Long non-coding RNA CASC2 regulates cell biological behaviour through the MAPK signalling pathway in hepatocellular carcinoma

The role of long non-coding RNA in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent liver malignancy with complex etiology and generally poor prognosis. Recently, long non-coding RNAs (lncRNAs), non-protein-coding RNA molecules exceeding 200 nucleotides, have emerged as pivotal players in HCC, influencing its initiation, progression, invasion, and metastasis. These lncRNAs modulate gene expression at epigenetic, transcriptional, and post-transcriptional levels, actively participating in the pathological and physiological processes of HCC. Understanding the intricate relationship between lncRNAs and HCC is important for improving prognosis and reducing mortality. This review summarizes advancements in elucidating the role of lncRNAs in HCC pathogenesis.

MAPK/ERK Signaling Pathway in Hepatocellular Carcinoma

Simple Summary

The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway is frequently activated in liver cancer, which is one of the most lethal cancers in humans. In addition to genetic mutation leading to persistent activation of effector molecules in the MAPK/ERK signaling cascade, there are alternative means by which the MAPK/ERK signaling pathway is activated in cancer. In this review, we will introduce the diverse modulators regulating the MAPK/ERK signaling pathway and consider the possibility of targeting the effectors and regulators in order to suppress the pro-tumorigenic MAPK/ERK signaling pathway, especially in liver cancer.

Abstract

Hepatocellular carcinoma (HCC) is a major health concern worldwide, and its incidence is increasing steadily. Recently, the MAPK/ERK signaling pathway in HCC has gained renewed attention from basic and clinical researchers. The MAPK/ERK signaling pathway is activated in more than 50% of human HCC cases; however, activating mutations in RAS and RAF genes are rarely found in HCC, which are major genetic events leading to the activation of the MAPK/ERK signaling pathway in other cancers. This suggests that there is an alternative mechanism behind the activation of the signaling pathway in HCC. Here, we will review recent advances in understanding the cellular and molecular mechanisms involved in the activation of the MAPK/ERK signaling pathway and discuss potential therapeutic strategies targeting the signaling pathway in the context of HCC.

The Impact of Long Non-Coding RNAs in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is among the utmost deadly human malignancies. This type of cancer has been associated with several environmental, viral, and lifestyle risk factors. Among the epigenetic factors which contribute in the pathogenesis of HCC is dysregulation of long non-coding RNAs (lncRNAs). These transcripts modulate expression of several tumor suppressor genes and oncogenes and alter the activity of cancer-related signaling axes. Several lncRNAs such as NEAT1, MALAT1, ANRIL, and SNHG1 have been up-regulated in HCC samples. On the other hand, a number of so-called tumor suppressor lncRNAs namely CASS2 and MEG3 are down-regulated in HCC. The interaction between lncRNAs and miRNAs regulate expression of a number of mRNA coding genes which are involved in the pathogenesis of HCC. H19/miR-15b/CDC42, H19/miR-326/TWIST1, NEAT1/miR-485/STAT3, MALAT1/miR-124-3p/Slug, MALAT1/miR-195/EGFR, MALAT1/miR-22/SNAI1, and ANRIL/miR-144/PBX3 axes are among functional axes in the pathobiology of HCC. Some genetic polymorphisms within non-coding regions of the genome have been associated with risk of HCC in certain populations. In the current paper, we describe the recent finding about the impact of lncRNAs in HCC.

The role of long non-coding RNA CASC2 in the carcinogenesis process

The lncRNA cancer susceptibility candidate 2 (CASC2) has been initially discovered in a genomic area on 10q26 that is commonly lost in human endometrial cancer. Subsequent assessments revealed its down-regulation in almost all kinds of cancer including glioma, breast cancer, colorectal cancer, lung cancer, ovarian cancer and hepatocellular carcinoma. Yet, it has been shown to be up-regulated in astrocytoma and in paclitaxel (PTX) resistant breast cancer tissues. In vitro studies have shown the role of this lncRNA in suppression of cell proliferation and induction of apoptosis. Animal studies have shown that over-expression of CASC2 suppresses tumorigenesis of human cancer cells in xenograft models. Diagnostic power of CASC2 levels has been evaluated in a number of human cancers and the best parameters have been demonstrated in pituitary adenomas and oral squamous cell carcinoma. Taken together, the main body of evidence show a tumor suppressor role of CASC2 and indicate up-regulation of this lncRNA as a putative therapeutic modality for human cancers. In this review, we summarize the data regarding expression pattern, function and diagnostic role of CASC2 in human cancer based on the results of cell line studies, animal investigations and human studies.

Role of miRNA sponges in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. HCC patients are commonly diagnosed at an advanced stage, for which highly effective therapies are limited. Hence, there is a growing need to discover promising biomarkers for HCC diagnosis, and in this context, microRNAs (miRNAs) hold great promise. MiRNAs function as gene expression regulators by directly binding messenger RNAs (mRNAs) and subsequently causing suppression of mRNA translation or degradation of target mRNAs. Two major types of noncoding RNAs act as competing endogenous sponges: circular RNAs and long non-coding RNAs.They can competitively bind to miRNA through miRNA response elements (MREs), thereby reducing the number of miRNAs binding mRNAs and regulating the expression of downstream target genes of miRNAs at the posttranscriptional level. The relationship between single miRNA sponge and HCC has been explored. However, comprehensive reviews on the sponge's function in HCC are lacking. In this review, we describe the methods to find endogenous sponges and construct exogenous sponges, and briefly compare endogenous and exogenous sponges. We also summarize the current progress on the functional role of miRNA sponges in HCC pathogenesis and present their potential value as diagnostic biomarkers and therapeutic targets. In-depth investigations on the function and mechanism of miRNA sponges in HCC will enrich our knowledge of HCC pathogenesis and contribute to the development of effective diagnostic biomarkers and therapeutic targets for HCC.

The Long Non-Coding RNA CASC2 Suppresses Cell Viability, Migration, and Invasion in Hepatocellular Carcinoma Cells by Directly Downregulating miR-183

PURPOSE

Hepatocellular carcinoma (HCC) is the most common malignant tumor of liver cells. Researchers have reported that cancer susceptibility candidate 2 (CASC2), a long non-coding RNA, is down-regulated in various cancers, including HCC. Our study aimed to investigate the molecular mechanism(s) of CASC2 in HCC.

MATERIALS AND METHODS

Real-time quantitative PCR (RT-qPCR) was used to analyze the expression of CASC2 and miR-183 in HCC tissues and cells. The viability of HCC SMMC-7721 and Huh-7 cells was detected through MTT assay. Colony formation assay was performed to assess the colony formation ability of HCC cells. The migration and invasion abilities of HCC cells were evaluated by Transwell assay. Western blot was conducted to examine levels of key Wnt/β-catenin signaling pathway factors, C-myc, cyclinD, survivin, and β-catenin. The interaction between CASC2 and miR-183 was affirmed by bioinformatics analysis and luciferase reporter assay.

RESULTS

CASC2 was down-regulated in HCC tissues and cell lines, while miR-183 was up-regulated. The expression of miR-183 was negatively correlated with CASC2 expression in HCC tissues. Overexpression of CASC2 inhibited cell viability, colony formation, migration, and invasion in HCC cells, as well as Wnt/β-catenin signaling pathway activity. miR-183 was a downstream target of CASC2 and negatively regulated by CASC2. Introduction of miR-183 rescued CASC2-induced suppressive effects on HCC cell viability, colony formation, migration, and invasion and Wnt/β-catenin signaling.

CONCLUSION

CASC2 inhibited cell viability and the colony formation, migration, and invasion abilities of HCC cells by directly downregulating miR-183 through inactivation of the Wnt/β-catenin signaling pathway.

Liquid Biopsy in Oligometastatic Prostate Cancer-A Biologist's Point of View

Prostate cancer (PCa) is the main cause of cancer-related mortality in males and the diagnosis, treatment, and care of these patients places a great burden on healthcare systems globally. Clinically, PCa is highly heterogeneous, ranging from indolent tumors to highly aggressive disease. In many cases treatment-generally either radiotherapy (RT) or surgery-can be curative. Several key genetic and demographic factors such as age, family history, genetic susceptibility, and race are associated with a high incidence of PCa. While our understanding of PCa, which is mainly based on the tools of molecular biology-has improved dramatically in recent years, efforts to better understand this complex disease have led to the identification of a new type of PCa-oligometastatic PCa. Oligometastatic disease should be considered an individual, heterogeneous entity with distinct metastatic phenotypes and, consequently, wide prognostic variability. In general, patients with oligometastatic disease typically present less biologically aggressive tumors whose metastatic potential is more limited and which are slow-growing. These patients are good candidates for more aggressive treatment approaches. The main aim of the presented review was to evaluate the utility of liquid biopsy for diagnostic purposes in PCa and for use in monitoring disease progression and treatment response, particularly in patients with oligometastatic PCa. Liquid biopsies offer a rapid, non-invasive approach whose use t is expected to play an important role in routine clinical practice to benefit patients. However, more research is needed to resolve the many existing discrepancies with regard to the definition and isolation method for specific biomarkers, as well as the need to determine the most appropriate markers. Consequently, the current priority in this field is to standardize liquid biopsy-based techniques. This review will help to improve understanding of the biology of PCa, particularly the recently defined condition known as "oligometastatic PCa". The presented review of the body of evidence suggests that additional research in molecular biology may help to establish novel treatments for oligometastatic PCa. In the near future, the treatment of PCa will require an interdisciplinary approach involving active cooperation among clinicians, physicians, and biologists.

Long non-coding RNAs (CASC2 and TUG1) in hepatocellular carcinoma: Clinical significance

BACKGROUND

The biology of hepatocellular carcinoma remains poorly understood. Long non-coding RNAs (lncRNAs) have been confirmed to be key regulators of most cell processes and cancer. The lncRNA cancer susceptibility candidate 2 (CASC2) was originally identified as a downregulated gene in endometrial cancer and acted as a tumor suppressor. The lncRNA taurine up-regulated gene 1 (TUG1) has been shown to play an oncogenic role in various cancers. However, the relative expression of CASC2 and TUG1 in hepatocellular carcinoma (HCC) on top of hepatitis C virus (HCV) and the relationship between both remains unclear. The present study aimed to evaluate both lncRNA CASC2 and TUG1 relative gene expression in whole blood of HCC/HCV patients in relation to HCV and healthy subjects and to relate them to each other and to different clinicopathological factors.

METHODS

The relative expression of CASC2 and TUG1 was estimated by a quantitative reverse transcriptase-polymerase chain reaction in 30 HCC/HCV patients and compared with 20 cases of HCV patients and 20 controls.

RESULTS

CASC2 was downregulated in HCC/HCV patients, whereas TUG1 was overexpressed in relation to HCV and the control group, indicating their antagonistic effect. This suggests their role in the pathogenesis of HCC on top of HCV. Their expression was correlated to Barcelona Clinic Liver Cancer stage and serum alpha-fetoprotein level.

CONCLUSIONS

CASC2 and TUG1 could be new potential biomarkers with a valid non-invasive technique.

Downregulation of the expression of the lncRNA MIAT inhibits melanoma migration and invasion through the PI3K/AKT signaling pathway

BACKGROUND

Long noncoding RNA MIAT expression is related to the development of some diseases. However, the role of MIAT in melanoma was has seldom been studied.

OBJECTIVE

To investigate the effect of the lncRNA MIAT on melanoma cells.

METHOD

Microarray was used to analyze the lncRNAs expression in tissue samples. The expression of the lncRNA MIAT was detected by qRT-PCR. A CCK-8 assay was used to assess cell viability, and cell counting was used to analyze cell proliferation. Wound healing and Transwell invasion assays were used to detect the migration and invasion abilities, respectively, of melanoma cells. Western blotting was performed to explore the molecular mechanisms of MIAT in melanoma.

RESULTS

The lncRNA MIAT was overexpressed in melanoma. The overexpression of MIAT promoted cell proliferation, cell invasion and migration, while the knockdown of MIAT expression got the opposite results. MIAT significantly upregulated the phosphorylation of PI3K and AKT and promoted cMyc and cyclin D1 protein expression.

CONCLUSION

LncRNA MIAT was a key factor to promote cell invasion, migration and proliferation through the PI3K/AKT signaling pathway. These findings may give us a potential way to treat melanoma.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

lncRNA BANCR suppresses cell viability and invasion and promotes apoptosis in non-small-cell lung cancer cells in vitro and in vivo

Background: As a leading cause of deaths worldwide, lung cancer is a collection of diseases with diverse etiologies which includes non-small-cell lung cancer (NSCLC). Increasing evidence reported that aberrant expression of BRAF activated non-coding RNA (BANCR) was involved in the tumorigenesis and progression of various malignancies. Purpose and methods: However, its role in NSCLC has not been completely clarified. In the present study, we identified the role of BANCR in the regulation of NSCLC cell viability, invasion, and apoptosis. Down-regulation of BANCR expression was significantly observed in different NSCLC cell lines (A549, H1299, H1650, H1975, SPC-A1, and PC-9), tumor tissue from NSCLC mouse model and 30 human NSCLC tissues compared with adjacent normal tissues. Result: Overexpression of BANCR in these six NSCLC cell lines attenuated the cell viability and invasion. An increased apoptotic level caused by BANCR overexpression was also detected and displayed a conversed influence on Bcl-2 and Bax expression in mRNA and protein level. Furthermore, we identified the effect of BANCR overexpression on tumor growth in NSCLC mouse model. The restoration of BANCR expression inhibits NSCLC. Conclusion: Taken together, our findings shed an insight on the novel molecular mechanisms of lung NSCLC oncogenesis and provide the information for new therapeutic approaches on the disease.

LncRNA CASC2 inhibits autophagy and promotes apoptosis in non-small cell lung cancer cells via regulating the miR-214/TRIM16 axis

Background: Dysregulated long noncoding RNAs (lncRNAs) have been frequently observed in various cancers including non-small cell lung cancer (NSCLC) and are closely associated with cancer progression. Previous studies also found that low expression of lncRNA cancer susceptibility candidate 2 (CASC2) functioned as a tumor suppressor in NSCLC. Our study aimed to explore the detailed molecular mechanism of CASC2 involved in NSCLC progression. Methods: The expressions of CASC2, tripartite motif-containing protein 16 (TRIM16) and miR-214 in NSCLC tissues and cells were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) or western blot. Flow cytometry analysis was performed to evaluate apoptosis. Autophagy was assessed using green fluorescent protein microtubule-associated protein 1 light chain 3α (GFP-LC3) puncta analysis, acridine orange (AO) staining and western blot. Luciferase reporter assay, RNA immunoprecipitation (RIP), RNA pull-down and immunofluorescence staining were employed to explore the association between CASC2, TRIM16 and miR-214. Results: CASC2 and TRIM16 expressions were significantly downregulated and miR-214 expression was dramatically upregulated in NSCLC tissues and cells. Overexpression of CASC2 induced apoptosis and inhibited autophagy in NSCLC cells. miR-214 was bound to CASC2 and its knockdown reversed the regulatory effect of CASC2 inhibition on apoptosis and autophagy in NSCLC cells. Moreover, TRIM16 was validated as a target of miR-214 and its interference attenuated miR-214 knockdown-mediated promotion of apoptosis and inhibition of autophagy. Besides, CASC2 enhanced TRIM16 expression through functioning as a competing endogenous RNA (ceRNA) for miR-214 in NSCLC cells. Conclusion: lncRNA CASC2 inhibited autophagy and promoted apoptosis in NSCLC cells via regulating the miR-214/TRIM16 axis, shedding light on the mechanism underlying NSCLC carcinogenesis.

Overexpression of cancer susceptibility candidate 2 inhibited progression of hepatocellular carcinoma cells

OBJECTIVE

Our study was aimed to investigate the effect of cancer susceptibility candidate 2 (CASC2) on the proliferation, cell cycle, apoptosis, and metastasis of hepatocellular carcinoma (HCC) cells.

METHODS

CASC2 expression in tumor tissues and HCC cells was tested by quantitative real-time polymerase chain reaction. After manipulating the expression of CASC2 in Hep3B and HepG2 cells, cells viability, including proliferation, apoptosis, cell-cycle distribution, migration, and invasion were examined by colony formation assay, flow cytometry, wound-healing assay, and transwell assay, respectively. The expression levels of proteins associated with the cell cycle and AKT/mTOR pathway were measured by the western blot. Stably transfected HepG2 cells were used to construct nude mice models, and tumorigenesis was evaluated to investigate the in vivo functions of CASC2 in HCC progression.

RESULTS

In tissues and cells of HCC, decreased CASC2 expressions were confirmed. Overexpression of CASC2 made cell cycle stagnated at G0/G1 phase and induced apoptosis. Meanwhile, the overexpression of CASC2 played significant roles in inhibiting the proliferation, migration, and invasion of HCC cells. Furthermore, In vivo experiment indicated that CASC2 restrained the growth of tumors.

CONCLUSION

Our study suggested that CASC2 promoted cell apoptosis and suppressed cell growth and metastasis in HCC, indicating that CASC2 might be a useful biomarker of HCC.

The value of long noncoding RNA CASC2 as a biomarker of prognosis in carcinomas: a meta-analysis

Lnc RNA Cancer Susceptibility Candidate 2(CASC2) has been shown to be aberrantly expressed in multiple types of cancer and might serve as a prognosis biomarker. The present meta-analysis was conducted to investigate whether the expression of CASC2 was associated with prognosis or clinicopathological features in correlative cancers. A total of 11 studies with 765 cancer patients were included by searching the electronic databases, the results found a significant association between high expression of CASC2 and longer OS in cancer patients (HR=0.43, 95% CI: 0.33-0.55, P =0.000).In addition, a significant correlation was observed between high level of CASC2 and earlier TNM stage(OR = 0.30, 95% CI =0.21-0.43, P < 0.001), smaller tumor size(OR = 0.28, 95% CI =0.12-0.66, P =0.004), better tumor differentiation(OR = 0.42, 95% CI =0.27-0.66, P =0.0002). In conclusion, CASC2 can serve as a novel marker predicting the prognosis and clinicopathological features in various cancers.

The role of lncRNA CASC2 on prognosis of malignant tumors: a meta-analysis and bioinformatics

Background

Cancer susceptibility candidate 2 (CASC2) is characterized as a tumor suppressor, which was first identified to be downregulated in endometrial carcinoma. Accumulating evidence was provided to testify the function of CASC2 in malignant tumors. However, a systematic and quantitative assessment is not available. The present study was designed to evaluate the role of CASC2 in multiple carcinomas through meta-analysis and bioinformatics.

Materials and methods

A systematic assessment of the relationship of CASC2 with tumors was performed by using several computerized databases from inception to December 1, 2017. Pooled HR with 95% CI was calculated to summarize the effect. The data on prognosis of malignant tumors were also downloaded from The Cancer Genome Atlas (TCGA) project, OncoLnc, TANRIC and lncRNAtor database.

Results

A total of 13 studies with 966 cancer patients were pooled in the analysis to evaluate the prognostic value of CASC2 in multiple tumors and the clinical features. The results of the meta-analysis revealed that low expression levels of CASC2 were associated with poor overall survival (OS) (pooled HR=0.39, 95% CI: 0.28–0.53, P<0.0001). CASC2 obviously has a negative correlation with advanced tumor node metastasis (TNM) stage, lymph node metastasis (LNM) and T stage, respectively (P<0.05). There was, however, no significant difference in gender, distant metastasis and high differentiation (P>0.05). In the Kaplan–Meier curves with log-rank analysis, higher expression of CASC2 was positively correlated with longer survival time than patients with a lower level (P<0.05), including kidney renal clear cell carcinoma, brain lower grade glioma, pancreatic adenocarcinoma and sarcoma.

Conclusion

Findings from this meta-analysis suggest that lower expression of CASC2 is associated with poorer prognosis of cancers, as well as advanced TNM, LNM and T stage. Data from the bioinformatics analysis revealed that higher expression of CASC2 was related to longer OS in patients with malignant tumors.

Prognostic value and clinical significance of long noncoding RNA CASC2 in human malignancies: a meta-analysis

Purpose

This meta-analysis aimed to assess the prognostic value of long noncoding RNA cancer susceptibility candidate 2 (CASC2) in human tumors.

Materials and methods

We searched the available databases up to December 2017. Pooled hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were used to examine the prognostic impact of CASC2 on overall survival (OS) in patients diagnosed with malignancies.

Results

A total of eight studies with 663 cancer patients were enrolled. Our results showed that high CASC2 expression level was associated with a favorable OS (HR=0.437, 95% CI: 0.345-0.554). The significant results were not altered by stratified analysis according to cancer type, sample size, follow-up months, and HR estimation method. A significant association of glioma tumor stage with CASC2 expression was detected (III-IV vs I-II: odds ratio=2.126, 95% CI: 1.032-4.378). CASC2 could be used as an independent prognostic factor for OS (HR=0.450, 95% CI: 0.336-0.602). Sensitivity analysis showed that no single study changed the pooled results significantly. Begg's funnel plot and Egger's test showed that no publication bias was detected.

Conclusion

High expression level of CASC2 is associated with favorable survival outcome for cancer patients, and CASC2 could be used as a prognostic predictor for cancers.

Long noncoding RNA CASC2 regulates hepatocellular carcinoma cell oncogenesis through miR-362-5p/Nf-κB axis

The long non-coding RNA segment cancer susceptibility candidate 2 (CASC2) has been shown to suppress tumor growth in a variety of cancers, including hepatocellular carcinoma (HCC). However, the mechanism by which CASC2 exerts control over HCC has yet to be established. In the present study, we first demonstrated that CASC2 is downregulated in human HCC tissues and HCC cell lines as compared to adjacent non-tumor tissues (NTTs) and a liver cell line, respectively. After finding that CASC2 knockdown significantly promotes HCC cells migration and invasion as well as that CASC2 overexpression inhibits cell migration and invasion, we identified the microRNA miR-362-5p as an endogenous target of CASC2. Through the use of wild type and mutant CASC2 binding sites inserted into psiCHECK-2 luciferase reporter plasmids, as well as qRT-PCR, we determined that CASC2 overexpression reduces miR-362-5p expression levels, while inhibiting CASC2 activity increases miR-362-5p expression. Past research has shown that miR-362-5p stimulates the NF-κB pathway, which has been implicated in the survival and proliferation of a variety of cancer cells. We therefore investigated the effects of CASC2 expression on NF-κB pathway activity. Ultimately, we determined that CASC2 regulates HCC cell activity by targeting miR-362-5p and thus inhibiting the NF-κB pathway. The present study not only identifies CASC2 as an important HCC cell regulator, but also suggests its mechanism of action. It therefore provides the basis for designing strategies to target CASC2 activity and thereby inhibit HCC growth and progression.

Long non-coding RNA GPR65-1 is up-regulated in gastric cancer and promotes tumor growth through the PTEN-AKT-slug signaling pathway

Increasing evidence has shown that abnormal expression of lncRNAs is involved in various biological behaviors and major cellular pathways of human cancers. However, the role of lncRNAs in the progression of gastric cancer has not been adequately investigated. Therefore, in this study, we investigated the expression levels of linc-GPR65-1 using Quantitative real-time PCR (qRT-PCR) and found that linc-GPR65-1 was significantly up-regulated in 50 gastric cancer tissues compared to the corresponding normal tissues. In addition, increased linc-GPR65-1 expression was associated with TNM stage (P = 0.037), tumor size (P = 0.024), distal metastasis (P = 0.023), and poor prognosis of gastric cancer patients. Moreover, functional assays indicated that decreased linc-GPR65-1 expression inhibited the aggressive phenotypes of gastric cancer cells, and enhanced linc-GPR65-1 expression resulted in the opposite phenomenon. Then, a cancer signaling phosphoantibody microarray was conducted to explore the potential mechanisms of linc-GPR65-1 in regulating gastric cancer progression and observed that linc-GPR65-1 could regulate the PTEN-AKT-slug signaling pathway. These data showed that linc-GPR65-1, regulating the PTEN-AKT-slug signaling pathway, might act as a tumor promoter and serve as a novel target for gastric cancer prevention and therapy.

LncRNA LINC00880 promotes cell proliferation, migration, and invasion while inhibiting apoptosis by targeting CACNG5 through the MAPK signaling pathway in spinal cord ependymoma

The present study was to investigate the effect of lncRNA LINC00880 targeting CACNG5 on cell proliferation, migration, invasion, and apoptosis in spinal cord ependymoma (SCE) through the MAPK signaling pathway. GEO database was used to download gene expression data related with SCE (GSE50161 and GSE66354) and annotation file. LncRNA with differential expression was predicted by Multi Experiment Matrix website (MEM). The target gene was analyzed by KEGG pathway enrichment analysis. SCE tissues and adjacent tissues were collected. The positive expression of CACNG5 protein was tested by immunohistochemistry. Expression of LINC00880, CACNG5, and MAPK signaling pathway-related proteins was measured with qRT-PCR and Western blotting. Cell proliferation, migration, invasion, cycle, and apoptosis were detected using MTT, Transwell assay, Scratch test, and Flow cytometry. SCE tissues showed increased LINC00880 expression. CACNG5 was a target gene of LINC00880 and correlated with MAPK signaling pathway. Compared with adjacent tissues, SCE tissues showed lower positive expression of CACNG5. Compared with the blank group, LINC00880 expression was higher in the LINC00880 vector and LINC00880 vector + CACNG5 vector groups, and lower in the si-LINC00880 and si-LINC00880 + si-CACNG5 groups; in the LINC00880 vector and si-CACNG5 groups, expression of survivin, p38MAPK, ERK1/2, JNK1/2/3 increased and CACNG5 and Bax expression reduced, the proliferation, invasion and migration of tumor cells increased, and apoptosis rate decreased. Opposite results were found in the si-LINC00880 and CACNG5 vector groups. The findings indicate that lncRNA LINC00880 targeting CACNG5 inhibits cell apoptosis and promotes proliferation, migration, and invasion in SCE through the MAPK signaling pathway.

CASC2/miR-24/miR-221 modulates the TRAIL resistance of hepatocellular carcinoma cell through caspase-8/caspase-3

Hepatocellular carcinoma is one of the most common solid tumors in the digestive system. The prognosis of patients with hepatocellular carcinoma is still poor due to the acquisition of multi-drug resistance. TNF Related Apoptosis Inducing Ligand (TRAIL), an attractive anticancer agent, exerts its effect of selectively inducing apoptosis in tumor cells through death receptors and the formation of the downstream death-inducing signaling complex, which activates apical caspases 3/8 and leads to apoptosis. However, hepatocellular carcinoma cells are resistant to TRAIL. Non-coding RNAs, including long non-coding RNAs (lncRNAs) and miRNAs have been regarded as major regulators of normal development and diseases, including cancers. Moreover, lncRNAs and miRNAs have been reported to be associated with multi-drug resistance. In the present study, we investigated the mechanism by which TRAIL resistance of hepatocellular carcinoma is affected from the view of non-coding RNA regulation. We selected and validated candidate miRNAs, miR-24 and miR-221, that regulated caspase 3/8 expression through direct targeting, and thereby affecting TRAIL-induced tumor cell apoptosis TRAIL resistance of hepatocellular carcinoma. In addition, we revealed that CASC2, a well-established tumor suppressive long non-coding RNA, could serve as a "Sponge" of miR-24 and miR-221, thus modulating TRAIL-induced tumor cell apoptosis TRAIL resistance of hepatocellular carcinoma. Taken together, we demonstrated a CASC2/miR-24/miR-221 axis, which can affect the TRAIL resistance of hepatocellular carcinoma through regulating caspase 3/8; through acting as a "Sponge" of miR-24 and miR-221, CASC2 may contribute to improving hepatocellular carcinoma TRAIL resistance, and finally promoting the treatment efficiency of TRAIL-based therapies.

Behind the curtain of non-coding RNAs; long non-coding RNAs regulating hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is one of the most common and aggressive cancers worldwide. HCC is the fifth common malignancy in the world and the second leading cause of cancer death in Asia. Long non-coding RNAs (lncRNAs) are RNAs with a length greater than 200 nucleotides that do not encode proteins. lncRNAs can regulate gene expression and protein synthesis in several ways by interacting with DNA, RNA and proteins in a sequence specific manner. They could regulate cellular and developmental processes through either gene inhibition or gene activation. Many studies have shown that dysregulation of lncRNAs is related to many human diseases such as cardiovascular diseases, genetic disorders, neurological diseases, immune mediated disorders and cancers. However, the study of lncRNAs is challenging as they are poorly conserved between species, their expression levels aren’t as high as that of mRNAs and have great interpatient variations. The study of lncRNAs expression in cancers have been a breakthrough as it unveils potential biomarkers and drug targets for cancer therapy and helps understand the mechanism of pathogenesis. This review discusses many long non-coding RNAs and their contribution in HCC, their role in development, metastasis, and prognosis of HCC and how to regulate and target these lncRNAs as a therapeutic tool in HCC treatment in the future.

LncRNA and mRNA integration network reconstruction reveals novel key regulators in esophageal squamous-cell carcinoma

Many experimental and computational studies have identified key protein coding genes in initiation and progression of esophageal squamous cell carcinoma (ESCC). However, the number of researches that tried to reveal the role of long non-coding RNAs (lncRNAs) in ESCC has been limited. LncRNAs are one of the important regulators of cancers which are transcribed dominantly in the genome and in various conditions. The main goal of this study was to use a systems biology approach to predict novel lncRNAs as well as protein coding genes associated with ESCC and assess their prognostic values. By using microarray expression data for mRNAs and lncRNAs from a large number of ESCC patients, we utilized "Weighted Gene Co-expression Network Analysis" (WGCNA) method to make a big coding-non-coding gene co-expression network, and discovered important functional modules. Gene set enrichment and pathway analysis revealed major biological processes and pathways involved in these modules. After selecting some protein coding genes involved in biological processes and pathways related to cancer, we used "LncTar", a computational tool to predict potential interactions between these genes and lncRNAs. By combining interaction results with Pearson correlations, we introduced some novel lncRNAs with putative key regulatory roles in the network. Survival analysis with Kaplan-Meier estimator and Log-rank test statistic confirmed that most of the introduced genes are associated with poor prognosis in ESCC. Overall, our study reveals novel protein coding genes and lncRNAs associated with ESCC, along with their predicted interactions. Based on the promising results of survival analysis, these genes can be used as good estimators of patients' survival, or even can be analyzed further as new potential signatures or targets for the therapy of ESCC disease.

BANCR: a novel oncogenic long non-coding RNA in human cancers

Long non-coding RNAs account for large proportion of non-coding transcripts in human genomes. Though they lack of open reading framework and cannot encode protein, they can control endogenous gene expression though regulating cell life activities. They serve as transcriptional modulator, posttranscriptional processor, chromatin remodeler and splicing regulator during the process of gene modification. Moreover, long non-coding RNAs were regarded as potential tumor markers for cancer diagnosis and prognosis. BANCR was identified as a cancer-promoting long non-coding RNA in melanoma tissues. Since then, increasing studies about BANCR in cancer progression were reported. BANCR was dysregulated in various cancers including melanoma, colorectal cancer, retinoblastoma, lung carcinoma and hepatocellular carcinoma, and increased BANCR expression cause poor prognosis and shorter survival rate of cancer patients. Furthermore, the functions and mechanisms of BANCR in cancer cells have been clarified. Here, we focus on the current research on the role of BANCR in the clinical management, progression and molecular mechanisms in human cancer.

Colon cancer associated transcripts in human cancers

Long non-coding RNAs serve as important regulators in complicated cellular activities, including cell differentiation, proliferation and death. Dysregulation of long non-coding RNAs occurs in the formation and progression of cancers. The family of colon cancer associated transcripts, long non-coding RNAs colon cancer associated transcript-1 and colon cancer associated transcript-2 are known as oncogenes involved in various cancers. Colon cancer associated transcript-1 is a novel lncRNA located in 8q24.2, and colon cancer associated transcript-2 maps to the 8q24.21 region encompassing rs6983267. Colon cancer associated transcripts have close associations with clinical characteristics, such as lymph node metastasis, high TNM stage and short overall survival. Knockdown of them can reverse the malignant phenotypes of cancer cells, including proliferation, migration, invasion and apoptosis. Moreover, they can increase the expression level of c-MYC and oncogenic microRNAs via activating a series of complex mechanisms. In brief, the family of colon cancer associated transcripts may serve as potential biomarkers or therapeutic targets for human cancers.