Silencing of lncRNA CCDC26 Restrains the Growth and Migration of Glioma Cells In Vitro and In Vivo via Targeting miR-203

Role of long noncoding RNAs in the regulation of alternative splicing in glioblastoma

Glioblastoma multiforme (GBM) is a highly severe primary brain tumor. Despite extensive research, effective treatments remain elusive. Long noncoding RNAs (lncRNAs) play a significant role in both cancer and normal biology. They influence alternative splicing (AS), which is crucial in cancer. Advances in lncRNA-specific microarrays and next-generation sequencing have enhanced understanding of AS. Abnormal AS contributes to cancer invasion, metastasis, apoptosis, therapeutic resistance, and tumor development, including glioma. lncRNA-mediated AS affects several cellular signaling pathways, promoting or suppressing cancer malignancy. This review discusses the lncRNAs regulating AS in glioblastoma and their mechanisms.

Could alder buckthorn (Frangula alnus Mill) be a source of chemotherapeutics effective against hepato- and colorectal carcinoma? An in vitro study

Among numerous types of cancer, hepatocellular and colorectal carcinoma are important causes of mortality. Given the nature of these cancer types and their resistance, it is of great importance to find new chemotherapeutics and therapy targets, so plant products seem to be an excellent choice in such search. The main goal of this study was to investigate anticancer activity of Frangula alnus ethyl-acetate extract (FA) and its dominant constituent emodin (E) on hepatocellular and colorectal carcinoma cell lines, HepG2 and HCT116, as well as on normal MRC-5 fibroblasts. Cytotoxicity was investigated in MTT test and both FA and E showed strong reduction of cell viability in cancer cells. Flow cytometer analysis demonstrated that FA and E led to G1 phase arrest and slight accumulation of cells in the G2/M phase; additionally, annexinV-FITC/7AAD dying showed that FA and E decreased cell viability and triggered apoptosis in all cell lines. FA and E evidenced strong genotoxic potential in comet assay performed on all cell lines, while tests measuring antioxidative potential (DPPH and TBA) demonstrated strong effect of FA. It could be concluded that both FA and E have significant anticancer activity against hepatocellular and colorectal carcinoma cell lines HepG2 and HCT116, but notable selectivity was not observed.

Pertinence of glioma and single nucleotide polymorphism of TERT, CCDC26, CDKN2A/B and RTEL1 genes in glioma: a meta-analysis

Background

Previous genetic-epidemiological studies considered TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) gene polymorphisms as the risk factors specific to glioma. However, the data samples of previous genetic-epidemiological studies are modest to determine whether they have definite association with glioma.

Method

The study paid attention to systematically searching databases of PubMed, Embase, Web of Science (WoS), Scopus, Cochrane Library and Google Scholars. Meta-analysis under 5 genetic models, namely recessive model (RM), over-dominant model (O-DM), allele model (AM), co-dominant model (C-DM) and dominant model (DM) was conducted for generating odds ratios (ORs) and 95% confidence intervals (CIs). That was accompanied by subgroup analyses according to various racial groups. The software STATA 17.0 MP was implemented in the study.

Result

21 articles were collected. According to data analysis results, in four genetic models (AM, RM, DM and C-DM) TERT gene rs2736100 polymorphism, CCDC26 gene rs4295627 polymorphism, CDKN2A/B gene rs4977756 polymorphism and RTEL1 gene rs6010620 polymorphisms increased the risk of glioma in Caucasians to different degrees. In Asian populations, the CCDC26 gene rs4295627 polymorphism and CDKN2A/B gene rs4977756 polymorphism did not exhibit a relevance to the risk of glioma. It is suggested to cautiously explain these results as the sample size is small.

Conclusion

The current meta-analysis suggested that the SNP of TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) genes in glioma might increase risk of glioma, but there are ethnic differences. Further studies evaluating these polymorphisms and glioma risk are warranted.

Update on Chemoresistance Mechanisms to First-Line Chemotherapy for Gallbladder Cancer and Potential Reversal Strategies

OBJECTIVE

Gallbladder cancer (GBC) mortality remains high and chemoresistance is increasing. This review consolidates what is known about the mechanisms of chemoresistance to inform and accelerate the development of novel GBC-specific chemotherapies.

METHODS

Studies related to GBC-related chemoresistance were systematically screened in PubMed using the advanced search function. Search terms included GBC, chemotherapy, and signaling pathway.

RESULTS

Analysis of existing studies showed that GBC has poor sensitivity to cisplatin, gemcitabine (GEM), and 5-fluorouracil. DNA damage repair-related proteins, including CHK1, V-SCR, and H2AX, are involved in tumor adaptation to drugs. GBC-specific chemoresistance is often accompanied by changes in the apoptosis and autophagy-related molecules, BCL-2, CRT, and GBCDRlnc1. CD44 + and CD133 + GBC cells are less resistant to GEM, indicating that tumor stem cells are also involved in chemoresistance. In addition, glucose metabolism, fat synthesis, and glutathione metabolism can influence the development of drug resistance. Finally, chemosensitizers such as lovastatin, tamoxifen, chloroquine, and verapamil are able improve the therapeutic effect of cisplatin or GEM in GBC.

CONCLUSIONS

This review summarizes recent experimental and clinical studies of the molecular mechanisms of chemoresistance, including autophagy, DNA damage, tumor stem cells, mitochondrial function, and metabolism, in GBC. Information on potential chemosensitizers is also discussed. The proposed strategies to reverse chemoresistance should inform the clinical use of chemosensitizers and gene-based targeted therapy for this disease.

HERV-K (HML-2) insertion polymorphisms in the 8q24.13 region and their potential etiological associations with acute myeloid leukemia

Human endogenous retroviruses (HERVs) are LTR retrotransposons that are present in the human genome. Among them, members of the HERV-K (HML-2) group are suspected to play a role in the development of different types of cancer, including lung, ovarian, and prostate cancer, as well as leukemia. Acute myeloid leukemia (AML) is an important disease that causes 1% of cancer deaths in the United States and has a survival rate of 28.7%. Here, we describe a method for assessing the statistical association between HERV-K (HML-2) transposable element insertion polymorphisms (or TIPs) and AML, using whole-genome sequencing and read mapping using TIP_finder software. Our results suggest that 101 polymorphisms involving HERV-K (HML-2) elements were correlated with AML, with a percentage between 44.4 to 56.6%, most of which (70) were located in the region from 8q24.13 to 8q24.21. Moreover, it was found that the TRIB1, LRATD2, POU5F1B, MYC, PCAT1, PVT1, and CCDC26 genes could be displaced or fragmented by TIPs. Furthermore, a general method was devised to facilitate analysis of the correlation between transposable element insertions and specific diseases. Finally, although the relationship between HERV-K (HML-2) TIPs and AML remains unclear, the data reported in this study indicate a statistical correlation, as supported by the χ² test with p-values < 0.05.

Necroptosis-related lncRNAs: establishment of a gene module and distinction between the cold and hot tumors in glioma

Background

Gliomas are the most common primary tumors of the central nervous system and portend a poor prognosis. The efficacy of emerging and promising immunotherapies varies significantly among individuals. Distinction and transformation of cold and hot tumors may improve the antitumor efficacy of immunotherapy.

Methods and Results

In this study, we constructed a necroptosis-related lncRNA module based on public databases. The association of this module with survival was assessed using the Cox regression, Kaplan-Meier survival analysis, and nomogram, external validation was also conducted in another public database. Furthermore, we performed gene set enrichment analysis (GSEA), immune checkpoint and tumor microenvironment analysis, and in vitro qRT-PCR validation. Finally, we clustered all samples into 2 clusters based on the expression of model lncRNAs and identified cluster 1 as cold tumors with fewer infiltrating T cells.

Conclusions

Identifying cold and hot tumors by necroptosis-related lncRNAs can help available immunotherapeutic strategies to achieve efficacy in the precise treatment of individuals. Prior treatment failure can be overcome by targeting necroptosis-related lncRNAs.

lncRNA polymorphism affects the prognosis of gastric cancer

Background

Previous studies have found that lncRNA polymorphisms are associated with the prognosis of gastric cancer (GC), but the specific roles of many lncRNA polymorphism sites in gastric cancer are still unclear. Our study aims to deeply explore the relationship between genetic polymorphism of lncRNA and the prognosis of GC.

Methods

The genotypes of candidate SNP locus were detected by Sequenom Mass ARRAY SNP. We deeply analyzed the association of lncRNA polymorphisms with GC prognosis by univariate and multivariate Cox regression, stratified analysis, conjoint analysis, and log-rank test.

Results

We found that mutations at rs2579878 and rs10036719 loci reduced the risk of poor prognosis of GC. Stratified analysis showed that rs2795025, rs10036719, and rs12516079 polymorphisms were all associated with tumor prognosis. In addition, conjoint analyses showed that the interaction between these two polymorphic sites (rs2795025 and rs12516079) could increase the risk of poor prognosis. Multivariate analysis also found that the AG/AA genotype of rs10036719 and AG genotype of rs12516079 were independent prognostic factors. Moreover, the high expression of both CCDC26 and LINC02122 were shown to be associated with the poor survival status of GC patients.

Conclusions

We find that the genetic polymorphism of lncRNA plays a role in the development of GC and is closely related to the survival time of patients. It could serve as a predictor of the prognosis of GC.

Metastasis associated long noncoding RNAs in glioblastoma: Biomarkers and therapeutic targets

Glioblastoma (GBM) is the most aggressive, malignant, and therapeutically challenging Grade IV tumor of the brain. Although the possibility of distant metastasis is extremely rare, GBM is known to cause intracranial metastasis forming aggressive secondary lesions resulting in a dismal prognosis. Metastasis also plays an important role in tumor dissemination and recurrence making GBM largely incurable. Recent studies have indicated the importance of long noncoding RNAs (lncRNAs) in GBM metastasis. lncRNAs are a class of regulatory noncoding RNAs (>200 nt) that interact with DNA, RNA, and proteins to regulate various biological processes. This is the first comprehensive review summarizing the lncRNAs associated with GBM metastasis and the underlying molecular mechanism involved in migration/invasion. We also highlight the complex network of lncRNA/miRNA/protein that collaborate/compete to regulate metastasis-associated genes. Many of these lncRNAs also show attractive potential as diagnostic/prognostic biomarkers. Finally, we discuss various therapeutic strategies and potential applications of lncRNAs as therapeutic targets for the treatment of GBM.

Role of mammalian long non-coding RNAs in normal and neuro oncological disorders

Long non-coding RNAs (lncRNAs) are expressed at lower levels than protein-coding genes but have a crucial role in gene regulation. LncRNA is distinct, they are being transcribed using RNA polymerase II, and their functionality depends on subcellular localization. Depending on their niche, they specifically interact with DNA, RNA, and proteins and modify chromatin function, regulate transcription at various stages, forms nuclear condensation bodies and nucleolar organization. lncRNAs may also change the stability and translation of cytoplasmic mRNAs and hamper signaling pathways. Thus, lncRNAs affect the physio-pathological states and lead to the development of various disorders, immune responses, and cancer. To date, ~40% of lncRNAs have been reported in the nervous system (NS) and are involved in the early development/differentiation of the NS to synaptogenesis. LncRNA expression patterns in the most common adult and pediatric tumor suggest them as potential biomarkers and provide a rationale for targeting them pharmaceutically. Here, we discuss the mechanisms of lncRNA synthesis, localization, and functions in transcriptional, post-transcriptional, and other forms of gene regulation, methods of lncRNA identification, and their potential therapeutic applications in neuro oncological disorders as explained by molecular mechanisms in other malignant disorders.

Is Emodin with Anticancer Effects Completely Innocent? Two Sides of the Coin

Many anticancer active compounds are known to have the capacity to destroy pathologically proliferating cancer cells in the body, as well as to destroy rapidly proliferating normal cells. Despite remarkable advances in cancer research over the past few decades, the inclusion of natural compounds in researches as potential drug candidates is becoming increasingly important. However, the perception that the natural is reliable is an issue that needs to be clarified. Among the various chemical classes of natural products, anthraquinones have many biological activities and have also been proven to exhibit a unique anticancer activity. Emodin, an anthraquinone derivative, is a natural compound found in the roots and rhizomes of many plants. The anticancer property of emodin, a broad-spectrum inhibitory agent of cancer cells, has been detailed in many biological pathways. In cancer cells, these molecular mechanisms consist of suppressing cell growth and proliferation through the attenuation of oncogenic growth signaling, such as protein kinase B (AKT), mitogen-activated protein kinase (MAPK), HER-2 tyrosine kinase, Wnt/-catenin, and phosphatidylinositol 3-kinase (PI3K). However, it is known that emodin, which shows toxicity to cancer cells, may cause kidney toxicity, hepatotoxicity, and reproductive toxicity especially at high doses and long-term use. At the same time, studies of emodin, which has poor oral bioavailability, to transform this disadvantage into an advantage with nano-carrier systems reveal that natural compounds are not always directly usable compounds. Consequently, this review aimed to shed light on the anti-proliferative and anti-carcinogenic properties of emodin, as well as its potential toxicities and the advantages of drug delivery systems on bioavailability.

LINC01158 works as an oncogene in glioma via sponging miR-6734-3p to boost CENPK expression

BACKGROUND

Long non-coding RNAs (lncRNAs) have been certified to play vital biological functions in glioma and have received considerable attention in the recent literature. Nonetheless, the role of LINC01158 in glioma remains to be elucidated.

METHODS

qRT-PCR, western blot and GEPIA database were applied for reporting the expression of CENPK and LINC01158 in glioma and the correlation between LINC01158 and CENPK expression. EdU, colony formation, CCK-8, caspase-3 activity and TUNEL assays probed the impacts of LINC01158 on glioma cell growth. Subcellular fractionation and FISH assays revealed the cellular distribution of LINC01158. Luciferase reporter and RIP assays examined ceRNA network of LINC01158, CENPK and miR-6734-3p.

RESULTS

LINC01158 and CENPK were both overexpressed in glioma and a positive regulation of LINC01158 on CENPK was corroborated. LINC01158 served a pro-proliferative and anti-apoptotic part in glioma by sponging miR-6734-3p to augment CENPK.

CONCLUSION

LINC01158 enhances CENPK by serving as sponge for miR-6734-3p to facilitate glioma development, proposing LINC01158 as a new player in glioma.

Long Noncoding RNA CCDC26 Promotes Thyroid Cancer Malignant Progression via miR-422a/EZH2/Sirt6 Axis

Purpose

Long noncoding RNAs are crucial regulators in thyroid cancer progression. However, the role of lncRNA CCDC26 in thyroid cancer remains unclear. Here, we aimed to explore the effect of CCDC26 on thyroid cancer progression and the underlying mechanism.

Materials and Methods

A total of 50 clinical thyroid cancer samples were studied in patients' samples, cultured cells, and nude mice before and after treatment using quantitative reverse transcription-PCR, CCK-8 assays, BrdU incorporation assays, Transwell assays, cell apoptosis analysis, luciferase reporter gene assay, RNA immunoprecipitation, Western blot analysis, and tumorigenicity analysis.

Results

CCDC26 expression was elevated in patients' thyroid cancer tissues and thyroid cancer cell lines. CCDC26 depletion remarkably reduced proliferation, invasion, and migration but induced apoptosis of thyroid cancer cells. Mechanically, miR-422a mimic remarkably reduced the luciferase activity of CCDC26 transfected cells but failed to affect cells transfected with CCDC26 containing the mutated miR-422a-binding site. RNA immunoprecipitation (RIP) assays showed that CCDC26 and miR-422a preferentially interacted with Ago2, but not IgG, in the micro-ribonucleoprotein complexes (miRNPs). CCDC26 depletion enhanced miR-422a expression and MiR-422a inhibitor reversed CCDC26 knockdown-induced inhibition of thyroid cancer progression in vitro. CCDC26 upregulated EZH2 and Sirt6 expression by sponging miR-422a in thyroid cancer cells. Tumorigenicity analysis in nude mice revealed that CCDC26 contributed to thyroid tumor growth via miR-422a/EZH2/Sirt6 axis in vivo.

Conclusion

CCDC26 promotes thyroid cancer malignant progression via miR-422a/EZH2/Sirt6 axis. This finding provides new insights into the mechanism by which CCDC26 promotes malignant thyroid cancer development, advances our understanding of lncRNAs' association with thyroid cancer, and indicates that CCDC26 and miR-422a may serve as potential targets for thyroid cancer.

Emodin enhances cisplatin sensitivity in non-small cell lung cancer through Pgp downregulation

Cisplatin resistance is one of the main causes of chemotherapy failure and tumor progression in non-small cell lung cancer (NSCLC). Emodin has been demonstrated to induce NSCLC cell apoptosis and act as a potential cancer therapeutic agent. However, whether emodin could affect NSCLC cell sensitivity toward cisplatin remains unclear. The present study aimed to determine the effect of emodin and cisplatin combination on the chemosensitivity of NSCLC cells. A549 and H460 cells were treated with different concentrations of cisplatin and/or emodin. Cell Counting Kit-8, fluorescence microscopy, immunofluorescence assays and flow cytometry were used to determine cell proliferation, drug efflux, DNA damage level and cell apoptosis, respectively. P-glycoprotein (Pgp) and multidrug resistance-associated protein 1 (MRP1) expression was detected by western blotting. The results demonstrated that emodin and cisplatin inhibited the proliferation of A549 and H460 cells. Furthermore, emodin inhibited the drug efflux in A549 and H460 cells in a dose-dependent manner. In addition, emodin enhanced cisplatin-induced apoptosis and DNA damage in A549 and H460 cells. Emodin also decreased Pgp expression in A549 and H460 cells in a dose-dependent manner; however, it had no effect on MRP1 expression. Taken together, the results from the present study demonstrated that emodin can increase A549 and H460 cell sensitivity to cisplatin by inhibiting Pgp expression. Emodin may therefore be considered as an effective adjuvant for cisplatin treatment.

8q24.21 Locus: A Paradigm to Link Non-Coding RNAs, Genome Polymorphisms and Cancer

The majority of the human genome is comprised of non-protein-coding genes, but the relevance of non-coding RNAs in complex diseases has yet to be fully elucidated. One class of non-coding RNAs is long non-coding RNAs or lncRNAs, many of which have been identified to play a range of roles in transcription and translation. While the clinical importance of the majority of lncRNAs have yet to be identified, it is puzzling that a large number of disease-associated genetic variations are seen in lncRNA genes. The 8q24.21 locus is rich in lncRNAs and very few protein-coding genes are located in this region. Interestingly, the 8q24.21 region is also a hot spot for genetic variants associated with an increased risk of cancer. Research focusing on the lncRNAs in this area of the genome has indicated clinical relevance of lncRNAs in different cancers. In this review, we summarise the lncRNAs in the 8q24.21 region with respect to their role in cancer and discuss the potential impact of cancer-associated genetic polymorphisms on the function of lncRNAs in initiation and progression of cancer.

Long non-coding RNAs in brain tumors

Long non-coding RNAs (lncRNAs) have been found to be central players in the epigenetic, transcriptional and post-transcriptional regulation of gene expression. There is an accumulation of evidence on newly discovered lncRNAs, their molecular interactions and their roles in the development and progression of human brain tumors. LncRNAs can have either tumor suppressive or oncogenic functions in different brain cancers, making them attractive therapeutic targets and biomarkers for personalized therapy and precision diagnostics. Here, we summarize the current state of knowledge of the lncRNAs that have been implicated in brain cancer pathogenesis, particularly in gliomas and medulloblastomas. We discuss their epigenetic regulation as well as the prospects of using lncRNAs as diagnostic biomarkers and therapeutic targets in patients with brain tumors.

LncRNA CCDC26 Interacts with CELF2 Protein to Enhance Myeloid Leukemia Cell Proliferation and Invasion via the circRNA_ANKIB1/miR-195-5p/PRR11 Axis

LncRNA CCDC26 is aberrantly expressed in myeloid leukemia (ML) and promotes myeloid leukemia progression, but the potential mechanism of CCDC26 in regulating ML progression is unclear. In this study, we observed that lncRNA CCDC26 was upregulated in both chronic and acute ML cell lines. LncRNA CCDC26 promoted the proliferation and invasion of K562 and HL-60 cells, which was determined by cell counting kit-8 test and Transwell invasion assay. Flow cytometry showed that lncRNA CCDC26 inhibited cell apoptosis. Bioinformatics and expression correlation analyses revealed that there was a potential interaction between CCDC26 and CUGBP Elav-like family member 2 (CELF2) protein, an RNA bind protein (RBP). Then the relationship between CCDC26 and the RBP CELF2 was identified by using RNA pull-down and RNA immunoprecipitation (RNA-IP) assays. Further analysis showed that overexpression of CCDC26 could noticeably upregulate circRNA_ANKIB1 expression via sponging CELF2. Subsequently, we found that overexpressed circRNA_ANKIB1 could significantly promote proline rich 11 (PRR11) protein expression by sponging miR-195a-5p. Moreover, PRR11 was also upregulated by CCDC26 and downregulated by CELF2. Mechanically, we uncovered that the miR-195a-5p inhibitor activated the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways through upregulating PRR11 protein expression. Furthermore, the inhibitors of AKT, p65-NF-κB, or Bcl-2 could inhibit the effect of the miR-195a-5p inhibitor on ML cell behaviors. In conclusion, lncRNA CCDC26 could upregulate PRR11 protein expression by sponging miR-195a-5p, thereby activating the PI3K/AKT and NF-κB pathways to enhance ML cell proliferation and invasion and suppress cell apoptosis.

A systematic review of long non-coding RNAs with a potential role in breast cancer

The human transcriptome contains many non-coding RNAs (ncRNAs), which play important roles in gene regulation. Long noncoding RNAs (lncRNAs) are an important class of ncRNAs with lengths between 200 and 200,000 bases. Unlike mRNA, lncRNA lacks protein-coding features, specifically, open-reading frames, and start and stop codons. LncRNAs have been reported to play a role in the pathogenesis and progression of many cancers, including breast cancer (BC), acting as tumor suppressors or oncogenes. In this review, we systematically mined the literature to identify 65 BC-related lncRNAs. We then perform an integrative bioinformatics analysis to identify 14 lncRNAs with a potential regulatory role in BC. The biological function of these 14 lncRNAs, their regulatory mechanisms, and roles in the initiation and progression of BC are discussed in this review. Additionally, we elaborate on the current and future applications of lncRNAs as diagnostic and/or therapeutic biomarkers in BC.

Long noncoding RNA CCDC26 as a modulator of transcriptional switching between fetal and embryonic globins

The CCDC26 gene is considered to encode a functional noncoding RNA associated with acute myeloid leukemia and other cancers. However, investigations into the physiological roles of CCDC26 are rare. Previously, we reported that CCDC26 regulated proliferation and cell death of leukemia cells through KIT, a receptor tyrosine kinase, by using K562 leukemia cells and their derivative CCDC26-knockdown (KD) cells. Here we propose a new role of CCDC26 in the differentiation of erythroid cells. We showed that expression of embryonic (ε- and ζ-) globins was markedly upregulated in CCDC26-KD cells compared with K562 control cells during hemin-induced differentiation. In contrast, expression of fetal-type γ-globin, a major globin expressed in original K562 cells, was decreased. These changes in the expression of globin genes mainly took place at the transcriptional level, with significant suppression of transcription of adult (β-, δ-) globins in CCDC26-KD cells. Re-introduction of exogenous CCDC26 into the CCDC26-KD cells recovered low-level expression of the embryonal globins. These results suggest CCDC26 has a role in switching transcription of globin genes in the differentiation of erythroid cells. The expression profile of the CCDC26-KD cells and control cells suggests FOG-2, a transcriptional modulator, as a candidate for a mediator of the CCDC26-associated regulation. We showed that both embryonic globins were transcriptionally activated in FOG-2-KD K562 cells. The KIT inhibitor ISCK03 suppressed the production of hemoglobin in K562 cells but did not affect transcription of globin genes. To summarize, FOG-2, but not KIT, is responsible for globin transcriptional regulation by CCDC26.

The Long Intergenic Noncoding RNA 00707 Sponges MicroRNA-613 (miR-613) to Promote Proliferation and Invasion of Gliomas

Background:

Glioma is one of the most deadly malignant tumors in humans. Long non-coding RNA (lncRNA) plays a key role in the occurrence, development and invasion of tumors by regulating oncogenic and tumor suppressor pathways. However, the role and action mechanism of long intergenic non-coding RNA 00707 (LINC00707) in gliomas have not been elucidated. This study aimed to investigate the interaction between LINC00707 and miR-613 as well as its role in gliomas.

Materials and Methods:

The expression levels of LINC00707 and miR-613 were detected by qRT-PCR. The chi-square test was used to analyze the correlation between LINC00707 expression and clinicopathological parameters. CCK-8 and colony formation assays were used to detect glioma cell proliferation; and wound healing and transwell assays were used to detect glioma cell migration and invasion. The relationship between LINC00707 and miR-613 was predicted by Starbase, and verified by qRT-PCR and dual luciferase reporter gene assay.

Results:

LINC00707 was up-regulated in gliomas. Up-regulated LINC00707 increased the proliferation, migration and invasion of glioma cells, and silenced LINC00707 reduced these abilities. The increase of the expression level of LINC00707 down-regulated miR-613 in glioma cells, while the inhibition of the expression level of LINC00707 up-regulated miR-613 in glioma cells. The high expression of LINC00707 was related to the Karnofsky performance status (KPS) score and WHO staging. LINC00707 could offset the ability of miR-613 to inhibit glioma proliferation and invasion.

Conclusion:

LINC00707 promotes proliferation and invasion of glioma cells by sponging miR-613. The regulatory axis of LINC00707/miR-613 provides new insights into the mechanism and treatment of gliomas.

Long non-coding RNAs as epigenetic mediator and predictor of glioma progression, invasiveness, and prognosis

Gliomas are aggressive brain tumors with high mortality rate. Over the past several years, non-coding RNAs, specifically the long non-coding RNAs (lncRNAs), have emerged as biomarkers of considerable interest. Emerging data reveals distinct patterns of expressions of several lncRNAs in the glioma tissues, relative to their expression in normal brains. This has led to the speculation for putative exploitation of lncRNAs as diagnostic biomarkers as well as biomarkers for targeted therapy. With a focus on lncRNAs that have shown promise as epigenetic biomarkers in the proliferation, migration, invasion, angiogenesis and metastasis in various glioma models, we discuss several such lncRNAs. The data from cell line / animal model-based studies as well as analysis from human patient samples is presented for the most up-to-date information on the topic. Overall, the information provided herein makes a compelling case for further evaluation of lncRNAs in clinical settings.

lncRNA MALAT1 promotes cell proliferation and invasion by regulating the miR-101/EZH2 axis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the oral cavity. Emerging evidence indicates that long non-coding (lnc)RNAs play a key role in the cellular processes of tumor cells, including glycolysis, growth and movement. Here, the purpose of this study was to explore the biological functions and potential mechanism of lncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) in OSCC. OSCC tissues and adjacent matched paraneoplastic normal tissues were collected from 20 OSCC patients. The expression of MALAT1 and miR-101 in OSCC tissues and cell lines (HSC3, SCC9, SCC15 and SCC25) were determined by real-time-polymerase chain reaction (qPCR). Caspase-3, xaspase-8 and EZH2 protein levels were determined by western blot analysis. MALAT1-mediated miRNAs were verified by bioinformatics analysis of StarBase and Luciferase reporter assay. Cell Counting Kit-8 (CCK-8) and Transwell assays were used for investigating MALAT1 effect on cell proliferation and invasion in the OSCC cells. qPCR analysis indicated that MALAT1 expression was obviously increased, and miR-101 was decreased in the OSCC tissues and cell lines. Functional studies revealed that overexpression of MALAT1 promoted OSCC cell proliferation and invasion. Further experiments revealed that miR-101 was a target of MALAT1 and that the miR-101 inhibitor abolished the effect of MALAT1 on OSCC cell proliferation and invasion. Enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) acted as a downstream effecter of MALAT1 in the OSCC cells. Collectively, these findings revealed that upregulation of MALAT1 facilitated OSCC proliferation and invasion by targeting the miR-101/EZH2 axis.

Tamoxifen inhibits cell proliferation by impaired glucose metabolism in gallbladder cancer

Gallbladder cancer (GBC) is the leading malignancy of biliary system showing refractory chemoresistance to current first‐line drugs. Growing epidemiological evidences have established that the incidence of GBC exhibits significant gender predominance with females two‐threefold higher than males, suggesting oestrogen/oestrogen receptors (ERs) signalling might be a critical driver of tumorigenesis in gallbladder. This study aims to evaluate the antitumour activity of tamoxifen (TAM), a major agent of hormonal therapy for breast cancer, in preclinical GBC model. Quantitative real‐time PCR was used to investigate mRNA levels. Protein expression was measured by immunohistochemistry and Western blot. Glycolytic levels were measured by glucose consumption and lactic acid measurement. The antitumour activity of TAM alone or with cisplatin was examined with CCK8 assay, colony formation, flow cytometry and in vivo models. The results revealed that ERɑ expression was higher in GBC tissues and predicted poor clinical outcomes. TAM was showed effective against a variety of GBC cell lines. Mechanical investigations revealed that TAM enabled potent reactive oxygen species (ROS) production by reduced nuclear factor Nrf2 expression and its target genes, leading to the activation of AMPK, which subsequently induced impaired glycolysis and survival advantages. Notably, TAM was demonstrated to sensitize GBC cells to cisplatin (CDDP) both in vitro and in vivo. In agreement with these findings, elimination of oestrogens by ovariectomy in nude mice prevented CDDP resistance. In summary, these results provide basis for TAM treatment for GBC and shed novel light on the potential application of endocrine therapy for patients with GBC.

lncRNA-CCDC26, as a novel biomarker, predicts prognosis in acute myeloid leukemia

The aim of the present study was to examine the expression and clinical significance of long non-coding RNA (lncRNA)-CCDC26 in patients with acute myeloid leukemia (AML), and to investigate the potential functions of CCDC26. The Gene Expression Omnibus database and reverse transcription-quantitative polymerase chain reaction analysis were used to detect the expression levels of CCDC26 in patients with AML and healthy volunteers. Clinical data for 93 patients with AML were collected to analyze the clinical significance of CCDC26. Weighted gene co-expression network analysis (WGCNA), a protein-protein interaction (PPI) network, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were used to examine the functions of CCDC26. The expression levels of CCDC26 in the initially diagnosed and relapsed patients with AML were significantly upregulated compared with the control group. The upregulated expression level of CCDC26 in patients with AML was significantly associated with age, anemia, risk stratification and remission. Furthermore, patients with a high CCDC26 expression level had a poorer overall survival (P=0.0105). In addition, the area under the curve (AUC)_1year and AUC_2year of CCDC26 for overall survival were 0.722 and 0.686, respectively. WGCNA, PPI network and KEGG pathway analysis revealed that CCDC26 was involved in the regulation of a number of biological processes. lncRNA-CCDC26 may serve as a novel biomarker for monitoring the progression and predicting the clinical outcome of AML.

Distinct Profiles of Cell-Free MicroRNAs in Plasma of Veterans with Post-Traumatic Stress Disorder

Dysregulation of circulating microRNAs (miRNAs) in body fluids has been reported in psychiatric disorders such as schizophrenia, bipolar disorder, major depressive disorder, and post-traumatic stress disorder (PTSD). Recent studies of various diseases showed that extracellular vesicles (EV) in body fluids can provide different spectra of circulating miRNAs and disease-associated signatures from whole fluid or EV-depleted fraction. However, the association of miRNAs in EVs to PTSD has not been studied. In this study, we performed a comprehensive profiling of miRNAs in whole plasma, extracellular vesicles (EV) and EV-depleted plasma (EVD) samples collected from combat veterans with PTSD and matched controls by utilizing a next-generation sequencing (NGS) platform. In total, 520 circulating miRNAs were quantified from 24 male Iraq and Afghanistan combat veterans with (n = 12) and without (n = 12) PTSD. The overall miRNA profiles in whole plasma, EV and EVD fractions were different and miRNAs affected by PTSD were also distinct in each sample type. The concentration changes of miR-203a-3p in EV and miR-339-5p in EVD were confirmed in an independent validation cohort that consisted of 20 veterans (10 with and 10 without PTSD) using qPCR. The target genes of these two miRNAs were involved in signaling pathways and comorbid conditions associated with PTSD (e.g., neurotransmitter systems such as dopaminergic and serotonergic signaling, inflammatory response, and cardiovascular diseases). Our findings suggest that PTSD may have different impacts on miRNAs encapsulated in vesicles and outside of vesicles. Further studies using larger samples are needed to evaluate the utility of these miRNAs as diagnostic biomarkers for PTSD.

The association of 6 variants of 8q24 and the risk of glioma: A meta-analysis

With the advances in sequencing technologies and genome-wide association studies (GWAS), several inherited variants that increase glioma risk have been identified. Ten studies including 8818 cases and 17,551 controls were collected to conduct a meta-analysis to evaluate the associations between 6 variants in 8q24 and glioma risk. Of the 6 variants located in 8q24, 2 have strong significant associations with the risk of glioma, including rs4295627 (P = .003, odds ratio [OR] = 1.21), rs55705857 (P = 2.31 × 10, OR = 3.54). In particular, both homozygous GG (P = 1.91 × 10, OR1 = 2.01) and heterozygous GT (P = 7.75 × 10, OR2 = 1.35) genotypes of rs4295627 were associated with glioma risk. Further studies are needed to explore the role of the 8q24 variants involved in the etiology of glioma.

Role of Circular RNAs in Preeclampsia

Circular RNAs (circRNAs) are noncoding RNAs characterized by circular covalently closed structures, which are generated by back-splicing. circRNA is more stable and conserved than linear RNA and exists in various organisms. Preeclampsia (PE), a common hypertensive disorder of pregnancy, has a profound impact on maternal and neonatal mortality and morbidity. Recent studies demonstrated that circRNAs were differentially expressed in PE maternal-fetal interface compared with those in the control and might mediate pathological processes in pregnancy complications. However, the mechanisms of action of circRNAs in PE are still unclear. Here, we provide a comprehensive review on the current state of knowledge on circRNAs associated with PE. We summarize the known expression profiles of circRNAs and discuss their potential application as biomarkers of PE. The possible mechanisms underlying circRNA dysregulation in the etiology of PE are also explored.

Knockdown of lncRNA-UCA1 inhibits the proliferation and migration of melanoma cells through modulating the miR-28-5p/HOXB3 axis

Long non-coding RNA urothelial carcinoma-associated 1 (UCA1) functions as an oncogene in different human cancers, including melanoma. However, the molecular mechanism of UCA1 underlying melanoma progression still remains largely unknown. In the present study, reverse transcription quantitative polymerase chain reaction and western blot analyses were used to examine the mRNA and protein expression levels, respectively. Cell Counting Kit-8 and wound healing assays were conducted to study cell proliferation and migration, respectively. A luciferase reporter assay was used to confirm the targeting relationship. It was demonstrated that UCA1 expression was increased in melanoma tissues and cell lines. In addition, UCA1 expression was higher in melanoma tissues at stage III-IV than in tissues at stage I-II. Inhibition of UCA1 expression markedly reduced melanoma cell proliferation and migration. Further investigation revealed that UCA1 functioned in melanoma cells through directly binding with microRNA (miR)-28-5p. The expression of miR-28-5p was significantly reduced in melanoma tissues and had an inverse correlation with UCA1 expression. In addition, miR-28-5p expression was higher in melanoma tissues at advanced stages than in stage I-II tissues. Furthermore, homeobox (HOX)B3 was identified as a target gene of miR-28-5p in melanoma cells, and HOXB3 overexpression reversed the suppressive effects of UCA1 downregulation on melanoma cell proliferation and migration. Finally, HOXB3 was upregulated in melanoma tissues compared with its expression in adjacent tissues, and HOXB3 expression was increased in melanoma tissues at advanced stages. Taken together, the regulatory network of the UCA1/miR-28-5p/HOXB3 axis in melanoma was demonstrated for the first time in the present study, expanding the understanding of the molecular mechanism underlying melanoma progression. Future studies may further confirm the function of this signaling pathway in vivo.

MicroRNA-130a regulated by HPV18 E6 promotes proliferation and invasion of cervical cancer cells by targeting TIMP2

Human papillomaviruses (HPVs) have important roles in the development and progression of cervical cancer, but the underlying mechanisms are yet to be fully elucidated. MicroRNA-130a (miR-130a) has previously been reported to promote cervical cancer growth. However, the underlying molecular mechanisms by which miR-130a promotes cervical cancer progression have remained largely elusive. In the present study, polymerase chain reaction and western blot analyses were performed to examine the expression levels of miR-130a and associated proteins. A wound healing assay and a Transwell assay were applied to study cell migration and invasion. A luciferase reporter gene assay was performed to confirm the targeting associations of miR-130a. It was observed that miR-130a was significantly upregulated in cervical cancer tissues compared with that in adjacent non-tumorous tissues. High expression of miR-130a was significantly associated with lymph node metastasis and an advanced clinical stage of cervical cancer. Furthermore, the expression of miR-130a was also higher in HPV(+) cervical cancer cell lines compared with that in HPV(-) cells. Knockdown of HPV18 E6 significantly inhibited the expression of miR-130a in HeLa cervical cancer cells. Furthermore, knockdown of miR-130a reduced the migration and invasion of HeLa cells. Tissue inhibitor of metalloproteinase 2 (TIMP2), an antagonist of matrix metalloproteinase 2 (MMP2), was identified as a novel, direct target gene of miR-130a. The expression of TIMP2 was negatively mediated by miR-130a, and HPV18 E6 inhibited the expression of TIMP2 in HeLa cells. Furthermore, knockdown of TIMP2 rescued the suppressive effects of miR-130a downregulation on the migration and invasion of HeLa cells. In summary, the present study suggests that HPV18 E6 promotes the expression of miR-130a, which further inhibits the expression of TIMP2 and promotes cervical cancer cell invasion. Therefore, HPV/miR-130a/TIMP2 signaling may be a potential target for the prevention of cervical cancer metastasis.

Non-Coding RNAs in Glioma

Glioma is the most aggressive brain tumor of the central nervous system. The ability of glioma cells to migrate, rapidly diffuse and invade normal adjacent tissue, their sustained proliferation, and heterogeneity contribute to an overall survival of approximately 15 months for most patients with high grade glioma. Numerous studies indicate that non-coding RNA species have critical functions across biological processes that regulate glioma initiation and progression. Recently, new data emerged, which shows that the cross-regulation between long non-coding RNAs and small non-coding RNAs contribute to phenotypic diversity of glioblastoma subclasses. In this paper, we review data of long non-coding RNA expression, which was evaluated in human glioma tissue samples during a five-year period. Thus, this review summarizes the following: (I) the role of non-coding RNAs in glioblastoma pathogenesis, (II) the potential application of non-coding RNA species in glioma-grading, (III) crosstalk between lncRNAs and miRNAs (IV) future perspectives of non-coding RNAs as biomarkers for glioma.

Identification of the key genes and long non‑coding RNAs in ankylosing spondylitis using RNA sequencing

Ankylosing spondylitis (AS) is an insidious and debilitating form of arthritis that involves the axial skeleton, and its etiology and pathogenesis remain unclear. In the present study, three patients with AS and three normal controls from our hospital were enrolled. RNA sequencing and bioinformatics analysis were performed in order to identify the differentially expressed (DE) mRNAs (DEmRNAs) and DE long non‑coding RNAs (DElncRNAs) between the patients with AS and normal controls. Construction of an AS‑specific protein‑protein interaction network, a weighted DElncRNA‑DEmRNA co‑expression network and functional annotation of the DEmRNAs co‑expressed with DElncRNAs was performed. Nearby cis‑targeted DEmRNAs or DElncRNAs were identified by searching for DEmRNAs that were transcribed within 100‑kb up‑ or downstream of DElncRNAs. Based on the Gene Expression Omnibus datasets GSE25101 and GSE73754, the expression of selected DEmRNAs and DElncRNAs were verified using published RNA sequencing data from blood samples, and receiver operating characteristic analysis of selected DEmRNAs was performed. Compared with the normal controls, 1,072 DEmRNAs and 372 DElncRNAs in the patients with AS were identified. Caspase recruitment domain family member 11 and DNA methyltransferase 1 have great diagnostic value for AS. MSTRG.8559 and LINC00987 were also identified as two hub DElncRNAs. The T‑cell receptor signaling pathway was a significantly enriched pathway of the DEmRNAs co‑expressed with DElncRNAs in patients with AS. In conclusion, the present study identified the key DEmRNAs and DElncRNAs in AS, which provides novel information for understanding the pathogenesis of AS and developing potential biomarkers for AS.

MicroRNA-101 inhibits cell migration and invasion in bladder cancer via targeting FZD4

Dysfunction of microRNAs (miRs) has been implicated in the development and progression of various human cancers. Our previous study demonstrated that miR-101 inhibited bladder cancer cell proliferation and invasion through inhibition of c-FOS expression. As an miR generally has many targets, other targets of miR-101 may also serve important roles in bladder cancer progression. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to examine mRNA and protein expression, respectively. Wound healing and Transwell assays were conducted to study cell migration and invasion, respectively. The luciferase reporter gene assay was performed to verify one of the targets of miR-101. The data in the present study indicate that the expression of miR-101 is significantly reduced in bladder cancer tissues compared with that in adjacent non-tumour tissues. In addition, miR-101 expression is also downregulated in bladder cancer cell lines compared with that in normal bladder epithelial cells. Furthermore, low expression of miR-101 was significantly associated with tumour metastasis, advanced clinical stage, and poor prognosis in bladder cancer. Frizzled class receptor 4 (FZD4) was identified as a novel target of miR-101 in bladder cancer cells. The expression of FZD4 was significantly upregulated in bladder cancer tissues and cell lines. Both miR-101 overexpression and FZD4 inhibition caused a significant reduction of the migration and invasion of bladder cancer cells, whereas overexpression of FZD4 reversed the suppressive effects of miR-101 on bladder cancer cell migration and invasion. In conclusion, it was demonstrated that miR-101 downregulation is associated with bladder cancer progression and that miR-101 can inhibit bladder cancer cell migration and invasion via directly targeting FZD4. The present study expands the understanding of the molecular mechanisms underlying bladder cancer progression.

Long non-coding RNA XIST serves an oncogenic role in osteosarcoma by sponging miR-137

The long non-coding RNA X inactive-specific transcript (XIST) has been implicated in certain human cancers, including osteosarcoma (OS), but the molecular mechanism of XIST underlying OS progression remains to be fully uncovered. In the present study, reverse transcription-quantitative polymerase chain reaction data demonstrated that XIST was significantly upregulated in OS tissues and cell lines (Saos-2, U2OS, HOS and MG63) compared with adjacent non-tumour tissues and normal human osteoblast cell line HFOB1.19. Bioinformatics analysis and luciferase reporter gene assay data demonstrated that XIST could directly target microRNA (miR)-137 and negatively regulate the expression of miR-137 in Saos-2 and U2OS cells. Furthermore, miR-137 was markedly downregulated in OS tissues and cell lines. An inverse association between XIST and miR-137 expression was observed in OS tissues. Knockdown of XIST caused a significant reduction in cell proliferation and invasion and suppressed matrix metalloproteinase (MMP2) and MMP9 protein levels in Saos-2 and U2OS cells. Furthermore, inhibition of miR-137 expression abolished the effects of XIST downregulation on the proliferation and invasion of OS cells. In summary, the present study suggests that XIST promotes OS cell proliferation and invasion by inhibition of miR-137 expression. Thus, XIST may be a potential therapeutic target for the treatment of OS.

Long non-coding RNA NEAT1 promotes migration and invasion of oral squamous cell carcinoma cells by sponging microRNA-365

Long non-coding RNA nuclear enriched abundant transcript 1 (NEAT1) has been demonstrated to serve key roles in numerous human cancer types, but its function in oral squamous cell carcinoma (OSCC) and underlying regulatory mechanism have not been evaluated. The present study demonstrated that expression of NEAT1 was significantly higher in OSCC tissue and cell lines compared with adjacent non-tumour tissue and normal oral keratinocytes, respectively. Additionally, upregulation of NEAT1 was significantly associated with advanced clinical stage and shorter survival time in patients with OSCC. Bioinformatics analysis and luciferase reporter gene assay data confirmed the interaction between NEAT1 and miR-365, and it was revealed that NEAT1 may downregulate microRNA (miR)-365 expression in OSCC cells. Furthermore, inhibition of NEAT1 expression led to a significant reduction in OSCC cell migration and invasion, which was accompanied by reduced matrix metalloproteinase (MMP)-2 and MMP9 protein expression. By contrast, inhibition of miR-365 eliminated suppressive effects of NEAT1 knockdown on OSCC cell migration and invasion. miR-365 was significantly downregulated in OSCC tissue and cell lines and an inverse correlation between miR-365 and NEAT1 expression in OSCC tissue was observed. To conclude, the present study demonstrated that NEAT1 promoted migration and invasiveness of OSCC cells by sponging miR-365. The current study suggests that NEAT1 may serve as a novel therapeutic target for the treatment of OSCC.

Long non-coding RNA TUG1 promotes osteosarcoma cell proliferation and invasion through inhibition of microRNA-212-3p expression

Taurine upregulated gene 1 (TUG1), a long non-coding RNA (lncRNA), has recently been suggested to be associated with the development of osteosarcoma (OS), but the underlying molecular mechanism still remains largely unclear. In the present study, it was revealed that TUG1 was significantly upregulated whereas miR-212-3p was significantly downregulated in OS tissues and cell lines, when compared with adjacent non-tumor tissues and normal osteoblasts cell lines, respectively. An inverse association between the TUG1 and miR-212-3p expression was also observed in OS tissues. Furthermore, TUG1 directly interacted with miR-212-3p and negatively regulated the expression of miR-212-3p in OS cells. In vitro experiments further indicated that inhibition of TUG1 suppressed the proliferation and invasion of OS cells. Furthermore, knockdown of miR-212-3p eliminated the suppressive effects of TUG1 inhibition on the proliferation and invasion of OS cells. Taken together, these findings demonstrate that TUG1 promotes OS cell proliferation and invasion by inhibition of miR-212-3p expression, thus suggesting that TUG1 may become a potential therapeutic target for OS.

MicroRNA-599 suppresses glioma progression by targeting RAB27B

MicroRNAs (miRNAs/miRs) serve tumor promoting or suppressive roles in different human cancer types, including glioma; however, the regulatory underlying mechanism by which miR-599 affects glioma progression remains largely unknown. The aim of the present study was to investigate the expression of miR-599 in glioma, as well as the underlying regulatory mechanism. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to examine mRNA and protein expression, respectively. MTT, wound healing and transwell assays were conducted to study cell proliferation, migration and invasion, respectively. A dual-luciferase reporter gene assay was used to confirm the targeting association between miR-599 and Ras-related protein Rab-27B (hereafter RAB27B). In the present study, miR-599 expression was observed to be significantly downregulated in human glioma tissues and cell lines, when compared with normal brain tissues and normal human astrocyte cells, respectively. Low miR-599 expression was significantly associated with glioma progression. Ectopic expression of miR-599 caused a significant reduction in the proliferation, migration and invasion of U-87MG Uppsala and U251 cells. Bioinformatics analysis and dual-luciferase reporter gene assay data identified that RAB27B was a direct target gene of miR-599. The mRNA and protein expression of RAB27B was significantly downregulated following miR-599 overexpression in U-87MG Uppsala and U251 cells. Rescue experiments demonstrated that RAB27B rescued the miR-599-induced inhibition of glioma cell growth, migration and invasion. In addition, RAB27B expression was significantly upregulated in glioma tissues and cell lines, and the expression levels of RAB27B were inversely correlated with miR-599 levels in glioma tissues; therefore, the present study demonstrated that miR-599 exerts a tumor-suppressive role in glioma progression by targeting RAB27B, indicating that miR-599 may be used as a potential candidate for glioma treatment.

Long non-coding RNA GAS5 inhibits ovarian cancer cell proliferation via the control of microRNA-21 and SPRY2 expression

In recent decades, numerous long non-coding (lnc)RNAs, including growth arrest-specific transcript 5 (GAS5), have been demonstrated to exert promoting or suppressive effects in human cancers. Decreased expression of the lncRNA GAS5 was reported to promote cell proliferation, migration and invasion and indicate poor prognosis in ovarian cancer. However, the exact underlying molecular mechanism through which GAS5 is involved in ovarian cancer growth remains unknown. The present study aimed to investigate the regulatory mechanism of GAS5 in ovarian cancer cell proliferation. Quantitative polymerase chain reaction and western blot analysis were used to examine RNA and protein expression, respectively. An MTT assay was used to examine cell proliferation. A luciferase reporter gene assay was conducted to verify the targeting relationship. It was identified that the expression levels of GAS5 and Sprouty homolog 2 (SPRY2) were significantly downregulated, while the expression level of microRNA (miR)-21 was significantly upregulated in ovarian cancer tissues and cell lines compared with adjacent non-tumor tissues and normal ovarian epithelial cells, respectively. Downregulation of GAS5 was significantly associated with advanced clinical stage. Luciferase assay data indicated that miR-21 was a direct target of GAS5 and that SPRY2 was a target gene of miR-21 in ovarian cancer-derived A2780 cells. GAS5 overexpression significantly inhibited the proliferation of ovarian cancer cells, which was accompanied by the downregulation of miR-21 and the upregulation of SPRY2. The overexpression of miR-21 caused a significant decrease in A2780 cell proliferation, which was accompanied by reduced SPRY2 expression. Furthermore, miR-21 overexpression attenuated the suppressive effects of GAS5 on A2780 cell proliferation and rescued the promoting effects of GAS5 on SPRY2 expression. In addition, the knockdown of SPRY2 also rescued the suppressive effects of GAS5 on the proliferation of A2780 cells. In summary, our study demonstrates that GAS5 exerts a suppressive effect on the proliferation of ovarian cancer cells, at least in part via the inhibition of miR-21 expression and subsequent increased SPRY2 expression. These findings suggest that the GAS5/miR-21/SPRY2 signaling pathway may be a potential therapeutic target in ovarian cancer.

Emodin inhibits epithelial‑mesenchymal transition and metastasis of triple negative breast cancer via antagonism of CC‑chemokine ligand 5 secreted from adipocytes

Triple negative breast cancer (TNBC) has the lowest survival rate of the breast cancer subtypes owing to its aggressive and metastatic behavior. It has been reported that peritumoral adipose tissue contributes to the cell invasiveness and dissemination of TNBC. Emodin is an active anthraquinone derivative isolated from Rheum palmatum, with anticancer properties that have been reported to inhibit lung metastasis in a nude mouse xenograft model. In the present study, the effects of emodin on human TNBC cells and adipocytes were investigated in vivo and in vitro. The TNBC cell lines MDA‑MB‑231 and MDA‑MB‑453 were co‑cultured with human adipocytes and treated with either emodin or epirubicin. Cell proliferation was assessed by MTT assay and migration and invasion were examined using a wound healing assay and a Transwell assay. interleukin‑8, CC‑chemokine ligand 5 (CCL5) and insulin‑like growth factor‑1 levels in the culture supernatants were detected by ELISA. The epithelial‑mesenchymal transition (EMT) or metastasis associated markers were determined by western blot analysis. Nude mice fed with a high fat and sugar diet were used investigate the in vivo effect of emodin. The results showed that emodin inhibited TNBC proliferation and invasion more efficiently than epirubicin when co‑cultured with adipocytes by downregulating the level of CCL5 in adipocyte supernatants; inhibiting the expression level of protein kinase B (AKT); and activating glycogen synthase kinase‑3i (GSK3) and β‑catenin. This led to the suppressed expression of EMT‑ and invasion‑associated markers, including vimentin, snail, matrix metalloproteinase (MMP)‑2 and MMP‑9, and upregulation of E‑cadherin, contributing to the inhibition of invasion. The in vivo assay showed that emodin inhibited tumor growth, and suppressed the lung and liver metastasis of TNBC cells by decreasing the secretion of CCL5 in mice fed a high fat and sugar diet more efficiently when compared with epirubicin. In conclusion, emodin inhibited the secretion of CCL5 from adipocytes, inhibited the EMT of TNBC cells, and inhibited tumor growth and lung and liver metastasis, which indicated a novel role of emodin in preventing the metastasis of TNBC.

The silencing of LncRNA-H19 decreases chemoresistance of human glioma cells to temozolomide by suppressing epithelial-mesenchymal transition via the Wnt/β-Catenin pathway

Introduction

Temozolomide (TMZ) is commonly used for glioma chemotherapy. However, TMZ resistance limits the therapeutic effect of TMZ in glioma treatment. LncRNA-H19 acts as an oncogenic LncRNA in some types of cancers and has been reported to be up-regulated in glioma.

Materials and methods

In our present study, we established TMZ-resistant glioma cells (U-251TMZ and M059JTMZ) to explore the effect of H19 on the chemoresistance of glioma cells.

Results

We observed that the expression of H19 was significantly increased in U-251TMZ and M059JTMZ cells. Knockdown of H19 expression using specific shRNA in U-251TMZ and M059JTMZ led to decreased half maximal inhibitory concentration (IC₅₀) values for TMZ and increased cell apoptosis rates, indicating that the silencing of H19 decreased chemoresistance of glioma cells to TMZ. In addition, silencing of H19 suppressed epithelial-mesenchymal transition (EMT) by increasing the expression of epithelial marker E-cadherin and decreasing the expression of mesenchymal marker Vimentin and ZEB1. Moreover, inducing EMT by TGF-β1 treatment led to increased IC₅₀ values for TMZ and decreased cell apoptosis rates compared with TMZ+H19 shRNA group, suggesting that the induction of EMT counteracted the inhibitory effect of H19 shRNA on chemoresistance of glioma cells to TMZ. Furthermore, the reduced expression of H19 down-regulated the expression of β-Catenin and its downstream targets c-myc and Survivin in TMZ-treated glioma cells. Activation of Wnt/β-Catenin pathway by Licl treatment promoted EMT and enhanced chemoresistance to TMZ compared with TMZ+H19 shRNA group.

Conclusion

Taken together, our data suggest that H19 decreased chemoresistance of glioma cells to TMZ by suppressing EMT via the inhibition of Wnt/β-Catenin pathway. Our study might represent a novel therapeutic target for TMZ-resistant glioma.

The long non-coding RNA SNHG14 inhibits cell proliferation and invasion and promotes apoptosis by sponging miR-92a-3p in glioma

Malignant glioma is one of the most common types of primary brain tumours. Long non-coding RNAs (lncRNAs) have recently emerged as a new class of therapeutic targets for many cancers. In this study, we aimed to explore the functional involvement of small nucleolar RNA host gene 14 (SNHG14) and its potential regulatory mechanism in glioma progression. SNHG14 was found to be downregulated in human glioma tissues and cell lines. SNHG14 significantly inhibited cell viability, reduced cell invasion, and induced apoptosis in glioma cell lines. Furthermore, a correlation analysis demonstrated that there was a negative correlation between SNHG14 expression and miR-92a-3p expression. Bioinformatics prediction and luciferase reporter assays demonstrated that miR-92a-3p could directly bind to SNHG14. miR-92a-3p was significantly upregulated in glioma and acted as an oncogene in glioma cells by inhibiting Bim. Moreover, mechanistic investigations showed that miR-92a-3p could reverse the tumour suppressive effects induced by SNHG14 in glioma, indicating that SNHG14 may act as an endogenous sponge that competes for binding to miR-92a-3p. Our results suggest that SNHG14 and miR-92a-3p may be promising molecular targets for glioma therapy.

Inhibition of telomerase using BIBR1532 enhances doxorubicin-induced apoptosis in pre-B acute lymphoblastic leukemia cells

OBJECTIVES

Interest into targeting telomerase in cancer has increased by the recent disclosure that elevated telomerase activity is associated with disease recurrence and poor outcome in cancers. In addition, cellular acquisition of unlimited replicative potential, which is closely related to the maintenance of telomeres mostly via the reactivation of telomerase, has been shown to confer loss of sensitivity to a wide range of anti-neoplastic agents.

METHODS

To evaluate whether telomerase inhibition using non-nucleosidic inhibitor of telomerase BIBR1532 could enhance cytotoxic effect of doxorubicin in acute lymphoblastic leukemia, Nalm-6 pre-B ALL cells were subjected to combination treatment and subsequent cell viability, growth kinetics, caspase-3 activity, and transcriptional alteration of p73, p21, FOXO3a, c-Myc, hTERT, and other apoptosis-related target genes were investigated.

RESULTS

Combination of BIBR1532 with doxorubicin produced a synergistic anticancer effect probably through induction of p73. Transcription factor p73 not only suppressed the proliferative capacity of the cells through induction of p21-mediated G1 arrest, but also down-regulated the mRNA level of hTERT and c-Myc. Our results also report that BIBR1532 induced a caspase-dependent apoptosis, at least partially, through heightened ROS levels, and noteworthy enhanced the pro-oxidant property of doxorubicin. In harmony, transcriptional repression of survivin could be a probable underlying mechanism for the induction of apoptosis through shifting the ratio of death promoters to death repressors via alteration of Bax and Bcl2 expression.

CONCLUSIONS

Overall, it seems that combination of BIBR1532 and doxorubicin could be a novel therapeutic strategy for acute lymphoblastic leukemia that may be clinically accessible in the near future.

Very low doses of ionizing radiation and redox associated modifiers affect survivin-associated changes in radiation sensitivity

Exposure of cells to a dose of ionizing radiation as low as 5mGy can induce changes in radiation sensitivity expressed by cells exposed to subsequent higher doses at later times. This is referred to as an adaptive effect. We describe a unique survivin-associated adaptive response in which increased radiation resistance or sensitization of cells can be induced by exposure to 5mGy or to the reactive oxygen species (ROS) generating drug Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a naturally occurring anthraquinone. The purpose of this study was to determine the role of ROS generating processes in affecting both the intracellular localization of the inhibitor of apoptosis protein survivin and its subsequent effect on radiation response in the presence or absence of the anti-oxidant N-acetyl-L-cysteine (NAC). Experiments were performed using two well characterized murine sarcomas: SA-NH p53 wild-type (WT) and FSa p53 mutant (Mut), grown either in culture or as solid tumors in the right hind legs of C3H mice. Doses of 5mGy or 50μM Emodin were used to induce changes in the response of these tumor cells to higher radiation exposures using a multi-dosing paradigm. Effects on radiation sensitivity were determined for SA-NH and FSa cells as a function of survivin translocation either to the cytoplasm or nucleus in the presence or absence of 10mM NAC treatment. In vitro survival assays (2Gy per fraction, two once daily fractions) and tumor growth delay (TGD) (5Gy per fraction, five once daily fractions) studies were performed. Intracellular localization of survivin was determined by enzyme-linked immunosorbent assay (ELISA) and correlated to survival response and treatment conditions. 2Gy alone had no effect on intracellular translocation of survivin. When preceded 15min earlier by 5mGy or Emodin exposures, survivin became elevated in the cytoplasm of p53 WT SA-NH as compared to the nuclei of p53 Mut FSa cells. SA-NH cells transfected with p53 small interfering RNA (siRNA), in contrast, responded similarly to p53 Mut FSa cells by becoming more radiation sensitive if exposed to 5mGy prior to each 2Gy irradiation. In contrast to their respective responses to five once daily 5Gy fractions, SA-NH tumors were protected by 5mGy exposures administered 15min prior to each daily 5Gy dose as evidenced by a more rapid growth (1.9 day decrease in TGD, P=0.032), while FSa tumors were sensitized, growing at a much slower rate (4.5 day increase in TGD, P<0.001). Exposure of SA-NH and FSa tumor cells to 10mM NAC inhibited the ability of 5mGy and Emodin to induce intracellular translocation of survivin and the corresponding altered adaptive survival response. The survivin-associated adaptive response can be induced following a multi-dosing scheme in which very low radiation doses are followed shortly thereafter by higher doses consistent with a standard image guided radiotherapy protocol that is currently widely used in the treatment of cancer. While induced by exposure to ROS generating stresses, the ultimate expression of changes in radiation response is dependent upon the bi-functionality of the tumor associated protein survivin and its intracellular translocation.

Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro by activating autophagy

AIM

A previous report shows that emodin extracted from the Chinese herbs rhubarb and giant knotweed rhizome can ameliorate the anticancer drug cisplatin-induced injury of HEK293 cells. In this study, we investigated whether and how emodin could protect renal tubular epithelial cells against cisplatin-induced nephrotoxicity in vitro.

METHODS

The viability and apoptosis of normal rat renal tubular epithelial cells (NRK-52E) were detected using formazan assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy maker LC3 I/II, and AMPK/mTOR signaling pathway-related proteins were measured with Western blot analysis. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy.

RESULTS

Cisplatin (10-50 μmol/L) dose-dependently induced cell damage and apoptosis in NRK-52E cells, whereas emodin (10 and 100 μmol/L) significantly ameliorated cisplatin-induced cell damage, apoptosis and caspase-3 cleavage. Emodin dose-dependently increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Furthermore, the protective effects of emodin were abolished by bafilomycin A1 (10 nmol/L), and mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) not only abolished emodin-induced autophagy activation, but also emodin-induced anti-apoptotic effects.

CONCLUSION

Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro through modulating the AMPK/mTOR signaling pathways and activating autophagy. Emodin may have therapeutic potential for the prevention of cisplatin-induced nephrotoxicity.

Emodin suppresses Wnt signaling in human colorectal cancer cells SW480 and SW620

Wnt signaling is involved in the regulation of cell proliferation, differentiation and apoptosis. Its aberrant activation is a key event in the pathogenesis and progression of human colorectal cancers. Dietary phytochemicals are gaining importance as chemotherapeutic agents owing to their potential to prevent, delay or reverse oncogenesis. Here we demonstrate that emodin (1,3,8-trihydroxy-6-methylanthraquinone), an anthraquinone present in the roots and bark of several medicinal plants, down regulates Wnt signaling pathway in human colorectal cancer cells (SW480 and SW620) by down regulating TCF/LEF transcriptional activity. Emodin significantly down regulated the expression of key players of Wnt signaling (β-catenin and TCF7L2) and also that of its various downstream targets (cyclin D1, c-Myc, snail, vimentin, MMP-2 and MMP-9). Two novel targets of emodin׳s action were discovered namely Wnt co-activator p300 (down regulated) and repressor HBP1 (up regulated). Morphological changes induced by emodin suggest mesenchymal to epithelial transition accompanied by the increase in E-cadherin expression in human colorectal cancer cells but a differentiation marker (alkaline phosphatase) was activated only in SW620 cells (metastatic origin) and not in SW480 cells (primary tumor-derived). Moreover, our data indicate that reactive oxygen species plays a key role in emodin-mediated down regulation of Wnt signaling as emodin-mediated inhibition of migration and induction of growth arrest were partially rescued by the reactive oxygen species scavenger ascorbic acid. Effects of emodin shown in this study may provide important insights for the use of this anthraquinone as a potential complementary and integrated medicine for the treatment of human colorectal cancer.

The combined effect of survivin-targeted shRNA and emodin on the proliferation and invasion of ovarian cancer cells

Survivin has been shown to be highly expressed in ovarian cancers, but not normal ovarian tissue, which makes it an attractive target for ovarian cancer treatment. Emodin is a traditional Chinese medicine that has been found to inhibit proliferation and induce apoptosis in ovarian cancer cells. Thus, in our study, we combined survivin-targeted shRNA (sur-shRNA) with emodin and tested the effects of this combination on ovarian cancer cells to identify more effective therapeutics against ovarian cancer. A sur-shRNA plasmid was constructed and transfected into the ovarian cancer cell lines SKOV3 and HO8910, and the cells were cultured for 24 h. The cells were then treated with emodin for specific time periods and assessed for viability and apoptosis using the MTT assay and flow cytometry, respectively. Cell invasion was also measured using a Matrigel invasion assay. The shRNA specific for survivin effectively reduced the expression of survivin at the mRNA and protein levels in SKOV3 and HO8910 cells. Both emodin and shRNA-mediated knockdown of survivin significantly inhibited cell proliferation, induced apoptosis, and suppressed invasion in SKOV3 and HO8910 cells (P<0.05). Moreover, the combination of the agents significantly enhanced these effects (P<0.05). We found that the combination of sur-shRNA and emodin could be effective in the treatment of ovarian cancer.

The distinct mechanisms of the antitumor activity of emodin in different types of cancer (Review)

Emodin, a tyrosine kinase inhibitor, is a natural anthraquinone derivative found in the roots and rhizomes of numerous plants. The inhibitory effect of emodin on mammalian cell cycle modulation in specific oncogene-overexpressing cells has formed the basis for using this compound as an anticancer drug. Previous reviews have summarized the antitumor properties of emodin. However, the specific molecular mechanisms of emodin-mediated tumor inhibition have not been completely elucidated over the last 5 years. Recently, there has been great progress in the preclinical study of the anticancer mechanisms of emodin. Our recent study revealed that emodin has therapeutic effects on pancreatic cancer through various antitumor mechanisms. Notably, the therapeutic efficacy of emodin in combination with chemotherapy was found to be higher than the comparable single chemotherapeutic regime, and the combination therapy also exhibited fewer side-effects. Despite these encouraging results, further investigation is warranted as emodin has been shown to modulate one or more key regulators of cancer growth. This review provides an overview of the distinct mechanisms of anticancer action of emodin in different body systems identified over the past 5 years. These new breakthrough findings may have important implications for targeted cancer therapy and for the future clinical use of emodin.