A FOXM1 related long non-coding RNA contributes to gastric cancer cell migration. Mol Cell Biochem. 2015;406:31-41. [PMID: 25907137 DOI: 10.1007/s11010-015-2421-3]

A new tandem repeat-enriched lncRNA XLOC_008672 promotes gastric carcinogenesis by regulating G3BP1 expression

Aberrant expression of forkhead box transcription factor 1 (FOXM1) plays critical roles in a variety of human malignancies and predicts poor prognosis. However, little is known about the crosstalk between FOXM1 and long noncoding RNAs (lncRNAs) in tumorigenesis. The present study identifies a previously uncharacterized lncRNA XLOC_008672 in gastric cancer (GC), which is regulated by FOXM1 and possesses multiple copies of tandem repetitive sequences. LncRNA microarrays are used to screen differentially expressed lncRNAs in FOXM1 knockdown GC cells, and then the highest fold downregulation lncRNA XLOC_008672 is screened out. Sequence analysis reveals that the new lncRNA contains 62 copies of 37-bp tandem repeats. It is transcriptionally activated by FOXM1 and functions as a downstream effector of FOXM1 in GC cells through in vitro and in vivo functional assays. Elevated expression of XLOC_008672 is found in GC tissues and indicates worse prognosis. Mechanistically, XLOC_008672 can bind to small nuclear ribonucleoprotein polypeptide A (SNRPA), thereby enhancing mRNA stability of Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) and, consequently, facilitating GC cell proliferation and migration. Our study discovers a new uncharacterized lncRNA XLOC_008672 involved in GC carcinogenesis and progression. Targeting FOXM1/XLOC_008672/SNRPA/G3BP1 signaling axis might be a promising therapeutic strategy for GC.

Targeting lncRNAs of colorectal cancers with natural products

Non-coding RNA (ncRNA) is one of the functional classes of RNA that has a regulatory role in various cellular processes, such as modulation of disease onset, progression, and prognosis. ncRNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), have been actively studied in recent years. The change in ncRNA levels is being actively studied in numerous human diseases, especially auto-immune disorders and cancers; however, targeting and regulating ncRNA with natural products to cure cancer has not been fully established. Recently many groups reported the relationship between ncRNA and natural products showing promising effects to serve as additional therapeutic approaches to cure cancers. This mini-review summarizes the aspects of lncRNAs related to cancer biology focusing on colorectal cancers that natural products can target.

Exosomal long non-coding RNAs: novel molecules in gastrointestinal cancers' progression and diagnosis

Gastrointestinal (GI) cancers arise in the GI tract and accessory organs, including the mouth, esophagus, stomach, liver, biliary tract, pancreas, small intestine, large intestine, and rectum. GI cancers are a major cause of cancer-related morbidity and mortality worldwide. Exosomes act as mediators of cell-to-cell communication, with pleiotropic activity in the regulation of homeostasis, and can be markers for diseases. Non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs), can be transported by exosomes derived from tumor cells or non-tumor cells. They can be taken by recipient cells to alter their function or remodel the tumor microenvironment. Moreover, due to their uniquely low immunogenicity and excellent stability, exosomes can be used as natural carriers for therapeutic ncRNAs in vivo. Exosomal lncRNAs have a crucial role in regulating several cancer processes, including angiogenesis, proliferation, drug resistance, metastasis, and immunomodulation. Exosomal lncRNA levels frequently alter according to the onset and progression of cancer. Exosomal lncRNAs can therefore be employed as biomarkers for the diagnosis and prognosis of cancer. Exosomal lncRNAs can also monitor the patient's response to chemotherapy while also serving as potential targets for cancer treatment. Here, we discuss the role of exosomal lncRNAs in the biology and possible future treatment of GI cancer.

Oncogenic Role of Exosomal Circular and Long Noncoding RNAs in Gastrointestinal Cancers

Circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs) are differentially expressed in gastrointestinal cancers. These noncoding RNAs (ncRNAs) regulate a variety of cellular activities by physically interacting with microRNAs and proteins and altering their activity. It has also been suggested that exosomes encapsulate circRNAs and lncRNAs in cancer cells. Exosomes are then discharged into the extracellular environment, where they are taken up by other cells. As a result, exosomal ncRNA cargo is critical for cell-cell communication within the cancer microenvironment. Exosomal ncRNAs can regulate a range of events, such as angiogenesis, metastasis, immune evasion, drug resistance, and epithelial-to-mesenchymal transition. To set the groundwork for developing novel therapeutic strategies against gastrointestinal malignancies, a thorough understanding of circRNAs and lncRNAs is required. In this review, we discuss the function and intrinsic features of oncogenic circRNAs and lncRNAs that are enriched within exosomes.

Targeting long non coding RNA by natural products: Implications for cancer therapy

In spite of achieving substantial progress in its therapeutic strategies, cancer-associated prevalence and mortality are persistently rising globally. However, most malignant cancers either cannot be adequately diagnosed at the primary phase or resist against multiple treatments such as chemotherapy, surgery, radiotherapy as well as targeting therapy. In recent decades, overwhelming evidences have provided more convincing words on the undeniable roles of long non-coding RNAs (lncRNAs) in incidence and development of various cancer types. Recently, phytochemical and nutraceutical compounds have received a great deal of attention due to their inhibitory and stimulatory effects on oncogenic and tumor suppressor lncRNAs respectively that finally may lead to attenuate various processes of cancer cells such as growth, proliferation, metastasis and invasion. Therefore, application of phytochemicals with anticancer characteristics can be considered as an innovative approach for treating cancer and increasing the sensitivity of cancer cells to standard prevailing therapies. The purpose of this review was to investigate the effect of various phytochemicals on regulation of lncRNAs in different human cancer and evaluate their capabilities for cancer treatment and prevention.

Expression and mechanism of exosome-mediated A FOXM1 related long noncoding RNA in gastric cancer

BACKGROUND

Forkhead box protein M1 (FOXM1) is an oncogene regulating tumor growth and metastasis. Exosome was suggested to mediate cell communication by delivering active molecules in cancers. However, the existence of FOXM1 in circulating exosomes and the role of exosome FOXM1 in gastric cancer (GC) were not clear. This study aims to investigate the potential role of FOXM1 related long noncoding RNA (FRLnc1) in exosomes in GC.

RESULTS

The prepared CD63 immunomagnetic beads (CD63-IMB) had the characteristics of good dispersity and high magnetic response. The isolated exosomes were presented with elliptical membranous particles under a transmission electron microscope (TEM), with the particle size of 89.78 ± 4.8 nm. Western blot (WB) results showed that the exosomes were rich in CD9 and CD81. The Dil-labeled exosomes were distributed around cytoplasm and nucleus of cells by imaging flow cytometry (IFC) analysis. The results of quantitative real-time PCR (qRT-PCR) revealed that the FRLnc1 expressions were up-regulated in GC cells, tumor tissues, and serum of GC patients. An obviously up-regulated FRLnc1 expression was found in serum exosomes of GC patients. Up-regulation of FRLnc1 expression was closely correlated to lymph node metastasis (LNM) and TNM stage with the combination of relevant clinicopathological parameter analysis. The in vitro functional analyses demonstrated that FRLnc1 knockdown by RNA interference suppressed cell proliferation and migration in HGC-27 cells, whereas FRLnc1 overexpression promoted cell proliferation and migration in MKN45 cells. After exosome treatment, the FRLnc1 expression was significantly increased in MKN45 cells, and the MKN45 cells showed increased ability of proliferation and migration.

CONCLUSION

GC cells-derived exosomes played roles in promoting the growth and metastasis of GC by transporting FRLnc1, suggesting that FRLnc1 in the exosomes may be a potential biomarker for the diagnosis and treatment of GC. The delivery of FRLnc1 by the exosomes may provide a new way for the treatment of GC. Trial registration 2020-KYSB-094. Registered 23 March 2020-Retrospectively registered.

FOXM1-induced miR-552 expression contributes to pancreatic cancer progression by targeting multiple tumor suppressor genes

Dysregulation of microRNAs (miRNAs) plays important roles during carcinogenesis. Forkhead box M1 (FOXM1), a well-known oncogenic transcription factor, has been implicated in the progression of multiple cancer types. To find out FOXM1-induced abnormal miRNAs in pancreatic cancer, we analyzed TCGA database and figured out miR-552 as the most relevant miRNA with FOXM1. Molecular experimental results demonstrated that FOXM1 transcriptionally activated miR-552 expression by directly binding to the promoter region of miR-552. In a pancreatic cancer tissue microarray, miR-552 expression was positively correlated with FOXM1 and high expression of miR-552 could predict poor patient outcome. Functionally, overexpression of miR-552 promoted pancreatic cancer cell migration and inhibition of miR-552 attenuated this phenotype. The inhibitory effect on cell migration caused by FOXM1 knockdown could be restored by exogenous expression of miR-552. By informatics analysis, we identified three tumor suppressor genes: DACH1, PCDH10 and SMAD4, all of which were negatively associated with FOXM1 and validated as functionally relevant targets of miR-552. Taken together, our findings provide a new FOXM1-miR-552-DACH1/PCDH10/SMAD4 axis to regulate pancreatic cancer cell progression and new opportunities for therapeutic intervention against this disease.

Fork head box M1 regulates vascular endothelial growth factor-A expression to promote the angiogenesis and tumor cell growth of gallbladder cancer

BACKGROUND

Gallbladder cancer (GBC) is an aggressive type of biliary tract cancer that lacks effective therapeutic targets. Fork head box M1 (FoxM1) is an emerging molecular target associated with tumor progression in GBC, and accumulating evidence suggests that vascular endothelial growth factor (VEGF) promotes various tumors by inducing neoangiogenesis.

AIM

To investigate the role of FoxM1 and the angiogenesis effects of VEGF-A in primary GBC.

METHODS

Using immunohistochemistry, we investigated FoxM1 and VEGF-A expression in GBC tissues, paracarcinoma tissues and cholecystitis tissues. Soft agar, cell invasion, migration and apoptosis assays were used to analyze the malignant phenotype influenced by FoxM1 in GBC. Kaplan-Meier survival analysis was performed to evaluate the impact of FoxM1 and VEGF-A expression in GBC patients. We investigated the relationship between FoxM1 and VEGF-A by regulating the level of FoxM1. Next, we performed MTT assays and Transwell invasion assays by knocking out or overexpressing VEGF-A to evaluate its function in GBC cells. The luciferase assay was used to reveal the relationship between FoxM1 and VEGF-A. BALB/c nude mice were used to establish the xenograft tumor model.

RESULTS

FoxM1 expression was higher in GBC tissues than in paracarcinoma tissues. Furthermore, the high expression of Foxm1 in GBC was significantly correlated with a malignant phenotype and worse overall survival. Meanwhile, high expression of FoxM1 influenced angiogenesis; high expression of FoxM1 combined with high expression of VEGF-A was related to poor prognosis. Attenuated FoxM1 significantly suppressed cell proliferation, transfer and invasion in vitro. Knockdown of FoxM1 in GBC cells reduced the expression of VEGF-A. Luciferase assay showed that FoxM1 was the transcription factor of VEGF-A, and knockdown VEGF-A in FoxM1 overexpressed cells could partly reverse the malignancy phenotype of GBC cells. In this study, we found that FoxM1 was involved in regulation of VEGF-A expression.

CONCLUSION

FoxM1 and VEGF-A overexpression were associated with the prognosis of GBC patients. FoxM1 regulated VEGF-A expression, which played an important role in the progression of GBC.

The Long Non-coding RNAs: Paramount Regulators of the NLRP3 Inflammasome

The NOD LRR pyrin domain containing protein 3 (NLRP3) inflammasome is a cytosolic multi-proteins conglomerate with intrinsic ATPase activity. Their predominant presence in the immune cells emphasizes its significant role in immune response. The downstream effector proteins IL-1β and IL-18 are responsible for the biological functions of the NLRP3 inflammasome upon encountering the alarmins and microbial ligands. Although the NLRP3 inflammasome is essential for host defense during infections, uncontrolled activation and overproduction of IL-1β and IL-18 increase the risk of developing autoimmune and metabolic disorders. Emerging evidences suggest the action of lncRNAs in regulating the activity of NLRP3 inflammasome in various disease conditions. The long non-coding RNA (lncRNA) is an emerging field of study and evidence on their regulatory role in various diseases is grabbing attention. Recent studies emphasize the functions of lncRNAs in the fine control of the NLRP3 inflammasome at nuclear and cytoplasmic levels by interfering in chromatin architecture, gene transcription and translation. Recently, lncRNAs are also found to control the activity of various regulators of NLRP3 inflammasome. Understanding the precise role of lncRNA in controlling the activity of NLRP3 inflammasome helps us to design targeted therapies for multiple inflammatory diseases. The present review is a novel attempt to consolidate the substantial role of lncRNAs in the regulation of the NLRP3 inflammasome. A deeper insight on the NLRP3 inflammasome regulation by lncRNAs will help in developing targeted and beneficial therapeutics in the future.

Competing Endogenous RNA Networks in the Epithelial to Mesenchymal Transition in Diffuse-Type of Gastric Cancer

Simple Summary

The diffuse-type of gastric cancer is associated with epithelial to mesenchymal transition. Loss of E-cadherin expression is the hallmark of this process and is largely due to the upregulation of the transcription factors ZEB1/2, Snail, Slug, and Twist1/2. However, miRNA and lncRNAs can also participate through these transcription factors which directly target E-cadherin. The competing endogenous RNA (ceRNA) network hypothesis state that lncRNA can sponge the miRNA pool that targets these transcripts. Based on the lack of said networks in the epithelial to mesenchymal transition, we performed a prediction analysis that resulted in novel ceRNA networks which will expand our knowledge of the molecular basis of the diffuse-type of gastric cancer.

Abstract

The diffuse-type of gastric cancer (DGC), molecularly associated with epithelial to mesenchymal transition (EMT), is increasing in incidence. Loss of E-cadherin expression is the hallmark of the EMT process and is largely due to the upregulation of the EMT-inducing transcription factors ZEB1/2, Snail, Slug, and Twist1/2. However, ncRNA, such as miRNA and lncRNAs, can also participate in the EMT process through the direct targeting of E-cadherin and other EMT-inducing transcription factors. Additionally, lncRNA can sponge the miRNA pool that targets these transcripts through competing endogenous RNA (ceRNA) networks. In this review, we focus on the role of ncRNA in the direct deregulation of E-cadherin, as well as EMT-inducing transcription factors. Based on the relevance of the ceRNA network hypothesis, and the lack of said networks in EMT, we performed a prediction analysis for all miRNAs and lncRNAs that target E-cadherin, as well as EMT-inducing transcription factors. This analysis resulted in novel predicted ceRNA networks for E-cadherin and EMT-inducing transcription factors (EMT-TFs), as well as the expansion of the molecular basis of the DGC.

FOXM1: a potential therapeutic target in human solid cancers

Introduction: FOXM1 is one of the most frequently overexpressed proteins in human solid cancers. Here, we discuss novel direct targets of FOXM1 as well as new pathways involving FOXM1, through which this protein exerts its oncogenic activity.Areas covered: We give a detailed review of FOXM1 transcriptional targets involved in 16 different types of human cancer as published in the literature in the last 5 years. We also discuss a novel positive feedback loop between FOXM1 and AKT - both well-established master regulators of cancer.Expert opinion: Despite the discovery of several FOXM1 inhibitors over the years (by our team and others), their therapeutic use is limited by their adverse off-target effects.Newly-discovered proteins regulated by FOXM1 present a promising alternative approach to target its pro-cancer activity. In addition, targeting regulating proteins that take part in the positive feedback loop between FOXM1/AKT has the double advantage of suppressing both, and can lead to developing novel anti-cancer drugs.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

Long non-coding RNA ZEB1-AS1 promotes colon adenocarcinoma malignant progression via miR-455-3p/PAK2 axis

Objective

The long non‐coding RNA zinc finger E‐box‐binding homeobox 1 antisense 1 (ZEB1‐AS1) acts as an oncogenic regulator in many human tumours. In the present study, we identify the role and potential molecular biological mechanisms of ZEB1‐AS1 in colon adenocarcinoma (COAD).

Methods

QRT‐PCR was used to detect the expression of ZEB1‐AS1, miR‐455‐3p and p21‐activated kinases 2 (PAK2) in COAD tissues. CCK8 assay, EdU assay, transwell assay and scratch wound assay were used to explore the biological function of ZEB1‐AS1 in COAD cells. Bioinformatics, luciferase reporter assays and an RNA pull‐down assay were used to demonstrate the mechanism of ZEB1‐AS1. We further explore the role of ZEB1‐AS1 in vivo though xenograft tumour assay.

Results

We found that ZEB1‐AS1 expression was significantly up‐regulated in COAD tissues, and high ZEB1‐AS1 level was correlated with the poor prognosis of COAD patients. MiR‐455‐3p plays an anti‐cancer role in COAD by targeting PAK2. We confirmed that ZEB1‐AS1 promotes PAK2 expression by sponging miR‐455‐3p, thus facilitating COAD cell growth and metastasis.

Conclusions

To sum up, this result illustrates the novel molecular mechanism of ZEB1‐AS1 in COAD and provides a new target for the diagnosis and treatment of COAD patients.

Phytochemicals as Modulators of Long Non-Coding RNAs and Inhibitors of Cancer-Related Carbonic Anhydrases

Long non-coding RNAs (lncRNAs) are classified as a group of transcripts which regulate various biological processes, such as RNA processing, epigenetic control, and signaling pathways. According to recent studies, lncRNAs are dysregulated in cancer and play an important role in cancer incidence and spreading. There is also an association between lncRNAs and the overexpression of some tumor-associated proteins, including carbonic anhydrases II, IX, and XII (CA II, CA IX, and CA XII). Therefore, not only CA inhibition, but also lncRNA modulation, could represent an attractive strategy for cancer prevention and therapy. Experimental studies have suggested that herbal compounds regulate the expression of many lncRNAs involved in cancer, such as HOTAIR (HOX transcript antisense RNA), H19, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), PCGEM1 (Prostate cancer gene expression marker 1), PVT1, etc. These plant-derived drugs or phytochemicals include resveratrol, curcumin, genistein, quercetin, epigallocatechin-3-galate, camptothcin, and 3,3'-diindolylmethane. More comprehensive information about lncRNA modulation via phytochemicals would be helpful for the administration of new herbal derivatives in cancer therapy. In this review, we describe the state-of-the-art and potential of phytochemicals as modulators of lncRNAs in different types of cancers.

Roles of E-cadherin and Noncoding RNAs in the Epithelial-mesenchymal Transition and Progression in Gastric Cancer

The epithelial–mesenchymal transition (EMT) is thought to be at the root of invasive and metastatic cancer cell spreading. E-cadherin is an important player in this process, which forms the structures that establish and maintain cell–cell interactions. A partial or complete loss of E-cadherin expression in the EMT is presumably mediated by mechanisms that block the expression of E-cadherin regulators and involve the E-cadherin-associated transcription factors. The protein is involved in several oncogenic signaling pathways, such as the Wnt/β-catenin, Rho GTPase, and EGF/EGFR, whereby it plays a role in many tumors, including gastric cancer. Such noncoding transcripts as microRNAs and long noncoding RNAs—critical components of epigenetic control of gene expression in carcinogenesis—contribute to regulation of the E-cadherin function by acting directly or through numerous factors controlling transcription of its gene, and thus affecting not only cancer cell proliferation and metastasis, but also the EMT. This review focuses on the role of E-cadherin and the non-coding RNAs-mediated mechanisms of its expressional control in the EMT during stomach carcinogenesis.

LONG-NONCODING RNAs in gastroesophageal cancers

Despite continuing improvements in multimodal therapies, gastro-esophageal malignances remain widely prevalent in the population and is characterized by poor overall and disease-free survival rates. Due to the lack of understanding about the pathogenesis and absence of reliable markers, gastro-esophageal cancers are associated with delayed diagnosis. The increasing understanding about cancer's molecular landscape in the recent years, offers the possibility of identifying 'targetable' molecular events and in particular facilitates novel treatment strategies and development of biomarkers for early stage diagnosis. At least 98% of our genome is actively transcribed into non-coding RNAs encompassing long non-coding RNAs (lncRNAs) constituted of transcripts longer than 200 nucleotides with no protein-coding capacity. Many studies have demonstrated that lncRNAs are functional genomic elements playing pivotal roles in main oncogenic processes. LncRNA can act at multiple levels developing a complex molecular network that can modulate directly or indirectly the expression of genes involved in tumorigenesis. In this review, we focus on lncRNAs as emerging players in gastro-esophageal carcinogenesis and critically assess their potential as reliable noninvasive biomarkers and in next generation targeted therapies.

Long non-coding RNAs involved in metastasis of gastric cancer

Gastric cancer (GC) is one of the most frequently diagnosed malignant diseases. The molecular mechanisms of metastasis remain unclear. Recently, studies have shown that long non-coding RNAs (lncRNAs) play critical roles in metastasis. Therefore, deeper understanding of this mechanism could provide potential diagnostic tools and therapeutic targets for metastatic GC. This review focuses on dysregulated lncRNAs in GC metastases. Due to the identification of multiple diverse mechanisms involved in GC metastasis, we classified them into seven categories, including lncRNAs related to epithelial-mesenchymal transition, regulation of degradation of extracellular matrix, angiopoiesis, vasculogenic mimicry, and immunologic escape. As the TNM stage is pivotal for evaluating the severity and prognosis of GC patients, we summarize the lncRNAs relevant to lymphatic metastasis, distant metastasis and TNM classification. This review summarizes the lncRNAs related to metastasis, which may provide insight into the mechanisms, and provide potential markers for prognostic prediction and monitoring the relapse of GC.

Long noncoding RNA CCAT1 acts as an oncogene and promotes chemoresistance in docetaxel-resistant lung adenocarcinoma cells

Chemoresistance remains one of the major obstacles in clinical treatment of lung adenocarcinoma (LAD). Indeed, docetaxel-resistant LAD cells present chemoresistance and epithelial-to-mesenchymal transition phenotypes. Long non-coding RNAs (lncRNAs) are known to promote tumorigenesis in many cancer types. Here, we showed that the lncRNA colon cancer-associated transcript-1 (CCAT1) was upregulated in docetaxel-resistant LAD cells. Furthermore, downregulation of CCAT1 decreased chemoresistance, inhibited proliferation, enhanced apoptosis and reversed the epithelial-to-mesenchymal transition phenotype of docetaxel-resistant LAD cells. We also found that the oncogenic function of CCAT1 in docetaxel-resistant LAD cells depended on the sponging of let-7c. In turn, the sponging of let-7c by CCAT1 released Bcl-xl (a let-7c target), thereby promoting the acquisition of chemoresistance and epithelial-to-mesenchymal transition phenotypes in docetaxel-resistant LAD cells. Our data reveal a novel pathway underlying chemoresistance and the epithelial-to-mesenchymal transition in docetaxel-resistant LAD cells.

α-Asarone suppresses the proliferation and migration of ASMCs through targeting the lncRNA-PVT1/miR-203a/E2F3 signal pathway in RSV-infected rats

Asthma is a chronic inflammatory pulmonary disease and respiratory syncytial virus (RSV) infection is a common cause of lower respiratory tract illness in infants and young children. α-Asarone presents many pharmacological effects and has been demonstrated to be useful in treating asthma. However, the functional mechanism of α-asarone in RSV-infected asthma has not been investigated. Long non-coding RNAs (lncRNAs) have been reported to play critical roles in many biological processes. Although many lncRNAs have been characterized, few were reported in asthma, especially in RSV-induced asthma. Currently, a novel post-transcriptional regulation has been proposed in which lncRNAs function as competing endogenous RNAs (ceRNAs) to competitively sponge miRNAs, thereby regulating the target genes. In the present study, we established an RSV-infected Sprague-Dawley rat model and demonstrated that lncRNA-PVT1 is involved in the mechanism of α-asarone in treating RSV-induced asthma, and lncRNA-PVT1 regulates the expression of E2F3 by functioning as a ceRNA which competitively sponges miR-203a.

Long Non-coding RNAs and their Role in Metastasis

The perception of long non-coding RNAs as chunk RNA and transcriptional noise has been steadily replaced by their role as validated targets for a diverse set of physiological processes in the past few years. However, for the vast majority of lncRNAs their precise mode of action and physiological function remain to be uncovered. A large body of evidence has revealed their essential role in all stages of cancirogenesis and metastasis. In this review we focus on the role of lncRNAs in metastasis. We grouped selected lncRNAs into three categories based on in vitro and in vivo mode of action-related studies and clinical relevance for metastasis. Grouped according to their mode of action, in category I we discuss lncRNAs such as CCAT2, DREH, LET, NKILA, treRNA, HOTAIR, H19, FENDRR, lincROR, MALAT, GClnc1, BCAR4, SCHLAP1 and lncRNA ATP, all lncRNAs with in vitro and in vivo metastasis-related data and clinical significance. In category II we discuss lncRNAs CCAT1, PCAT1, PTENgp1, GPLINC, MEG3, ZEB2-AS, LCT13, ANRIL, NBAT1 and lncTCF7 all characterized by their mode of action in vitro and clinical significance, but pending or preliminary in vivo data. Finally, under category III, we discuss lncRNAs BANCR, FRLnc1, SPRY4-IT1 and LIMT with partially or poorly-resolved mode of action and varying degree of validation in clinical metastasis. Finally we discuss metastasis-related translational aspects of lncRNAs.

Increased MIR31HG lncRNA expression increases gefitinib resistance in non-small cell lung cancer cell lines through the EGFR/PI3K/AKT signaling pathway

The aim of the present study was to gain insight into the molecular mechanism of gefitinib resistance in non-small cell lung cancer (NSCLC), and demonstrate whether long noncoding RNA (lncRNA) expression signatures differ between gefitinib-sensitive PC9 and gefitinib-resistant PC9 (PC9-R) cell lines. PC9 and PC9-R cells were treated with gefitinib and, after 48 h, proliferation and apoptosis were analyzed using a Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Microarray expression profiling of lncRNAs was undertaken in both PC9 and PC9-R cells, and the expression profiles were verified by reverse transcription quantitative-polymerase chain reaction. The EGFR/PI3K/AKT signaling pathway and mitochondrial apoptosis protein expression levels were assessed by western blot analysis. The PC9 cell line treated with gefitinib had a more significant effect on cell viability and apoptosis than the PC9-R cell line (P<0.05). Expression of various lncRNAs differed significantly between the two cell lines, and MIR31HG expression in particular was significantly higher in PC9-R cells. As expected, MIR31HG lncRNA knockdown sensitized PC9-R cells to gefitinib, and further experiments revealed that turning off the EGFR/PI3K/AKT signaling pathway activated expression of p53 in PC9-R cells transfected with si-MIR31HG. Furthermore, PC9-R cells transfected with si-MIR31HG induced cell apoptosis through the mitochondrial apoptosis pathway, and arrested the cell cycle in the G0/G1 phase. The results of the current study suggest that MIR31HG lncRNA levels in PC9-R cells are higher than in PC9 cells. Furthermore, overexpression of MIR31HG lncRNAs may contribute to gefitinib resistance in PC9-R cells through the EGFR/PI3K/AKT pathway, which impacts on cell proliferation, apoptosis and the cell cycle. MIR31HG lncRNA may therefore be a novel candidate biomarker for future therapeutic strategies involving EGFR-TKIs.

A Positive Feedback Loop of lncRNA-PVT1 and FOXM1 Facilitates Gastric Cancer Growth and Invasion

Purpose: The long, noncoding RNA (lncRNA) PVT1 is an important epigenetic regulator with a critical role in human tumors. Here, we aimed to investigate the clinical application and the potential molecular mechanisms of PVT1 in gastric cancer tumorigenesis and progression.Experimental Design: The expression level of PVT1 was determined by RT-qPCR analysis in 190 pairs of gastric cancer tissues and adjacent normal gastric mucosa tissues (ANT). The biologic functions of PVT1 were assessed by in vitro and in vivo functional experiments. RNA protein pull-down assays and LS/MS mass spectrometry analysis were performed to detect and identify the PVT1- interacting protein FOXM1. Protein-RNA immunoprecipitation assays were conducted to examine the interaction of FOXM1 and PVT1 Chromatin immunoprecipitation (ChIP) and luciferase analyses were utilized to identify the binding site of FOXM1 on the PVT1 promoter.Results: The lncRNA PVT1 was significantly upregulated in gastric cancer tissues compared with ANTs. High expression of PVT1 predicted poor prognosis in patients with gastric cancer. PVT1 enhanced gastric cancer cell proliferation and invasion in vitro and in vivoPVT1 directly bound FOXM1 protein and increased FOXM1 posttranslationally. Moreover, PVT1 is also a FOXM1-responsive lncRNA, and FOXM1 directly binds to the PVT1 promoter to activate its transcription. Finally, PVT1 fulfilled its oncogenic functions in a FOXM1-mediated manner.Conclusions: Our study suggests that PVT1 promotes tumor progression by interacting with FOXM1. PVT1 may be a valuable prognostic predictor for gastric cancer, and the positive feedback loop of PVT1-FOXM1 could be a therapeutic target in pharmacologic strategies. Clin Cancer Res; 23(8); 2071-80. ©2016 AACR.

Long non-coding RNA H19 regulates FOXM1 expression by competitively binding endogenous miR-342-3p in gallbladder cancer

Background

Long non-coding RNA (lncRNA) H19 has been reported to involve in many kinds of human cancers and functions as an oncogene. Our previous study found that H19 was over-expressed in gallbladder cancer (GBC) and was shown to promote tumor development in GBC. However, the competing endogenous RNA (ceRNA) regulatory network involving H19 in GBC progression has not been fully elucidated. We aim to detect the role of H19 as a ceRNA in GBC.

Methods and Results

In this study, the expression of H19 and miR-342-3p were analyzed in 35 GBC tissues and matched normal tissues by using quantitative polymerase chain reaction (qRT-PCR). We demonstrated H19 was overexpressed and negatively correlated with miR-342-3p in GBC. By dual-luciferase reporter assays, RNA-binding protein immunoprecipitation (RIP) and RNA pull-down assays, we verified that H19 was identified as a direct target of miR-342-3p. QRT-PCR and Western-blotting assays demonstrated that H19 silencing down-regulated, whereas over-expression enhanced the expression of miR-342-3p targeting FOXM1 through competitively ‘sponging’ miR-342-3p. Furthermore, transwell invasion assays and cell cycle assays indicated that H19 knockdown inhibited both cells invasion and proliferation, but this effects was attenuated by co-transfection of siRNA-H19 and miR-342-3p inhibitor in GBC cells. In vivo, tumor volumes were decreased significantly in H19 silenced group compared to the control group, but was attenuated by co-transfection of shRNA-H19 and miR-342-3p inhibitor, which were stablely constructed through lenti-virus vector.

Conclusion

Our results suggest a potential ceRNA regulatory network involving H19 regulates FOXM1 expression by competitively binding endogenous miR-342-3p in GBC. This mechanism may contribute to a better understanding of GBC pathogenesis and provides potential therapeutic strategy for GBC.

Tumor-suppressive functions of long-chain acyl-CoA synthetase 4 in gastric cancer

Long chain acyl CoA synthetase 4 (ACSL4) is a key enzyme in fatty acid metabolism with marked preference for arachidonic acid (AA). Recent reports have implicated its crucial roles in tumorigenesis. However in gastric cancer (GC), the expression and function of ACSL4 remain unclear. In the present study, we identified ACSL4 as a potential tumor suppressor in GC. The ACSL4 expression in GC samples was evaluated by real-time PCR and immunohistochemistry. The results indicated that the mRNA and protein levels of ACSL4 were frequently downregulated in cancer tissues compared with the adjacent non-cancerous mucosa control tissues. Cell-based functional assays exhibited that ectopic expression of ACSL4 inhibits cell growth, colony formation and cell migration, whereas ACSL4 knockdown enhanced these effects. In a nude mice model, ACSL4 knockdown also promoted subcutaneous xenografts' growth in vivo. Moreover, western blot analysis revealed that ACSL4 expression had a significant effect on FAK and P21 protein level. These findings suggest that ACSL4 plays a tumor-suppressive role and could be a potential therapeutic target in GC.

Long noncoding RNAs in gastric cancer: functions and clinical applications

Over the last two decades, genome-wide studies have revealed that only a small fraction of the human genome encodes proteins; long noncoding RNAs (lncRNAs) account for 98% of the total genome. These RNA molecules, which are >200 nt in length, play important roles in diverse biological processes, including the immune response, stem cell pluripotency, cell proliferation, apoptosis, differentiation, invasion, and metastasis by regulating gene expression at the epigenetic, transcriptional, and posttranscriptional levels. However, the detailed molecular mechanisms underlying lncRNA function are only partially understood. Recent studies showed that many lncRNAs are aberrantly expressed in gastric cancer (GC) tissues, gastric juice, plasma, and cells, and these alterations are linked to the occurrence, progression, and outcome of GC. Here, we review the current knowledge of the biological functions and clinical aspects of lncRNAs in GC.

Long noncoding RNAs as potential biomarkers in gastric cancer: Opportunities and challenges

Gastric cancer (GC) is a major threat to human health, and its prognosis is poor due to the lack of appropriate biomarkers. LncRNAs are a group of non-protein-coding RNAs that regulate gene expression at the transcriptional or posttranscriptional level. LncRNAs play essential roles in GC initiation and development in the same way as oncogenes or tumour suppressor genes. Recent investigations have revealed that lncRNAs are often aberrantly expressed in GC; are involved in cell proliferation, apoptosis, migration and invasion; and correlate with the malignant phenotype of GC. LncRNAs, especially the lncRNAs present in the blood and gastric juice, show potential value as biomarkers for the diagnosis of GC or for determining disease prognosis. However, there are still many challenges to be faced before lncRNAs can be used in clinical applications. In this review, we summarise lncRNAs as the potential biomarkers for GC and the current challenges associated with the clinical application.