promoted apoptosis, while hucMSCs or 1 × 10⁹/mL exosomes promoted cell proliferation, accelerated cell cycle, and promoted calcium deposits and the expression of OCN, RUNX2, collagen I and ALP. In hFOB1.19 cells, exosomes from hucMSCs with LINC00520 knockdown reduced the survival and calcium deposits, arrested the cell cycle, and enhanced the apoptosis, while exosomes from hucMSCs overexpressing LINC00520 enhance the proliferation and calcium deposits and accelerated the cell cycle.

CONCLUSIONS

LINC00520 functions as a modulator of calcium deposits, and exosomes derived from hucMSCs overexpressing LINC00520 might be a novel therapeutic approach for osteoporosis.

N6-methyladenosine-mediated upregulation of LINC00520 accelerates breast cancer progression via regulating miR-577/POSTN axis and downstream ILK/AKT/mTOR signaling pathway

Various lncRNAs have been reported to be closely associated with cancer initiation and progression in breast cancer (BC), including LINC00520. However, the role and underlying mechanisms by which LINC00520 affects BC aggressiveness have not been fully delineated, and this study aimed to explore this issue. Through performing qRT-PCR analysis, we proved that LINC00520 was significantly upregulated in BC tissues and cells, compared with normal tissues and cells. Higher expression of LINC00520 was closely related to higher tumor grade, poor differentiation and shorter survival in BC patients. Next, the loss-of-function experiments evidenced that silencing LINC00520 suppressed BC cell proliferation, migration and epithelial-mesenchymal transition (EMT) in vitro, and inhibited tumorigenesis in vivo. Interestingly, we found that LINC00520 expression was positively regulated by METTL3-mediated N6-methyladenosine(m⁶A) modification in BC. Furthermore, we identified the tumor-suppressor miR-577 as the binding target of LINC00520 in BC. Mechanistically, LINC00520 elevated POSTN level via sponging miR-577, resulting in the activation of the downstream tumor-promoting ILK/Akt/mTOR pathway. Finally, the rescuing experiments evidenced that both POSTN knockdown and ILK/Akt/mTOR pathway inhibitor OSU-T315 abrogated the promoting effects of miR-577 ablation on the malignant phenotypes in BC. Collectively, this study firstly verified that LINC00520 acted as a ceRNA of miR-577 to advance BC aggressiveness in a m⁶A-dependent manner, providing novel biomarkers for BC diagnosis and therapy.

STAT3-mediated upregulation of LINC00520 contributed to temozolomide chemoresistance in glioblastoma by interacting with RNA-binding protein LIN28B

A considerable number of glioblastoma (GBM) patients developed drug resistance to Temozolomide (TMZ) during chemotherapy, resulting in therapeutic failure and tumor recurrence. However, the exact mechanism of TMZ chemoresistance in GBM is still poorly clarified. As a novel identified lncRNA, LINC00520 was located on chromosome 14 and overexpressed in multiple human cancers. This study was designed and conducted to investigate the role and underlying mechanism of LINC00520 in GBM chemoresistance to TMZ. The qRT-PCR assay demonstrated that LINC00520 was significantly overexpressed in TMZ-sensitive and/or TMZ-resistant GBM cells (P < 0.001). The silencing of LINC00520 markedly reduced the cell viability, suppressed colony formation, induced cell apoptosis and G1/S phase arrest in TMZ-resistant cells (P < 0.001). In contrast, overexpression of LINC00520 conferred TMZ-resistant phenotype of GBM cells in vitro (P < 0.001). The orthotopic xenograft model was established and the results indicated that the volume of tumor xenografts in vivo was markedly inhibited by TMZ treatment after the silencing of LINC00520 (P < 0.001). Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay revealed a strong affinity of transcription factor STAT3 to the promoter regions of LINC00520, suggesting that STAT3 mediated the aberrant expression of LINC00520 in GBM. Further experiments demonstrated that LINC00520 could interact with RNA-binding protein LIN28B to inhibit autophagy and reduce DNA damage, thereby contributing to TMZ chemoresistance in GBM. These findings suggested that STAT3/LINC00520/LIN28B axis might be a promising target to improve TMZ chemoresistance of GBM.

LINC00520: A Potential Diagnostic and Prognostic Biomarker in Cancer

Long non-coding RNA (lncRNA) is important in the study of cancer mechanisms. LINC00520 is located on human chromosome 14q22.3 and is a highly conserved long non-coding RNA. LINC00520 is widely expressed in various tissues. The expression of LINC00520 is regulated by transcription factors such as Sp1, TFAP4, and STAT3. The high expression of LINC00520 is significantly related to the risk of 11 cancers. LINC00520 can competitively bind 10 miRNAs to promote tumor cell proliferation, invasion, and migration. In addition, LINC00520 is involved in the regulation of P13K/AKT and JAK/STAT signaling pathways. The expression of LINC00520 is significantly related to the clinicopathological characteristics and prognosis of tumor patients and is also related to the sensitivity of HNSCC to radiotherapy. Here, this article summarizes the abnormal expression pattern of LINC00520 in cancer and its potential molecular regulation mechanism and points out that LINC00520 can be used as a potential biomarker for cancer diagnosis, prognosis, and treatment.

LINC00520 up-regulates SOX5 to promote cell proliferation and invasion by miR-4516 in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common human cancers. Long non-coding RNA (lncRNA) has been demonstrated to play an important role in regulating tumor development. The current study aims to explore the specific role of LINC00520 during HCC progression. The present study identified that LINC00520 was upregulated in HCC tissues and indicated poor patient survival. Overexpression of LINC00520 promoted HCC cell proliferation, migration and invasion, while LINC00520 downregulation led to the opposite effects. Besides, LINC00520 knockdown was found to inhibit tumor growth in vivo. Furthermore, LINC00520 acted as a sponge of miR-4516 to regulate SRY-related high mobility group box 5 (SOX5). In addition, the inhibition of miR-4516 partly reversed the inhibitory effect of LINC00520 silencing on HCC cell proliferation, migration and invasion. In conclusion, the inhibition of LINC00520 suppressed HCC cell proliferation, migration and invasion through mediating miR-4516/SOX5 axis. Therefore, our study provides a basis for the development of treatment strategies for HCC.

LncRNA LINC00520 aggravates cell proliferation and migration in lung adenocarcinoma via a positive feedback loop

Background

Lung adenocarcinoma (LUAD) is the most common histological subtype of primary lung cancer. To identify the biomarker of diagnosis for LUAD is of great significance. Long non-coding RNAs (lncRNAs) were previously revealed to exert vital effects in numerous cancers. LncRNA long intergenic non-protein coding RNA 520 (LINC00520) served as an oncogene in various cancers. Therefore, our study was specially designed to probe the role of LINC00520 in LUAD.

Results

LINC00520 expression was detected by RT-qPCR. Next, function of LINC00520 in LUAD was verified by in vitro loss-of-function experiments. DNA pull down, ChIP, RIP, and luciferase reporter assays were conducted to reveal the regulatory mechanism of LINC00520. We found that LINC00520 was upregulated in LUAD. Additionally, LINC00520 upregulation is associated with the poor prognosis for patients with LUAD. Furthermore, LINC00520 downregulation suppressed LUAD cell proliferation and migration and induced cell apoptosis. Forkhead box P3 (FOXP3) is identified as the transcription factor to transcriptionally activate LINC00520. Moreover, LINC00520 positively upregulated FOXP3 expression via sponging miR-3611 in LUAD cells. Subsequently, rescue experiments delineated that miR-3611 downregulation or FOXP3 overexpression reversed the effects of silenced LINC00520 on proliferative and migratory capabilities in LUAD cells.

Conclusion

This study innovatively indicated that lncRNA LINC00520 facilitated cell proliferative and migratory abilities in LUAD through interacting with miR-3611 and targeting FOXP3, which may provide a potential novel insight for treatment of LUAD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01657-6.

Long noncoding RNA LINC00520 accelerates lung adenocarcinoma progression via miR-1252-5p/FOXR2 pathway

It has been corroborated that long noncoding RNA (lncRNA) played fundamental function in various human malignancies development including lung adenocarcinoma (lung ADC). In our study, LINC00520 roles in lung ADC tumorigenesis were explored. We found that LINC00520 level was elevated in lung ADC tissues and cell lines. Besides, the LINC00520 expression had a negative connection with miR-1252-5p level in lung ADC tissues. Additionally, our results demonstrated the reciprocal repression influence between LINC00520 and miR-1252-5p. Moreover, luciferase reporter assays, RIP (RNA-binding protein immunoprecipitation) and pull down assays revealed that miR-1252-5p regulated LINC00520 in RISC-dependent. Furthermore, knockdown of LINC00520 inhibited lung ADC cells proliferation, migration and invasion, while co-transfection with a miR-1252-5p inhibitor inverted these influences. Additionally, the findings also demonstrated that FOXR2 was a target of miR-1252-5p; thus, LINC00520 could regulate FOXR2 level. Moreover, LINC00520 silencing suppressed the tumor growth of lung ADC in vivo. In summary, our data indicated that LINC00520 may act as a ceRNA to modulated FOXR2 level by sponging miR-1252-5p, which might bring a potential and effective biomarker to lung ADC treatment.

Silencing of long non-coding RNA LINC00520 promotes radiosensitivity of head and neck squamous cell carcinoma cells

Aberrant expression of LINC00520 has been identified in head and neck squamous carcinoma (HNSCC). However, its function in the radiosensitivity of HNSCC remain unclear. Herein, we aimed to define the role LINC00520 in the radiosensitivity of HNSCC and identify the underlying mechanism. Tumour tissues and adjacent normal tissue were collected from HNSCC patients. Differentially expressed genes (DEGs) in HNSCC tumour were obtained from the cancer genome atlas (TCGA) database. Interactions between LINC00520 and miR-195, homeobox A10 (HOXA10) and miR-195 were evaluated by dual-luciferase reporter gene assay, RNA Immunoprecipitation (RIP), and RNA pull-down assay. The effects of LINC00520/miR-195/HOXA10 on radiosensitivity of HNSCC were analysed in the evaluation of radiotherapy outcome. Cell proliferation, invasion, migration, and apoptosis of HNSCC cells were accessed via gain- and loss-of-function approaches. Tumour xenograft in nude mice was conducted in order to confirm the results in vivo. LINC00520 was upregulated while miR-195 was downregulated in HNSCC cells and tissues. Silencing LINC00520 or overexpressing miR-195 promoted radiosensitivity and inhibited cell proliferation, invasion, migration, and apoptosis in HNSCC. Moreover, these in vitro findings were reproduced in vivo in human HNSCC xenograft in nude mice. LINC00520/miR-195/HOXA10 is involved in the radiosensitivity mediation, providing potential therapeutic target for HNSCC treatment.

Long noncoding RNA LINC00520 accelerates progression of papillary thyroid carcinoma by serving as a competing endogenous RNA of microRNA-577 to increase Sphk2 expression

The long noncoding RNA (lncRNA) LINC00520 is an important modulator of the oncogenicity of multiple human cancers. However, whether LINC00520 is involved in the malignancy of papillary thyroid carcinoma (PTC) has not been extensively studied until recently. Therefore, the present study aimed to detect LINC00520 expression and evaluate its clinical significance in PTC. Functional experiments were conducted to test the biological role(s) and underlying mechanisms of LINC00520 in PTC progression. Reverse transcription quantitative polymerase chain reaction was performed to detect LINC00520 expression in PTC. A series of functional experiments, including Cell Counting Kit-8 assay, flow cytometry, Transwell migration assay, and tumor xenograft assay, was employed to investigate the biological roles of LINC00520 in PTC cells. High LINC00520 expression was verified in PTC tissues and cell lines, and this high expression was associated with the unfavorable clinicopathological parameters and short overall survival of patients. Functionally, LINC00520 interference resulted in a significant decrease in PTC cell proliferation, migration, and in vitro invasion and an increase in cell apoptosis. Further, its downregulation impaired tumor growth in vivo. Mechanistically, LINC00520 functioned as a competing endogenous RNA by sponging microRNA-577 (miR-577) and thereby increasing sphingosine kinase 2 (Sphk2) expression. Rescue experiments revealed that inhibiting miR-577 or restoring Sphk2 could abrogate the effects of LINC00520 silencing on the malignant phenotypes of PTC. LINC00520 functioned as an oncogenic lncRNA in PTC, and it facilitated PTC progression by regulating the miR-577/Sphk2 axis, suggesting that the LINC00520/miR-577/Sphk2 axis is an effective target in anticancer management.

Long noncoding RNA LINC00520 accelerates the progression of colorectal cancer by serving as a competing endogenous RNA of microRNA-577 to increase HSP27 expression

The long noncoding RNA (lncRNA) LINC00520 is an important modulator of the oncogenicity of multiple human cancers. However, whether LINC00520 is involved in the malignant characteristics of colorectal cancer (CRC) has not been extensively studied until recently. Therefore, the present study aimed to detect LINC00520 expression in CRC and evaluate its clinical significance in patients with CRC. Functional experiments were conducted to test the biological roles and underlying mechanisms of LINC00520 in CRC progression. In this study, high-LINC00520 expression was verified in CRC tissues and cell lines, and this high expression was associated with patients' unfavorable clinicopathological parameters and shorter overall survival and disease-free survival. Functionally, interference of LINC00520 resulted in a significant decrease of CRC cell proliferation, migration, colony forming ability, and invasion. Mechanistically, LINC00520 functioned as a competing endogenous RNA by sponging microRNA-577 (miR-577) and thereby increasing heat shock protein 27 (HSP27) expression. Rescue experiments revealed that inhibiting miR-577 or restoring HSP27 could abrogate the effects of LINC00520 silencing on malignant phenotypes of CRC. LINC00520 functioned as an oncogenic lncRNA in CRC, and it facilitated CRC progression by regulating the miR-577/HSP27 axis, suggesting that the LINC00520/miR-577/HSP27 axis is an effective target in anticancer management.

Characterization of lncRNA LINC00520 and functional polymorphisms associated with breast cancer susceptibility in Chinese Han population

Background

The aim was to evaluate the association between the LINC00520 genetic polymorphisms and breast cancer (BC) susceptibility.

Methods

Nine single‐nucleotide polymorphisms (SNPs) on LINC00520 genotyping were performed in 504 BC patients and 505 cancer‐free controls in Chinese Han population to study the relationship between LINC00520 polymorphism and BC susceptibility. qRT‐PCR and luciferase tests were used to explore how rs12880540 affected the expression of LINC00520.

Results

The genotype GG (OR:3.58, 95%CI:1.32‐9.69) in rs8012083 increased the risk of triple‐negative BC. The genotype GG (OR:0.31, 95%CI:0.14‐0.69) in rs8012083, the genotype AA (OR:2.74, 95%CI:1.01‐7.42) in rs2152275, and genotype TG (OR:1.62, 95%CI:1.04‐2.52) in rs12880540 were associated with HER‐2 status. The dominant (OR:0.65, 95%CI:0.45‐0.95) and overdominant genetic model (OR:0.67, 95%CI:0.46‐0.98) consistently showed that rs11622641 T was significantly associated with lower risk of BC. Similarly, the recessive genetic model (OR:1.57, 95%CI:1.07‐2.30) of rs12880540 and the dominant (OR:1.62, 95%CI:1.24‐2.11) and overdominant (OR:1.56, 95%CI:1.19‐2.03) genetic model of rs2152278 may increase the risk of BC. The relative expression of LINC00520 increased linearly with the increase in the number of rs12880540 mutations. rs12880540 alleles were due to the interaction between LINC00520 and miR‐3122 at T, but the mutation of rs12880540 G > T had no effect on the binding ability of LINC00520 and miR‐3122.

Conclusion

A genetic variant of rs8012083 in LINC00520 may be used as a biomarker for triple‐negative BC after further evaluation of diagnostic tests. The genetic variant of LINC00520 was related to the susceptibility of BC, and rs12880540 might affect the corresponding mRNA expression of lncRNA LINC00520.

LINC00520 targeting miR-27b-3p regulates OSMR expression level to promote acute kidney injury development through the PI3K/AKT signaling pathway

BACKGROUND

Acute kidney injury (AKI) shows several kinds of disorders, which acutely harm the kidney. However, the current medical methods have limited therapeutic effects. The present study aimed to find out the molecular mechanism of AKI pathogenesis, which may provide new insights for future therapy.

METHODS

Bioinformatic analysis was conducted using the R language (AT&T BellLaboratories, University of Auckland, New Zealand) to acquire the differentially expressed long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) in AKI. The expression levels of RNAs and related proteins in tissues and cells were detected by quantitative real-time PCR (qRT-PCR) and western blot. Dual-luciferase reporter gene assays were performed to verify the target relationship between microRNA (miRNA) and lncRNA as well as miRNA and mRNA. Flow cytometry and tunnel assay were used to detect the cell apoptotic rate in AKI.

RESULTS

LINC00520, miR-27b-3p, and OSMR form an axis to regulate AKI. Knockdown of LINC00520 reduced acute renal injury both in vitro and in vivo. LINC00520 activated the PI3K/AKT pathway to aggravate renal ischemia/reperfusion injury, while upregulation of miR-27b-3p or downregulation of OSMR could accelerate the recovery of AKI.

CONCLUSION

Overexpression of LINC00520 contributes to the aggravation of AKI by targeting miR-27b-3p/ OSMR.

[Expression and clinical significance of long non-coding RNA LINC00520 in laryngeal squamous cell carcinoma]

Objective:To investigate the expression of LINC00520 in laryngeal squamous cell carcinoma(LSCC),and analyze its relevance and roles in carcinogenesis and development of LSCC.Method:The expression of LINC00520 in laryngeal squamous cell carcinoma tissue and paired adjacent normal tissue was determined by real-time PCR.The relationship between the expression of LINC00520 and the clinicopathological characteristics including clinical stage,pathological type,histological grade and lymph node metastasis of LSCC was analyzed.Result:(1)The LINC00520 expression level was significantly upregulated in LSCC tissues compared to that of paired adjacent normal tissues(P<0.000 1).(2)There were no statistical differences of the LINC00520 expression level among supraglottic,glottic and subglottic LSCCs(P>0.05).The LINC00520 expression level had no significant changes in poorly differentiated LSCC compared with that of well and moderately differentiated counterparts(P>0.05).Moreover,the expression of LINC00520 had no significant difference between T1+T2 stage and T3+T4 stage LSCC tissues(P>0.05).Interestingly,the LINC00520 level in LSCC with lymph node metastasis was significantly higher than that in patients without lymph node metastasis(P<0.01).Conclusion:Upregulation of LINC00520 in LSCC may contribute to its metastasis.

LINC00520 is induced by Src, STAT3, and PI3K and plays a functional role in breast cancer

Long non-coding RNAs (lncRNAs) have been implicated in normal cellular homeostasis as well as pathophysiological conditions, including cancer. Here we performed global gene expression profiling of mammary epithelial cells transformed by oncogenic v-Src, and identified a large subset of uncharacterized lncRNAs potentially involved in breast cancer development. Specifically, our analysis revealed a novel lncRNA, LINC00520 that is upregulated upon ectopic expression of oncogenic v-Src, in a manner that is dependent on the transcription factor STAT3. Similarly, LINC00520 is also increased in mammary epithelial cells transformed by oncogenic PI3K and its expression is decreased upon knockdown of mutant PIK3CA. Additional expression profiling highlight that LINC00520 is elevated in a subset of human breast carcinomas, with preferential enrichment in the basal-like molecular subtype. ShRNA-mediated depletion of LINC00520 results in decreased cell migration and loss of invasive structures in 3D. RNA sequencing analysis uncovers several genes that are differentially expressed upon ectopic expression of LINC00520, a significant subset of which are also induced in v-Src-transformed MCF10A cells. Together, these findings characterize LINC00520 as a lncRNA that is regulated by oncogenic Src, PIK3CA and STAT3, and which may contribute to the molecular etiology of breast cancer.