LncRNA-LINC00472 suppresses the malignant progression of non-small cell lung cancer via modulation of the miRNA-1275/Homeobox A2 axis

BACKGROUND

Long non-coding RNAs (lncRNAs) are increasingly observed as regulatory factors for the initiation and progression of varying kinds of cancers. However, studies on lncRNAs in non-small cell lung cancer (NSCLC) progression are currently lacking.

OBJECTIVES

We intended to determine the role of lncRNA LINC00472 and its downstream regulatory mechanism in NSCLC, thus providing novel ideas for targeted therapies for NSCLC.

MATERIAL AND METHODS

The target signaling axis comprising the lncRNA/microRNA/mRNA was identified through bioinformatics analysis. Subcellular localization of LINC00472 was assessed with fluorescence in situ hybridization (FISH). Cellular function experiments were conducted to examine the proliferation, migration, invasion, and apoptosis of NSCLC cells, and dual-luciferase and RNA binding protein immunoprecipitation assays were performed to validate the binding relationship. Quantitative real-time polymerase chain reaction (qPCR) and western blot were utilized to assess the expression levels of the investigated gene and protein, respectively.

RESULTS

The LINC00472 expression was markedly decreased in NSCLC tissues and cells. The FISH, combined with nuclear-cytoplasm separation assay, demonstrated that LINC00472 was mainly located in the cytoplasm. The overexpression of LINC00472 restrained proliferation and metastasis of NSCLC in vitro. The LINC00472 could target and repress miR-1275 level, and overexpression of LINC00472 reduced the miR-1275-dependent malignant cell phenotype in NSCLC. Further study revealed that HOXA2 was a downstream target of miR-1275 and was negatively modulated by miR-1275. Rescue assays exhibited that the overexpression of miR-1275 or inhibition of HOXA2 reversed the impact of LINC00472 overexpression on the malignant progression of NSCLC cells. The LINC00472 repressed the epithelial-mesenchymal transition (EMT) of NSCLC cells through miR-1275/HOXA2.

CONCLUSIONS

The LINC00472 functioned as a competing endogenous RNA to modulate HOXA2 level by sponging miR-1275 in NSCLC. Simultaneously, the LINC00472/miR-1275/HOXA2 axis may be a possible therapeutic target and biomarker for NSCLC.

A review on the role of LINC00472 in malignant and non-malignant disorders

Long intergenic non-protein coding RNA 472 (LINC00472) has been shown to regulate diverse cellular functions and contribute to the etiology of human disorders. LINC00472 gene is located on 6q13 and has different alternatively spliced transcripts. Expression pattern and function of LINC00472 have been evaluated in different types of cancers and some other disorders, including atherosclerosis, sepsis-induced acute hepatic injury, atrial fibrillation, neuropathic pain, primary biliary cholangitis and sepsis-induced cardiac dysfunction. This lincRNA can serve as a sponge for miR-24-3p, miR-196b-5p, miR-23a-3p, miR-93-5p, miR-4311, miR-455-3p and a number of other miRNAs. LINC00472 is able to regulate several pathways, including MEK/ERK, NF-kB, PTEN/PI3K/AKT, and STAT3 signaling pathways. This raises some concerning aspects that need to be investigated further and clarified in relation to diseases. Increasing our understanding of LINC00472's crucial roles will open new doors for creating effective therapeutic approaches against cancer and related diseases. The current study aims at providing an overview of functions of LINC00472 in malignant and non-malignant disorders.

Long non-coding RNA LINC00472 inhibits oral squamous cell carcinoma via miR-4311/GNG7 axis

Emerging studies indicate that long non-coding RNAs play important roles in oral squamous cell carcinoma (OSCC). However, the function of the majority of long non-coding RNAs is still unclear. Recently, LINC00472 has been reported to play crucial roles in multiple cancers. However, the role of LINC00472 in oral squamous cell carcinoma (OSCC) is still not clear. This study found that LncRNA LINC00472 was significantly down-regulated in several squamous cell carcinoma cancer tissues and OSCC cell lines. Over-expression of LINC00472 in OSCC cells inhibited OSCC progression and alleviated OSCC immune responses. Additionally, we confirmed that LINC00472 functioned as an hsa-miR-4311 sponge and regulated the expression of GNG7 (guanine nucleotide-binding protein, gamma 7). Also, we found that LINC00472 over-expression could suppress xenograft tumor growth in vivo. Our study provides evidence that LINC00472 plays an essential role in inhibiting oral squamous cell carcinoma progression and affecting immune responses by directly binding to hsa-miR-4311 to regulate the expression of GNG7 positively.

Long Noncoding RNA 00472: A Novel Biomarker in Human Diseases

Long non-coding RNAs (lncRNAs) play important roles in human diseases. They control gene expression levels and influence various biological processes through multiple mechanisms. Functional abnormalities in lncRNAs are strongly associated with occurrence and development of various diseases. LINC00472, which is located on chromosome 6q13, is involved in several human diseases, particularly cancers of the breast, lung, liver, osteosarcoma, bladder, colorectal, ovarian, pancreatic and stomach. Importantly, LINC00472 can be used as a biomarker for breast cancer cell sensitivity to chemotherapeutic regimens, including doxorubicin. LINC00472 is regulated by microRNAs and several signaling pathways. However, the significance of LINC00472 in human diseases has not been clearly established. In this review, we elucidate on the significance of LINC00472 in various human diseases, indicating that LINC00472 may be a diagnostic, prognostic as well as therapeutic target for these diseases.

The long intergenic non-protein coding RNA 472 (LINC00472) aggravates neuropathic pain through the microRNA-300/high mobility group box protein 1 axis: a study using the chronic constrictive injury rat model

BACKGROUND

This study investigated the role and molecular mechanisms of the long intergenic non-protein coding RNA 472 (LINC00472) in neuropathic pain using a chronic constrictive injury (CCI) rat model.

METHODS

CCI rat model was established and PC12 cells were induced by LPS to simulate neuropathological injury in vivo and in vitro. The levels of LINC00472, miR-300, and high mobility group box protein 1 (HMGB1) in the spinal cord tissue of CCI rats and PC12 pheochromocytoma cells were assessed by qRT-PCR and western blot. The effects of LINC00472 on neuropathic pain in the CCI rats were observed by their pain behavior. ELISA was used to detect the levels of inflammatory cytokines in rat tissues and cells. The molecular mechanisms of LINC00472 were verified by luciferase experiments, RNA immunoprecipitation, and RNA pull down assays.

RESULTS

The expression of LINC00472 and HMGB1 were upregulated, and the expression of miR-300 was downregulated in the spinal cord tissues of CCI rats and in PC12 cells. The upregulation of LINC00472 in CCI rats significantly induced the occurrence of neuropathic pain. In addition, downregulation of LINC00472 inhibited the inflammatory response of CCI rats and PC12 cells. This study identified miR-300 as a target gene of LINC00472, and HMGB1 as the target gene of miR-300. Further experiments confirmed that the expression of anti-miR-300 could partially reverse the anti-inflammatory effects and the reduction of neuropathic pain induced by low expression of LINC00472.

CONCLUSIONS

LINC00472 promotes the progression of neuropathic pain by reducing miR-300 expression and increasing HMGB1 expression. The LINC00472/miR-300/HMGB1 axis may be a novel therapeutic target for neuropathic pain.

LINC00472 regulates vascular smooth muscle cell migration and proliferation via regulating miR-149-3p

LncRNAs are one group of gene modulators functioning via several mechanisms in pathological and physiological conditions. We noted that LINC00472 expression level is elevated in atherosclerotic coronary tissues compared with normal coronary artery samples. LINC00472 is also upregulated in vascular smooth muscle cells (VSMCs) induced by TNF-α and PDGF-BB. Ectopic expression of LINC00472 induced VSMC migration and proliferation. The predicted binding sequence between miR-149-3p and LINC00472 was analyzed by LncBase Predicted. Overexpression of miR-149-3p decreases the luciferase activity of wild-type reporter plasmid, but not the mutant one. Ectopic expression of LINC00472 suppresses the expression of miR-149-3p in VSMCs. Furthermore, we demonstrated that miR-149-3p expression is decreased in atherosclerotic coronary tissues. MiR-149-3p was downregulated in VSMCs induced by TNF-α and PDGF-BB. Overexpression of LINC00472 induces VSMC migration and proliferation via regulating miR-149-3p. These data suggested that LINC00472 acts a critical role in the migration and proliferation of VSMCs partly via modulating miR-149-3p.

Methylation-dependent MCM6 repression induced by LINC00472 inhibits triple-negative breast cancer metastasis by disturbing the MEK/ERK signaling pathway

Long noncoding RNAs (lncRNAs) have been identified to be dysregulated in multiple cancer types, which are speculated to be of vital significance in regulating several hallmarks of cancer biology. Triple-negative breast cancer (TNBC) is acknowledged as an aggressive subtype of breast cancer. In this study, we found the lncRNA LINC00472 was poorly expressed in TNBC tissues and cells. Overexpression of LINC00472 could inhibit the proliferation, invasion and migration of MDA-MB-231 cells. On the contrary, minichromosome maintenance complex component 6 (MCM6) was highly expressed in TNBC tissues and MDA-MB-231 cells due to suppressed methylation. LINC00472 induced site-specific DNA methylation and reduced the MCM6 expression by recruiting DNA methyltransferases into the MCM6 promoter. Since the restoration of MCM6 weakened the tumor-suppressive effect of LINC00472 on MDA-MB-231 cells, LINC00472 potentially acted as a tumor suppressor by inhibiting MCM6. In addition, in vivo experiments further substantiated that overexpression of LINC00472 inhibited tumor growth and metastasis to lungs by decreasing the expression of MCM6. Overall, the present study demonstrated that LINC00472-mediated epigenetic silencing of MCM6 contributes to the prevention of tumorigenesis and metastasis in TNBC, providing an exquisite therapeutic target for TNBC.

Down-regulation of long noncoding RNA LINC00472 alleviates sepsis-induced acute hepatic injury by regulating miR-373-3p/TRIM8 axis

BACKGROUND

The long noncoding RNAs (lncRNAs) have been confirmed to be involved in sepsis-induced organ injury. Here, we first investigated the functional role and the underlying mechanism of lncRNA LINC00472 in sepsis-induced acute hepatic injury (AHI).

METHODS

Human liver THLE-3 cells were treated with lipopolysaccharide (LPS) to mimic sepsis-induced AHI in vitro; intraperitoneal injection of LPS in rats were used as an in vivo model of AHI induced by sepsis. The expressions of LINC00472, miR-373-3p, and TRIM8 mRNA were detected by qRT-PCR. The effects of LINC00472 and miR-373-3p on the viability of THLE-3 cells were assessed by CCK-8 assay. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to determine the binding relationship between LINC00472 and miR-373-3p as well as between miR-373-3p and TRIM8. The expressions of apoptosis-related proteins and TRIM8 were detected by Western blot; the levels of ALT, AST, TNF-α, IL-6, and IL-10 in the serum of rats were measured using ELSA assay.

RESULTS

LINC00472 and TRIM8 were significantly upregulated in liver tissues and THLE-3 cells in sepsis-induced AHI models, while miR-373-3p was downregulated. Silencing of LINC00472 promoted cell viability and suppressed cell apoptosis in LPS-treated THLE-3 cells, whereas upregulation of LINC00472 had the opposite effect. Moreover, LINC00472 served as a sponge for miR-373-3p and negatively regulated its expression. miR-373-3p mimics could promote THLE-3 cell viability and suppress cell apoptosis. Additionally, TRIM8 was a direct target of miR-373-3p, which was downregulated in LINC00472-silenced cells and upregulated by the miR-373-3p inhibitor. Further, the co-transfection of miR-373-3p inhibitor reversed the effects of LINC00472 knockdown on cell viability and apoptosis. Downregulation of LINC00472 in rats restored the levels of ALT, AST, IL-6, IL-10, and TNF-α.

CONCLUSION

Downregulation of LINC00472 ameliorates sepsis-induced AHI by regulating the miR-373-3p/TRIM8 axis.

Down-regulation of LINC00472 promotes osteosarcoma tumorigenesis by reducing FOXO1 expressions via miR-300

BACKGROUND

Osteosarcoma (OS) is one of the most common types of primary bone tumors which poses negative effects on the bones of both young children and adolescents. LncRNA LINC00472 has been reported to be involved with poor prognostics in breast cancer and ovarian cancer. As a new lncRNA, its role in OS remains to be elusive. Herein, we are focused to explore its regulatory mechanism in the development of OS.

METHODS

qRT-PCR was utilized to examine the expressions of LINC00472 and miR-300 in OS tissues and cell lines. OS cell lines of U2OS and MG63 were used to investigate the biological function of LINC00472. Xenograft tumor model was built in nude mice with MG63 cells.

RESULTS

The expressions of LINC00472 were inhibited in OS tissues and cells, and were negatively related to the expressions of miR-300. LINC00472 directly targeted miR-300. FOXO1 was inhibited in OS tissues and its expressions were negatively related to the expressions of miR-300. LINC00472 over-expressions decreased cell proliferation abilities and colony formation abilities. These effects were mediated by miR-300. The silence of LINC00472 and over-expressions of miR-300 suppressed FOXO1 expressions. LINC00472 greatly reduced tumor growth in vivo and this effect was attenuated by miR-300 mimic.

CONCLUSIONS

From all the experiments and observations, we demonstrated that LINC00472 could be a potential tumor suppressor in OS through interacting with miR-300 and FOXO1.

Matrine Restrains Cell Growth and Metastasis by Up-Regulating LINC00472 in Bladder Carcinoma

Purpose

Bladder Carcinoma (BC) is a malignant carcinoma with a high incidence in masculinity. We preliminarily researched the efficacy and mechanism of matrine (MAT) in T24 and 5637 cells.

Patients and Methods

CCK-8, flow cytometry, migration and invasion means were adopted to detect cell viability, apoptosis, migratory and invasive potentials. Moreover, LINC00472 expression was changed via transfection assays and was tested by RT-qPCR. Western blot was used for investigating the levels of CyclinD1, p53, Bcl-2, Bax, pro-Caspase-3, Cleaved-Caspase-3, β-actin, programmed cell death protein 4 (PDCD4) and relate-proteins of cell pathways. Tumor volume and weight were tested via animal experiments.

Results

MAT could not affect the growth of SV-HUC-1 cell but MAT promoted tumor cell apoptosis but restrained viability, invasion and migration. Furthermore, LINC00472 was prominently low expressed in BC tissues. MAT positively regulated LINC00472 and transfection with si-00472 could partly reverse the efficacies of MAT. Moreover, MAT enhanced PDCD4 expression by up-regulating LINC00472. Besides, we discovered MAT elevated PTEN but restrained PI3K/AKT proteins. Finally, tumor volume and weight were declined by MAT in vivo via up-regulating LINC00472.

Conclusion

MAT restrained cell growth and metastasis but promoted PDCD4 expression by up-regulating LINC00472 via restraining PTEN/PI3K/AKT pathway in BC.

Long non-coding RNA LINC00472 suppresses hepatocellular carcinoma cell proliferation, migration and invasion through miR-93-5p/PDCD4 pathway

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer and the second leading cause of cancer-related deaths. In the present study, we have demonstrated that long non-coding RNA (lncRNA) LINC00472 was low expressed in human HCC tissues and cell lines compared with adjacent non-tumor liver tissues and normal liver cell lines respectively. LINC00472 was also low expressed in HCC tissues from patients with metastasis compared with tissues from patients without metastasis. Expression level of LINC00472 was positively correlated with patient overall survival (OS) rate. Forced expression of LINC00472 suppressed cell proliferation, migration, invasion and promoted cell apoptosis in HCC cells Huh-7 and SMMC-7721. MiR-93-5p was a direct target of LINC00472, and miR-93-5p directly targeted PDCD4. The miR-93-5p/PDCD4 pathway mediated the suppressing role of LINC00472 in HCC cells. Therefore, LINC00472 was an important tumor suppressor in human HCC, which could be used as a bio-marker for HCC therapy.

ERα upregulates the expression of long non-coding RNA LINC00472 which suppresses the phosphorylation of NF-κB in breast cancer

PURPOSE

Low expression of long intergenic non-coding RNA LINC00472 in breast cancer is associated with aggressive tumors and unfavorable disease outcomes in multiple clinical datasets, but the reasons for these associations were unknown.

METHODS

To study the mechanisms underlying the lncRNA's connection to breast cancer, we investigated the molecular targets and regulation of LINC00472 in breast cancer cells, and analyzed relevant molecular features in relation to patient survival. Gene expression profiles of breast cancer cells overexpressing LINC00472 were analyzed for its regulatory pathways and downstream targets. Effects of LINC00472 overexpression on cell behaviors were evaluated in vitro and in vivo. Meta-analysis was performed using online datasets and our own study.

RESULTS

Analysis of LINC00472 transcriptome revealed ERα upregulation of LINC00472 expression, and an ERα-binding site in the LINC00472 promoter was identified. Evaluation of LINC00472 overexpression also indicated a possible link between LINC00472 and NF-κB. Cell experiments confirmed that LINC00472 suppressed the phosphorylation of p65 and IκBα through binding to IKKβ, inhibiting its phosphorylation. High LINC00472 expression inhibited tumor growth both in vitro and in vivo and suppressed aggressive tumor cell behaviors in vitro. Suppressing LINC00472 expression in ER-positive tumor cells increased cell aggressive behaviors. Tamoxifen treatment of ER-positive cells inhibited ERα and LINC00472 expression and increased p65 and IκBα phosphorylation. Meta-analysis showed that LINC00472 expression were higher in ER-positive than ER-negative tumors and that high expression was associated with better disease outcomes in ER-positive patients.

CONCLUSIONS

The study demonstrates that ERα upregulates LINC00472 which suppresses the phosphorylation of NF-κB, and suggests that endocrine treatment may lower LINC00472 and increase NF-κB activities, leading to tumor progression and disease recurrence.

Long Noncoding RNA LINC00472 Inhibits Proliferation and Promotes Apoptosis of Lung Adenocarcinoma Cells via Regulating miR-24-3p/ DEDD

OBJECTIVE

We aimed to detect the role of LINC00472 via regulating miR-24-3p and death effector domain-containing DNA-binding protein in lung adenocarcinoma.

METHODS

Long noncoding RNA, microRNA, and messenger RNA levels were determined using reverse transcription quantitative polymerase chain reaction. The expression of death effector domain-containing DNA-binding protein was determined using Western blot assay. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and colony formation assay were conducted to explore the proliferation of cells. The cell apoptosis was tested by flow cytometry assay. Target relationships between miR-24-3p, death effector domain-containing DNA-binding protein, and LINC00472 were validated by dual-luciferase reporter gene assay.

RESULTS

LINC00472 and death effector domain-containing DNA-binding protein were found to be underexpressed, whereas miR-24-3p was found overexpressed in lung adenocarcinoma cell lines and tissues. Both LINC00472 and death effector domain-containing DNA-binding protein can bind to miR-24-3p. Overexpression of LINC00472 led to higher death effector domain-containing DNA-binding protein level, demoting cell proliferation while promoting apoptosis. Overexpression of miR-24-3p reduced death effector domain-containing DNA-binding protein level, which facilitated cell proliferation and inhibited cell apoptosis, as well as to some extent restrained the effects of LINC00472. The high expression of miR-24-3p in tumor cells was negatively related to LINC00472 and death effector domain-containing DNA-binding protein, whereas the expression of LINC00472 and that of death effector domain-containing DNA-binding protein were positively correlated.

CONCLUSION

Our findings suggested that LINC00472 contributed to the increase in lung adenocarcinoma cell apoptosis and the inhibition of proliferation via regulating miR-24-3p/ DEDD, which might provide a novel insight into potential therapeutic approach for lung adenocarcinoma.

Regulatory network analysis of LINC00472, a long noncoding RNA downregulated by DNA hypermethylation in colorectal cancer

Colorectal cancer (CRC), one of the common malignant cancers in the world, is caused by accumulated alterations of genetic and epigenetic factors over a long period of time. Along with that protein-coding genes being identified as oncogenes or tumor suppressors in CRC, a number of lncRNAs have also been found to be associated with CRC. Considering the important regulatory role of lncRNAs, the first goal of this study was to identify CRC-associated lncRNAs from a public database. One such lncRNA, LINC00472, was verified to be downregulated in CRC cell lines and cancer tissues compared with adjacent tissues. In addition, the down-regulation of LINC00472 seemed to be caused by DNA hypermethylation at its promoter region. Furthermore, the expression of LINC00472 and DNA methylation of promoter were significantly correlated with clinicopathological features. And DNA hypermethylation of LINC00472 may serve as a better diagnostic biomarker than its expression for CRC. Finally, we predicted the functions of LINC00472 and constructed a regulatory network and found LINC00472 may be involved in cell cycle and cell proliferation processes. Our results may provide a clue to further research into the function and regulatory mechanism of LINC00472 in CRC.

Prognostic and predictive values of long non-coding RNA LINC00472 in breast cancer. Oncotarget. 2015;6:8579-8592. [PMID: 25865225 PMCID: PMC4496168 DOI: 10.18632/oncotarget.3287]

LINC00472 is a novel long intergenic non-coding RNA. We evaluated LINC00472 expression in breast tumor samples using RT-qPCR, performed a meta-analysis of over 20 microarray datasets from the Gene Expression Omnibus (GEO) database, and investigated the effect of LINC00472 expression on cell proliferation and migration in breast cancer cells transfected with a LINC00472-expressing vector. Our qPCR results showed that high LINC00472 expression was associated with less aggressive breast tumors and more favorable disease outcomes. Patients with high expression of LINC00472 had significantly reduced risk of relapse and death compared to those with low expression. Patients with high LINC00472 expression also had better responses to adjuvant chemo- or hormonal therapy than did patients with low expression. Results of meta-analysis on multiple studies from the GEO database were in agreement with the findings of our study. High LINC00472 was also associated with favorable molecular subtypes, Luminal A or normal-like tumors. Cell culture experiments showed that up-regulation of LINC00472 expression could suppress breast cancer cell proliferation and migration. Collectively, our clinical and in vitro studies suggest that LINC00472 is a tumor suppressor in breast cancer. Evaluating this long non-coding RNA in breast tumors may have prognostic and predictive value in the clinical management of breast cancer.

LINC00472 expression is regulated by promoter methylation and associated with disease-free survival in patients with grade 2 breast cancer

Long non-coding RNAs (lncRNAs) are a class of newly recognized DNA transcripts that have diverse biological activities. Dysregulation of lncRNAs may be involved in many pathogenic processes including cancer. Recently, we found an intergenic lncRNA, LINC00472, whose expression was correlated with breast cancer progression and patient survival. Our findings were consistent across multiple clinical datasets and supported by results from in vitro experiments. To evaluate further the role of LINC00472 in breast cancer, we used various online databases to investigate possible mechanisms that might affect LINC00472 expression in breast cancer. We also analyzed associations of LINC00472 with estrogen receptor, tumor grade, and molecular subtypes in additional online datasets generated by microarray platforms different from the one we investigated previously. We found that LINC00472 expression in breast cancer was regulated more possibly by promoter methylation than by the alteration of gene copy number. Analysis of additional datasets confirmed our previous findings of high expression of LINC00472 associated with ER-positive and low-grade tumors and favorable molecular subtypes. Finally, in nine datasets, we examined the association of LINC00472 expression with disease-free survival in patients with grade 2 tumors. Meta-analysis of the datasets showed that LINC00472 expression in breast tumors predicted the recurrence of breast cancer in patients with grade 2 tumors. In summary, our analyses confirm that LINC00472 is functionally a tumor suppressor, and that assessing its expression in breast tumors may have clinical implications in breast cancer management.