Sp1-mediated transcriptional regulation of MALAT1 plays a critical role in tumor

Targeting NSCLC drug resistance: Systems biology insights into the MALAT1/miR-145-5p axis and Wip1 in regulating ferroptosis and apoptosis

The long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (lncRNA MALAT1) and microRNA-145-5p (miR-145) axis play a pivotal role in regulating drug resistance, apoptosis and senescence in non-small cell lung cancer (NSCLC). MALAT1 drives drug resistance by suppressing miR-145 and activating MUC1, thereby inhibiting ferroptosis; however, its precise role in regulating ferroptosis in NSCLC remains unclear. Therefore, we propose a computational modelling approach to unravel the impact of the MALAT1/miR-145 axis on ferroptosis and drug resistance, to identify potential therapeutic strategies that promote ferroptosis. Using Boolean logic and a stochastic updating scheme, we developed and validated a robust regulatory model that encompasses ferroptosis, apoptosis, senescence and drug resistance pathways. The model, based on extensive literature and validated through gain- and loss-of-function perturbations, demonstrated strong alignment with observed clinical data that were not included in its construction. Our analysis identified three previously unreported feedback loops, miR-145/Wip1/p53, miR-145/Myc/MALAT1 and miR-145/MUC1/BMI1, establishing miR-145 as a central regulator in NSCLC. Perturbations targeting MALAT1 and wild-type p53-induced phosphatase 1 (Wip1) revealed potential therapeutic opportunities, with miR-145 activation emerging as a promising strategy to induce ferroptosis and overcome drug resistance. These findings highlight the MALAT1/miR-145 axis as a transformative therapeutic target, presenting a computational foundation to advance NSCLC treatment strategies.

Comprehensive insights and In silico analysis into the emerging role of LincRNAs in lung diseases pathogenesis; a step toward ncRNA precision

Long non-coding RNAs (lncRNAs) have emerged as essential regulators of gene expression, significantly influencing various biological processes. Approximately half of all lncRNAs are classified as long intergenic non-coding RNAs (lincRNAs), which are situated among coding genes. Recent studies have documented the role of lincRNAs in the pathogenesis of lung diseases, including lung cancer, pulmonary fibrosis, and pulmonary arterial hypertension. These lincRNAs can modulate gene expression through various mechanisms, including epigenetic modifications, transcriptional regulation, and post-transcriptional regulation. By functioning as competing endogenous RNAs (ceRNAs), lincRNAs can affect the activity of microRNAs (miRNAs) and their corresponding target genes. This review delves into the intricate mechanisms by which lincRNAs contribute to the development and progression of various lung diseases. Furthermore, it discusses the potential of lincRNAs as therapeutic targets.

Novel bioinformatic approaches show the role of driver genes in the progression of cervical cancer: An in-silico study

Background

The goal of this bioinformatics research is to get a comprehensive understanding of the driver genes and their function in the development, progression, and treatment of cervical cancer. This study constitutes a pioneering attempt, adding to our knowledge of genetic diversity and its ramifications.

Material and methods

In this project, we use bioinformatics and systems biology methods to identify candidate transcription factors and the genes they regulate in order to identify microRNAs and LncRNAs that regulate these transcription factors and lead to the discovery of new medicines for the treatment of cervical cancer. From the differentially expressed genes available via GEO's GSE63514 accession, we use driver genes to choose these candidates. We then used the WGCNA tool in R to rebuild the co-expression network and its modules. The hub genes of each module were determined using CytoHubba, a Cystoscope plugin. The biomarker potential of hub genes was analyzed using the UCSC Xena browser and the GraphPad prism program. The TRRUST database is used to locate the TFs that regulate the expression of these genes. In order to learn how drugs, MicroRNAs, and LncRNAs interact with transcription factors, we consulted the Drug Target Information Database (DGIDB), the miRWalk database, and the LncHub database. Finally, the online database Enrichr is utilized to analyze the enrichment of Gene Ontology and KEGG pathways.

Results

By combining the mRNA expression levels of 2041 driver genes from 14 early-stage Cervical cancer and 24 control samples, a co-expression network was built. The cluster analysis shows that the collection of shared genes may be broken down into seven distinct groups, or "modules." According to the average linkage hierarchical clustering and Summary smaller than 2, we found five modules (represented by the colors blue, brown, red, green, and grey) in our research. Then, we identify 5 high-degree genes from these modules that may serve as diagnostic biomarkers (ZBBX, PLCH1, TTC7B, DNAH7, and ZMYND10). In addition, we identify four transcription factors (SRF, RELA, NFKB1, and SP1) that regulate the expression of genes in the co-expression module. Drugs, microRNAs, and long noncoding RNAs are then shown to cooperate with transcription factors. At last, the KEGG database's pathways were mined for information on how the co-expression module fits within them. More clinical trials are required for more trustworthy outcomes, and we collected this data using bioinformatics methods.

Conclusion

The major goal of this research was to identify diagnostic and therapeutic targets for cervical cancer by learning more about the involvement of driver genes in cancer's earliest stages.

Puzzling out the role of MIAT LncRNA in hepatocellular carcinoma

A non-negligible part of our DNA has been proven to be transcribed into non-protein coding RNA and its intricate involvement in several physiological processes has been highly evidenced. The significant biological role of non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs) has been variously reported. In the current review, the authors highlight the multifaceted role of myocardial infarction-associated transcript (MIAT), a well-known lncRNA, in hepatocellular carcinoma (HCC). Since its discovery, MIAT has been described as a regulator of carcinogenesis in several malignant tumors and its overexpression predicts poor prognosis in most of them. At the molecular level, MIAT is closely linked to the initiation of metastasis, invasion, cellular migration, and proliferation, as evidenced by several in-vitro and in-vivo models. Thus, MIAT is considered a possible theranostic agent and therapeutic target in several malignancies. In this review, the authors provide a comprehensive overview of the underlying molecular mechanisms of MIAT in terms of its downstream target genes, interaction with other classes of ncRNAs, and potential clinical implications as a diagnostic and/or prognostic biomarker in HCC.

DNM3OS/miR-127-5p/CDH11, activates Wnt3a/β-catenin/LEF-1 pathway to form a positive feedback and aggravate spine facet joint osteoarthritis

Spinal facet joint osteoarthritis (FJOA) is an OA disease with pathogenesis and progression uncovered. Our present study was performed to elucidate the role of DNM3OS on spinal FJOA. In this study, spine facet joint tissue of patients were collected. In vitro and in vivo models were constructed with SW1353 cells and rats. Hematoxylin and eosin (HE) staining, Safranin O-fast Green, Alcian blue staining, and Tolueine blue O (TBO) staining were employed for histology analyses. Quantitative PCR, western blotting, and Immunofluorescence were performed to evaluate the expression of genes. The levels of inflammatory cytokines were measured by enzyme-linked immunosorbent assay analysis. Cell Counting Kit-8 and flow cytometry were used for cell activity and apoptosis evaluation. The targeting sites between microRNA (miR)-127-5p and cadherin 11 (CDH11) were predicted TargetScan and miRbase database and confirmed by Dual-luciferase reporter assays. CHIP and EMS assay were employed to confirm the binding of LEF1and DNM3OS promoter. Our results showed that DNM3OS was found to upregulated, while miR-127-5p was downregulated in severe FJOA patients and inflammation-induced chondrosarcoma SW1353 cells. DNM3OS reduced cell activity, induced cell apoptosis and extracellular matrix (ECM) degradation by sponging miR-127-5p in vitro. miR-127-5p targeted CDH11 and inhibited wnt3a/β-catenin pathway to regulate OA in vitro. LEF1 promoted DNM3OS transcription to form a positively feedback in activated wnt3a/β-catenin pathway. In vivo rat model also confirmed that DNM3OS aggravated FJOA. In summary, DNM3OS/miR-127-5p/CDH11 enhanced Wnt3a/β-Catenin/LEF-1 pathway to form a positive feedback and aggravate spinal FJOA.

Modulation of long noncoding RNAs by polyphenols as a novel potential therapeutic approach in lung cancer: A comprehensive review

Lung cancer stands as a formidable global health challenge, necessitating innovative therapeutic strategies. Polyphenols, bioactive compounds synthesized by plants, have garnered attention for their diverse health benefits, particularly in combating various cancers, including lung cancer. The advent of whole-genome and transcriptome sequencing technologies has illuminated the pivotal roles of long noncoding RNAs (lncRNAs), operating at epigenetic, transcriptional, and posttranscriptional levels, in cancer progression. This review comprehensively explores the impact of polyphenols on both oncogenic and tumor-suppressive lncRNAs in lung cancer, elucidating on their intricate regulatory mechanisms. The comprehensive examination extends to the potential synergies when combining polyphenols with conventional treatments like chemotherapy, radiation, and immunotherapy. Recognizing the heterogeneity of lung cancer subtypes, the review emphasizes the need for the integration of nanotechnology for optimized polyphenol delivery and personalized therapeutic approaches. In conclusion, we collect the latest research, offering a holistic overview of the evolving landscape of polyphenol-mediated modulation of lncRNAs in lung cancer therapy. The integration of polyphenols and lncRNAs into multidimensional treatment strategies holds promise for enhancing therapeutic efficacy and navigating the challenges associated with lung cancer treatment.

Long Noncoding RNA MALAT1: Salt-Sensitive Hypertension

Hypertension stands as the leading global cause of mortality, affecting one billion individuals and serving as a crucial risk indicator for cardiovascular morbidity and mortality. Elevated salt intake triggers inflammation and hypertension by activating antigen-presenting cells (APCs). We found that one of the primary reasons behind this pro-inflammatory response is the epithelial sodium channel (ENaC), responsible for transporting sodium ions into APCs and the activation of NADPH oxidase, leading to increased oxidative stress. Oxidative stress increases lipid peroxidation and the formation of pro-inflammatory isolevuglandins (IsoLG). Long noncoding RNAs (lncRNAs) play a crucial role in regulating gene expression, and MALAT1, broadly expressed across cell types, including blood vessels and inflammatory cells, is also associated with inflammation regulation. In hypertension, the decreased transcriptional activity of nuclear factor erythroid 2-related factor 2 (Nrf2 or Nfe2l2) correlates with heightened oxidative stress in APCs and impaired control of various antioxidant genes. Kelch-like ECH-associated protein 1 (Keap1), an intracellular inhibitor of Nrf2, exhibits elevated levels of hypertension. Sodium, through an increase in Sp1 transcription factor binding at its promoter, upregulates MALAT1 expression. Silencing MALAT1 inhibits sodium-induced Keap1 upregulation, facilitating the nuclear translocation of Nrf2 and subsequent antioxidant gene transcription. Thus, MALAT1, acting via the Keap1-Nrf2 pathway, modulates antioxidant defense in hypertension. This review explores the potential role of the lncRNA MALAT1 in controlling the Keap1-Nrf2-antioxidant defense pathway in salt-induced hypertension. The inhibition of MALAT1 holds therapeutic potential for the progression of salt-induced hypertension and cardiovascular disease (CVD).

SP1 transcriptionally activates HTR2B to aggravate traumatic spinal cord injury by shifting microglial M1/M2 polarization

BACKGROUND

Spinal cord injury (SCI) can result in structural and functional damage to the spinal cord, which may lead to loss of limb movement and sensation, loss of bowel and bladder control, and other complications. Previous studies have revealed the critical influence of trans-acting transcription factor 1 (SP1) in neurological pathologies, however, its role and mechanism in SCI have not been fully studied.

METHODS

The study was performed using mouse microglia BV2 stimulated using lipopolysaccharide (LPS) and male adult mice subjected to spinal hitting. Western blotting was performed to detect protein expression of SP1, 5-hydroxytryptamine (serotonin) receptor 2B (HTR2B), BCL2-associated x protein (Bax), B-cell lymphoma-2 (Bcl-2), inducible nitric oxide synthase (iNOS), clusters of differentiation 86 (CD86), Arginase 1 (Arg-1) and clusters of differentiation 206 (CD206). Cell viability and apoptosis were analyzed by MTT assay and TUNEL assay. mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-4 (IL-4) and tumor necrosis factor-β (TNF-β) were quantified by quantitative real-time polymerase chain reaction. The association of SP1 and HTR2B was identified by chromatin immunoprecipitation assay and dual-luciferase reporter assay. HE staining assay was performed to analyze the pathological conditions of spinal cord tissues.

RESULTS

LPS treatment induced cell apoptosis and inhibited microglia polarization from M1 to M2 phenotype, accompanied by an increase of Bax protein expression and a decrease of Bcl-2 protein expression, however, these effects were relieved after SP1 silencing. Mechanism assays revealed that SP1 transcriptionally activated HTR2B in BV2 cells, and HTR2B knockdown rescued LPS-induced effects on BV2 cell apoptosis and microglial M1/M2 polarization. Moreover, SP1 absence inhibited BV2 cell apoptosis and promoted microglia polarization from M1 to M2 phenotype by decreasing HTR2B expression. SCI mouse model assay further showed that SP1 downregulation could attenuate spinal hitting-induced promoting effects on cell apoptosis of spinal cord tissues and microglial M1 polarization.

CONCLUSION

SP1 transcriptionally activated HTR2B to aggravate traumatic SCI by shifting microglial M1/M2 polarization.

A dynamic Boolean network reveals that the BMI1 and MALAT1 axis is associated with drug resistance by limiting miR-145-5p in non-small cell lung cancer

Patients with non-small cell lung cancer (NSCLC) are often treated with chemotherapy. Poor clinical response and the onset of chemoresistance limit the anti-tumor benefits of drugs such as cisplatin. According to recent research, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA related to cisplatin resistance in NSCLC. Furthermore, MALAT1 targets microRNA-145-5p (miR-145), which activates Krüppel-like factor 4 (KLF4) in associated cell lines. B lymphoma Mo-MLV insertion region 1 homolog (BMI1), on the other hand, inhibits miR-145 expression, which stimulates Specificity protein 1 (Sp1) to trigger the epithelial-mesenchymal transition (EMT) process in pemetrexed-resistant NSCLC cells. The interplay between these molecules in drug resistance is still unclear. Therefore, we propose a dynamic Boolean network that can encapsulate the complexity of these drug-resistant molecules. Using published clinical data for gain or loss-of-function perturbations, our network demonstrates reasonable agreement with experimental observations. We identify four new positive circuits: miR-145/Sp1/MALAT1, BMI1/miR-145/Myc, KLF4/p53/miR-145, and miR-145/Wip1/p38MAPK/p53. Notably, miR-145 emerges as a central player in these regulatory circuits, underscoring its pivotal role in NSCLC drug resistance. Our circuit perturbation analysis further emphasizes the critical involvement of these new circuits in drug resistance for NSCLC. In conclusion, targeting MALAT1 and BMI1 holds promise for overcoming drug resistance, while activating miR-145 represents a potential strategy to significantly reduce drug resistance in NSCLC.

YY1-regulated lncRNA SOCS2-AS1 suppresses HCC cell stemness and progression via miR-454-3p/CPEB1

BACKGROUND

Cancer stem cells are one fundamental reason for the high recurrence rate of hepatocellular carcinoma (HCC) and its resistance to treatment. This study explored the mechanism by which SOCS2-AS1 affects HCC cell stemness.

METHODS

Stem cells of HCC cell lines Huh7 and SNU-398 were sorted as NANOG-positive by flow cytometry. Stem cell sphere formation ability was detected. Stem cell viability, migration, invasion, and apoptosis were assessed by colony formation assays, Transwell assays, wound-healing assays, and TUNEL assays, respectively. The binding sites for SOCS2-AS1, miR-454-3p, miR-454-3p, and CPEB1 mRNA were assessed by dual-luciferase reporter assays. Quantitative real-time PCR (qPCR) and Western blot studies were performed to evaluate gene expression levels. ChIP and EMSA assays were conducted to confirm that YY1 binds with the SOCS2-AS1 promoter. A subcutaneous xenograft model was used to verify results in vivo. Tumor tissues were analyzed by H&E and TUNEL staining.

RESULTS

SOCS2-AS1 was expressed at low levels in NANOG+ HCC stem cells, and HCC patients with a high level of SOCS2-AS1 expression had a higher survival rate. SOCS2-AS1 inhibited HCC cell stemness, migration, and invasion, and increased the cisplatin sensitivity of HCC cells by regulating miR-454-3p/CPEB1. YY1 was confirmed as a transcription factor of SOCS2-AS1, and served to inhibit SOCS2-AS1 transcription. YY1 knockdown suppressed HCC stemness via SOCS2-AS1. The role of SOCS2-AS1 was confirmed in a subcutaneous xenograft model, and SOCS2-AS1 overexpression enhanced the inhibitory effect of cisplatin on HCC in vivo.

CONCLUSIONS

YY1-regulated lncRNA SOCS2-AS1 suppresses HCC cell stemness and progression via miR-454-3p/CPEB1.

Elevated expression of the membrane-anchored serine protease TMPRSS11E in NSCLC progression

TMPRSS11E was found to be upregulated in human nonsmall cell lung cancer samples (NSCLC) and cell lines, and high expression was associated with poor survival of NSCLC patients. The results of in vitro and in vivo experiments showed that overexpressing TMPRSS11E resulted in A549 cell proliferation and migration promotion, while the TMPRSS11E S372A mutant with the mutated catalytic domain lost the promoting function. In addition, in mouse xenograft models, silencing TMPRSS11E expression inhibited the growth of 95D cell-derived tumors. To explore the mechanism of marked upregulation of TMPRSS11E in NSCLC cells, promoter analysis, EMSA, and ChIP assays were performed. STAT3 was identified as the transcription factor responsible for TMPRSS11E transcription. Moreover, the purified recombinant TMPRSS11E catalytic domain exhibited enzymatic activity for the proteolytic cleavage of PAR2. Recombinant TMPRSS11E catalytic domain incubation further activated the PAR2-EGFR-STAT3 pathway. These findings established a mechanism of TMPRSS11E-PAR2-EGFR-STAT3 positive feedback, and the oncogenic role of TMPRSS11E as a PAR2 modulator in NSCLC was revealed.

Long non-coding RNAs and microRNAs as crucial regulators in cardio-oncology

Cancer is one of the leading causes of morbidity and mortality worldwide. Significant improvements in the modern era of anticancer therapeutic strategies have increased the survival rate of cancer patients. Unfortunately, cancer survivors have an increased risk of cardiovascular diseases, which is believed to result from anticancer therapies. The emergence of cardiovascular diseases among cancer survivors has served as the basis for establishing a novel field termed cardio-oncology. Cardio-oncology primarily focuses on investigating the underlying molecular mechanisms by which anticancer treatments lead to cardiovascular dysfunction and the development of novel cardioprotective strategies to counteract cardiotoxic effects of cancer therapies. Advances in genome biology have revealed that most of the genome is transcribed into non-coding RNAs (ncRNAs), which are recognized as being instrumental in cancer, cardiovascular health, and disease. Emerging studies have demonstrated that alterations of these ncRNAs have pathophysiological roles in multiple diseases in humans. As it relates to cardio-oncology, though, there is limited knowledge of the role of ncRNAs. In the present review, we summarize the up-to-date knowledge regarding the roles of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in cancer therapy-induced cardiotoxicities. Moreover, we also discuss prospective therapeutic strategies and the translational relevance of these ncRNAs.

LncRNA MALAT1 was regulated by HPV16 E7 independently of pRB in cervical cancer cells

High-risk human papillomavirus (HPV) infection was one of the first step in the process of carcinogenesis in cervical cancers. The expression of viral oncoprotein E7 was essential in this process by inactivating the tumor suppressor proteins RB, in addition to interacting with other host proteins. LncRNA MALAT1 was found to be altered in human cervical cancer tissues, suggesting an important role in tumorigenesis. Moreover, MALAT1 was also overexpressed in HPV16 positive cervical cancer cell lines in an HPV16 E7 dependent manner. To explore the mechanism of E7 involved in MALAT1 up-regulation, the deletion mutant E7∆N and E7∆C were constructed to test the functional domain of E7 for MALAT1 regulation. ChIP, EMSA and UV crosslink were performed to detect the interaction between E7 and MALAT1 promoter. E7 and E7∆N mutant were observed that could bind with MALAT1 promoter directly and interacted with SP1 to form triple complex. E7-SP1 interaction contributed to the transcription activation of MALAT1 promoter. E7 and E7∆N also could promote cell proliferation, invasion, and migration, and the stimulating effect could be reversed by siMALAT1. Here we showed that HPV16 E7 as well as E7∆N could associate with SP1 and bound directly to MALAT1 promoter in vitro and in vivo. This function way of E7 was independent of pRB in cervical cancer cells. To our knowledge, this was the first reported function model for E7 as transcription activator to directly bind to the target promoter.

Transcription factors specificity protein and nuclear receptor 4A1 in pancreatic cancer

Specificity protein (Sp) transcription factors (TFs) Sp1, Sp3 and Sp4, and the orphan nuclear receptor 4A1 (NR4A1) are highly expressed in pancreatic tumors and Sp1 is a negative prognostic factor for pancreatic cancer patient survival. Results of knockdown and overexpression of Sp1, Sp3 and Sp4 in pancreatic and other cancer lines show that these TFs are individually pro-oncogenic factors and loss of one Sp TF is not compensated by other members. NR4A1 is also a pro-oncogenic factor and both NR4A1 and Sp TFs exhibit similar functions in pancreatic cancer cells and regulate cell growth, survival, migration and invasion. There is also evidence that Sp TFs and NR4A1 regulate some of the same genes including survivin, epidermal growth factor receptor, PAX3-FOXO1, α5- and α6-integrins, β1-, β3- and β4-integrins; this is due to NR4A1 acting as a cofactor and mediating NR4A1/Sp1/4-regulated gene expression through GC-rich gene promoter sites. Several studies show that drugs targeting Sp downregulation or NR4A1 antagonists are highly effective inhibitors of Sp/NR4A1-regulated pathways and genes in pancreatic and other cancer cells, and the triterpenoid celastrol is a novel dual-acting agent that targets both Sp TFs and NR4A1.

MALAT1 modulated FOXP3 ubiquitination then affected GINS1 transcription and drived NSCLC proliferation

An increasing number of studies have shown that long-noncoding RNAs (lncRNAs) are involved in the post-translational modifications (PTMs) of protein in a variety of tumors. However, little is known about the exact regulation mechanism of lncRNAs in regulating PTMs in non-small-cell lung carcinoma (NSCLC) proliferation. Metastasis-associated lung adenocarcinoma transcript1 (MALAT1) and GINS complex subunit 1(GINS1) both were upregulated and promoted proliferation progression in NSCLC. In this study, the clinicopathologic significance of MALAT1 and GINS1 in NSCLC was investigated, a positive correlation in their expression was found. The silencing of MALAT1 decreased GINS1 expression and inhibited NSCLC proliferation in vitro and in vivo. The upregulation of GINS1 reversed NSCLC proliferation inhibited by MALAT1 knockdown. FOXP3 (forkhead box protein 3) was identified as the critical transcription factor for GINS1 transcription. In addition, MALAT1 could stabilize FOXP3 by binding to zinc finger (ZF) domain and leucine zipper (LZ) domain of FOXP3. Interestingly, these two domains were also interaction domains for FOXP3 binding with E3 ligase STUB1 (STIP1 homology and U-box containing protein 1). In this way, MALAT1 masked the protein-interacting domain, and inhibited FOXP3 ubiquitination by STUB1. Together, our results identified a novel regulatory axis of MALAT1-FOXP3-GINS1, and demonstrated that MALAT1 played an important modulatory role in PTM of FOXP3 which affects GINS1 transcription and drives proliferation character in NSCLC.

Updated review on green tea polyphenol epigallocatechin-3-gallate as a cancer epigenetic regulator

In-depth insights in cancer biology over the past decades have highlighted the important roles of epigenetic mechanisms in the initiation and progression of tumorigenesis. The cancer epigenome usually experiences multiple alternations, including genome-wide DNA hypomethylation and site-specific DNA hypermethylation, various histone posttranslational modifications, and dysregulation of non-coding RNAs (ncRNAs). These epigenetic changes are plastic and reversible, and could potentially occur in the early stage of carcinogenesis preceding genetic mutation, offering unique opportunities for intervention therapies. Therefore, targeting the cancer epigenome or cancer epigenetic dysregulation with some selected agents (called epi-drugs) represents an evolving and promising strategy for cancer chemoprevention and therapy. Phytochemicals, as a class of pleiotropic molecules, have manifested great potential in modulating different cancer processes through epigenetic machinery, of which green tea polyphenol epigallocatechin-3-gallate (EGCG) is one of the most extensively studied. In this review, we first summarize epigenetic events involved in the pathogenesis of cancer, including DNA/RNA methylations, histone modifications and ncRNAs' dysregulations. We then focus on the recently discovered roles of phytochemicals, with a special emphasis on EGCG, in modulating different cancer processes through regulating epigenetic machinery. We finally discuss limitations of EGCG as an epigenetic modulator for cancer chemoprevention and treatment and offer potential strategies to overcome the shortcomings.

Regulatory Networks of LncRNA MALAT-1 in Cancer

Long noncoding (lnc)RNAs are a group of RNAs with a length greater than 200 nt that do not encode a protein but play an essential role in regulating the expression of target genes in normal biological contexts as well as pathologic processes including tumorigenesis. The lncRNA metastasis-associated lung adenocarcinoma transcript (MALAT)-1 has been widely studied in cancer. In this review, we describe the known functions of MALAT-1; its mechanisms of action; and associated signaling pathways and their clinical significance in different cancers. In most malignancies, including lung, colorectal, thyroid, and other cancers, MALAT-1 functions as an oncogene and is upregulated in tumors and tumor cell lines. MALAT-1 has a distinct mechanism of action in each cancer type and is thus at the center of large gene regulatory networks. Dysregulation of MALAT-1 affects cellular processes such as alternative splicing, epithelial–mesenchymal transition, apoptosis, and autophagy, which ultimately results in the abnormal cell proliferation, invasion, and migration that characterize cancers. In other malignancies, such as glioma and endometrial carcinoma, MALAT-1 functions as a tumor suppressor and thus forms additional regulatory networks. The current evidence indicates that MALAT-1 and its associated signaling pathways can serve as diagnostic or prognostic biomarker or therapeutic target in the treatment of many cancers.

GAS5‑mediated regulation of cell signaling (Review)

In recent years, an increasing number of long non-coding RNAs (lncRNAs) have been discovered using microarrays and nucleic acid sequencing technology. LncRNAs exert crucial biological functions by regulating signaling pathways. In particular, the lncRNA growth arrest-specific transcript 5 (GAS5) has been documented to serve a crucial role in numerous signaling pathways. This article discusses the latest developments in the association between GAS5 and microRNA (miRNA), p53, mTOR, glucocorticoid response element (GRE) and AKT in order to investigate the roles served by GAS5. miRNAs can activate related signaling pathways and GAS5 can combine with miRNA to regulate related signaling pathways. GAS5 may regulate p53 expression via derivation of snoRNA, but the underlying mechanism requires further investigation. GAS5 overxpresion reduces the expression level of mTOR, which is induced by inhibiting miR-106a-5p expression. GAS5 is a sponge of GR, and serves a role in controlling and maintaining glucocorticoid sensitivity and drug resistance via competitive combination with GR. GAS5 can interact with miRNAs, such as miR-21 and miR-532-5p, to regulate the expression of AKT signaling pathway, affecting cell survival and apoptosis. Collectively, the data indicate that GAS5 serves a key role in the miRNA, p53, mTOR, GRE, and AKT signaling pathways. GAS5 regulates complex intracellular signaling pathways primarily through three modes of action, all of which are interrelated: Signal, decoy and guide. In the present article, latest developments in the association between GAS5 and a number of cellular signaling pathways are discussed to examine the tumor suppressive role of GAS5.

Lack of association of metastasis-associated lung adenocarcinoma transcript 1 variants with melanoma skin cancer risk

The long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been implicated in melanoma. Polymorphisms in MALAT1 may play a vital role in the progress of melanoma by its regulative function. However, potential genetic variants in MALAT1 affecting the risk of melanoma onset have not been explored. In this study, two single nucleotide polymorphisms (rs3200401 and rs619586) in MALAT1 were selected for genotyping of 334 melanoma patients and 291 cancer-free controls in an Italian population. The results showed that MALAT1 rs3200401 and rs619586 were not associated with melanoma risk. A further breakdown analysis by sex stratification also indicated a lack of association between these polymorphisms and melanoma. In addition, we tested 450 bp of the proximal 5´ flanking region of the gene for the presence of polymorphisms that could be associated with melanoma risk and found no variants in 96 melanoma patients. In conclusion, our results suggest that there is no contribution of MALAT1 rs3200401 and rs619586 polymorphisms or polymorphisms in the core promoter that could be associated with the risk of melanoma skin cancer in this specific study setting. Further validation will be required in larger studies involving different settings/larger populations in order to reach conclusive results.

Exosomal Long Non-Coding RNAs in Lung Diseases

Within the non-coding genome landscape, long non-coding RNAs (lncRNAs) and their secretion within exosomes are a window that could further explain the regulation, the sustaining, and the spread of lung diseases. We present here a compilation of the current knowledge on lncRNAs commonly found in Chronic Obstructive Pulmonary Disease (COPD), asthma, Idiopathic Pulmonary Fibrosis (IPF), or lung cancers. We built interaction networks describing the mechanisms of action for COPD, asthma, and IPF, as well as private networks for H19, MALAT1, MEG3, FENDRR, CDKN2B-AS1, TUG1, HOTAIR, and GAS5 lncRNAs in lung cancers. We identified five signaling pathways targeted by these eight lncRNAs over the lung diseases mentioned above. These lncRNAs were involved in ten treatment resistances in lung cancers, with HOTAIR being itself described in seven resistances. Besides, five of them were previously described as promising biomarkers for the diagnosis and prognosis of asthma, COPD, and lung cancers. Additionally, we describe the exosomal-based studies on H19, MALAT1, HOTAIR, GAS5, UCA1, lnc-MMP2-2, GAPLINC, TBILA, AGAP2-AS1, and SOX2-OT. This review concludes on the need for additional studies describing the lncRNA mechanisms of action and confirming their potential as biomarkers, as well as their involvement in resistance to treatment, especially in non-cancerous lung diseases.

Long noncoding RNA LINC00657 induced by SP1 contributes to the non-small cell lung cancer progression through targeting miR-26b-5p/COMMD8 axis

Non-small-cell lung cancer (NSCLC) is a kind of lung cancer with high incidence and poor outcomes all over the world. Studies have validated that the upregulation of long noncoding RNA LINC00657 is related to several cancers. Nevertheless, the underlying regulatory mechanism of LINC00657 in NSCLC has not been well elucidated. In the present study, quantitative reverse-transcription polymerase chain reaction (RT-qPCR) revealed that LINC00657 level was apparently elevated in NSCLC cells. Loss-of function assays demonstrated that LINC00657 silence retarded cell proliferation and migration in NSCLC cells. Moreover, the chromatin immunoprecipitation result identified the transcription factor SP1 could bind with LINC00657 promoter, and RT-qPCR proved SP1 positively regulated LINC00657 expression in NSCLC cells. In addition, the mechanistic investigations unveiled that LINC00657 was an endogenous sponge of miR-26b-5p and therefore boosted the expression of copper metabolism MURR1 domain-containing 8 (COMMD8), one of the targets of miR-26b-5p. Besides, miR-26b-5p could negatively regulate LINC00657 or COMMD8 in NSCLC cells. With the application of rescue assays, we uncovered that overexpression of COMMD8 partly mitigated the impairment of LINC00657 repression on NSCLC cell proliferation and migration. Together, our study illustrated that SP1-stimulated LINC00657 promoted NSCLC progression through targeting miR-26b-5p/COMMD8 axis, offering a novel potential therapeutic target for NSCLC.

Long non-coding RNA in lung cancer

Lung cancer is the leading cause of cancer-related death worldwide. Owing to the difficulty in early diagnosis and the lack of effective treatment strategies, the 5-year survival rates for lung cancer remain very low. With the development of whole genome and transcriptome sequencing technology, long non-coding RNA (lncRNA) has attracted increasing attention. LncRNAs regulate gene expression at the epigenetic, transcriptional and post-transcriptional levels and are widely involved in a variety of diseases, including tumorigenesis. In lung cancer studies, multiple differentially expressed lncRNAs have been identified; several lncRNAs were identified as oncogenic lncRNAs with tumor-driving effects, while other lncRNAs play a role in tumor inhibition and are called tumor-suppressive lncRNAs. These tumor-suppressive lncRNAs are involved in multiple physiological processes such as cell proliferation, apoptosis, and metastasis and thus participate in tumor progression. In this review, we discussed the oncogenic and tumor-suppressive lncRNAs in lung cancer, as well as their biological functions and regulatory mechanisms. Furthermore, we found the potential significance of lncRNAs in clinical diagnosis and treatment.

Sp1 is Involved in Vertebrate LC-PUFA Biosynthesis by Upregulating the Expression of Liver Desaturase and Elongase Genes

The rabbitfish Siganus canaliculatus was the first marine teleost demonstrated to have the ability for the biosynthesis of long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) from C18 PUFA precursors, and all the catalytic enzymes including two fatty acyl desaturase 2 (Δ4 Fads2 and Δ6/Δ5 Fads2) and two elongases (Elovl4 and Elovl5) have been identified, providing a good model for studying the regulatory mechanisms of LC-PUFA biosynthesis in fish. Stimulatory protein 1 (Sp1) has been speculated to be a vital transcription factor in determining the promoter activity of Fads-like genes in fish, however its regulatory effects on gene expression and LC-PUFA biosynthesis have not been demonstrated. Bioinformatic analysis predicted potential Sp1 binding sites in the promoters of the rabbitfish Δ6/Δ5 fads2 and elovl5, but not in Δ4 fads2 promoter. Here we cloned full-length cDNA of the rabbitfish sp1 gene, which encoded a putative protein of 701 amino acids, and was expressed in all tissues studied with highest levels in gill and eyes. The dual luciferase reporter assay in HepG2 line cells demonstrated the importance of the Sp1 binding site for the promoter activities of both Δ6/Δ5 fads2 and elovl5. Moreover, the electrophoretic mobility shift assay confirmed the direct interaction of Sp1 with the two promoters. Insertion of the Sp1 binding site of Δ6/Δ5 fads2 promoter into the corresponding region of the Δ4 fads2 promoter significantly increased activity of the latter. In the Siganus canaliculatus hepatocyte line (SCHL) cells, mRNA levels of Δ6/Δ5 fads2 and elovl5 were positively correlated with the expression of sp1 when sp1 was overexpressed or knocked-down by RNAi or antagonist (mithramycin) treatment. Moreover, overexpression of sp1 also led to a higher conversion of 18:2n−6 to 18:3n−6, 18:2n−6 to 20:2n−6, and 18:3n−3 to 20:3n−3, which related to the functions of Δ6/Δ5 Fads2 and Elovl5, respectively. These results indicated that Sp1 is involved in the transcriptional regulation of LC-PUFA biosynthesis by directly targeting Δ6/Δ5 fads2 and elovl5 in rabbitfish, which is the first report of Sp1 involvement in the regulation of LC-PUFA biosynthesis in vertebrates.

Hypoxia induces cancer cell-specific chromatin interactions and increases MALAT1 expression in breast cancer cells

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA overexpressed in various cancers that promotes cell growth and metastasis. Although hypoxia has been shown to up-regulate MALAT1, only hypoxia-inducible factors (HIFs) have been implicated in activation of the MALAT1 promoter in specific cell types and other molecular mechanisms associated with hypoxia-mediated MALAT1 up-regulation remain largely unknown. Here, we demonstrate that hypoxia induces cancer cell-specific chromatin-chromatin interactions between newly identified enhancer-like cis-regulatory elements present at the MALAT1 locus. We show that hypoxia-mediated up-regulation of MALAT1 as well as its antisense strand TALAM1 occurs in breast cancer cells, but not in nontumorigenic mammary epithelial cells. Our analyses on the MALAT1 genomic locus discovered three novel putative enhancers that are located upstream and downstream of the MALAT1 gene body. We found that parts of these putative enhancers are epigenetically modified to a more open chromatin state under hypoxia in breast cancer cells. Furthermore, our chromosome conformation capture experiment demonstrated that noncancerous cells and breast cancer cells exhibit different interaction profiles under both normoxia and hypoxia, and only breast cancer cells gain specific chromatin interactions under hypoxia. Although the HIF-2α protein can enhance the interaction between the promoter and the putative 3' enhancer, the gain of chromatin interactions associated with other upstream elements, such as putative -7 and -20 kb enhancers, were HIF-independent events. Collectively, our study demonstrates that cancer cell-specific chromatin-chromatin interactions are formed at the MALAT1 locus under hypoxia, implicating a novel mechanism of MALAT1 regulation in cancer.

The functional roles of exosomal long non-coding RNAs in cancer

Exosomes are extracellular membranous vesicles that are secreted by various cell types. Exosomes have become indispensable facilitators in the exchange of information between cells. More importantly, exosomes perform a crucial role in a variety of diseases including cancers. Long non-coding RNAs (lncRNAs) are over 200 nucleotides long transcripts that exhibit no or limited protein-coding potentials. LncRNAs are an emerging group of regulatory RNAs and can be selectively packaged into exosomes. Exosomal lncRNAs play a central role in carcinogenesis and cancer progression by modulating tumor growth, metastasis, angiogenesis and chemoresistance. Moreover, exosomal lncRNAs function as messengers in cell-to-cell communication, and thus remodel the tumor microenvironment. Their function relevance in cancer biology hints at the possibility of employing exosomal lncRNAs as promising, non-invasive biomarkers for further cancer therapy. In this review, we provide an overview of current research on the functional roles of exosomal lncRNAs in cancer and discuss their potential clinical applications as diagnostic biomarkers and therapeutic targets for cancers.

DNA methylation status of TBX20 in patients with tetralogy of Fallot

Background

TBX20 plays an important role in heart development; however, its epigenetic regulation in the pathogenesis of tetralogy of Fallot (TOF) remains unclear.

Methods

The methylation levels of the TBX20 promoter region in the right ventricular myocardial tissues of TOF and control samples were measured by the Sequenom MassARRAY platform. Bisulphite-sequencing PCR (BSP) was used to confirm the TBX20 methylation of CpG sites in cells. Dual-luciferase reporter assays were performed to detect the influence of TBX20 methylation and Sp1 transcription factors on gene activity. An electrophoretic mobility shift assay (EMSA) was used to explore the binding of the Sp1 transcription factor to the TBX20 promoter.

Results

TOF cases had a significantly lower TBX20_M1 methylation level than controls (median methylation: 20.40% vs. 38.73%; p = 0.0047). The Sp1 transcription factor, which binds to Sp1 binding sites in the TBX20_M1 region and promotes TBX20 gene activity, was blocked by the methylation of Sp1 binding sites in normal controls. With decreasing methylation in the TOF cases, the Sp1 transcription factor can bind to its binding site within the TBX20 promoter M1 region and promote TBX20 gene expression.

Conclusions

Hypomethylation of the TBX20 promoter region was observed in the TOF cases, and the high expression of the TBX20 gene may be caused by activated Sp1 transcription factor binding because of the decreasing methylation at the Sp1 transcription factor binding sites within TBX20_M1.

Functional role of long non-coding RNA CASC19/miR-140-5p/CEMIP axis in colorectal cancer progression in vitro

BACKGROUND

Long non-coding RNAs (lncRNAs) are widely involved in tumor regulation. Nevertheless, the role of the lncRNA cancer susceptibility 19 (CASC19) in colorectal cancer (CRC) has yet to be fully clarified.

AIM

To explore the effect of CASC19 on proliferation and metastasizing ability of CRC cells.

METHODS

CASC19 expression in human CRC tissues, pair-matched adjacent normal colon tissues, and CRC cells was detected using quantitative real-time PCR (qRT-PCR). CASC19 expression, as well as its relation to overall survival, was extrapolated by Kaplan-Meier survival analysis together with multivariable Cox regression assay. In vitro experiments were performed to confirm whether CASC19 regulates CRC cell invasion, migration, proliferation, and apoptosis.

RESULTS

CASC19 expression was markedly upregulated in CRC tissues and CRC cell lines (P < 0.05). qRT-PCR revealed that CASC19 expression was higher in 25 tissue samples from patients with aggressive CRC compared with the 27 tissue samples from patients with nonaggressive CRC (P < 0.05). Higher CASC19 expression was associated with poorer patient prognoses. Furthermore, in vitro experiments demonstrated that CASC19 overexpression enhanced CRC cell invasion, migration, and proliferation. CASC19 overexpression enhanced the expression of cell migration inducing hyaluronidase 1 (CEMIP) and epithelial-mesenchymal transition markers. MiR-140-5p was found to be able to bind directly to CASC19 and CEMIP. Overexpression of miR-140-5p reversed the effect of CASC19 on cell proliferation and tumor migration, as well as suppressed CASC19-induced CEMIP expression.

CONCLUSION

CASC19 positively regulates CEMIP expression through targeting miR-140-5p. CASC19 may possess an oncogenic function in CRC progression, highlighting its potential as an essential biomarker in CRC diagnosis and therapy.

Upregulation of Long Noncoding RNA GAS5 Inhibits Lung Cancer Cell Proliferation and Metastasis via miR-205/PTEN Axis

Background

Long noncoding RNA (lncRNA) is a key part of noncoding RNA class and increasing evidences have manifested that it plays a significant role in the physiology and pathology. The growth arrest-specific transcript 5 (GAS5) is a vital tumor suppressor in some types of cancers. However, the function of GAS5 in lung cancer remains largely no clear. The purpose of the current study was to identify the biological role of GAS5 in non-small cell lung cancer (NSCLC).

Material/Methods

To study the role of GAS5 in the NSCLC, the RT-PCR, Western Blot, Luciferase assay, and RNA immunoprecipitation assay was employed to determine the relationship of GAS5, miR-205, and PTEN. CCK8 assay, Cell migration and invasion assay was used for the role of GAS5 in lung cancer cell proliferation and metastasis.

Results

The results indicated that GAS5 was drastically downregulated in lung cancer cell lines. Further functional analysis showed that down-expression of GAS5 remarkably induced NSCLC growth, migration, and invasion. The luciferase reporter assays determined that miR-205 was a direct target of GAS5 in lung cancer. Moreover, the Phosphatase and tensin homologue (PTEN) was known as a direct target of miR-205 and miR-205/PTEN rescued the effects of GAS5 in NSCLC cells.

Conclusions

To sum up, our results illustrate that upregulation of GAS5 in NSCLC suppresses its growth, migration, and invasion via the miR-205/PTEN axis.

Downregulation of MALAT1 alleviates saturated fatty acid-induced myocardial inflammatory injury via the miR-26a/HMGB1/TLR4/NF-κB axis

Purpose: The increased level of saturated fatty acids (SFAs) is found in patients with diabetes, obesity, and other metabolic disorders. SFAs can induce lipotoxic damage to cardiomyocytes, but the mechanism is unclear. The long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acts as a key regulator in palmitic acid (PA)-induced hepatic steatosis, but its role in PA-induced myocardial lipotoxic injury is still unknown. The aim of this study was to explore the role and underlying mechanism of MALAT1 in PA-induced myocardial lipotoxic injury. Methods: MALAT1 expression in PA-treated human cardiomyocytes (AC16 cells) was detected by RT-qPCR. The effect of MALAT1 on PA-induced myocardial injury was measured by Cell Counting Kit-8, lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) assays. Apoptosis was detected by flow cytometry. The activities of cytokines and nuclear factor (NF)-κB were detected by enzyme-linked immunosorbent assay. The interaction between MALAT1 and miR-26a was evaluated by a luciferase reporter assay and RT-qPCR. The regulatory effects of MALAT1 on high mobility group box 1 (HMGB1) expression were evaluated by RT-qPCR and western blotting. Results: MALAT1 was significantly upregulated in cardiomyocytes after PA treatment. Knockdown of MALAT1 increased the viability of PA-treated cardiomyocytes, decreased apoptosis, and reduced the levels of LDH, CK-MB, TNF-α, and IL-1β. Moreover, we found that MALAT1 specifically binds to miR-26a and observed a reciprocal negative regulatory relationship between these factors. We further found that the downregulation of MALAT1 represses HMGB1 expression, thereby inhibiting the activation of the Toll-like receptor 4 (TLR4)/NF-κB-mediated inflammatory response. These repressive effects were rescued by an miR-26a inhibitor. Conclusion: We demonstrate that MALAT1 is induced by SFAs and its downregulation alleviates SFA-induced myocardial inflammatory injury via the miR-26a/HMGB1/TLR4/NF-κB axis. Our findings provide new insight into the mechanism underlying myocardial lipotoxic injury.

Long noncoding RNA MALAT1 acts as a potential biomarker in cancer diagnosis and detection: a meta-analysis

AIM

it has been reported that metastasis-associated lung adenocarcinoma transcript 1 is abnormally expressed in various cancers.

METHODS

eligible studies fulfilling the search criteria were selected from the online databases. Statistical analysis was performed based on the platforms of STATA 14.0.

RESULTS

12 studies were included in this study comprising 741 cases and 794 controls. The pooled results were shown as follows: sensitivity, 0.74 (95% CI: 0.64-0.82), specificity, 0.83 (95% CI: 0.75-0.88), positive likelihood ratio (PLR), 4.2 (95% CI: 3.00-5.90), negative likelihood, 0.32 (95% CI: 0.23-0.43), diagnostic odds ratio, 13 (95%CI: 8.00-21.00) and area under the curve, 0.85 (95%CI: 0.82-0.88). Deeks' funnel plot asymmetry test (p = 0.70) suggested no potential publication bias.

CONCLUSION

long noncoding RNA Metastasis-associated lung adenocarcinoma transcript 1 might be a usable biomarker for cancer diagnosis and detection.

Long Noncoding RNA PRRG4-4 Promotes Viability, Cell Cycle, Migration, and Invasion in Lung Cancer Cells

There is a perception that long noncoding RNA (lncRNA) has relationship with carcinogenesis. Many studies have previously identified and validated that the section of chromosome 11p13 is associated with high incidence of tumor. In this study, we investigated a new lncRNA, named lncPRRG4-4, mapped to 11p13 and suspected that lncPRRG4-4 was a potential lung cancer-related gene. To explore its role in carcinogenesis, we first demonstrated that lncPRRG4-4 was upregulated in lung cancer tissues compared with adjacent nontumor tissues and functioned as an oncogene in lung cancer cells. The lncPRRG4-4 was significantly upregulated in lung cancer tissues compared with adjacent normal counterparts (mean ± standard deviation: 0.12 ± 0.84 vs. 0.05 ± 0.22; p < 0.001). Patients with metastasis exhibited high levels of lncPRRG4-4 expression than those without metastasis in both the southern samples (p = 0.045) and eastern samples (p = 0.030), total samples (p = 0.004). In addition, downregulation of lncPRRG4-4 expression inhibited lung cancer proliferation, viability, migration, and invasion ability, arrested cell cycle, facilitated apoptosis, and vice versa. Taken together, these observations suggested that the lncPRRG4-4 functions as an oncogene in lung cancer cells.

MALAT1: A long non-coding RNA highly associated with human cancers

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a well-known lncRNA associated with numerous diseases, particularly cancer, has received increased attention. The expression of MALAT1 was determined to be upregulated in numerous types of tumors and MALAT1 exhibited effects on tumor cell proliferation, migration, invasion and apoptosis. The abnormal expression of MALAT1 was identified in almost in every organ of the digestive system. MALAT1 performed an important role in the pathological alterations of organs that are associated with sex hormones and several reproductive system cancers. MALAT1 participates in molecular pathways. In the clinical application of MALAT1, MALAT1 was considered as a potential biomarker for the diagnosis and prediction of cancers, and may also serve as therapeutic target for treatment of specific tumors. This review summarizes the abnormal expression of MALAT1 in cancer, its significant effect on the primary features of cancer, as well as the underlying molecular mechanisms of MALAT1 in various cancers. According to studies on MALAT1, we introduce the upstream and downstream substances associated with the function of MALAT1. These reviewed studies promote the clinical application of MALAT1 in the aspect of diagnosis and treatment of different cancers, and may help point out new study directions for MALAT1.

Long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 promotes lung adenocarcinoma by directly interacting with specificity protein 1

Metastasis-associated lung adenocarcinoma transcript 1 (malat1) is an oncogenic long non-coding RNA (lncRNA) which has been proven to be associated with various types of tumors. Transcription factor specificity protein 1 (SP1) is overexpressed in many types of cancers. Previously, we observed that malat1 expression level is regulated by SP1 in lung cancer. In the present study, we found that transfection of expression construct of malat1 5' end fragment M5 enhances stability and transcriptional activity of SP1. Various SP1 target genes are also upregulated following overexpression of malat1 M5 in lung adenocarcinoma cells. We also showed that malat1 M5 interacts with the C-terminal domain of SP1 by RNA immunoprecipitation (RIP) assay coupled with UV cross-linking. Malat1-SP1 association results in increase of SP1 stability. In turn, SP1 promotes malat1 transcription, thus forming a positive feedback loop. In conclusion, our data show that in lung adenocarcinoma cells, malat1 interacts with SP1 protein and promotes SP1-mediated transcriptional regulation of SP1 target genes.

MicroRNA-22 suppresses the growth, migration and invasion of colorectal cancer cells through a Sp1 negative feedback loop

MicroRNAs have recently emerged as regulators of many biological processes including cell proliferation, development and differentiation. This study identified that miR-22 was statistically decreased in colorectal cancer clinical specimens and highly metastatic cell lines. Moreover, low miR-22 expression was associated with tumor metastasis, advanced clinical stage and relapse. Consistent with clinical observations, miR-22 significantly suppressed the ability of colorectal cancer cells to growth and metastasize in vitro and in vivo. Sp1 was validated as a target of miR-22, and ectopic expression of Sp1 compromised the inhibitory effects of miR-22. In addition, Sp1 repressed miR-22 transcription by binding to the miR-22 promoter, hence forming a negative feedback loop. Further study has shown that miR-22 suppresses the activity of PTEN/AKT pathway by Sp1. Our present results implicate the newly indentified miR-22/Sp1/PTEN/AKT axis might represent a potential therapeutic target for colorectal cancer.

Role of metastasis-associated lung adenocarcinoma transcript-1 (MALAT-1) in pancreatic cancer

Metastasis-associated lung adenocarcinoma transcript-1 (MALAT-1) is a long non-coding RNA (lncRNA) that is a negative prognostic factor for patients with pancreatic cancer and several other tumors. In this study, we show that knockdown of MALAT-1 in Panc1 and other pancreatic cancer cell lines decreases cell proliferation, survival and migration. We previously observed similar results for the lncRNAs HOTTIP and HOTAIR in Panc1 cells; however, RNAseq comparison of genes regulated by MALAT-1 shows minimal overlap with HOTTIP/HOTAIR-regulated genes. Analysis of changes in gene expression after MALAT-1 knockdown shows that this lncRNA represses several tumor suppressor-like genes including N-myc downregulated gene-1 (NDRG-1), a tumor suppressor in pancreatic cancer that is also corepressed by EZH2 (a PRC2 complex member). We also observed that Specificity proteins Sp1, Sp3 and Sp4 are overexpressed in Panc1 cells and Sp knockdown or treatment with small molecules that decrease Sp proteins expression also decrease MALAT-1 expression. We also generated Kras-overexpressing p53L/L;LSL-KrasG12DL/+;p48Cre+/- (p53L/L/KrasG12D) and p53L/+;LSLKrasG12DL/+;p48Cre+/- (p53L/+/KrasG12D) mice which are p53 homo- and heterozygous, respectively. These mice rapidly develop pancreatic ductal adenocarcinoma-like tumors and were crossed with MALAT-1-/- mice. We observed that the loss of one or two MALAT-1 alleles in these Ras overexpressing mice does not significantly affect the time to death; however, the loss of MALAT-1 in the p53-/+ (heterozygote) mice slightly increases their lifespan.

Nuclear Long Noncoding RNAs: Key Regulators of Gene Expression

A significant portion of the human genome encodes genes that transcribe long nonprotein-coding RNAs (lncRNAs). A large number of lncRNAs localize in the nucleus, either enriched on the chromatin or localized to specific subnuclear compartments. Nuclear lncRNAs participate in several biological processes, including chromatin organization, and transcriptional and post-transcriptional gene expression, and also act as structural scaffolds of nuclear domains. Here, we highlight recent studies demonstrating the role of lncRNAs in regulating gene expression and nuclear organization in mammalian cells. In addition, we update current knowledge about the involvement of the most-abundant and conserved lncRNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), in gene expression control.

Recent advances in nanomedicine and survivin targeting in brain cancers

Brain cancer is a highly lethal disease, especially devastating toward both the elderly and children. This cancer has no therapeutics available to combat it, predominately due to the blood-brain barrier (BBB) preventing treatments from maintaining therapeutic levels within the brain. Recently, nanoparticle technology has entered the forefront of cancer therapy due to its ability to deliver therapeutic effects while potentially passing physiological barriers. Key nanoparticles for brain cancer treatment include glutathione targeted PEGylated liposomes, gold nanoparticles, superparamagnetic iron oxide nanoparticles and nanoparticle-albumin bound drugs, with these being discussed throughout this review. Recently, the survivin protein has gained attention as it is over-expressed in a majority of tumors. This review will briefly discuss the properties of survivin, while focusing on how both nanoparticles and survivin-targeting treatments hold potential as brain cancer therapies. This review may provide useful insight into new brain cancer treatment options, particularly survivin inhibition and nanomedicine.

Oct4 transcriptionally regulates the expression of long non-coding RNAs NEAT1 and MALAT1 to promote lung cancer progression

BACKGROUND

Oct4, a key stemness transcription factor, is overexpressed in lung cancer. Here, we reveal a novel transcription regulation of long non-coding RNAs (lncRNAs) by Oct4. LncRNAs have emerged as important players in cancer progression.

METHODS

Oct4 chromatin-immunoprecipitation (ChIP)-sequencing and several lncRNA databases with literature annotation were integrated to identify Oct4-regulated lncRNAs. Luciferase activity, qRT-PCR and ChIP-PCR assays were conducted to examine transcription regulation of lncRNAs by Oct4. Reconstitution experiments of Oct4 and downstream lncRNAs in cell proliferation, migration and invasion assays were performed to confirm the Oct4-lncRNAs signaling axes in promoting lung cancer cell growth and motility. The expression correlations between Oct4 and lncRNAs were investigated in 124 lung cancer patients using qRT-PCR analysis. The clinical significance of Oct4/lncRNAs signaling axes were further evaluated using multivariate Cox regression and Kaplan-Meier analyses.

RESULTS

We confirmed that seven lncRNAs were upregulated by direct binding of Oct4. Among them, nuclear paraspeckle assembly transcript 1 (NEAT1), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and urothelial carcinoma-associated 1 (UCA1) were validated as Oct4 transcriptional targets through promoter or enhancer activation. We showed that lung cancer cells overexpressing NEAT1 or MALAT1 and the Oct4-silenced cells reconstituted with NEAT1 or MALAT1 promoted cell proliferation, migration and invasion. In addition, knockdown of NEAT1 or MALAT1 abolished Oct4-mediated lung cancer cell growth and motility. These cell-based results suggested that Oct4/NEAT1 or Oct4/MALAT1 axis promoted oncogenesis. Clinically, Oct4/NEAT1/MALAT1 co-overexpression was an independent factor for prediction of poor outcome in 124 lung cancer patients.

CONCLUSIONS

Our study reveals a novel mechanism by which Oct4 transcriptionally activates NEAT1 via promoter and MALAT1 via enhancer binding to promote cell proliferation and motility, and led to lung tumorigenesis and poor prognosis.

[Comprehensive Identification of MicroRNAs Regulated by Long Non-coding RNA MALAT1]

BACKGROUND

Long non-coding RNA (lncRNA) plays important regulatory roles in the development and invasion of various cancers. The aim of current study is to comprehensively identify microRNAs (miRNA) regulated by lncRNA MALAT1 via experimental and bioinformatics methods.

METHODS

Antisense oligonucleotides (ASO) specifically targeting MALAT1 were designed and synthesized. After knockdown of MALAT1 by ASO in A549 cells, miRNA expression changes were profiled by TqaMan Low Density Array (TLDA). Gene set enrichment analysis (GSEA) was used to search enriched miRNAs among differentially expressed genes after knockdown of MALAT1.

RESULTS

After efficient knockdown of MALAT1 by ASO, 153 miRNAs were differentially expressed, 131 up-regulated and 22 down-regulated. Among the 458 differentially expressed genes after MALAT1 silence, GSEA results revealed lots of enriched miRNAs. There were 28 overlapped miRNAs between TLDA and GSEA results, suggesting these 28 miRNAs are regulated by MALAT1.

CONCLUSIONS

This study comprehensively identified MALAT1 regulated miRNAs, providing resources for further research.

Disrupting MALAT1/miR-200c sponge decreases invasion and migration in endometrioid endometrial carcinoma

Endometrioid endometrial carcinoma (EEC) is the most common gynecologic malignancy around the world. Epithelial-to-mesenchymal transition (EMT) is a core process during EEC cell invasion. The abnormal expression of the long noncoding RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) or miR-200 family members were shown to facilitate EMT in multiple human cancers, but the regulatory mechanism by which MALAT1 and miR-200 act remains unknown. Previous studies have shown that miR-200 family members are enriched in EEC as well as melanoma and some ovarian carcinomas. In the present study, we first showed that miR-200c levels were higher in most EEC specimens than in non-tumor tissues, while MALAT1 levels were lower. Moreover, we found that miR-200c bound directly to MALAT1 using luciferase reporter and qRT-PCR assays. MALAT1 and miR-200c are reciprocally repressed, and TGF-β increased MALAT1 expression by inhibiting miR-200c. When the interaction between miR-200c/MALAT1 was interrupted, the invasive capacity of EEC cells was decreased and EMT markers expression were altered in vitro. A xenograft tumor model was used to show that targeting the miR-200c/MALAT1 axis inhibited EEC growth and EMT-associated protein expression in vivo. In summary, miR-200c/MALAT1 axis is a target with therapeutic potential in EEC. However, different expression model of miR-200c and MALAT1 in EEC with that in other organ carcinomas needs further mechanism researches.

Long noncoding RNA MALAT1 can serve as a valuable biomarker for prognosis and lymph node metastasis in various cancers: a meta-analysis

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a newly discovered long intergenic noncoding RNA (lincRNA), has been reported to be aberrantly expressed in various cancers, and may serve as a novel potential biomarker for cancer prognosis. This meta-analysis was conducted to investigate the effects of MALAT1 on cancer prognosis and lymph node metastasis.

METHODS

A quantitative meta-analysis was performed using a systematic search of PubMed, Medline and Web of Science databases to identify eligible papers on prognostic value of MALAT1 in cancers. The pooled hazard ratios (HRs) or odds ratios (OR) with a 95 % confidence interval (95 % Cl) were calculated to evaluate its prognostic value.

RESULTS

A total of 2094 patients from 17 studies between 2003 and 2016 were included. The results revealed that elevated MALAT1 expression was significantly associated with poor overall survival (OS) in 11 types of cancers (HR = 1.91, 95 % CI 1.49-2.34). Furthermore, subgroup analysis indicated that region of study (Germany, Japan or China), cancer type (digestive system cancers, urinary system cancers or respiratory system cancers) and sample size (more or less than 100) did not alter the significant predictive value of MALAT1 in OS from various types of cancer. In addition, upregulation of MALAT1 expression was significantly associated with poor disease-free survival (HR = 2.29, 95 % CI 1.24-3.35), and recurrence-free survival (HR = 2.09, 95 % CI 0.81-3.37). The results showed that the incidence of lymph node metastasis was higher in high MALAT1 expression group than that in low MALAT1 expression group (OR = 1.67, 95 % CI 1.30-2.15).

CONCLUSIONS

This meta-analysis revealed that elevated MALAT1 expression may serve as a novel predictive biomarker for poor survival and lymph node metastasis in different types of cancer.

MALAT1 functions as a competing endogenous RNA to mediate Rac1 expression by sequestering miR-101b in liver fibrosis

Emerging evidence shows that Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) plays a pivotal role in cell proliferation, migration, and invasion in tumors. However, the biological role and underlying mechanism of MALAT1 in liver fibrosis remains undefined. In this study, up-regulation of MALAT1 was observed in fibrotic liver tissues and in activated hepatic stellate cells (HSCs). In addition, depletion of MALAT1 inhibited the activation of HSCs in vitro and attenuated collagen deposits in vivo. Our results demonstrated that MALAT1 expression is negatively correlated with microRNA-101b (miR-101b) expression. Furthermore, there was a negative feedback loop between the levels of MALAT1 and miR-101b. Luciferase reporter assay indicated that MALAT1 and RAS-related C3 botulinum substrate 1 (Rac1) are targets of miR-101b. We uncovered that MALAT1 regulates Rac1 expression through miR-101b as a competing endogenous RNA (ceRNA), thereby influencing the proliferation, cell cycle and activation of primary HSCs. Collectively, The ceRNA regulatory network may prompt a better understanding of liver fibrogenesis and contribute to a novel therapeutic strategy for liver fibrosis.

Hypoxic Preconditioning Inhibits Hypoxia-induced Apoptosis of Cardiac Progenitor Cells via the PI3K/Akt-DNMT1-p53 Pathway

Research has demonstrated that hypoxic preconditioning (HP) can enhance the survival and proliferation of cardiac progenitor cells (CPCs); however, the underlying mechanisms are not fully understood. Here, we report that HP of c-kit (+) CPCs inhibits p53 via the PI3K/Akt-DNMT1 pathway. First, CPCs were isolated from the hearts of C57BL/6 mice and further purified by magnetic-activated cell sorting. Next, these cells were cultured under either normoxia (H0) or HP for 6 hours (H6) followed by oxygen-serum deprivation for 24 hours (24h). Flow cytometric analysis and MTT assays revealed that hypoxia-preconditioned CPCs exhibited an increased survival rate. Western blot and quantitative real-time PCR assays showed that p53 was obviously inhibited, while DNMT1 and DNMT3β were both significantly up-regulated by HP. Bisulphite sequencing analysis indicated that DNMT1 and DNMT3β did not cause p53 promoter hypermethylation. A reporter gene assay and chromatin immunoprecipitation analysis further demonstrated that DNMT1 bound to the promoter locus of p53 in hypoxia-preconditioned CPCs. Together, these observations suggest that HP of CPCs could lead to p53 inhibition by up-regulating DNMT1 and DNMT3β, which does not result in p53 promoter hypermethylation, and that DNMT1 might directly repress p53, at least in part, by binding to the p53 promoter locus.

miRNA-223 inhibits epithelial-mesenchymal transition in gastric carcinoma cells via Sp1

Sp1 plays critical roles in epithelial-mesenchymal transition (EMT) of certain cancer. However, few studies have indicated whether Sp1 is involved in the EMT of gastric cancer, and whether abnormal expression of Sp1 in gastric cancer EMT is regulated in a post-transcriptional manner, and the involvement of miRNAs in this regulation. In this study, we selected 20 cases of gastric cancers, their liver metastases and para-carcinoma tissues to examine the levels of Sp1 protein and mRNA by immunohistochemistry and fluorescent PCR, which showed that Sp1 was increased in gastric cancers and their metastases compared with adjacent tissues, but there was no difference in Sp1 mRNA between these three groups, suggesting changes in Sp1 may be attributed to inactivation of post-transcriptional regulation. We verified by a luciferase reporter system that miRNA-223 binds to 3'-UTR of Sp1 gene and inhibits its translation, in agreement with negative correlation between miRNA-223 and Sp1 protein levels in gastric cancer cells. By employing TGF-β1 to induce MGC-803, BGC-823 and SGC-7901, we successfully built cellular EMT model. Then, we overexpressed miRNA-223 in the model by using a lentiviral system, which diminished EMT indicators and suppressed proliferation and invasion ability, and induced apoptosis. Finally, we verified the specificity of the regulation pathway miRNA-223/Sp1/EMT. These findings suggest that low expression of miRNA-223 in gastric cancer cells is an important cause for EMT. miRNA-223 specifically regulates the EMT process of gastric cancer cells through its target gene Sp1. Overexpression of miRNA-223 in these cells inhibits EMT via the miRNA-223/Sp1/EMT pathway.

Ginsenoside Rg3 induces FUT4-mediated apoptosis in H. pylori CagA-treated gastric cancer cells by regulating SP1 and HSF1 expressions

Helicobacter pylori (H. pylori) cytotoxin associated antigen A (CagA) plays a significant role in the development of gastric cancer. Ginsenoside Rg3 is a herbal medicine which inhibits cell proliferation and induces apoptosis in various cancer cells. Fucosylation plays important roles in cancer biology as increased fucosylation levels of glycoproteins and glycolipids have been reported in many cancers. Fucosyltransferase IV (FUT4) is an essential enzyme, catalyzes the synthesis of LewisY oligosaccharides and is regulated by specificity protein 1 (SP1) and heat shock factor protein 1 (HSF1) transcription factors. Herein, we studied the mechanism action of Rg3 apoptosis induction in gastric cancer cells. We treated the gastric cancer cells with CagA followed by Rg3, and analyzed their ability to induce apoptosis by evaluating the role of FUT4 as well as SP1 and HSF1 expressions by Western blot, flow cytometry and ELISA. We found that Rg3 significantly induced apoptosis in CagA treated gastric cancer cells, as evidenced by nuclear staining of 4-6-diamidino-2-phenylindole (DAPI) and Annexin-V/PI double-labeling. In addition, Rg3 significantly increased the expression of pro-apoptotic proteins and triggered the activation of caspase-3, -8, and -9 and PARP. Moreover, Rg3-induced apoptotic mechanisms indicated that Rg3 inhibited FUT4 expression through SP1 upregulation and HSF1 downregulation. Hence, Rg3 therapy is an effective strategy for gastric cancer treatment. Furthermore SP1 and HSF1 may serve as potential diagnostic and therapeutic targets for gastric cancer.

Transcription Factor Sp1 Promotes the Expression of Porcine ROCK1 Gene

Rho-associated, coiled-coil containing protein kinase 1 (ROCK1) gene plays a crucial role in maintaining genomic stability, tumorigenesis and myogenesis. However, little is known about the regulatory elements governing the transcription of porcine ROCK1 gene. In the current study, the transcription start site (TSS) was identified by 5'-RACE, and was found to differ from the predicted one. The region in ROCK1 promoter which is critical for promoter activity was investigated via progressive deletions. Site-directed mutagenesis indicated that the region from -604 to -554 bp contains responsive elements for Sp1. Subsequent experiments showed that ROCK1 promoter activity is enhanced by Sp1 in a dose-dependent manner, whereas treatment with specific siRNA repressed ROCK1 promoter activity. Electrophoretic mobility shift assay (EMSA), DNA pull down and chromatin immunoprecipitation (ChIP) assays revealed Sp1 can bind to this region. qRT-PCR and Western blotting research followed by overexpression or inhibition of Sp1 indicate that Sp1 can affect endogenous ROCK1 expression at both mRNA and protein levels. Overexpression of Sp1 can promote the expression of myogenic differentiation 1(MyoD), myogenin (MyoG), myosin heavy chain (MyHC). Taken together, we conclude that Sp1 positively regulates ROCK1 transcription by directly binding to the ROCK1 promoter region (from -604 to -532 bp) and may affect the process of myogenesis.

Prognostic value of long non-coding RNA MALAT1 in cancer patients

Metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) was identified to be the first long non-coding RNA as a biomarker of independent prognostic value for early stage non-small cell lung cancer patient survival. In recent years, the association between upregulated tissue MALAT1 level and incidence of various cancers including bladder cancer, colorectal cancer, and renal cancer has been widely discussed. The aim of our present study was to assess the potential prognostic value of MALAT1 in various human cancers. PubMed, Embase, Ovid, and Cochrane Library databases were systematically searched, and eligible studies evaluating the prognostic value of MALAT1 in various cancers were included. Finally, 11 studies encompassing 1216 participants reporting with sufficient data were enrolled in the current meta-analysis. The pooled hazard ratio (HR) was 2.05 (95 % confidence interval (CI) 1.64-2.55, p < 0.01) for overall survival (OS) and 2.66 (95 % CI 1.86-3.80, p < 0.01) for disease-free survival (DFS). In conclusion, high tissue MALAT1 level was associated with an inferior clinical outcome in various cancers, suggesting that MALAT1 might serve as a potential prognostic biomarker for various cancers.

The Malat1 long non-coding RNA is upregulated by signalling through the PERK axis of unfolded protein response during flavivirus infection

Flavivirus infection causes host cell death by initiation of an unfolded protein response (UPR). UPR is initiated following activation of three ER-membrane resident sensors, PERK, IRE1α and ATF6, which are otherwise kept inactive through association with the ER-chaperone GRP78. Activation precedes cellular and molecular changes that act to restore homeostasis but might eventually initiate apoptosis. These changes involve influencing function of multiple genes by either transcriptional or post-transcriptional or post-translational mechanisms. Transcriptional control includes expression of transcription factor cascades, which influence cognate gene expression. Malat1 is a long non-coding RNA which is over-expressed in many human oncogenic tissues and regulates cell cycle and survival. In this report, for the first time we show activation of Malat1 following infection by two flaviviruses, both of which activate the UPR in host cells. The temporal kinetics of expression was restricted to later time points. Further, Malat1 was also activated by pharmacological inducer of UPR, to a similar degree. Using drugs that specifically inhibit or activate the PERK or IRE1α sensors, we demonstrate that signalling through the PERK axis activates this expression, through a transcriptional mechanism. To our knowledge, this is the first report of an UPR pathway regulating the expression of an lncRNA.