MALAT1 Knockdown Research Articles

LncRNA MALAT1 facilitates inflammasome activation via epigenetic suppression of Nrf2 in Parkinson\u2019s disease

The goal of the present study was to elucidate the mechanism by which long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (lncRNA MALAT1) promotes inflammation in Parkinson’s disease (PD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to induce PD development in C57BL/6 mice, and tyrosine hydroxylase (TH) expression was analysed by immunohistochemical analysis. Western blot and qPCR analyses were conducted to assess the expression of protein and mRNA levels, respectively. Lipopolysaccharide/adenosine triphosphate (LPS/ATP) was used to activate microglia in vitro. Chromatin immunoprecipitation (ChIP), RNA pull-down and RNA immunoprecipitation chip (RIP) assays were performed to investigate the interaction among specific molecules. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell viability and proliferation. Flow cytometry was performed to analyse cell apoptosis after staining. The dichlorofluorescein diacetate (DCFH-DA) assay was used to measure the generation of reactive oxygen species (ROS) in cells. The results showed that MALAT1 was highly expressed in the brains of MPTP-induced PD model mice and in LPS/ATP-induced microglia cells. Knockdown of MALAT1 inhibited elevated nuclear factor (erythroid-derived 2)-like-2 factor (NRF2) expression, thereby inhibiting inflammasome activation and ROS production. MALAT1 was shown to promote neuroinflammation by recruiting enhancer of zeste homologue 2 (EZH2) to the promoter of NRF2, suppressing Nrf2 expression. In summary, MALAT1 epigenetically inhibits NRF2, thereby inducing inflammasome activation and reactive oxygen species (ROS) production in PD mouse and microglial cell models.

LncRNA MALAT1 mediates doxorubicin resistance of hepatocellular carcinoma by regulating miR-3129-5p/Nova1 axis.

Drug resistance is one of the major challenges for cancer therapies. In recent years, research on disease-related molecular signaling pathways has become the key ways to understand and overcome obstacles. Dysregulation of MALAT1 could regulate doxorubicin resistance of hepatocellular carcinoma (HCC), but how MALAT1 involving in managing doxorubicin resistance remains unclear yet. We aimed to elucidate the specific molecular mechanism of MALAT1 with doxorubicin resistance in HCC cells. Quantitative real-time polymerase chain reaction (qRT-PCR) was engaged to detect the expression levels of MALAT1, miR-3129-5p and Nova1 mRNA; MTT, western blot, flow cytometry and luciferase reporter assays were executed to identify the influence of MALAT1 on doxorubicin resistance of HCC cells. Xenograft tumor model was created to confirm the biological function of MALAT1 in doxorubicin resistance of HCC cells in vivo. MALAT1 and Nova1 were upregulated, while miR-3129-5p expression was decreased in doxorubicin-resistant HCC tissues and cells. Knockdown of MALAT1 regulated doxorubicin resistance of HCC cells through inhibiting cell proliferation, migration, invasion and promoting apoptosis, but antisense miR-3129-5p released the functional effect of MALAT1 knockdown. Nova1, as a target gene of miR-3129-5p, reversed the results of miR-3129-5p expression and enhanced doxorubicin resistance of HCC cells. Xenograft tumor model suggested that dysregulation of MALAT1 regulated tumor growth and Nova1 to mediate doxorubicin resistance of HCC cells by as a sponge for miR-3129-5p in vivo. Elevation of LncRNA MALAT1 mediated doxorubicin resistance and the progression of HCC via a MALAT1/miR-3129-5p/Nova1 axis. This study would be expected to enrich the understanding of doxorubicin resistance of HCC and provide new ideas for HCC treatment strategies.

LncRNA MALAT1 inhibits apoptosis of endometrial stromal cells through miR-126-5p-CREB1 axis by activating PI3K-AKT pathway.

Endometriosis is a common, chronic and painful disease in women, whose pathogenesis remains not entirely clear. Long non-coding RNA (lncRNA) MALAT1 participates in the development of endometriosis. This study further investigated the regulation of MALAT1-miR-126-5p-CREB1 axis in the pathological process of endometriosis. MALAT1, miR-126-5p, and CREB1 levels in human endometrial stromal cells (HESCs) were detected by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Protein levels were determined by Western blotting. Cell viability and apoptosis was assessed by MTT assay and annexin V-FITC staining, respectively. The interactivity between miR-126-5p and MALAT1 (or CREB1) was assessed by dual luciferase reporter system. Knockdown of MALAT1 or CREB1 restrained proliferation and induced apoptosis as confirmed by upregulating cleaved caspase-3 and Bax, and down-regulating Bcl-2 in HESCs, while inhibition of miR-126-5p presented the opposite results. Moreover, silencing of MALAT1 triggered apoptosis of HESCs via targeting miR-126-5p. In addition, miR-126-5p directly regulated CREB1 expression via binding to its 3' non-coding region. Finally, miR-126-5p inhibitor-mediated apoptosis inhibition was restrained by CREB1 silencing via inactivation of PI3K-AKT pathway in HESCs. Taken together, our study firstly demonstrates that MALAT1 regulates apoptosis of HESCs through miR-126-5p/CREB1 axis mediated PI3K/AKT pathway. Our findings explained the pathogenesis of endometriosis and offered promising therapeutic option for endometriosis.

MALAT1 Promotes Cell Tumorigenicity Through Regulating miR-515-5p/EEF2 Axis in Non-Small Cell Lung Cancer.

BackgroundPrevious studies suggested long noncoding RNA metastasis associated with lung adenocarcinoma transcript 1 (lncRNA MALAT1) acted as a tumor promoter to promote cell carcinogenesis in non-small cell lung cancer (NSCLC). MALAT1 was found to exist in serum exosomes of several cancers. However, the role of exosomal-derived MALAT1 in NSCLC remains poorly understood.Materials and MethodsExosomes were isolated using the ExoQuick precipitation kit. Western blot was used to detect the protein expression of CD3, CD63, apoptosis- and metastasis-related protein. The expression of MALAT1, microRNA (miR)-515-5p and eukaryotic elongation factor 2 (EEF2) mRNA was detected using quantitative real-time polymerase chain reaction. Cell viability, apoptosis, or invasion were measured using 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay, flow cytometry or transwell assay, respectively. The interaction between miR-515-5p and MALAT1 or EEF2 was confirmed by dual-luciferase reporter assay. In vivo experiments were conducted through the murine xenograft model.ResultsMALAT1 was highly expressed in serum and cell exosomes from NSCLC patients. MALAT1 knockdown repressed cell proliferation, invasion and induced cell apoptosis in vitro as well as inhibited tumor growth in vivo in NSCLC. Subsequently, we confirmed that MALAT1 was a sponge of miR-515-5p, and EEF2 was a target of miR-515-5p. Furthermore, MALAT1 served as a sponge of miR-515-5p to regulate EEF2 expression in NSCLC cells. More importantly, MALAT1 deletion performed anti-tumor effects by interacting with miR-515-5p/EEF2 axis in vitro and in vivo in NSCLC.ConclusionMALAT1 knockdown repressed NSCLC tumorigenicity by inhibiting cell proliferation, invasion and promoting apoptosis through regulating miR-515-5p/EEF2, besides, MALAT1 was highly enriched in exosomes of NSCLC, suggesting a possible molecular-targeted therapy for NSCLC patients.

LncRNA MALAT1 Promotes OGD-Induced Apoptosis of Brain Microvascular Endothelial Cells by Sponging miR-126 to Repress PI3K/Akt Signaling Pathway.

Ischemic stroke (IS) is a common disease that seriously endangers human health. Patients with IS present with increased death of brain microvascular endothelial cells (BMECs). MALAT1 is found to be upregulated in IS patients. However, the function of MALAT1 in IS pathogenesis still remains unclear. This study aimed to investigate the role of MALAT1 in IS in vitro model and the related molecular mechanisms. The expressions of MALAT1 and miR-126 were detected by qPCR. The in vitro IS model was established by treating BMECs with oxygen-glucose deprivation (OGD). Cell viability and cell apoptosis were assessed by MTT assay and flow cytometry, respectively. Luciferase assay was conducted to examine the interplay between MALAT1 and miR-126. Western blotting was used to determine the protein levels of apoptosis-associated proteins (e.g. caspase 3, Bax and Bcl-2) and PI3K/Akt pathway-related proteins (e.g. PI3K, Akt, p-PI3K, p-Akt). OGD induced upregulation of MALAT1 and downregulation of miR-126 in HBMECs. MALAT1 knockdown promoted the proliferation of HBMECs and reduced the proportion of apoptotic HBMECs by regulating the expression of apoptosis-related proteins. MALAT1 targeted and negatively regulated miR-126 expression. Overexpression of miR-126 activated the PI3K/Akt pathway, which in turn affected the proliferation and apoptosis of HBMECs. MALAT1 negatively regulated PI3K/Akt pathway. MALAT1 inhibited the proliferation and induced the apoptosis of OGD-induced HBMECs through suppressing PI3K/AKT pathway by sponging miR-126, providing a potential therapeutic target for IS.

The Long Non-Coding RNA MALAT1 Enhances Ovarian Cancer Cell Stemness by Inhibiting YAP Translocation from Nucleus to Cytoplasm.

BackgroundThe purpose of this work was to unearth the effects and underlying mechanism of long non-coding RNA (lncRNA) MALAT1 in ovarian cancer cell stemness.Material/MethodsWestern blot, quantitative polymerase chain reaction (qPCR) and sphere forming analysis were performed to evaluate the stem-like traits of cells and MALAT1-induced effects on ovarian cancer cell stemness. Cell viability was performed to evaluate MALAT1 role in the chemoresistance of ovarian cancer cells. RNA immunoprecipitation (RIP) and luciferase reporter analysis were constructed to investigate the underlying mechanisms.ResultsHere, qPCR assay showed that MALAT1 level was remarkably higher in non-adherent spheres formed by adherent ovarian cancer cells, as well as cisplatin-resistant ovarian cancer cells. Additionally, MALAT1 knockdown reduced ovarian cancer cell stemness, characterized as the decrease of sphere forming ability, expression of stemness regulatory masters, and attenuation of cisplatin resistance. Moreover, MALAT1 interacted with yes-associated protein (YAP), inhibited its nuclear-cytoplasm translocation, promoted YAP protein stability and expression and thus increased its activity. Notably, rescuing expression of YAP attenuated the inhibition of MALAT1 knockdown on ovarian cancer cell stemness.ConclusionsIn conclusion, these results demonstrate a MALAT1/YAP axis responsible for ovarian cancer cell stemness.

MALAT1 Decreases the Sensitivity of Head and Neck Squamous Cell Carcinoma Cells to Radiation and Cisplatin.

Two-thirds of head and neck squamous cell carcinoma (HNSCC) patients present with locally advanced (LA) stages and have a poor survival rate. The aim of this study was to investigate the roles of the long non-coding RNAs MALAT1 on radiation and cisplatin sensitivity of HNSCC cells. Clonogenic, cell viability, and apoptosis assays were performed in cells following MALAT1 knockdown using CRISPR/Cas9 system. MALAT1 was overexpressed in HNSCC cell lines as compared to a non-tumorigenic cell line. The number of colonies formed after radiation was significantly reduced in MALAT1 knockdown cells. The IC50 value of cisplatin in MALAT1 knockdown cells was lower than that of the control cells. MALAT1 knockdown resulted in cell cycle arrest at G2/M phase, DNA damage and apoptotic cell death. MALAT1 knockdown enhanced the sensitivity of HNSCC cells to radiation and cisplatin partly through the induction of G2/M cell cycle arrest resulting in DNA damage and apoptosis.

LncRNA MALAT1 Promotes EMT Process and Cisplatin Resistance of Oral Squamous Cell Carcinoma via PI3K/AKT/m-TOR Signal Pathway.

BackgroundCisplatin (DDP) is the first-line chemotherapy agent for the treatment of oral squamous cell carcinoma (OSCC). The emergence of DDP resistance leads to diminished drug efficacy and survival benefit. lncRNA MALAT1 has been considered as one of the most important factors in OSCC. It has also been reported to enhance chemo-resistance in other kinds of carcinomas. However, little is known about the role of lncRNA MALAT1 in DDP resistance of OSCC.Materials and MethodsTwo kinds of human DDP-resistant cell lines (CAL-27R and SCC-9R) were developed from cisplatin-naïve cell lines (CAL-27 and SCC-9, respectively) as in vitro cell models. Cell transfection was performed to overexpress or knockdown MALAT1 in these cells. Mouse xenograft models were also established. The following measurements were performed: cell proliferation, colony formation, wound healing, transwell, and TUNEL assays, as well as Western blot and immunofluorescence staining.ResultsDDP-resistant cells showed higher expression level of MALAT1 compared to cisplatin-naïve cells. The overexpression of MALAT1 in cisplatin-naïve cells enhanced DDP resistance and suppressed apoptosis in OSCC cells. However, the knockdown of MALAT1 in DDP-resistance cells induced apoptotic cell death and restored the sensitivity to DDP. Further analyses suggested that MALAT1 might promote DDP resistance via regulating P-glycoprotein expression, epithelial–mesenchymal transition process, and the activation of PI3K/AKT/m-TOR signaling pathway.ConclusionMALAT1 might be a potential therapeutic target for the treatment of DDP-resistant OSCC.

Extracellular vesicles from human embryonic stem cell-derived cardiovascular progenitor cells promote cardiac infarct healing through reducing cardiomyocyte death and promoting angiogenesis

Human pluripotent stem cells (hPSCs)-derived cardiovascular progenitor cells (CVPCs) are a promising source for myocardial repair, while the mechanisms remain largely unknown. Extracellular vesicles (EVs) are known to mediate cell–cell communication, however, the efficacy and mechanisms of hPSC-CVPC-secreted EVs (hCVPC-EVs) in the infarct healing when given at the acute phase of myocardial infarction (MI) are unknown. Here, we report the cardioprotective effects of the EVs secreted from hESC-CVPCs under normoxic (EV-N) and hypoxic (EV-H) conditions in the infarcted heart and the long noncoding RNA (lncRNA)-related mechanisms. The hCVPC-EVs were confirmed by electron microscopy, nanoparticle tracking, and immunoblotting analysis. Injection of hCVPC-EVs into acutely infracted murine myocardium significantly improved cardiac function and reduced fibrosis at day 28 post MI, accompanied with the improved vascularization and cardiomyocyte survival at border zones. Consistently, hCVPC-EVs enhanced the tube formation and migration of human umbilical vein endothelial cells (HUVECs), improved the cell viability, and attenuated the lactate dehydrogenase release of neonatal rat cardiomyocytes (NRCMs) with oxygen glucose deprivation (OGD) injury. Moreover, the improvement of the EV-H in cardiomyocyte survival and tube formation of HUVECs was significantly better than these in the EV-N. RNA-seq analysis revealed a high abundance of the lncRNA MALAT1 in the EV-H. Its abundance was upregulated in the infarcted myocardium and cardiomyocytes treated with hCVPC-EVs. Overexpression of human MALAT1 improved the cell viability of NRCM with OGD injury, while knockdown of MALAT1 inhibited the hCVPC-EV-promoted tube formation of HUVECs. Furthermore, luciferase activity assay, RNA pull-down, and manipulation of miR-497 levels showed that MALAT1 improved NRCMs survival and HUVEC tube formation through targeting miR-497. These results reveal that hCVPC-EVs promote the infarct healing through improvement of cardiomyocyte survival and angiogenesis. The cardioprotective effects of hCVPC-EVs can be enhanced by hypoxia-conditioning of hCVPCs and are partially contributed by MALAT1 via targeting the miRNA.

LncRNA-Malat1 is Involved in Lipotoxicity-Induced ß-cell Dysfunction and the Therapeutic Effect of Exendin-4 via Ptbp1.

Increasing evidence indicates that long noncoding RNAs (lncRNAs) have crucial roles in various biological processes. However, the contribution of lncRNAs to β-cell dysfunction and their roles in diabetes therapeutics remain poorly understood. The aim of this study was to identify the lncRNAs dysregulated in diabetic islets and to explore the lncRNAs involved in β-cell function as potential therapeutic targets. By using RNA sequencing and real-time PCR, we identified thousands of lncRNAs in the islets of db/db mice and db/m littermate mice. Among the differentially expressed lncRNAs, lncRNA-Malat1 (metastasis-associated lung adenocarcinoma transcript 1) was reduced in the islets of db/db mice and palmitate-treated MIN6 cells. The results of TUNEL, Western blot and flow cytometric analyses, and GSIS assays revealed that Malat1 knockdown significantly induced β-cell apoptosis and inhibited insulin secretion. Mechanistically, RNA immunoprecipitation showed that Malat1 enhanced polypyrimidine tract-binding protein 1 (Ptbp1) protein stability by direct interaction, thereby adjusting the ratio of pyruvate kinase muscle (PKM) isoforms 1 and 2 (PKM1/PKM2). Moreover, luciferase assay and chromatin immunoprecipitation indicated that Malat1 was transcriptionally activated by pancreatic and duodenal homeobox 1 (Pdx1), through which exendin-4 alleviated lipotoxicity-induced β-cell damage. In summary, our findings suggested the involvement of Malat1 in β-cell dysfunction under diabetic conditions via the Malat1/Ptbp1/PKM2 pathway. In addition, exendin-4 ameliorated β-cell impairment by Pdx1-mediated Malat1 upregulation. Hence, Malat1 may serve as a therapeutic target for the treatment of type 2 diabetes.

Denosumab inhibits MCF-7 cell line-induced spontaneous osteoclastogenesis via the RANKL/MALAT1/miR-124 axis.

BackgroundDenosumab is an inhibitor of receptor activator of NF-κB ligand (RANKL), which inhibits bone metastasis (BM) in breast cancer (BC), but does not completely control cancer cell BM in some BC patients. This study was designed to study whether denosumab inhibits human BC cells (MCF-7) cell line-induced spontaneous osteoclastogenesis via RANKL/metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-124 axis.MethodsWe established a co-culture system of MCF-7-induced spontaneous osteoclastogenesis in RAW 264.7 cells, and denosumab is added into the co-culture system to inhibit RAW 264.7 cell differentiation into osteoclasts. Real-time PCR (RT-PCR), immunofluorescence and western blotting analysis were used to detect gene expression, while tartrate-resistant acid phosphatase (TRAP) staining was used to assess osteoclast formation.ResultsDenosumab inhibits MCF-7 cell line-induced spontaneous osteoclastogenesis, and the inhibition of denosumab was found to be more pronounced after MALAT1 downregulation and miR-124 overexpression. However, MALAT1 knockdown or miR-124 overexpression did not alter RANKL protein expression. Moreover, the dual luciferase gene reporter system showed that miR-124 targeted the inhibition of MALAT1, while si-MALAT1 upregulated miR-124 expression. miR-124-mimics were able to decrease the expression of Rab27a, IL-11, activated T-cell nuclear factor 1 (NFATc1) and TARP protein.ConclusionsDenosumab inhibits MALAT1 expression by inhibiting RANKL, thereby upregulating miR-124 expression, which ultimately inhibits MCF-7 cell line-induced pseudo osteoclastogenesis.

LncRNA MALAT1 induces the dysfunction of β cells via reducing the histone acetylation of the PDX-1 promoter in type 1 diabetes

BackgroundType 1 diabetes (T1DM) severely threatens human health, and the dysfunction of insulin-secreting β cells in islets is related to the reduced PDX-1 expression. It has been reported that long non-coding RNA MALAT1 regulates β cell function, while the potential mechanism is unclear. MethodsIslets were isolated from non-obese diabetic (NOD) mice and wild type (WT) mice. Mouse islets and β cell line (Min6) were stimulated by IL-1β. The expression of MALAT1 was determined using real-time PCR, while the PDX-1 protein expression was determined using western blotting. ChIP-qPCR was carried out to determine the histone acetylation of the PDX-1 promoter. ResultsIn NOD islets and IL-1β-stimulated Min6 cells, the expression of MALAT1 was increased, while the mRNA and protein levels of PDX-1 were decreased at an age/time-dependent manner. Overexpressing MALAT1 suppressed the H3 histone acetylation of the PDX-1 promoter, inhibiting both mRNA and protein expressions of PDX-1. Knocking down MALAT1 restored the decrease of the histone acetylation of the PDX-1 promoter, as well as the PDX-1 expression, which was reduced by IL-1β stimulation. Under high glucose stimulation, the overexpression of PDX-1 alone restored the insulin secretion which was inhibited by the simultaneous overexpression of MALAT1 and PDX-1. Under high glucose and IL-1β stimulation, the simultaneous knockdown of MALAT1 and PDX-1 reduced the enhancement of the insulin secretion which was raised by knocking down MALAT1 alone. ConclusionMALAT1 induces the dysfunction of β cells via reducing the H3 histone acetylation of the PDX-1 promoter and subsequently inhibiting the expression of PDX-1, thus suppressing the insulin secretion.

MALAT1 Protected the Angiogenesis Function of Human Brain Microvascular Endothelial Cells (HBMECs) Under Oxygen Glucose Deprivation/re-oxygenation (OGD/R) Challenge by Interacting with miR-205-5p/VEGFA Pathway

Long non-coding RNA MALAT1 was previously revealed to express abnormally in animal and cellular models of stroke, suggesting its indispensable role in stroke. The aims of the present study were to further investigate the functions of MALAT1 and to elucidate the underlying molecular mechanisms. Oxygen glucose deprivation/re-oxygenation (OGD/R) challenge was used in human brain microvascular endothelial cells (HBMECs) to mimic stroke injury in vitro. MALAT1 and miR-205-5p expression levels were evaluated by qRT-PCR. A tube formation assay was employed to verify the angiogenesis of HBMECs. Cell proliferation and apoptosis were evaluated using the ErdU assay and flow cytometry analysis, respectively. The interaction between miR-205-5p and MALAT1 was verified by dual-luciferase reporter assay. MALAT1 and miR-205-5p were both significantly upregulated in the serum of CIS patients and HBMECs under OGD/R, and the tube formation of HBMECs was damaged after OGD/R treatment. Silencing miR-205-5p remarkably promoted HBMEC proliferation and angiogenesis to resist OGD/R injury. Knockdown of MALAT1 markedly inhibited HBMEC proliferation and angiogenesis, and meanwhile promoted apoptosis induced by OGD/R treatment. Most importantly, MALAT1 acted as a competing endogenous RNA (ceRNA) of miR-205-5p via direct bonding with each other in HBMECs under OGD/R damage, indirectly upregulating the downstream targeted gene VEGFA. MALAT1 protected the angiogenesis function of HBMECs under OGD/R conditions by interacting with miR-205-5p/VEGFA pathway.

LncRNA MALAT1 silencing protects against cerebral ischemia-reperfusion injury through miR-145 to regulate AQP4

BackgroundThe present study aimed to verify whether long noncoding RNA (lncRNA) MALAT1 is involved in brain tissue damage induced by ischemia-reperfusion injury, and to explore the mechanism by which MALAT1 regulates aquaporin 4 (AQP4).MethodsIn this study, we established glucose deprivation (OGD)/reoxygenation (RX) astrocyte cell model and middle cerebral artery occlusion (MCAO)/reperfusion mouse model in vitro and in vivo. Then cell counting kit-8 assay, flow cytometry analysis, Triphenyltetrazolium chloride (TTC) staining, and western blotting were used to determine cell viability, cell apoptosis, cerebral infarction volume, and the abundance of AQP4, respectively.ResultsWe found that the level of MALAT1 was significantly upregulated in both the MCAO/reperfusion model and OGD/RX model. Knockdown of MALAT1 increased cell viability and reduced cell apoptosis in MA-C cells, while an AQP4 siRNA combined with a siRNA targeting MALAT1 could not enhance this effect. Further experiments showed that MALAT1 positively regulated AQP4 expression via miR-145. The MALAT1 siRNA did not alleviate the exacerbation of damage after miR-145 inhibitor action. However, an miR-145 inhibitor reversed the protection effects of MALAT1, indicating that MALAT1 silencing protects against cerebral ischemia-reperfusion injury through miR-145. TTC staining showed that the infracted area of whole brain was significantly attenuated in treated with sh-MALAT1 group in vivo.ConclusionTaken together, our study confirmed that MALAT1 promotes cerebral ischemia-reperfusion injury by affecting AQP4 expression through competitively binding miR-145, indicating that MALAT1 might be a new therapeutic target for treatment cerebral ischemic stroke.

LncRNA MALAT1 Regulates the Cell Proliferation and Cisplatin Resistance in Gastric Cancer via PI3K/AKT Pathway.

BackgroundMany studies showed that long non-coding RNA MALAT1 is served as an oncogene. However, the specific role of MALAT1 in gastric cancer is not fully elucidated. The aim of this study is to elucidate the regulatory effects of MALAT1 on tumor development and cisplatin resistance in gastric cancer.MethodsTCGA database was applied to investigate the expression levels of MALAT1 in GC tissues and normal gastric tissues and its correlation with GC patients’ survival. Univariate and multivariate analysis were performed to investigate whether MALAT1 expression is an independent risk for overall survival of gastric cancer patients. The expression of MALAT1 was detected by Quantitative real-time PCR. After knockdown or overexpression of MALAT1, the cellular functions of GC cells were detected by cell-proliferation, flow cytometry, transwell assay and colony formation assays, respectively. Western blot analysis was performed to detect the protein levels of Bcl-2 and key genes in the PI3K/AKT pathway in GC cells. Finally, CCK-8 assay was performed to explore the effect of MALAT1 on cisplatin resistance of GC cells.ResultsHigher expression of MALAT1 was detected in GC tissues than that of adjacent normal tissues, high MALAT1 expression is an independent risk for overall survival of gastric cancer patients. Knockdown of MALAT1 inhibited proliferation, migration and invasion of GC cells, while overexpression of MALAT1 Overexpression of MALAT1 yielded opposite results. Western blot results showed that protein expressions of p-PI3K, p-AKT and p-STAT3 were downregulated after MALAT1 knockdown in GC cells, while these proteins were upregulated after MALAT1 overexpression. Additionally, the IC50 in MGC803/CDDP cells transfected with si-MALAT1 was lower than in those transfected with si-NC. The apoptotic rate in MGC803 cells transfected with pcDNA-MALAT1 was remarkably lower than those transfected with NC.ConclusionWe demonstrated that MALAT1 is highly expressed in GC, high MALAT1 expression is an independent risk factor for OS among GC patients. Moreover, MALAT1 promotes malignant progression of GC and contributes to cisplatin resistance of GC cells, indicating MALAT1 may serve as a biological hallmark for predicting the prognosis of GC.

The knockdown of MALAT1 inhibits the proliferation, invasion and migration of hemangioma endothelial cells by regulating MiR-206 / VEGFA axis

AimLncRNA MALAT1 is involved in regulation of angiogenesis, however, its expression and mechanism in infantile hemangioma (IH) are less reported. The study aimed to investigate MALAT1 in IH and to reveal the potential mechanism of MALAT1 acting on IH. MethodsIsolated form IH tissue, human CD31+ hemangioma endothelial cells (HemECs) were cultured and sorted by magnetic-activated cell sorting (MACS). Quantitative real-time (qRT)-PCR was performed to detect the expressions of MALAT1, miR-206 and VEGFA. The correlations among MALAT1, miR-206 and VEGFA were confirmed by bioinformatics analysis and dual-luciferase reporter assay. The effects of MALAT1, miR-206 and VEGFA on cell proliferation were detected by cell counting kit-8 (CCK-8) and cell colony formation assay. Flow cytometry, wound scratch, Transwell and Tube formation assay were performed to determine cell apoptosis, migration, invasion and vasoformation, respectively. Apoptosis-related proteins were determined by Western blot. ResultsThe results showed that MALAT1 and VEGFA were high-expressed and miR-206 was low-expressed in IH tissues. SiMALAT1 negatively affected the cell proliferation, migration, invasion and vasoformation of HemECs and promoted apoptosis of HemECs. Moreover, Bcl-2 expression was significantly inhibited and the expressions of Bax and c cleaved-3 were greatly promoted. MALAT1 directly targeted and inhibited the expression of miR-206, and VEGFA was predicted to be the target gene for miR-206. SiMALAT1 suppressed the cell proliferation, migration, invasion and vasoformation of HemECs through modulating miR-206/VEGFA axis. ConclusionKnock-down of MALAT1 inhibits the growth of HemECs through regulating miR-206/VEGFA axis, indicating that MALAT1 is a potential therapeutic mechanism for the treatment of IH.

LncRNA MALAT1 modulates oxaliplatin resistance of gastric cancer via sponging miR-22-3p.

ObjectiveVarious regulatory mechanisms have been demonstrated to be associated with cancer progression. ncRNA and mRNA play important roles in gastric cancer (GC) cell growth and drug resistance, respectively. However, the regulatory network of ncRNA and mRNA in GC oxaliplatin (OXA) resistance has not been fully clarified.MethodsThe expression of miR-22-3p, MALAT1, and zinc finger protein 91 (ZFP91) was detected in tissues and cells using quantitative real-time PCR. The protein level of ZFP91 was measured by Western blot analysis. Luciferase reporter, pull-down, and RNA immunoprecipitation assays were used to determine the relationship between MALAT1, miR-22-3p, and ZFP91. MTT assay was applied to measure cell survival and proliferation. Cell apoptosis was detected using flow cytometry. Tumor xenograft assay was used to detect the function of miR-22-3p in vivo.ResultsIn this study, we found that MALAT1 and ZFP91 expression was upregulated while the expression of miR-22-3p was downregulated in GC/OXA tissues and cells. Additionally, miR-22-3p was a target miRNA of MALAT1 and ZFP91 was a target mRNA of miR-22-3p. Functional studies showed that the knockdown of MALAT1 or overexpression of miR-22-3p inhibited GC/OXA cell survival, proliferation, and drug resistance as well as induced apoptosis, which could be reversed by the inhibition of miR-22-3p or overexpression of ZFP91.ConclusionWe observed a new regulatory network for MALAT1 in drug resistance of GC. MALAT1 modulates ZFP91 to promote GC cells OXA resistance via sponging miR-22-3p.

Propofol facilitates cisplatin sensitivity via lncRNA MALAT1/miR-30e/ATG5 axis through suppressing autophagy in gastric cancer

AimsRecently, chemoresistance has been recognized as an obstacle in the treatment of gastric cancer (GC). The aim of this study was to investigate the biological functions and underlying mechanisms of propofol in GC chemoresistance. Main methodsCCK-8 assay, flow cytometry and immunofluorescent staining were performed to assess the IC50 concentration, cell apoptosis and autophagy activity of cisplatin in both GC chemosensitive cells (SGC7901) and chemoresistant cells (SGC7901/CDDP). The expression pattern of MALAT1 in GC cells was detected by qRT-PCR. The shRNAs and overexpressing plasmids were employed for the loss or gain-of-function. Dual-luciferase reporter assay was subjected to verify the binding relationship between MALAT1 and miR-30e. Besides, ATG5 mRNA and protein levels were determined using qRT-PCR and western blot analysis. Furthermore, GC xenograft mice model was established to validate the in vitro findings. Key findingsChemoresistant GC cells presented higher IC50 of cisplatin, increased autophagy activity and stronger expression of MALAT1. The application of propofol promoted cell apoptosis and reduced the activity of autophagy through downregulating MALAT1. Silencing of MALAT1 inhibited chemo-induced autophagy, whereas MALAT1 overexpression promoted autophagy in GC cells. Mechanistic researches demonstrated that MALAT1 could bind with miR-30e to regulate ATG5 expression, thus causing the suppression of autophagy. In vivo GC xenograft model treated with both propofol and cisplatin also showed significantly decreased tumor size and weight, which was enhanced by knockdown of MALAT1. SignificanceAltogether, our study revealed a novel mechanism of propofol of lncRNA MALAT1/miR-30e/ATG5 mediated autophagy-related chemoresistance in GC, casting new lights on the understanding of propofol.

MALAT1 is involved in type I IFNs-mediated systemic lupus erythematosus by up-regulating OAS2, OAS3, and OASL

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with an aberrant activation of immune cells partly due to the dysfunction of cytokines such as type I interferons (IFNs). Long non-coding RNA MALAT1 has been found to play a pathogenic role in SLE; however, the underlying mechanisms are still poorly understood. Bioinformatics analysis showed the up-regulation of type I IFN downstream effectors OAS2, OAS3, and OASL (OAS-like) in CD4+ T cells, CD19+ B cells, and CD33+ myeloid cells in patients with active SLE compared to healthy participants. In this study, peripheral blood mononuclear cells (PBMCs), CD19+ B, and CD4+ T cells were isolated from active SLE patients and healthy participants. PCR was performed to quantify MALAT1, OAS2, OAS3, and OASL expression in immune cells. MALAT1, OAS2, OAS3, and OASL were knocked down in CD4+ T cells to investigate the regulatory effect of MALAT1 on the effectors and their involvement in type I IFNs-mediated inflammation. Results showed higher OAS2, OAS3, and OASL expression in active SLE patients. MALAT1 expression was positively correlated to OAS2, OAS3, and OASL expression in CD19+ B or CD4+ T cells. MALAT1 knockdown decreased OAS2, OAS3, and OASL expression. Treatment with IFN-α-2a increased the expression of TNF-α, IL-1β, and IFN-α in CD4+ T cells. However, knockdown of MALAT1, OAS2, OAS3, and OASL alone inhibited the effect of IFN-α-2a on TNF-α and IL-1β. This study suggested the involvement of MALAT1 in type I IFNs-mediated SLE by up-regulating OAS2, OAS3, and OASL.

LncRNA MALAT1 knockdown alleviates myocardial apoptosis in rats with myocardial ischemia-reperfusion through activating PI3K/AKT signaling pathway.

To observe the effect of long non-coding ribonucleic acid metastasis-associated lung adenocarcinoma transcript 1 (lncRNA MALAT1) on the myocardial ischemia-reperfusion (I/R) injury in rats and to explore its potential mechanism, to provide certain references for clinical prevention and treatment of myocardial I/R injury. A total of 60 male Wistar rats were randomly divided into the Control group (n=20), I/R group (n=20) and I/R + MALAT1 small-interfering RNA (siRNA) group (n=20) using a random number table. The I/R model was established through recanalization after ligation of left anterior descending coronary artery (LAD), and the MALAT1 knockdown model was established via tail intravenous injection of MALAT1 siRNA in the I/R + MALAT1 siRNA group. The ejection fraction (EF%) and fractional shortening (FS%) of rats in each group were detected via echocardiography and the infarction area in each group was detected using 2,3,5-triphenyl tetrazolium chloride (TTC) assay. Moreover, the morphological changes in myocardial cells in each group were detected via hematoxylin-eosin (H&E) staining, and the myocardial apoptosis level was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. At the same time, the expression levels of the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and pro-apoptotic protein Bcl-2 associated X protein (Bax) in myocardial tissues in each group were determined via Western blotting. Finally, the effect of MALAT1 knockdown on the phosphatidylinositol 3-hydroxy kinase/protein kinase B (PI3K/AKT) protein expression was detected via Western blotting. The expression level of lncRNA MALAT1 in myocardial tissues was significantly higher in the I/R group than that in the Control group (p<0.05). The MALAT1 knockdown could significantly improve the cardiac insufficiency caused by I/R injury, and increase both EF% and FS% in rats (p<0.05). In addition, the MALAT1 knockdown could markedly inhibit myocardial infarction caused by I/R injury and reduce the infarction area from (62.12 ± 1.29) to (27.66 ± 3.58; p<0.05). The results of the H&E staining showed that the myofilaments were arranged more orderly, the degrees of degradation and necrosis were lower and the cellular edema was significantly alleviated in the I/R + MALAT1 siRNA group compared with those in the I/R group. According to the results of TUNEL staining, the rats in I/R + MALAT1 siRNA group had a markedly lower level of myocardial apoptosis than the I/R group (p<0.05), and the Bax/Bcl-2 ratio also remarkably declined in the I/R + MALAT1 siRNA group (p<0.05). Furthermore, the results of Western blotting revealed that MALAT1 siRNA could significantly reverse the I/R injury-induced inhibition on the AKT phosphorylation (p<0.05). The MALAT1 knockdown can markedly improve the I/R-induced myocardial injury and promote the cardiac function of rats, whose mechanism may be related to the activation of the AKT signaling pathway by MALAT1 siRNA. Therefore, lncRNA MALAT1 is expected to be a new therapeutic target for myocardial I/R injury.