The functional pathway analysis and clinical significance of miR-20a and its related lncRNAs in breast cancer

BackgroundmiR-20a is a critical molecule in various biological processes and cancer progression procedures. However, its relationships with lncRNAs and their functional pathway analysis in breast tumorigenesis are less intensively studied.MethodsThe expression data from TCGA database and multiple bioinformatics resources were used to check the expression levels, survival curves, interactions and functional illustrations of miR-20a and its related lncRNAs (XIST, H19 and MALAT1) in breast cancer patients. The luciferase reporter assays and Pearson's correlation analyses were utilized to verify the direct regulatory relationship between miR-20a and three lncRNAs (XIST, H19 and MALAT1). In vitro cell proliferation, migration and invasion assays, were performed to check the biological effects of miR-20a and XIST in different breast cancer cell lines. The receiver operating characteristic curve (ROC) analyses were done for evaluating diagnostic values of serum miR-20a and XIST in breast cancer patients.ResultsThe miR-20a expression was significantly up-regulated in both breast cancer samples and serum samples, and correlated with poor survival rate in breast cancer patients. LncRNAs (XIST, H19 and MALAT1) directly bound to hsa-miR-20a and were negatively correlated with hsa-miR-20a expression in breast cancer patient samples. For functional illustrations and downstream signaling pathways analysis, XIST, H19 and MALAT1 mainly shared their regulatory functions in cell motility and interleukin signaling in breast cancer progression. Additionally, over-expression of miR-20a and inhibition of XIST promoted breast cancer cell growth, migration and invasion in vitro, and serum miR-20a and XIST served as potential diagnostic biomarkers for breast cancer with the area under ROC curve (AUC) of 0.87 (95% CI = 0.78 to 0.97), and 0.78 (95% CI = 0.67 to 0.89) respectively.ConclusionsTaken together, these findings provide us novel insights and avenues for utilizing miR-20a and its related lncRNAs as potential diagnostic biomarkers and promising therapeutic targets for breast cancer treatment.     

Identification and targeting of G-quadruplex structures in MALAT1 long non-coding RNA

RNA G-quadruplexes (rG4s) have functional roles in many cellular processes in diverse organisms. While a number of rG4 examples have been reported in coding messenger RNAs (mRNA), so far only limited works have studied rG4s in non-coding RNAs (ncRNAs), especially in long non-coding RNAs (lncRNAs) that are of emerging interest and significance in biology. Herein, we report that MALAT1 lncRNA contains conserved rG4 motifs, forming thermostable rG4 structures with parallel topology. We also show that rG4s in MALAT1 lncRNA can interact with NONO protein with high specificity and affinity in vitro and in nuclear cell lysate, and we provide cellular data to support that NONO protein recognizes MALAT1 lncRNA via rG4 motifs. Notably, we demonstrate that rG4s in MALAT1 lncRNA can be targeted by the rG4-specific small molecule, peptide, and L-aptamer, leading to the dissociation of MALAT1 rG4-NONO protein interaction. Altogether, this study uncovers new and important rG4s in MALAT1 lncRNAs, reveals their specific interactions with NONO protein, offers multiple strategies for targeting MALAT1 and its RNA–protein complex via its rG4 structure and illustrates the prevalence and significance of rG4s in ncRNAs.     

Overexpression of MALAT1 contributes to cervical cancer progression by acting as a sponge of miR-429

Cervical cancer remains a malignant type of tumor and is the fourth leading cause of cancer-related death among females. MALAT1 has been identified as a tumor oncogene in various cancers. Our present study aimed to explore the biological role of MALAT1 in cervical cancer. We observed that MALAT1 was significantly upregulated in human cervical cancer cell lines compared with the ectocervical epithelial cells. MALAT1 was repressed by transfection with LV-shMALAT1, whereas increased by LV-MALAT1 in HeLa and Caski cells. Silencing of MALAT1 obviously reduced cervical cell viability, induced cell apoptosis, and repressed cell invasion capacity. Conversely, overexpression of MALAT1 exhibited an opposite phenomenon. Furthermore, miR-429 was predicted as a direct target of MALAT1, and it was dramatically decreased in cervical cancer cells. It has been shown that miR-429 plays a crucial role in cervical cancer progression. In our current study, the targeting correlation between MALAT1 and miR-429 was confirmed by luciferase reporter assays and RIP experiments. Finally, in vivo animal models were established, and we indicated that MALAT1 inhibited cervical cancer progression via targeting miR-429. These findings revealed that MALAT1 can sponge miR-429 and regulate cervical cancer pathogenesis in vivo and in vitro. In conclusion, we indicated that the MALAT1/miR-429 axis was involved in cervical cancer development.     

Long non‐coding RNA MALAT1 mediates hypoxia‐induced pro‐survival autophagy of endometrial stromal cells in endometriosis

Endometriosis is a common gynecological disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells. Hypoxia has been implicated as a crucial microenvironmental factor that contributes to endometriosis. It has been reported that long non‐coding RNA MALAT1 (lncRNA‐MALAT1) highly expressed in endometriosis and up‐regulated by hypoxia. Hypoxia may also induce autophagy, which might act as cell protective mechanism. However, the relationship between lncRNA‐MALAT1 and autophagy under hypoxia conditions in endometriosis remains unknown. In the present study, we found that both lncRNA‐MALAT1 and autophagy level were up‐regulated in ectopic endometrium from patients with endometriosis, and its expression level correlates positively with that of hypoxia‐inducible factor‐1α (HIF‐1α). In cultured human endometrial stromal cells, both lncRNA‐MALAT1 and autophagy were induced by hypoxia in a time‐dependent manner and lncRNA‐MALAT1 up‐regulation was dependent on HIF‐1α signalling. Our analyses also show that knockdown of lncRNA‐MALAT1 suppressed hypoxia induced autophagy. Furthermore, inhibiting autophagy with specific inhibitor 3‐Methyladenine (3‐MA) and Beclin1 siRNA enhanced apoptosis of human endometrial stromal cells under hypoxia condition. Collectively, our findings identify that lncRNA‐MALAT1 mediates hypoxia‐induced pro‐survival autophagy of endometrial stromal cells in endometriosis.     

The oncogenic role of SAMMSON lncRNA in tumorigenesis: A comprehensive review with especial focus on melanoma

LncRNA Survival Associated Mitochondrial Melanoma Specific Oncogenic Non-coding RNA (SAMMSON) is located on human chromosome 3p13, and its expression is upregulated in several tumours, including melanoma, breast cancer, glioblastoma and liver cancer and has an oncogenic role in malignancy disorders. It has been reported that SAMMSON impacts metabolic regulation, cell proliferation, apoptosis, EMT, drug resistance, invasion and migration. Also, SAMMSON is involved in regulating several pathways such as Wnt, MAPK, PI3K, Akt, ERK and p53. SAMMSON is considered a potential diagnostic and prognostic biomarker in several types of cancer and a suitable therapeutic target. In addition, the highly expressed SAMMSON is closely associated with clinicopathological features of various cancers. SAMMSON has a significant role in regulating epigenetic processes by regulating histone protein or the status of DNA methylation. Herein for the first time, we comprehensively summarized the currently available SAMMSON, molecular regulatory pathways, and clinical significance. We believe that clarifying all the molecular aspects of this lncRNA can be a good guide for cancer studies in the future.     

Long Non-Coding RNA MALAT1 Mediates Transforming Growth Factor Beta1-Induced Epithelial-Mesenchymal Transition of Retinal Pigment Epithelial Cells

Purpose

To study the role of long non-coding RNA (lncRNA) MALAT1 in transforming growth factor beta 1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells.

Methods

ARPE-19 cells were cultured and exposed to TGF-β1. The EMT of APRE-19 cells is confirmed by morphological change, as well as the increased expression of alpha-smooth muscle actin (αSMA) and fibronectin, and the down-regulation of E-cadherin and Zona occludin-1(ZO-1) at both mRNA and protein levels. The expression of lncRNA MALAT1 in RPE cells were detected by quantitative real-time PCR. Knockdown of MALAT1 was achieved by transfecting a small interfering RNA (SiRNA). The effect of inhibition of MALAT1 on EMT, migration, proliferation, and TGFβ signalings were observed. MALAT1 expression was also detected in primary RPE cells incubated with proliferative vitreoretinopathy (PVR) vitreous samples.

Results

The expression of MALAT1 is significantly increased in RPE cells incubated with TGFβ1. MALAT1 silencing attenuates TGFβ1-induced EMT, migration, and proliferation of RPE cells, at least partially through activating Smad2/3 signaling. MALAT1 is also significantly increased in primary RPE cells incubated with PVR vitreous samples.

Conclusion

LncRNA MALAT1 is involved in TGFβ1-induced EMT of human RPE cells and provides new understandings for the pathogenesis of PVR.     

The cytoplasmic expression of FSTL3 correlates with colorectal cancer progression,metastasis status and prognosis

Follistatin-like (FSTL) family members are associated with cancer progression. However, differences between FSTL members with identical cancer types have not been systematically investigated. Among the most malignant tumours worldwide, colorectal cancer (CRC) has high metastatic potential and chemoresistance, which makes it challenging to treat. A systematic examination of the relationship between the expression of FSTL family members in CRC will provide valuable information for prognosis and therapeutic development. Based on large cohort survival analyses, we determined that FSTL3 was associated with a significantly worse prognosis in CRC at the RNA and protein levels. Immunohistochemistry staining of CRC specimens revealed that FSTL3 expression levels in the cytosol were significantly associated with a poor prognosis in terms of overall and disease-free survival. Molecular simulation analysis showed that FSTL3 participated in multiple cell motility signalling pathways via the TGF-β1/TWIST1 axis to control CRC metastasis. The findings provide evidence of the significance of FSTL3 in the oncogenesis and metastasis of CRC. FSTL3 may be useful as a diagnostic or prognostic biomarker, and as a potential therapeutic target.     

Expression profile of lncRNAs and miRNAs in esophageal cancer: Implications in diagnosis,prognosis, and therapeutic response

Esophageal cancer is the seventh most common cancer worldwide. Although a number of environmental and lifestyle-related risk factors have been identified for this kind of cancer, the exact molecular mechanisms of tumor evolution have not been clarified yet. Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) as important regulators of gene expression and chromatin configuration have essential roles in the pathogenesis of esophageal cancer. They have been shown to alter the function of cancer-related signaling pathways such as phosphoinositide 3-kinase/protein kinase B and Wnt pathway, thus they might modulate the response of patients to pathway-targeted therapies. Moreover, a number of lncRNAs, such as AFAP1-AS1, UCA1, HOTAIR, LOC285194, and TUSC7, are involved in conferring chemoresistant/radioresistant in esophageal cancer cells. A complex network of interaction exists between lncRNAs and miRNAs in the context of esophageal cancer. Finally, various panels of lncRNAs and miRNAs have been introduced that can predict the survival of esophageal cancer patients. In this review article, we summarize the recent findings regarding the role of miRNAs and lncRNAs in the pathogenesis of esophageal cancer with the special focus on their regulatory roles on signaling pathways, their potential as diagnostic/prognostic markers, and their relevance with therapeutic response.     

MALAT1/miR-185-5p mediated high glucose-induced oxidative stress,mitochondrial injury and cardiomyocyte apoptosis via the RhoA/ROCK pathway

To explore the underlying mechanism of lncRNA MALAT1 in the pathogenesis of diabetic cardiomyopathy (DCM). DCM models were confirmed in db/db mice. MiRNAs in myocardium were detected by miRNA sequencing. The interactions of miR-185-5p with MALAT1 and RhoA were validated by dual-luciferase reporter assays. Primary neonatal cardiomyocytes were cultured with 5.5 or 30 mmol/L D-glucose (HG) in the presence or absence of MALAT1-shRNA and fasudil, a ROCK inhibitor. MALAT1 and miR-185-5p expression were determined by real-time quantitative PCR. The apoptotic cardiomyocytes were evaluated using flow cytometry and TUNEL staining. SOD activity and MDA contents were measured. The ROCK activity, phosphorylation of Drp1^S616, mitofusin 2 and apoptosis-related proteins were analysed by Western blotting. Mitochondrial membrane potential was examined by JC-1. MALAT1 was significantly up-regulated while miR-185-5p was down-regulated in myocardium of db/db mice and HG-induced cardiomyocytes. MALAT1 regulated RhoA/ROCK pathway via sponging miR-185-5p in cardiomyocytes in HG. Knockdown of MALAT1 and fasudil all inhibited HG-induced oxidative stress, and alleviated imbalance of mitochondrial dynamics and mitochondrial dysfunction, accompanied by reduced cardiomyocyte apoptosis. MALAT1 activated the RhoA/ROCK pathway via sponging miR-185-5p and mediated HG-induced oxidative stress, mitochondrial damage and apoptosis of cardiomyocytes in mice.