Noncoding RNA Metastasis-associated Lung Adenocarcinoma Transcript 1 Research Articles

The long non-coding RNA MALAT1 promotes ovarian cancer progression by regulating RBFOX2-mediated alternative splicing.

Ovarian cancer metastasizes via direct seeding, whereby cancer cells shed from the primary site, resist cell death in the peritoneal cavity, then metastasize to peritoneal organs. We sought to identify molecular mechanisms that facilitate ovarian cancer cell anchorage independent survival. Gene expression profiling was performed on ovarian cancer cells grown in attached or forced suspension culture and confirmed by RT-qPCR. Anoikis was measured by Caspase 3/7 assay. Since the long non-coding RNA Metastasis Associated Lung Adenocarcinoma transcript 1 (MALAT1) was among the transcripts most highly increased in forced suspension culture, modified anti-sense oligonucleotides (ASO) were used to inhibit its expression. Knockdown of RBFOX2 and KIF1B was performed using shRNAs. Publically available datasets were analyzed for association of MALAT1 gene expression with clinicopathological variables. In multiple anoikis-resistant ovarian cancer cell lines MALAT1 expression increased after 24 and 48 h in forced suspension culture compared to attached culture. High MALAT1 is associated with increased stage, recurrence, and reduced survival in ovarian cancer, and in a small percentage of ovarian cancers MALAT1 is amplified. MALAT1 knockdown resulted in decreased proliferation, invasion, anchorage-independent growth, and increased anoikis. Suppression of MALAT1 also resulted in decreased expression of RBFOX2, and alternative processing of the pro-apoptotic tumor suppressor gene KIF1B. RBFOX2 suppression resulted in preferential splicing of the pro-apoptotic isoform of KIF1B (KIFB1B-beta) and increased anoikis. The lncRNA MALAT1 facilitates a pro-metastatic phenotype in ovarian cancer by promoting alternative RNA processing and differential expression of anti-apoptosis and epithelial to mesenchymal transition (EMT)-related genes.

The long non-coding RNA MALAT1 is increased in renal ischemia-reperfusion injury and inhibits hypoxia-induced inflammation

Background: To investigate the expression of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in renal ischemia-reperfusion injury and explore its role in acute kidney injury.Methods: 18 mice were randomly divided into a sham operation group (Sham) and an ischemia-reperfusion group (IR) in which animals were sacrificed at 6 h or 12 h after surgery. The kidneys were harvested to measure the expression of MALAT1 mRNA. HK2 cells were treated with cobalt chloride (CoCl2) to mimic hypoxia or transfected with siRNA to knockdown MALAT1 before CoCl2 treatment. After that, MALAT1 was analyzed by RT-PCR (reverse transcription-polymerase chain reaction). HIF-1ɑ (hypoxia-inducible factor-1 alpha) and NF-κB (nuclear factor-kappa B) was measured by Western blot. The concentrations of IL-6 (interleukin-6) and TNF-ɑ (tumor necrosis factor-alpha) in the media were detected by ELISA (enzyme-linked immunosorbent assay).Results: The expression of MALAT1 in the IR (6 h/12 h) group was significantly higher than that in the sham group. In HK2 cells, MALAT1 was significantly increased at 1 h, 3 h, and 6 h after CoCl2 treatment but had reduced to the basal level at 12 h and 24 h. Knockdown of MALAT1 by siRNA significantly up-regulated the expression of HIF-1ɑ and NF-κB proteins in CoCl2-treated HK2 cells. In addition, the concentrations of IL-6 and TNF-ɑ were increased by MALAT1 siRNA transfection in CoCl2-treated HK2 cells.Conclusion: The expression of MALAT1 is increased in renal ischemia-reperfusion injury. It is likely that MALAT1 inhibits the hypoxia-induced inflammatory response through the NF-κB pathway.

Long non-coding RNA MALAT1 and microRNA-499a expression profiles in diabetic ESRD patients undergoing dialysis: a preliminary cross-sectional analysis

Background: Circulating non-coding RNAs (ncRNAs) have been implicated in health and disease. This study aimed to evaluate the serum expression profile of microRNA-499a (miR-499a) and its selected bioinformatically predicted partner long-ncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) in diabetes-related end-stage renal disease (ESRD) patients and to correlate the expressions with the patients' clinicolaboratory data.Subjects and methods: Real-time quantitative polymerase chain reaction was applied in diabetics with and without ESRD (n = 90 for each).Results: Serum MALAT1 expression levels were increased in the ESRD group relative to diabetics without ESRD with median (quartile) values of 10.5 (1.41–126.7) (p < .001). However, miR-499a levels were decreased in more than half of ESRD patients with a median of 0.96 (0.13–3.14). Both MALAT1 and miR-499a expression levels were inversely correlated in the ESRD patient-group.Conclusions: MALAT1 up-regulation and miR-499 down-regulation might be involved in diabetic nephropathy-related ESRD pathogenesis. Functional validation studies are warranted to confirm the MALAT1/miR-499a partnership.

Long noncoding RNA MALAT1 alleviates lipopolysaccharide-induced inflammatory injury by upregulating microRNA-19b in murine chondrogenic ATDC5 cells.

Osteoarthritis is the most frequent chronic bone-joint disease in middle-aged and older people worldwide. This study investigated the effects of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on lipopolysaccharide (LPS)-induced murine chondrogenic ATDC5 cell inflammatory injury. Cell viability and apoptosis were assessed using cell counting kit-8 assay and annexin V-phycoerythrin (PE) staining, respectively. The expression levels of interleukin-1β (IL)-1β, IL-6, IL-8, tumor necrosis factor α (TNF-α), MALAT1, and microRNA-19b (miR)-19b were measured using quantitative reverse-transcription polymerase chain reaction. Enzyme-linked immunosorbent assay was conducted to detect the concentrations of IL-1β, IL-6, IL-8, and TNF-α in culture supernatant of ATDC5 cells. Expressions of key factors involved in cell apoptosis, proinflammatory response, Wnt/β-catenin, and nuclear factor κB (NF-κB) pathways were analyzed using Western blot analysis. We found that LPS treatment remarkably induced ATDC5 cell apoptosis and inflammatory injury. MALAT1 was upregulated in LPS-stimulated ATDC5 cells. Overexpression of MALAT1 significantly reversed the LPS-induced ATDC5 cell inflammatory injury, while suppression of MALAT1 had opposite effects. Further results showed that MALAT1 positively regulated the expression of miR-19b in ATDC5 cells. Knockdown of miR-19b reversed the protective effect of MALAT1 on LPS-induced ATDC5 cells. In addition, MALAT1 reduced LPS-induced Wnt/β-catenin and NF-κB pathways activation in ATDC5 cells by upregulating miR-19. To conclude, our research verified that MALAT1 alleviated LPS-induced ATDC5 cell inflammatory injury by upregulating miR-19b and inactivating Wnt/β-catenin and NF-κB pathways. This finding will be helpful for further understanding the critical roles of MALAT1 and miR-19b in osteoarthritis and may provide possible targets for osteoarthritis diagnosis and treatment.

Abstract A065: MicroRNA-338-5p/-421 mediated regulation of oncogenic long noncoding RNA MALAT1 abrogates prostate cancer progression and metastases

Abstract Prostate cancer (PCa) is one of the leading cause of cancer-associated death among men worldwide. Understanding the mechanism underpinning the disease pathogenesis is therefore critical in developing novel therapeutic strategies for this disease. Multiple lines of evidence suggest that noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are implicated in PCa progression and metastases. To date, great efforts have been put forth to characterize the role of miRNAs in regulating the expression of coding transcripts. However, little is known about the influence of miRNAs on the expression of noncoding transcripts such as lncRNAs. Thus, elucidating the role of miRNAs in modulating the expression of lncRNAs in PCa is crucial in order to understand their functional significance and potential utility for therapeutic interventions. Previously, we demonstrated that miR-338-5p and miR-421 exhibit tumor-suppressive properties in prostate cancer by inducing S-phase arrest, inhibiting epithelial-to-mesenchymal transition (EMT) and cancer stemness (unpublished data). Moreover, ectopic expression of these miRNAs abrogated tumor growth and distant metastases in murine xenograft model. Further, to gain insights into the biologic functions altered by miR-338-5p and miR-421, we performed global gene expression profiling of 22RV1 cells overexpressing these miRNAs. Our analysis revealed several lncRNAs deregulated by these miRNAs. One of the lncRNA found to be downregulated upon overexpression of miR-338-5p/miR-421was an oncogenic lncRNA, Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1), which is known to be profoundly upregulated across many cancers including prostate. Moreover, in silico miRNA prediction tools indicated putative binding sites of miR-338-5p and miR-421 on the 3’ end of MALAT1. The binding of miR-338-5p and miR-421 on MALAT1 was further confirmed by luciferase reporter assay, indicating miRNA-mediated post-transcriptional regulation. Furthermore, analysis of RNA-seq data from The Cancer Genome Atlas for prostate adenocarcinoma (TCGA-PRAD) revealed an inverse correlation of miR-338-5p/miR-421 with MALAT1 expression in PCa patients, which in turn confirms the notion that these miRNAs suppress the expression of onco-lncRNA MALAT1. Taken together, our findings indicate that oncogenic lncRNA, MALAT1 is a target of tumor suppressor miRNAs, miR-338-5p/miR-421. More importantly, we elucidated a novel miRNA-lncRNA regulatory network that is miR-338-5p/miR-421-MALAT1 axis in PCa pathogenesis and a potential therapeutic strategy for PCa patients. Citation Format: Anjali Yadav, Vipul Bhatia, Ritika Tiwari, Shivansh Nigam, Apul Goel, Bushra Ateeq. MicroRNA-338-5p/-421 mediated regulation of oncogenic long noncoding RNA MALAT1 abrogates prostate cancer progression and metastases [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A065.

Long noncoding RNA MALAT1 regulates HDAC4-mediated proliferation and apoptosis via decoying of miR-140-5p in osteosarcoma cells.

Noncoding RNAs regulate the initiation and progression of osteosarcoma (OS). The role of long noncoding RNA metastasis‐associated lung adenocarcinoma transcript 1 (MALAT1) playing in OS and whether the function it working out was achieved through HDAC4 pathway remain uncovered. In this study, we illustrated that MALAT1 was upregulated and was correlated with poor prognosis in OS patients. Meanwhile, we demonstrated that a depression of MALAT1 suppressed proliferation and promoted apoptosis in OS cell line HOS and 143B. Further, we verified that MALAT1 exerting its function via upregulating of histone deacetylase 4 (HDAC4). Through an online prediction, a series of luciferase assays and RNA pull‐down assays, we demonstrated that both MALAT1 and HDAC4 were the targets of microRNA‐140‐5p (miR‐140‐5p) via sharing a similar microRNA responding elements. Even further, we revealed that MALAT1 served as a ceRNA of HDAC4 via decoying of miR‐140‐5p. Finally, we proved that MALAT1 promoted OS tumor growth in an in vivo animal study. In summary, the outcomes of this study demonstrated the complex ceRNA network among MALAT, miR‐140‐5p, and HDAC4‐mediated proliferation and apoptosis in OS. This study might provide a new axial in molecular treatment of OS.

High expression of long non-coding RNA MALAT1 in breast cancer is associated with poor relapse-free survival.

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been identified as a prognostic marker for the metastasis of early-stage non-small cell lung cancer (NSCLCs). We studied MALAT1 expression in breast cancer in relation to disease features and patient survival. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to measure MALAT1 expression in tumor samples of 509 breast cancer patients. Hazards ratios (HRs) and 95% confidence intervals (CIs) were calculated to assess the association between MALAT1 expression and breast cancer survival using the Cox proportional hazards regression model, and the analysis was adjusted for age at surgery, tumor grade, disease stage, and hormone receptor status. Meta-analysis of multiple microarray datasets from online databases and our own study was performed to evaluate the association of MALAT1 with breast cancer survival. Patients with low-grade or ER-positive tumors had higher expression of MALAT1 compared to those with high-grade (p = 0.013) or ER-negative (p = 0.0002) tumors. Patients with PR-positive tumors also had higher MALAT1 expression than those with PR-negative tumors (p < 0.0001). In patients with positive hormone receptors or low tumor grade, tumors with high MALAT1 expression were more likely to recur. Survival analysis showed that patients with high expression of MALAT1 had a twofold increase in risk of relapse (p = 0.0083) compared to those with low expression. This association remained significant after adjustment for age at surgery, disease stage, tumor grade, and hormone receptor status. Meta-analysis showed that high MALAT1 expression was associated with poor relapse-free survival in patients with hormone receptor-positive tumors (HR 1.44, 95% CI 1.08-1.92). High expression of lncRNA MALAT1 is associated with breast cancer relapse and may play a role in tumor progression.

Long noncoding RNA MALAT1 contributes to inflammatory response of microglia following spinal cord injury via the modulation of a miR-199b/IKKβ/NF-κB signaling pathway.

Long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was widely recognized to be implicated in human cancer, vascular diseases, and neurological disorders. This study was to explore the role and underlying mechanism of MALAT1 in acute spinal cord injury (ASCI). ASCI models in adult rats were established and demonstrated by a numerical decrease in BBB scores. Expression profile of MALAT1 and miR-199b following ASCI in rats and in vitro was determined using quantitative real-time PCR. RNA pull-down assays combined with RIP assays were performed to explore the interaction between MALAT1 and miR-199b. In the present study, MALAT1 expression was significantly increased (2.4-fold that of control) in the spinal cord of the rat contusion epicenter accompanied by activation of IKKβ/NF-κB signaling pathway and an increase in the level of proinflammatory cytokines TNF-α and IL-1β. Upon treatment with LPS, MALAT1 expression dramatically increased in the microglia in vitro, but knockdown of MALAT1 attenuated LPS-induced activation of MGs and TNF-α and IL-1β production. Next, we confirmed that LPS-induced MALAT1 activated IKKβ/NF-κB signaling pathway and promoted the production of proinflammatory cytokines TNF-α and IL-1β through downregulating miR-199b. More importantly, MALAT1 knockdown gradually improved the hindlimb locomotor activity of ASCI rats as well as inhibited TNF-α, IL-1β levels, and Iba-1 protein, the marker of activated microglia in injured spinal cords. Our study demonstrated that MALAT1 was dysregulated in ASCI rats and in LPS-activated MGs, and MALAT1 knockdown was expected to attenuate ASCI through repressing inflammatory response of MGs.

Long noncoding RNA MALAT1 regulates generation of reactive oxygen species and the insulin responses in male mice

The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA and its overexpression is associated with the development of many types of malignancy. MALAT1 null mice show no overt phenotype. However, in transcriptome analysis of MALAT1 null mice we found significant upregulation of nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) regulated antioxidant genes including Nqo1 and Cat with significant reduction in reactive oxygen species (ROS) and greatly reduced ROS-generated protein carbonylation in hepatocyte and islets. We performed lncRNA pulldown assay using biotinylated antisense oligonucleotides against MALAT1 and found MALAT1 interacted with Nrf2, suggesting Nrf2 is transcriptionally regulated by MALAT1. Exposure to excessive ROS has been shown to cause insulin resistance through activation of c-Jun N-terminal kinase (JNK) which leads to inhibition of insulin receptor substrate 1 (IRS-1) and insulin-induced phosphorylation of serine/threonine kinase Akt. We found MALAT1 ablation suppressed JNK activity with concomitant insulin-induced activation of IRS-1 and phosphorylation of Akt suggesting MALAT1 regulated insulin responses. MALAT1 null mice exhibited sensitized insulin-signaling response to fast-refeeding and glucose/insulin challenges and significantly increased insulin secretion in response to glucose challenge in isolated MALAT1 null islets, suggesting an increased insulin sensitivity. In summary, we demonstrate that MALAT1 plays an important role in regulating insulin sensitivity and has the potential as a therapeutic target for the treatment of diabetes as well as other diseases caused by excessive exposure to ROS.

Chronic oxymatrine treatment induces resistance and epithelial‑mesenchymal transition through targeting the long non-coding RNA MALAT1 in colorectal cancer cells.

A major reason for colorectal cancer (CRC) chemoresistance is the enhanced migration and invasion of cancer cells, such as the cell acquisition of epithelial-mesenchymal transition (EMT). Long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of lncRNA MALAT1 in chemoresistance and EMT is not well known. In the present study, we focused on the effect of oxymatrine on CRC cells and further investigated the role of MALAT1 in oxymatrine-induced resistance and EMT process. The human CRC cell line HT29 was exposed to increasing doses of oxymatrine to establish stable cell lines resistant to oxymatrine. The established HT29 oxymatrine resistant cells showed an EMT phenotype including specific morphologic changes, enhanced migratory and invasive capacity, and downregulation of E-cadherin protein expression. Subsequently, high-throughput HiSeq sequencing and RT-qPCR showed that lncRNA MALAT1 was significantly upregulated in the oxymatrine resistant cells (P<0.01), while knockdown of MALAT1 partially reversed the EMT phenotype in HT29 resistant cells. Furthermore, oxymatrine treatment suppressed the migration and invasion ability of CRC cells, however, this effect was significantly reversed by overexpression of MALAT1. Finally, we investigated the clinical role of MALAT1 and found that high lncRNA MALAT1 expression level is associated with poor prognosis in CRC patients receiving oxymatrine treatment (P<0.01). In conclusion, we demonstrate that lncRNA MALAT1 is a stimulator for oxymatrine resistance in CRC and it may provide therapeutic and prognostic information for CRC patients.

Association analyses of genetic variants in long non-coding RNA MALAT1 with breast cancer susceptibility and mRNA expression of MALAT1 in Chinese Han population

The long non-coding RNA (lncRNA) Metastasis-associated lung adenocarcinoma transcript 1(MALAT1) has been implicated in breast cancer (BC). Polymorphisms in MALAT1 may play a vital role in the progress of breast cancer by its regulation function. However, potential genetic variants in MALAT1 affecting the development of BC is rarely explored. In our current molecular epidemiology study, all three tagging SNPs (rs3200401, rs619586 and rs7927113) in lncRNA MALAT1 were selected for genotyping in 487BCE patients and 489 cancer-free controls in Chinese Han population, and futher experiment of quantitative real-time (qRT) PCR was conducted to examine the relative expression of MALAT1. The results showed that individuals with genotype AG of rs619586 has a decreased risk of BC in codominant model (OR: 0.684, 95%CI: 0.478–0.979), dominant mode (OR: 0.675, 95%CI: 0.479–0.951) and over-dominant model (OR: 0.692, 95%CI: 0484–0.989). Also, qRT-PCR results revealed that the expression for MALAT1 with AG (0.827±0.490), GG (0.511±0.149) and AG+GG genotypes (0.743±0.447) of rs619586 was significantly lower than that with genotype AA (1.511±0.737). In addition, females with genotype CT of rs3200401 had a lower risk of BC in the codominant model (OR: 0.75, 95%CI: 0.559–1.007) and over-dominant model (OR: 0.741, 95%CI: 0.552–0.993). In summary, our results implied that the genetic variants of lncRNA MALAT1 were associated with the susceptibility of BC, and meaningful genetic alteration might affect the corresponding mRNA expression of lncRNA MALAT1.

Mechanism of long non-coding RNA MALAT1 in lipopolysaccharide-induced acute kidney injury is mediated by the miR-146a/NF-κB signaling pathway.

The present study aimed to examine the expression and function of the metastasis-associated lung adenocarcinoma transcript1 (MALAT1)/microRNA (miR)-146a/nuclear factor (NF)-κB axis in lipopolysaccharide(LPS)-induced acute kidney injury (AKI). The mRNA levels of MALAT1 and miR-146a in AKI tissues and cells were detected using reverse transcription-quantitative polymerase chain reaction analysis. The NF-κB pathway proteins and cell viability were assessed using western blot analysis and the MTT method, respectively. The secretion of inflammatory factors was determined using the ELISA method. The present study also examined effects of the abnormal expression of MALAT1 and miR-146a on cytokines and the NF-κB pathway. A potential binding region between MALAT1 and miR-146a was confirmed via RNA immunoprecipitation. The results revealed that the upregulation of MALAT1 reduced the expression of miR‑146a, and there was a negative linear correlation between MALAT1 and miR-146a in a RNA-induced silencing complex‑dependent manner. The expression levels of miR-146a were lower in the kidney injury specimens and NRK-52Ecells, compared with those in the controls. MALAT1 knockdown and the overexpression of miR-146a reduced the production of phosphorylated inhibitor of NF-κB and np65 protein. miR‑146a was found to be transcriptionally induced by NF-κB, and miR-146a repressed the pro-inflammatory NF-κB pathway and downstream transcription factors. Taken together, these data indicated that the MALAT1/miR‑146a/NF-κB pathway exerted key functions in LPS-induced AKI, and provided novel insights into the mechanisms of this therapeutic candidate for the treatment of the disease.

MALAT1/miR-124/Capn4 axis regulates proliferation, invasion and EMT in nasopharyngeal carcinoma cells

ABSTRACTBackground: Long non-coding RNA MALAT1 (Metastasis-associated lung Adenocarcinoma transcript-1) has been demonstrated to play a critical role in the regulation of cancer progression and metastasis. However, little is known about MALAT1 in nasopharyngeal carcinoma (NPC) pathogenesis and progression.Methods: Quantitative real-time PCR (qRT-PCR) was conducted to measure the expression of MALAT1, miR-124 and Capn4 mRNA in NPC cell lines. The protein level of Capn4 was examined by western blot analysis. Cell proliferation was detected by MTT assay, trypan blue exclusion method and colony formation analysis. Cell invasion was determined by transwell chamber assay. Expression of EMT-related proteins was detected by western blot. The potential targets of MALAT1 and miR-124 were verified by target prediction and luciferase reporter assay.Results: MALAT1 and Capn4 were upregulated while miR-124 expression was downregulated in NPC cell lines. MALAT1 knockdown inhibited proliferation, invasion and EMT of NPC cells. Moreover, MALAT1 improved Capn4 expression by sponging miR-124. MALAT1 upregulation abated miR-124-induced repression on NPC cell proliferation, invasion and EMT. Furthermore, Capn4 overexpression reversed the inhibitory effect of MALAT1 silencing on proliferation, invasion and EMT of NPC cells.Conclusion: MALAT1 promoted proliferation, invasion and EMT of NPC cells through de-repressing Capn4 by sponging miR-124. The present study revealed a novel MALAT1/miR-124/Capn4 regulatory axis in NPC, contributing to a better understanding of the NPC pathogenesis and providing a promising therapeutic target for NPC therapy.

Role of Long Non-Coding RNA MALAT1 in the Pathogenesis of Diabetic Retinopathy

Introduction: With increasing number of people living with diabetes the prevalence of diabetic complications is drastically increasing. A better understanding of the pathogenesis of diabetic complications is needed for effective therapy. Here we examined a novel mechanism mediated through a long non-coding RNA, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) in diabetic retinopathy (DR).

Diagnostic efficacy of long non-coding RNA MALAT-1 in human cancers: a meta-analysis study.

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) is one kind of long non-coding RNAs (lncRNAs) that has been recognized as a hallmark of the onset and development of several carcinomas. This study seek to meta-analyze the overall diagnostic efficacy of elevated MALAT-1 expression profile for human cancers. Studies on the diagnostic performance of MALAT-1 in cancers were retrieved by searching the online databases. The combined effect sizes were summarized using a bivariate meta-analysis model. Impacts of publication bias on the pooled effect sizes were assessed using “Duval and Tweedie nonparametric trim and fill method”. Sensitivity analysis and meta-regression test were applied to deeply trace the heterogeneity sources among eligible studies. A total of 14 studies with 1342 cancer cases were included. The combined effect sizes showed that MALAT-1 expression profiling conferred an estimated sensitivity of 0.69 (95% CI: 0.62–0.75) (I2 = 84.01%, P < 0.001), specificity of 0.85 (95% CI: 0.79–0.90) (I2 = 87.95%, P < 0.001) and AUC (area under curve) of 0.83 in distinguishing cancer patients from noncancerous contrasts. Moreover, stratified analysis depending on cancer type manifested that elevated MALAT-1 harbored a promising efficacy in the diagnosis of pulmonary tumors (AUC = 0.90), digestive system tumors (AUC = 0.84), gynecologic cancers (AUC = 0.84) and nasopharyngeal carcinoma (AUC = 0.84), particularly in confirming the subtype of squamous carcinoma (AUC = 0.91) and non-small cell lung carcinoma (AUC = 0.88) in lung cancer. Other analyses based on test matrix and ethnicity also presented robust results. Collectively, elevated MALAT-1 could be developed as an auxiliary molecular marker to aid in cancer diagnosis.

Long noncoding RNA MALAT1 promotes cell proliferation through suppressing miR-205 and promoting SMAD4 expression in osteosarcoma.

Increasing evidences have indicated that long non-coding RNAs (lncRNAs) play an important role in multiply biological processes including cell development, differentiation, proliferation and invasion. The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), is a highly conserved nuclear ncRNA and a key regulator of metastasis development in several cancers. However, its role in osteosarcoma progression is not well known. In this study, we sought to determine the clinical and bilogical role of MALAT1 in osteosarcoma progression. RT-qPCR analysis showed that MALAT1 expression was significantly increased in primary osteosarcoma tissues and cell lines. Kaplan-Meier analysis indicated that patients with high expression of MALAT1 was associated with poor overall survival compared with the low expressing patients. Furthermore, the gain and loss function assay showed that miR-205 was suppressed by MALAT1 in osteosarcoma and this interaction between miR-205 and MALAT1 has reciprocal effects. Cell viability assay showed that MALAT1 promoted MG-63 and SAOS-2 cell growth through suppressing miR-205. Subsequently, the downstream gene SMAD4 was identified as a direct functional target of miR-205, and miR-205 suppressed osteosarcoma cell growth through suppressing SMAD4. Finally, we demonstrated that MALAT1 promoted osteosarcoma progression via a miR-205-SMAD4 axis. In conclusion, we revealed that enhanced MALAT1 expression predicted unfavourable outcome in osteosarcoma and promoted cell proliferation through suppressing miR-205 and activating SMAD4 function. Thus, lncRNA MALAT1 may serve as a promising prognostic and therapeutic target for osteosarcoma patients.

Long non-coding RNA MALAT1 for promoting metastasis and proliferation by acting as a ceRNA of miR-144-3p in osteosarcoma cells.

Long non-coding RNAs (lncRNAs) are involved in various biological processes and diseases including osteosarcoma. Long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is overly expressed in osteosarcoma. But the function and mechanism it works on in osteosarcoma proliferation and metastasis mediated by Rho associated coiled-coil containing protein kinase 1 (ROCK1) and Rho associated coiled-coil containing protein kinase 2 (ROCK2) remain unclear. In the present study, an elevated MALAT1 was found in osteosarcoma tissues and cell lines, and the elevated MALAT1 was correlated with a poor prognosis in osteosarcoma patients. The functional experiments show that a decreased MALAT1 could remarkably inhibit osteosarcoma cell metastasis and proliferation but induce cell cycle arrest, indicating that MALAT1 functioned as an oncogene in osteosarcoma. Furthermore, we confirmed that MALAT1 and ROCK1/ROCK2 which were targeted by microRNA-144-3p (miR-144-3p) shared the same miR-144-3p combining site. Furthermore, the constructed luciferase assay verified that MALAT1 was a target of miR-144-3p. Additionally, the results of a qRT-PCR demonstrated that MALAT1 and miR-144-3p repressed each other's expression in a reciprocal manner. Finally, we affirmed that an overexpression of MALAT1 inhibited ROCK1/ROCK2 expression and its mediated metastasis and proliferation by working as a competitive endogenous RNA (ceRNA) via miR-144-3p.In summary, the findings of this study based on the ceRNA theory, combining the research foundation of miR-144-3p, ROCK1 and ROCK2, taking MALAT1 as a new point of study, provided new insights into molecular level proliferation reversal and metastasis of osteosarcoma.

Quantitative proteomics reveals that long non-coding RNA MALAT1 interacts with DBC1 to regulate p53 acetylation

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a broadly expressed lncRNA involved in many aspects of cellular processes. To further delineate the underlying molecular mechanism, we employed a high-throughput strategy to characterize the interacting proteins of MALAT1 by combining RNA pull-down, quantitative proteomics, bioinformatics, and experimental validation. Our approach identified 127 potential MALAT1-interacting proteins and established a highly connected MALAT1 interactome network consisting of 788 connections. Gene ontology annotation and network analysis showed that MALAT1 was highly involved in five biological processes: RNA processing; gene transcription; ribosomal proteins; protein degradation; and metabolism regulation. The interaction between MALAT1 and depleted in breast cancer 1 (DBC1) was validated using RNA pull-down and RNA immunoprecipitation. Further mechanistic studies reveal that MALAT1 binding competes with the interaction between sirtuin1 (SIRT1) and DBC1, which then releases SIRT1 and enhances its deacetylation activity. Consequently, the deacetylation of p53 reduces the transcription of a spectrum of its downstream target genes, promotes cell proliferation and inhibits cell apoptosis. Our results uncover a novel mechanism by which MALAT1 regulates the activity of p53 through the lncRNA–protein interaction.

The long non-coding RNA MALAT1 promotes the migration and invasion of hepatocellular carcinoma by sponging miR-204 and releasing SIRT1

Increasing evidence supports the significance of long non-coding RNA in cancer development. Several recent studies suggest the oncogenic activity of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in hepatocellular carcinoma. In this study, we explored the molecular mechanisms by which MALAT1 modulates hepatocellular carcinoma biological behaviors. We found that microRNA-204 was significantly downregulated in sh-MALAT1 HepG2 cell and 15 hepatocellular carcinoma tissues by quantitative real-time polymerase chain reaction analysis. Through bioinformatic screening, luciferase reporter assay, RNA-binding protein immunoprecipitation, and RNA pull-down assay, we identified microRNA-204 as a potential interacting partner for MALAT1. Functionally, wound-healing and transwell assays revealed that microRNA-204 significantly inhibited the migration and invasion of hepatocellular carcinoma cells. Notably, sirtuin 1 was recognized as a direct downstream target of microRNA-204 in HepG2 cells. Moreover, si-SIRT1 significantly inhibited cell invasion and migration process. These data elucidated, by sponging and competitive binding to microRNA-204, MALAT1 releases the suppression on sirtuin 1, which in turn promotes hepatocellular carcinoma migration and invasion. This study reveals a novel mechanism by which MALAT1 stimulates hepatocellular carcinoma progression and justifies targeting metastasis-associated lung adenocarcinoma transcript 1 as a potential therapy for hepatocellular carcinoma.

Abstract MIP-057: TARGETING THE LONG–NONCODING RNA MALAT1 IN OVARIAN CANCER

Abstract PURPOSE: Ovarian cancer metastasizes via direct seeding, whereby cells must resist anoikis (detachment-induced cell death) in the peritoneal cavity before invading through the mesothelium to metastasize into peritoneal organs. The molecular mechanisms that facilitate these processes are not fully understood. Using an unbiased screen, we identified the long non-coding RNA MALAT1 (metastasis associated lung adenocarcinoma transcript 1) as being a potential regulator of anoikis resistance. We hypothesized that MALAT1 promotes progression through the early steps of metastasis, including anoikis resistance, peritoneal invasion, and metastatic outgrowth, and that therapeutic inhibition of MALAT1 will reduce ovarian tumor burden and metastatic spread. EXPERIMENTAL PROCEDURES: Modified anti-sense oligonucleotides (ASO) targeting MALAT1 were used to inhibit MALAT1 expression in ovarian cancer cell lines (OVCA420, HEY, OV1847). Transfections were performed using lipofectamine as well as novel lipid-based nanoparticles that are minimally toxic and have potential in vivo applications. Transcriptome profiling was performed on Affymetrix arrays. Migration and invasion assays were performed on an XCelligence Real Time Cell Analyzer, and proliferation was measured by crystal violet. Anoikis was measured using Caspase 3/7 assay. Knockdown of RBFOX2 and KIF1B-beta was performed using shRNAs. Gene expression was measured by RT-qPCR. Publicly available datasets including the Cancer Genome Atlas were analyzed for association of MALAT1 gene expression and DNA copy number with clinicopathologic variables. RESULTS: MALAT1 gene expression significantly increased after 24 hours in forced suspension culture versus attached culture in multiple anoikis-resistant ovarian cancer cell lines. MALAT1 knockdown via ASO resulted in decreased proliferation, migration, invasion, anchorage-independent growth, and increased anoikis. Lipid nanoparticle-mediated delivery of MALAT1-targeted ASO resulted in effective gene knockdown with minimal off-target toxicity. Transcriptome profiling of MALAT1-knockdown cells revealed significant changes in splicing patterns, including alternative splicing of the pro-apoptotic gene KIF1B (Kinesin Family Member 1B). MALAT1 knockdown resulted in decreased gene expression of the splicing factor RBFOX2 (RNA Binding Protein Fox-1, Homolog 2), which is associated with epithelial-to-mesenchymal transition (EMT). KIF1B contains RBFOX2 binding sites within spliced regions, suggesting that MALAT1 may control alternative splicing through regulation of RBFOX2. Indeed, RBFOX2 knockdown resulted in increased expression of the pro-apoptotic isoform of KIF1B (KIF1B-beta), as well as increased anoikis. Furthermore, knockdown of KIF1B-beta reversed the apoptotic effects of MALAT1-knockdown. In ovarian cancer patients, high MALAT1 gene expression is associated with higher stage disease, increased risk of recurrence, and reduced overall survival. Additionally, MALAT1 is amplified in 3% of ovarian cancers, and amplification is associated with increased MALAT1 gene expression and reduced overall survival. CONCLUSIONS: The lncRNA MALAT1 facilitates a pro-metastatic phenotype in ovarian cancer cells by promoting alternative splicing and differential expression of anti-apoptotic and EMT-related genes. In vivo studies to determine the efficacy of MALAT1-knockdown via lipid-mediated delivery to inhibit progression of ovarian cancer cell lines and patient derived xenografts are ongoing. Citation Format: Michael A Gordon, Dawn R Cochrane, Jamie Betker, Tom Anchordoquy, Jennifer K Richer. TARGETING THE LONG–NONCODING RNA MALAT1 IN OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr MIP-057.