LncRNA MALAT1 knockdown inhibits the development of choroidal neovascularization

In the pathogenesis of age-related macular degeneration, long non-coding RNAs have become important regulators. This study aimed to investigate the role of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the progression of choroidal neovascularization (CNV) and the underlying mechanisms. The in vivo and in vitro model of CNV was established using laser-induced mouse CNV model and human choroidal vascular endothelial cells (HCVECs) exposed to hypoxia respectively. We explore the role of MALAT1 in the pathogenesis of CNV by using the small interference RNA both in vivo and in vitro. MALAT1 expression was found to be upregulated in the retinal pigment epithelial-choroidal complexes. MALAT1 knockdown inhibited CNV development and leakage in vivo and decreased HCVECs proliferation, migration, and tube formation in vitro. MALAT1 performed the task as a miR-17-5p sponge to regulate the expression of vascular endothelial growth factor A (VEGFA) and E26 transformation specific-1 (ETS1). This study provides a new perspective on the pathogenesis of CNV and suggests that the axis MALAT/miR-17-5p/VEGFA or ETS1 may be an effective therapeutic target for CNV.

MALAT1 lncRNA and Parkinson's Disease: The role in the Pathophysiology and Significance for Diagnostic and Therapeutic Approaches

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder. PD is characterized by progressive loss of dopamine-producing neurons in the substantia nigra (SN) region of brain tissue followed by the α-synuclein-based Lewy bodies' formation. These conditions are manifested by various motor and non-motor symptoms such as resting tremor, limb rigidity, bradykinesia and posture instability, cognitive impairment, sleep disorders, and emotional and memory dysfunctions. Long non-coding RNAs (lncRNAs) are closely related to protein-coding genes and are involved in various biological processes. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) lncRNA is involved in different pathways, including alternative splicing, transcriptional regulation, and post-transcriptional regulation, and also interacts with RNAs as a miRNA sponge. MALAT1 is highly expressed in brain tissues and several lines of evidence suggested it is probably involved in synapse generation and other neurophysiological pathways. This narrative review discussed all aspects of MALAT1-associated mechanisms involved in the PD pathogenesis, i.e., perturbed α-synuclein homeostasis, apoptosis and autophagy, and neuro-inflammation. Lastly, the possible applications of MALAT1 as a diagnostic biomarker and its importance to developing therapeutic strategies were highlighted. The literature search was conducted using neurodegeneration, neurodegenerative disorders, Parkinson's disease, lncRNA, and MALAT1 as search items in Google Scholar, Web of Knowledge, PubMed, and Scopus up to December 2021.

Analysis of the regulation of metastasis-associated lung adenocarcinoma transcript 1 on the biological behavior of breast cancer

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a class of long non-coding RNA (lncRNA) that has been proved to be closely related to many cancers.

METHODS

The relevant research on MALAT1 in cancers published in recent years were collected and integrated. CiteSpace was employed to draw a knowledge map of MALAT1 in breast cancer, to evaluate the research front-burner issues. Then, multiple microarray data sets were searched from online data for meta-analysis to evaluate the relationship between MALAT1 and breast cancer survival rate.

RESULTS

The results showed that MALAT1 had been widely studied in the proliferation and differentiation of cancer cells, and MALAT1 might regulate breast cancer through the PI3K/AKT/mTOR signaling pathway. In addition, high expression of MALAT1 had a significant correlation with relapse-free survival (HR: 1.51, 95% CI: 0.79-2.29), while there was no significant correlation between MALAT1 expression and overall survival (HR: 1.09, 95% CI: 0.63-1.72).

CONCLUSIONS

The expression level of lncRNA MALAT1 was closely related to cancer progression and prognosis of cancer patients. Moreover, the expression of MALAT1 was strongly associated with the survival rate of recurrence-free breast cancer. However, since the present study only adopted the existing literature for visual analysis, subsequent experiments are needed to be done to verify this conclusion. It is hoped that this work could provide a theoretical foundation for promoting the clinical adoption of MALAT1 in the prediction, diagnosis, and treatment of breast cancer, and point out a new direction for the in-depth exploration of the function of MALAT1.

MALAT1 gene rs600231 polymorphism positively associated with acute coronary syndrome in Chinese population: a case-control study

Background

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been recognized as a major player in the pathogenesis of coronary artery disease (CAD). The aim of the study was to determine the association between polymorphisms of the MALAT1 gene and acute coronary syndrome (ACS) in a Chinese population in Xinjiang.

Methods

In the case-control study, we genotyped three nucleotide polymorphisms (rs3200401, rs4102217, rs600231) of the MALAT1 gene using SNPscan^TM typing assays (1,053 controls and 929 ACS patients). Furthermore, we explored a predictive model using MALAT1 rs600231 and clinical variables to predict the risk of ACS. Finally, the relative expression of long noncoding RNA (lncRNA) MALAT1 was also measured in 92 ACS patients and 92 controls using quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The prevalence of the GG genotype of rs600231 in ACS group was higher than that in control group (15.7% vs. 14.7%, P=0.048). The dominant model differed (AG + GG vs. AA) and the G allele of rs600231 in ACS group was higher than that in control group (for dominant model: 66.2% vs. 60.9%, P=0.014; for allele: 41.0% vs. 37.8%, P=0.042). Multivariate logistic regression analysis and the predictive nomogram model showed that the dominant model of rs600231 remained an independent risk factor for ACS [odds ratio (OR) =1.32, 95% confidence interval (CI): 1.07-1.63, P=0.009]. The area under the receiver operating characteristic (ROC) curve (AUC) for the nomogram model for the prediction of ACS was 0.738 (95% CI: 0.716-0.761). In addition, in the AG and GG phenotypes, the relative expression of lncRNA MALAT1 was significantly higher in ACS patients than in controls with the same phenotypes (P<0.05). Among ACS group, compared to other genotype carriers, the relative expression level of MALAT1 in GG genotype carriers was higher (P<0.05).

Conclusions

The present study suggested that the AG and GG genotype of rs600231 in MALAT1 gene was independently associated with ACS, and could be a risk genetic marker of ACS in a Chinese population in Xinjiang.

Knocking Down Long Noncoding RNAs Using Antisense Oligonucleotide Gapmers

Long noncoding RNAs (lncRNAs) are a class of RNA with 200 nucleotides or longer that are not translated into protein. lncRNAs are highly abundant; a study estimates that at least four times more lncRNAs are typically present than coding RNAs in humans. However, function of more than 95% of human lncRNAs are still unknown. Synthetic antisense oligonucleotides called gapmers are powerful tools for lncRNA loss-of-function studies. Gapmers contain a central DNA part, which activates RNase H-mediated RNA degradation, flanked by modified oligonucleotides, such as 2'-O-methyl RNA (2'OMe), 2'-O-methoxyethyl RNA (2'MOE), constrained ethyl nucleosides (cEt), and locked nucleic acids (LNAs). In contrast to siRNA or RNAi-based methods, antisense oligonucleotide gapmer-based knockdown is often more effective against nuclear-localized lncRNA targets, since RNase H is mainly localized in nuclei. As such, gapmers are also potentially a powerful tool for therapeutics targeting lncRNAs in various diseases, including cancer, cardiovascular diseases, lung fibrosis, and neurological/neuromuscular diseases. This chapter will discuss the development and applications of gapmers for lncRNA loss-of-function studies and tips to design effective antisense oligonucleotides.

Long non-coding RNA MALAT1 targeting STING transcription promotes bronchopulmonary dysplasia through regulation of CREB

Bronchopulmonary dysplasia (BPD) is a severe complication of preterm infants characterized by increased alveolarization and inflammation. Premature exposure to hyperoxia is believed to be a key contributor to the pathogenesis of BPD. No effective preventive or therapeutic agents have been created. Stimulator of interferon gene (STING) is associated with inflammation and apoptosis in various lung diseases. Long non-coding RNA MALAT1 has been reported to be involved in BPD. However, how MALAT1 regulates STING expression remains unknown. In this study, we assessed that STING and MALAT1 were up-regulated in the lung tissue from BPD neonates, hyperoxia-based rat models and lung epithelial cell lines. Then, using the flow cytometry and cell proliferation assay, we found that down-regulating of STING or MALAT1 inhibited the apoptosis and promoted the proliferation of hyperoxia-treated cells. Subsequently, qRT-PCR, Western blotting and dual-luciferase reporter assays showed that suppressing MALAT1 decreased the expression and promoter activity of STING. Moreover, transcription factor CREB showed its regulatory role in the transcription of STING via a chromatin immunoprecipitation. In conclusion, MALAT1 interacts with CREB to regulate STING transcription in BPD neonates. STING, CREB and MALAT1 may be promising therapeutic targets in the prevention and treatment of BPD.

lncRNA MALAT1 mediated high glucose-induced HK-2 cell epithelial-to-mesenchymal transition and injury

Epithelial-to-mesenchymal transition (EMT) and injury of tubular cells play critical roles in the pathogenesis of diabetic nephropathy (DN). lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been shown to be involved in DN progression. However, whether MALAT1 induces EMT and injury in tubular cells is unclear. Here, we investigated the effects of MALAT1 on human proximal tubular cells (HK-2 cells) and the underlying mechanism. We performed qPCR to detect MALAT1, E-cadherin, α-smooth muscle actin (α-SMA), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). Additionally, we conducted Western blot analyses to measure E-cadherin, α-SMA, cyclin D1, c-Myc, and β-catenin in HK-2 cells cultured with normal glucose and high glucose (HG) and in transfected cells or cells treated with LiCl and DKK-1. The β-catenin localization was observed using immunofluorescence, and the protein levels of NGAL and KIM-1 were evaluated by ELISA. We found that HG-upregulated MALAT1 decreased E-cadherin and increased α-SMA, KIM-1, NGAL, cyclin D1, c-Myc, and β-catenin in HK-2 cells. LiCl exposure increased the expression of α-SMA but decreased that of E-cadherin on the base of knocking down MALAT1, and decreased NGAL and KIM-1 expression. DKK-1 showed the opposite effects. Our results suggested that upregulated MALAT1 induced EMT in HG-treated HK-2 cells through activating the Wnt/β-catenin pathway. However, MALAT1-mediated injury in HK-2 cells was not mediated by activation of the Wnt/β-catenin pathway. Our results indicate that MALAT1 might serve as a novel therapeutic target for suppressing the progression of DN.

LncRNA MALAT1 Promotes Cancer Metastasis in Osteosarcoma via Activation of the PI3K-Akt Signaling Pathway

BACKGROUND/AIMS

LncRNAs have been reported to be vital regulators of the progression of osteosarcoma, although the underlying mechanisms are not completely understood.

METHODS

The levels of MALAT1 and miR-129-5p expression were measured using qRT-PCR. Cell growth was determined using the CCK-8 and colony formation assays. Cell migration and invasion were detected using the wound healing and Transwell invasion assays, respectively. Tumor growth was determined with a xenograft model.

RESULTS

MALAT1 was significantly up-regulated in osteosarcoma tissues compared with adjacent non-tumor soft tissues. Overexpression of MALAT1 promoted osteosarcoma cell proliferation, migration, and invasion in vitro and enhanced tumor growth in a tumor xenograft mouse model. MALAT1 promoted osteosarcoma progression by modulating stem cell-like properties. Moreover, rescue experiment and luciferase reporter assay results indicated that MALAT1 modulates RET expression by sponging miR-129-5p in osteosarcomas. Furthermore, MALAT1 augmented the expression of downstream proteins of the RET-Akt pathway. MALAT1 was consistently significantly increased in osteosarcoma tissues and MALAT1 expression was positively correlated with tumor size and metastasis. High expression of MALAT1 was significantly associated with poor outcomes in patients with osteosarcomas. MALAT1 expression was positively related to RET and negatively related to miR-129-5p in osteosarcoma samples and xenograft tumors. MALAT1 functioned as an oncogenic lncRNA in osteosarcomas and was as an independent prognostic indicator.

CONCLUSION

Our data revealed for the first time that MALAT1 increases stem cell-like properties by up-regulating RET via sponging miR-129-5p, and thus activates the PI3K-Akt signaling pathway and provides potential therapeutic targets for osteosarcoma treatment.

A genetic variant in long non-coding RNA MALAT1 associated with survival outcome among patients with advanced lung adenocarcinoma: a survival cohort analysis

Background

Recently studies have demonstrated that the long non-coding RNA (lncRNA) metastasis associated lung adenocarcinoma transcript 1 (MALAT1) may participate in the development and progression of lung cancer. In this study, we hypothesized that genetic variant of this lncRNA may affect the prognosis of lung cancer patients.

Methods

We conducted a follow-up study for 538 patients with non–small cell lung carcinoma (NSCLC), including 140 early-staged (stage I and II) and 398 advanced staged (stage III and IV) patients. The genetic variant rs3200401 in MALAT1 was then genotyped among this population by using TaqMan assay. The association of this variant with overall survival of these patients was further analyzed.

Results

It was shown that among the advanced lung adenoma patients, subjects carrying rs3200401 CT and CT + TT genotypes had significantly longer median survival time (MST = 29.9, 28.9 vs. 19.3 month, Long-rank P = 0.019 and 0.024, respectively) and decreased death risks [crude HR (95% CI) = 0.65 (0.43–0.98) and 0.64 (0.44–0.95), P = 0.040 and 0.025, respectively], when compared to subjects wtih the MALAT1 rs3200401 CC genotype. However, the beneficial effect of rs3200401 was not seen among early NSCLC and advanced lung squamous cell carcinoma patients. We further tested the TCGA data, and found that a higher expression of MALAT1 was associated with metastatic of advanced lung adenocarcinoma but not with lung squamous cell carcinoma.

Conclusions

The rs3200401 T allele located on the lncRNA MALAT1 was associated with a better survival for advanced lung adenocarcinoma patients, which may offer a novel prognostic biomarker for this patient subgroup. However, these results need to be validated in larger populations of lung cancer and the biological function of this variant still warrants further investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3151-6) contains supplementary material, which is available to authorized users.