High MALAT1 Expression Research Articles

Abstract 2997: Identification of novel long non-coding RNAs in mantle cell lymphoma patients

Abstract Mantle Cell Lymphoma (MCL) is a rare and incurable type of B-cell non-Hodgkin lymphoma that affects about 4,000 people per year in the United States. Despite intense research to identify novel therapeutic approaches, the median progression-free survival after first-line treatment is four years. For this reason, the discovery of novel therapeutic targets remains crucial. Over half of the human genome is actively transcribed as non-coding RNAs. Among them, the non-coding RNAs that are longer than 200 nucleotides are named long non-coding RNAs (lncRNAs). lncRNAs have been shown to play essential roles in several human diseases, including cancer, by modulating cell cycle, immune response, or stemness through their interactions with DNA, protein, and RNA. For this reason, we decided to perform an RNA sequencing (RNA-Seq) profiling to identify the dysregulated lncRNAs in MCL. In more detail, we performed RNA-Seq in a cohort of 18 MCL patients compared to normal B-cells from the peripheral blood of healthy donors (HD). Reads were first trimmed for quality filtering, and adapters were removed using Trim Galore. Trimmed reads were mapped to the human genome (HG38 assembly) using HISAT 2. All the reads mapped inside the genomic coordinates of lncRNAs, reported in the GTF annotation file of GENCODE v43, were counted by featureCounts. Differential expression analysis between MCL samples vs HD was performed by LIMMA. To validate the results obtained from our internal MCL cohort, we also downloaded publicly available RNA-Seq data of 16 MCL patients and analyzed them using the previously described pipeline. Our analyses revealed several dysregulations in lncRNA expression occurring in MCL. Precisely, we identified 385 upregulated and 387 downregulated lncRNAs (|log2FC| > 0.58 and adjusted p-value < 0.05) in our internal MCL cohort, and 63% of them were also confirmed in the external cohort. Notably, the lncRNA called MALAT1 showed the highest significant upregulation in both cohorts, reinforcing this lncRNA's pivotal role in cancer development. To study the potential involvement of MALAT1 in MCL, we compared the MCL samples with higher MALAT1 expression (upper quartile) against those with lower expression (lower quartile) in both cohorts. The identified differentially expressed genes were used as input for a mechanistic network-based topological pathway analysis using MITHrIL. The analysis revealed that the KEGG pathway "Cell Cycle" was among the top upregulated pathways in MCL samples with high MALAT1 expression, suggesting the relevance of this lncRNA in promoting cellular proliferation, as also reported in the literature for other tumor types. In conclusion, our is the first study to describe the novel dysregulation signature of lncRNAs in MCL in two independent cohorts. Citation Format: Alessandro LaFerlita, Satishkumar Singh, Anuvrat Sircar, Robert Baiocchi, Natarajan Muthusamy, Lapo Alinari, Narendranath Epperla, Lalit Sehgal. Identification of novel long non-coding RNAs in mantle cell lymphoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2997.

Expression Pattern and Prognostic Significance of the Long Non-Coding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 in Chronic Lymphocytic Leukemia.

Dysregulated expression of the long non-coding RNA MALAT1 has been implicated in the pathogenesis and progression of a variety of cancers, including hematological malignancies, but it has been poorly investigated in chronic lymphocytic leukemia (CLL). In this study, the expression of MALAT1 was measured using a quantitative reverse-transcriptase polymerase chain reaction in the peripheral blood mononuclear cells of 114 unselected, newly diagnosed CLL patients in order to analyze its association with clinical, laboratory, and molecular patients' characteristics at diagnosis, as well as its prognostic relevance. MALAT1 was found to be upregulated in CLL patients in comparison to healthy controls, and expression levels were not related to age, leukocyte, lymphocyte and platelet count, serum β2-microglobulin, and IGHV somatic hypermutational status. On the other hand, high MALAT1 expression was associated with several favorable prognostic markers (high hemoglobin, low serum lactate dehydrogenase, earlier clinical stages, CD38-negative status), but also with unfavorable cytogenetics. Furthermore, an association between high MALAT1 levels and longer time to first treatment and overall survival in IGHV-unmutated CLL subtype was observed. In summary, our results imply that high MALAT1 expression at diagnosis may be a predictor of better prognosis and point to MALAT1 expression profiling as a candidate biomarker potentially useful in clinical practice.

MALAT1 expression is associated with aggressive behavior in indolent B-cell neoplasms

MALAT1 long non-coding RNA has oncogenic roles but has been poorly studied in indolent B-cell neoplasms. Here, MALAT1 expression was analyzed using RNA-seq, microarrays or qRT-PCR in primary samples from clinico-biological subtypes of chronic lymphocytic leukemia (CLL, n = 266), paired Richter transformation (RT, n = 6) and follicular lymphoma (FL, n = 61). In peripheral blood (PB) CLL samples, high MALAT1 expression was associated with a significantly shorter time to treatment independently from other known prognostic factors. Coding genes expressed in association with MALAT1 in CLL were predominantly related to oncogenic pathways stimulated in the lymph node (LN) microenvironment. In RT paired samples, MALAT1 levels were lower, concordant with their acquired increased independency of external signals. Moreover, MALAT1 levels in paired PB/LN CLLs were similar, suggesting that the prognostic value of MALAT1 expression in PB is mirroring expression differences already present in LN. Similarly, high MALAT1 expression in FL predicted for a shorter progression-free survival, in association with expression pathways promoting FL pathogenesis. In summary, MALAT1 expression is related to pathophysiology and more aggressive clinical behavior of indolent B-cell neoplasms. Particularly in CLL, its levels could be a surrogate marker of the microenvironment stimulation and may contribute to refine the clinical management of these patients.

A feedback loop between lncRNA MALAT1 and DNMT1 promotes triple-negative breast cancer stemness and tumorigenesis

ABSTRACT Background The function of long non-coding RNA (lncRNA) MALAT1 in regulating triple-negative breast cancer (TNBC) stemness and tumorigenesis was investigated. Methods Sphere formation and colony formation assays coupled with flow cytometry were employed to evaluate the percentage of CD44high/CD44low cells, and ALDH+ cells were performed to evaluate the stemness. Bisulfite sequencing PCR (BSP) was employed to detect the methylation level of MALAT1. Tumor xenograft experiment was performed to evaluate tumorigenesis in vivo. Finally, dual-luciferase reporter and RIP assays were employed to verify the binding relationship between MALAT1 and miR-137. Results Our results revealed that MALAT1 and BCL11A were highly expressed in TNBC, while miR-137 and DNMT1 were lowly expressed. Our results proved that MALAT1 positively regulated BCL11A expression through targeting miR-137. Functional experiments revealed that MALAT1 inhibited DNMT1 expression through acting on the miR-137/BCL11A pathway to enhance TNBC stemness and tumorigenesis. We also found that high MALAT1 expression in TNBC was related to the DNMT1-mediated hypomethylation of MALAT1. As expected, DNMT1 overexpression could remarkably inhibit TNBC stemness and tumorigenesis, which was eliminated by MALAT1 overexpression. Conclusion MALAT1 downregulated DNMT1 by miR-137/BCL11A pathway to enhance TNBC stemness and tumorigenesis; meanwhile, DNMT1/MALAT1 formed a positive feedback loop to continuously promote TNBC malignant behaviors.

Prognostic value of long non-coding RNA MALAT1 in hepatocellular carcinoma: A study based on multi-omics analysis and RT-PCR validation.

Background: This study aimed to explore the relationship between MALAT1 and the prognosis of patients with hepatocellular carcinoma (HCC). Methods: We constructed a MALAT1 protein-protein interaction network using the STRING database and a network of competing endogenous RNAs (ceRNAs) using the StarBase database. Using data from the GEPIA2 database, we studied the association between genes in these networks and survival of patients with HCC. The potential mechanisms underlying the relationship between MALAT1 and HCC prognosis were studied using combined data from RNA sequencing, DNA methylation, and somatic mutation data from The Cancer Genome Atlas (TCGA) liver cancer cohort. Tumor tissues and 19 paired adjacent non-tumor tissues (PANTs) from HCC patients who underwent radical resection were analyzed for MALAT1 mRNA levels using real-time PCR, and associations of MALAT1 expression with clinicopathological features or prognosis of patients were analyzed using log-rank test and Gehan-Breslow-Wilcoxon test. Results: Five interacting proteins and five target genes of MALAT1 in the ceRNA network significantly correlated with poor survival of patients with HCC (p < 0.05). High MALAT1 expression was associated with mutations in two genes leading to poor prognosis and may upregulate some prognostic risk genes through methylation. MALAT1 was significantly co-expressed with various signatures of genes involved in HCC progression, including the cell cycle, DNA damage repair, mismatch repair, homologous recombination, molecular cancer m6A, exosome, ferroptosis, infiltration of lymphocyte (p < 0.05). The expression of MALAT1 was markedly upregulated in HCC tissues compared with PANTs. In Kaplan-Meier analysis, patients with high MALAT1 expression had significantly shorter progression-free survival (PFS) (p = 0.033) and overall survival (OS) (p = 0.023) than those with low MALAT1 expression. Median PFS was 19.2months for patients with high MALAT1 expression and 52.8months for patients with low expression, while the corresponding median OS was 40.5 and 78.3months. In subgroup analysis of patients with vascular invasion, cirrhosis, and HBsAg positive or AFP positive, MALAT1 overexpression was significantly associated with shorter PFS and OS. Models for predicting PFS and OS constructed based on MALAT1 expression and clinicopathological features had moderate predictive power, with areas under the receiver operating characteristic curves of 0.661-0.731. Additionally, MALAT1 expression level was significantly associated with liver cirrhosis, vascular invasion, and tumor capsular infiltration (p < 0.05 for all). Conclusion: MALAT1 is overexpressed in HCC, and higher expression is associated with worse prognosis. MALAT1 mRNA level may serve as a prognostic marker for patients with HCC after hepatectomy.

Oncogenic lncRNA MALAT-1 recruits E2F1 to upregulate RAD51 expression and thus promotes cell autophagy and tumor growth in non-small cell lung cancer.

LncRNA MALAT-1 expression is involved in regulating activities of non-small-cell lung cancer (NSCLC) cells. This study aimed to investigate the effects of lncRNA MALAT-1 on chemosensitivity of NSCLC cells by regulating autophagy. We first validated the expression of lncRNA MALAT-1 in NSCLC cell lines. NSCLC cell lines with high lncRNA MALAT-1 expression were exposed to doxorubicin (DOX) to assess chemosensitivity. Further LncMAP database retrieval and ChIP, RIP and luciferase activity assays were conducted to explore interplay between lncRNA MALAT-1, RAD51, and E2F1. Immunofluorescence staining was performed to evaluate formation of autophagosomes in NSCLC cells. Ectopic expression and knockdown methods were used for in vitro mechanism experiments and in vivo substantiation. LncRNA MALAT-1 was overexpressed in NSCLC cells, and could promote NSCLC cell autophagy and inhibit its chemosensitivity. In vitro cell mechanism verification experiments showed that lncRNA MALAT-1 could recruit transcription factor E2F1 to bind to the promoter of RAD51, so as to promote the transcriptional expression of RAD51. In addition, cell function experiments in vitro showed that ectopically expressed lncRNA MALAT-1 promoted NSCLC cell autophagy and inhibited its chemosensitivity, while RAD51 knockdown negated its effect. Finally, in vivo animal experiments confirmed that lncRNA MALAT-1 silencing could impede the tumor growth. Taken together, this study revealed that silencing lncRNA MALAT-1 enhanced chemosensitivity of NSCLC cells by promoting autophagy, highlighting a feasible approach to prevent chemoresistance in NSCLC treatment.

Early-stage colon cancer with high MALAT1 expression is associated with the 5-Fluorouracil resistance and future metastasis.

This study aimed to investigate the role of long noncoding RNA (LncRNA) expression profiles to predict relapse and 5-FU response in patients with stage I/II colon cancer (CC). The expression level of 15 LncRNA was analyzed in stage I/II colon tumors of 126 CC patients. To confirm the findings in-vitro, 5FU-resistant HT29 cells were generated by subjecting HT-29 cells to the increasing concentrations of 5FU for 6months. The 5FU resistance was observed in WST-1 and Annexin V analyses. The colony formation and wound healing assays were assessed to determine the metastatic properties of the cells. Expression levels of LncRNAs and mRNA of EMT-related genes were determined by RT-PCR. The role of LncRNA on metastasis and 5FU sensitivity were confirmed in pcDNA3.0-PTENP1 and si-MALAT1 expressed 5FU-resistant HT29 cell lineages. High MALAT1 (p = 0.0002) and low PTENP1 (p = 0.0044) expressions were significantly associated with 5-FU resistance and tumor relapse in stage I/II CC. The invasiveness and colony-forming characteristics of 5-FU-resistant cell lineages were higher as compared to the parent HT-29. Moreover, the expression of MALAT1 (p = 0.0009) was increased while the expression of PTENP1 (p = 0.0158) decreased in 5FU-resistant-HT-29 cells. Si-MALAT1 treatment increased cell sensitivity to 5FU, whereas it decreased invasive behaviors of 5 FU-resistant-HT-29 cells. MALAT1 may be a biomarker in predicting recurrence in early-stage CC. Our findings suggest that a cell-based therapy to target MALAT1 could be established for these patients to prevent metastasis and 5-FU resistance.

Coexistence of TERT C228T mutation and MALAT1 dysregulation in primary glioblastoma: new prognostic and therapeutic targets

ABSTRACT Objective: This study was designed to conduct molecular classification based on IDH1/2, TERT, ATRX, and DAXX changes in pediatric and adult primary glioblastoma (GB) and to analyze the potential interaction of LncRNA MALAT1 in the determined homogeneous subgroups. Methods: We analyzed the expression profiles of ATRX/DAXX and MALAT1 using the qRT-PCR method and IDH and TERT mutation status using DNA sequencing analysis in 85 primary pediatric and adult GB patients. Results: IDH1 mutation was observed in 5 (5.88%) and TERT mutation in 65 (76.47%) primary pediatric and adult GB patients. ATRX and DAXX were detected in 18 (21.18%) and 7 (8.24%) patients. TERT mutation and loss of ATRX/DAXX were associated with short overall survival (p < 0.001, p < 0.001, respectively). Patients carrying especially TERT C228T mutation had worse prognosis (p < 0.001). Six subgroups were obtained from the genetic analysis. Among the subgroups, MALAT1 was highly expressed in group A that had a single TERT mutation as compared to that in groups D and E (p = 0.001 and p < 0.001, respectively); further, high MALAT1 expression was associated with worse prognosis in patients with C228T mutation (p < 0.001). Conclusions: Our findings highlight that the presence of TERT C228T mutation and expression of MALAT1 can be used as primary targets during the follow-up of primary GB patients and in the development of new treatment strategies.

LncRNA-MALAT1 is a promising biomarker for prognostic evaluation of tongue squamous cell carcinoma.

MALAT1 is recognized as an oncogenic lncRNA in various malignancies. Here, the authors aim to explore the association of MALAT1 expression and prognostic implication in tongue squamous cell carcinoma (SCC). The tongue tissues of 128 tongue SCC cases satisfying strict follow-up criteria and 28 normal cases were subjected to qRT-PCR assay for monitoring MALAT1 expression. Chi-square test was applied to explore the correlation between MALAT1 expression and clinicopathological features of tongue SCC. Kaplan-Meier analysis was used to calculate survival rates. Cox proportional hazard analysis was adopted to analyze the relationship between prognostic factors and patient survival. The expression of MALAT1 was upregulated in tongue SCC, compared to normal tongue tissues. The expression level of MALAT1 was correlated to differentiation and stage of tongue SCC, and high MALAT1 expression was associated with low disease-free survival and overall survival rates. Moreover, advanced tongue SCC patients with high MALAT1 level had lower disease-free survival and decreased overall survival rate than patients with low MALAT1 level. These results revealed that MALAT1 overexpression can be considered as a significant prognostic factor to independently predict the disease-free survival and overall survival rate of tongue SCC. The expression level of MALAT1 is closely related with progression of tongue SCC. Furthermore, MALAT1 can serve as an independent biomarker for prognostic evaluation of tongue SCC.

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.

Long non-coding RNA MALAT1 as a valuable biomarker for prognosis in osteosarcoma: A systematic review and meta-analysis.

Long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (lncRNA, MALAT1) has been found to be aberrantly expressed in osteosarcoma, while high MALAT1 expression is correlated with both metastasis and prognosis. This meta-analysis set out to investigate the prognostic value of lncRNA MALAT1 in patients living with osteosarcoma. We conducted a systematical search of available databases from inception to May 2019. Odds ratios (OR) of clinical parameters, as well as hazard ratio (HR) of overall survival (OS), were calculated in order to evaluate the relationship between MALAT1 expression and the prognosis of patients living with osteosarcoma. Nine eligible studies which included a total of 599 osteosarcoma patients were enrolled in the present study. Pooled results found that high MALAT1 expression was associated with clinical stage and distant metastasis, but not age, gender, tumor anatomical location or tumor size. When compared to patients with low MALAT1 expression, patients with high MALAT1 expression were markedly correlated with a worse OS. Moreover, MALAT1 may be an independent predictive factor for OS in patients living with osteosarcoma. This meta-analysis suggests that high MALAT1 expression is associated with advanced clinicopathological features as well as unfavorable prognosis. LncRNA MALAT1 has the potential to serve as a moderate prognostic biomarker for osteosarcoma.

MALAT1 promotes proliferation, migration, and invasion of MG63 cells by upregulation of TGIF2 via negatively regulating miR-129.

PurposeThis article aimed to investigate the mechanism by which MALAT1 and miR-129 affected the development of osteosarcoma.MethodsTumor tissues and adjacent tissues of 23 osteosarcoma patients were collected. Normal osteoblasts hFOB1.19 and osteosarcoma cells MG63 were cultured. MG63 cells were transfected and grouped: si-negative control (NC) group, si-MALAT1 group, miR-129 NC group, miR-129 mimics group, p-Empty vector group, p-MALAT1 group, p-MALAT1+ miR-129 mimics group, and p-MALAT1+ si-TGIF2 group. Luciferase reporter assay, Cell Counting Kit-8 assay, Transwell assay, quantitative reverse transcription PCR, Western blot, and Pearson correlation analysis were performed.ResultsMALAT1 expression in tumor tissues and MG63 cells was increased (P<0.01). High MALAT1 expression predicted poor prognosis of osteosarcoma patients. MG63 cells of si-MALAT1 group exhibited much lower cell viability, migration, and invasive cell numbers when compared with si-NC group (P<0.01). For MG63 cells of miR-129 mimics group, they had markedly lower cell viability, migration, and invasive cell numbers than miR-129 NC group (P<0.01). miR-129 was targetedly and negatively regulated by MALAT1. TGIF2, which was targetedly and negatively regulated by miR-129, was overexpressed in tumor tissues and MG63 cells (P<0.01). miR-129 overexpresison and TGIF2 downregulation significantly reversed the enhanced cell viability, migration, and invasion induced by MALAT1 (P<0.01).ConclusionMALAT1 promotes TGIF2 expression through negative regulation of miR-129, which further promotes the proliferation, migration, and invasion of MG63 cells.

Clinical Values of Long Non-coding RNAs in Bladder Cancer: A Systematic Review.

Background: Increasing evidence shows that dysregulated expression of long non-coding RNAs (lncRNAs) can serve as diagnostic or prognostic markers in bladder cancer. The aim of this study was to evaluate the clinical values of dysregulated lncRNAs in bladder cancer.Methods: Eligible studies were systematically searched in PubMed, Embase, and Web of Science databases from inception to December 2017. Odds ratios (OR) were calculated to investigate the correlation between lncRNAs and clinicopathological parameters. Pooled hazard ratios (HR) and 95% confidence interval (CI) were calculated to explore the prognostic value of lncRNAs in bladder cancer. Pooled diagnostic parameters were also calculated to estimate the performance of lncRNAs in diagnosing bladder cancer. All statistical analyses were performed by using STATA 13.1 program.Results: A total of 37 relevant studies were included to the present systematic review according to the inclusion and exclusion criteria, including 26 on clinicopathological parameters, 19 on prognosis, and 7 on diagnosis. For clinicopathological parameters, MALAT1 expression was significantly associated with lymph node metastasis (OR = 2.731; 95% CI: 1.409–5.292; p = 0.003), and high-level expression of XIST was related to larger tumor size (OR = 2.473; 95% CI: 1.159–5.276; p = 0.019) and higher TNM stage (OR = 0.400; 95% CI, 0.184–0.868; p = 0.020). For the prognostic values, the most significant association was observed between increased expressions of SPRY4-IT1 and poor overall survival (OS) (HR = 3.716; 95% CI: 2.084–6.719; p < 0.001); high MALAT1 expression was significantly associated with poor OS (HR = 1.611; 95% CI: 1.076–2.412; p = 0.020). For the diagnostic values, UCA1 expression profile achieved a combined AUC of 0.92, with sensitivity of 0.84 and specificity of 0.89 in distinguishing patients with bladder cancer from non-cancerous controls.Conclusions: In summary, systematic review elaborated that abnormal lncRNAs expression can serve as potential markers for prognostic evaluation in bladder cancer patients. In addition, the diagnostic meta-analysis concluded that abnormally expressed UCA1 can function as potential diagnostic markers for bladder cancer.

Long non-coding RNA MALAT1 promotes proliferation and invasion via targeting miR-129-5p in triple-negative breast cancer

BackgroundLong non-coding RNA Metastasis associated lung adenocarcinoma transcript 1(lncRNA MALAT1) play important roles in tumor progression. In the present study, we determined the regulatory function of MALAT1 in triple-negative breast cancer (TNBC). MethodsA total of 43 cases of TNBC tissues and paired adjacent non-tumor tissues were collected for the research. MALAT1 expression was explored by qRT-PCR. In vitro functional validation experiments were used to determine the effect of MALAT1 on TNBC progression. We further identified the downstream target miRNAs for MALAT1. ResultsRelative expression of MALAT1 was increased in TNBC tissues and cell lines. High MALAT1 expression was closely correlated to advance clinical features and poor overall survival in TNBC patients. Function assay showed that MALAT1 silencing significantly decreased cell proliferation, migration, and invasion. Flow cytometry assay revealed that MALAT1 inhibition significantly induced cell cycle arrest in the G0/G1 phase. In addition, we showed that the roles of MALAT1 on TNBC cells progression was mediated by miR-129-5p. ConclusionOur results demonstrated that the “MALAT1-miR-129-5p” axis might play an important role in the progression of TNBC, thereby might provide a potential therapeutic strategy for the treatment of TNBC.

MALAT1 Is Associated with Poor Response to Oxaliplatin-Based Chemotherapy in Colorectal Cancer Patients and Promotes Chemoresistance through EZH2.

A major reason for oxaliplatin chemoresistance in colorectal cancer is the acquisition of epithelial-mesenchymal transition (EMT) in cancer cells. The long noncoding RNA (lncRNA), MALAT1, is a highly conserved nuclear ncRNA and a key regulator of metastasis development in several cancers. However, its role in oxaliplatin-induced metastasis and chemoresistance is not well known. In this study, we aim to investigate the prognostic and therapeutic role of lncRNA MALAT1 in colorectal cancer patients receiving oxaliplatin-based therapy and further explore the potential transcriptional regulation through interaction with EZH2 based on the established HT29 oxaliplatin-resistant cells. Our results showed that high MALAT1 expression was associated with reduced patient survival and poor response to oxaliplatin-based chemotherapy in advanced colorectal cancer patients. Oxaliplatin-resistant colorectal cancer cells exhibited high MALAT1 expression and EMT. LncRNA MALAT1 knockdown enhances E-cadherin expression and inhibits oxaliplatin-induced EMT in colorectal cancer cells. EZH2 is highly expressed and associated with the 3' end region of lncRNA MALAT1 in colorectal cancer, and this association suppressed the expression of E-cadherin. Furthermore, targeted inhibition of MALAT1 or EZH2 reversed EMT and chemoresistance induced by oxaliplatin. Finally, the interaction between lncRNA MALAT1 and miR-218 was observed, which further indicated its prognostic value in patients who received standard FOLFOX (oxaliplatin combine with 5-fluorouracil and leucovorin) treatment. In conclusion, this study illuminates the prognostic role of lncRNA MALAT1 in colorectal cancer patients receiving oxaliplatin-based treatment and further demonstrates how lncRNA MALAT1 confers a chemoresistant function in colorectal cancer. Thus, lncRNA MALAT1 may serve as a promising prognostic and therapeutic target for colorectal cancer patients. Mol Cancer Ther; 16(4); 739-51. ©2017 AACR.

MALAT1 is a prognostic factor in glioblastoma multiforme and induces chemoresistance to temozolomide through suppressing miR-203 and promoting thymidylate synthase expression.

Glioblastoma multiforme (GBM) is the most malignant brain tumor with limited therapeutic options. Temozolomide (TMZ) is a novel cytotoxic agent used as first-line chemotherapy for GBM, however, some individual cells can't be isolated for surgical resection and show treatment-resistance, thus inducing poor prognosis. By using the HiSeq sequencing and bioinformatics methods, we identified lncRNAs showing different expression levels in TMZ-resistant and non-resistant patients. RT-qPCR was then performed in tissues and serum samples, and lncRNA MALAT1 was finally identified to show considerable discriminating potential to identify responding patients from non-responding patients. Moreover, high serum MALAT1 expression was associated with poor chemoresponse and survival in GBM patients receiving TMZ treatment. Subsequently, the TMZ resistant cell lines were established, and the CCK8 assay showed that lncRNA MALAT1 knockdown significantly reversed TMZ resistance in GBM cells. The gain and loss-function experiments revealed that miR-203 was down-regulated by MALAT1 and this interaction has reciprocal effects. Besides, thymidylate synthase (TS) mRNA was identified as a direct target of miR-203. LncRNA MALAT1 inhibition re-sensitized TMZ resistant cells through up-regulating miR-203 and down-regulating TS expression. On the other hand, MALAT1 overexpression promoted resistance by suppressing miR-203 and promoting TS expression. In conclusion, our integrated approach demonstrates that enhanced expression of lncRNA MALAT1 confers a potent poor therapeutic efficacy and inhibition of MALAT1 levels could be a future direction to develop a novel therapeutic strategy to overcome TMZ resistance in GBM patients.

The Association between Abnormal Long Noncoding RNA MALAT-1 Expression and Cancer Lymph Node Metastasis: A Meta-Analysis.

Previous studies have investigated that the expression levels of MALAT-1 were higher in cancerous tissues than matched histologically normal tissues. And, to some extent, overexpression of MALAT-1 was inclined to lymph node metastasis. This meta-analysis collected all relevant articles and explored the association between MALAT-1 expression levels and lymph node metastasis. We searched PubMed, EmBase, Web of Science, Cochrane Library, and OVID to address the level of MALAT-1 expression in cancer cases and noncancerous controls (accessed February 2015). And 8 studies comprising 696 multiple cancer patients were included to assess this association. The odds ratio (OR) and its corresponding 95% confidence interval (CI) were calculated to assess the strength of the association using Stata 12.0 version software. The results revealed there was a significant difference in the incidence of lymph node metastasis between high MALAT-1 expression group and low MALAT-1 expression group (OR = 1.94, 95% CI 1.15–3.28, P = 0.013 random-effects model). Subgroup analysis indicated that MALAT-1 high expression had an unfavorable impact on lymph node metastasis in Chinese patients (OR = 1.87, 95% CI 1.01–2.46). This study demonstrated that the incidence of lymph node metastasis in patients detected with high MALAT-1 expression was higher than that in patients with low MALAT-1 expression in China.

Prognostic significance of long non-coding RNA MALAT-1 in various human carcinomas: a meta-analysis.

The long non-coding RNA MALAT-1 plays an important role in cancer prognosis. The present research aimed to elucidate its precise predictive value in various human carcinomas. A quantitative meta-analysis was performed by searching PubMed, Embase, Web of Science, and Cochrane Library (most recently, January 2015) databases, and extracting data from studies that investigated the association between MALAT-1 expression and survival outcomes in patients of various cancers. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated as a measure of generalized effect. This meta-analysis included 1317 cases from 12 datasets. Our investigation revealed that poor overall survival (OS; HR = 2.14, 95% CI = 1.74-2.64) and shortened disease-free, recurrence-free, disease-specific, or progression-free survival (HR = 2.13, 95% CI = 1.22-3.72) can be predicted by high MALAT-1 expression for various cancers. Moreover, elevated MALAT-1 levels significantly correlated with decreased OS in a renal cell carcinoma (RCC) subgroup (HR = 3.43, 95% CI = 1.80-6.53). These results imply that MALAT-1 can be used to predict unfavorable prognoses for several cancers, particularly RCC.

Long Non-Coding RNA MALAT1 Is Associated with the Progression of Multiple Myeloma and Induced By Cellular Stress

Background: Recent transcriptome-wide analyses have revealed an overwhelming amount of transcribed, but not translated, non-coding RNAs capable of influencing diverse cellular processes such as proliferation, apoptosis, and motility. Long non-coding RNA (lncRNAs), which are commonly defined as transcripts >200 nt in length, have emerged as a class of key regulatory RNA. LncRNAs are deregulated in diverse human cancers and associated with disease progression; however, little is known about its role in multiple myeloma (MM). To elucidate the role of lncRNAs in MM, we studied the expression patterns of several well-known lncRNAs in the plasma cells of MM, MGUS and plasmacytoma patients and the function in MM cell lines in vitro. Moreover, to reveal the distinct lncRNA signature comprehensively, we performed next-generation sequencing-based RNA sequencing.Methods: CD138+ plasma cells from bone marrow (BM) mononuclear cells were obtained from 110 MM patients, 48 MGUS patients, 19 control subjects and 1 patient with extramedullary plasmacytoma of the liver and analyzed after obtaining informed consent from all the patients. The expression levels of lncRNAs MALAT1, ANRIL, HOTAIR, HOTTIP, and XIST were determined by a RQ-PCR analysis. RNase H-activating LNA™ GapmeR antisense oligonucleotides were used to knockdown lncRNA in vitro in MM cell lines. The cell lines were then treated with bortezomib, MG132, doxorubicin and hypoxic conditions to evaluate the effects of cytotoxic stress on the lncRNA expression. This study was approved by the IRB of Gunma University Hospital in accordance with the Declaration of Helsinki.Results: A significant higher level of MALAT1 expression was observed in BM plasma cells of MM patients (4.49) compared to MGUS patients (1.51) and control subjects (0.55) (p<0.001). Strikingly, MALAT1 expression in extramedullary plasmacytoma of the liver was 140-fold higher compared with BM plasma cells obtained at the same time of sampling (433.7 vs 3.21). MALAT1 expression was higher in MM patients with t(4;14) and del 17p (10.05 vs 3.90, p=0.049; 5.22 vs 2.76, p=0.03, respectively), but no difference was observed between stages according to the International Staging System (ISS) (p=0.87). Neither the overall survival nor the progression-free survival differed between patients with high and low MALAT1 expression. ANRIL expression levels were diverse according to the patients (range, 0 to 294.3), however, the median expression was significantly higher in MM patients (p<0.001). HOTAIR and HOTTIP expression levels were not detected in most samples, and XIST expression was found only in female patient samples as expected. Interestingly, the MM cell lines KMS12PE, OPM2, KMS11 treated with bortezomib showed elevated MALAT1 expression by 4.3 -21.8 fold and ANRIL by 2.2-4.7 fold; however, this increase was not observed in bortezomib-resistant cell lines. Another proteasome inhibitor, MG132, and a low dose of the cytotoxic drug doxorubicin also elevated both lncRNAs in the cell lines. Hypoxic stress, which has been shown to induce MALAT1 in vascular cells, did not increase either lncRNA. MALAT1 knockdown by GapmeR did not affect cell proliferation. It has been shown that MALAT1 enhances cell motility of lung adenocarcinoma cells by influencing cell motility associated genes; however, the expression of previously reported affected genes, such as HMMR, CTHRC1 and ROD1, was not altered in the MALAT1 knockdown MM cell lines. Although t(4;14) was associated with a high MALAT1 expression in the patient samples, MMSET knockdown by siRNA did not change the MALAT1 expression in the cell lines, thus MMSET was not a regulator of MALAT1. RNA sequencing of MM and MGUS samples revealed a distinct lncRNA expression signature as well as protein coding genes.Conclusion: Significant upregulation of lncRNAs MALAT1 and ANRIL might be associated with MM progression. Given that MALAT1 is associated with lung cancer metastasis, MALAT1 might be strongly associated with extramedullary plasmacytoma formation due to its high expression in liver plasmacytoma. Genotoxic and ER stress induced by therapeutic drugs might upregulate MALAT1 expression, leading to extramedullary extension, which is a recent problem in MM treatment. Determining the distinct lncRNA signature of MM is a current important issue to clarify the molecular mechanisms underlying MM progression for the development of novel therapies. DisclosuresNo relevant conflicts of interest to declare.

Molecular Characterization of SRSF2 Mutation Identifies a Clinically Relevant Lncrna (MALAT1) in Chronic Myelomonocytic Leukemia (CMML)

SRSF2 is mutated at proline 95 (P95) in approximately 45% of patients with CMML. The consequence of SRSF2 P95H mutations on splicing has been associated with change in target RNA motif preference compared to wild type that favors CCNG over GGNG resulting in aberrant splicing abnormalities. Although this has led to several downstream mis-spliced candidates that may contribute to SRSF2 leukemic pathogenesis, the biologic consequences of SRSF2 mutation have not been fully elucidated and its effect on non-splicing pathways has yet to be explored.SRSF2 has two major functions within the nucleus: (1) bind to cis elements on pre-mRNA transcripts that functionally redefines putative exon-intron boundaries and (2) interact with other members of the spliceosome complex at nuclear suborganelles known as speckles. To explore the effects of SRSF2 P95 mutation on nuclear speckle dynamics, we transfected HeLa cells with GFP-SRSF2 wildtype (WT) and mutant (MT) constructs and performed Fluorescent Recovery After Photo-bleaching (FRAP) to determine the mutant specific kinetics of SRSF2 molecules localized to the nuclear speckle. Using this approach, we confirmed that SRSF2 WTs are characterized by complete photo-recovery with a half-life of approximately 35 (30-42) seconds as previously reported. However, when we performed FRAP of GFP-SRSF2 MTs a statistically significant difference in photo-recovery was observed compared to WT cells (Fig. 1a). The difference between baseline fluorescence and maximal recovered fluorescence in SRSF2 MT cells, or the immobile fraction, suggests that trapped bleached SRSF2 molecules are sterically inhibiting the diffusion of unbleached SRSF2 molecules.We reasoned that the observed differences in RNA binding capacity and nuclear speckle dynamics could be related. This rationale identified MALAT1 as a link connecting both increased RNA binding and nuclear speckle trafficking abnormalities because it is a Long Non-Coding (lnc) RNA that localizes to and has a critical role in SR protein recruitment and retention to the nuclear speckle. MALAT1, which is highly enriched for CCNG motifs, has also been demonstrated to bind to SRSF2 directly and has been implicated in a wide spectrum of carcinomas making it an attractive intermediary to study in our system.To determine whether SRSF2 MTs have increased MALAT1 binding capacity compared to SRSF2 WT, we performed RNA IP of myc-his-SRSF2 WT and MT transfected HeLa cells. Using this approach, we demonstrated a 60% enrichment of MALAT1 in SRSF2 WT transfected cells and a 120-150% enrichment of MALAT1 in SRSF2 MT cells compared to the empty vector control (Fig. 1b-c). We next performed the above FRAP experiment in the context of MALAT1 depletion and demonstrated that observed immobile fraction seen in SRSF2 MT cells is rescued (Fig. 1d).To determine the clinical relevance of MALAT1 in CMML we profiled a cohort of 54 CMML cases for MALAT1 expression by PCR. As shown in Figure 2a-b and d-e, MALAT1 expression is statistically elevated in CMML BMNCs and is among the highest differentially expressed transcripts in CMML monocytes (CD14+). We additionally characterized SRSF2 expression in our CMML BMNCs and CD14+ cohort and identified a linear correlation (Pearson R=0.7 p<0.05) between SRSF2 expression and MALAT1 expression (Figure 2c). Further, CMML patients with high MALAT1 expression in the BMNC compartment had inferior overall and leukemia-free survival (Fig. 2f-g).Given its relevance in solid tumors and its over-expression in CMML, we explored the consequence of MALAT1 depletion on human monocytic leukemic cells. We first performed ultra-deep RNA sequencing of the THP-1 cell line treated with two MALAT-1 depleting ASOs or matched chemistry specific controls. IPA analysis of differentially expressed transcripts identified a c-Myc gene signature that was validated by western blot analysis demonstrating reduction of c-Myc in THP-1 MALAT1-depleted cells. Colony formation assays using the THP-1 cell line demonstrated that MALAT-1 depletion resulted in decreased colony-forming capacity (CFC). MALAT-1 ASOs were also capable of depleting MALAT-1 in primary CMML BMNCs and were associated with a decreased CFC suggesting that MALAT-1 is a potential therapeutic target. Taken together, our data identifies SRSF2 P95 mutation nuclear trafficking abnormalities and identifies a novel clinically relevant lncRNA in CMML. [Display omitted] [Display omitted] DisclosuresKomrokji:Celgene: Consultancy, Research Funding; Incite: Consultancy; Novartis: Speakers Bureau; GSK: Research Funding. List:Celgene Corporation: Honoraria, Research Funding.