Non-coding RNAs and gastric cancer

NRAS Contributes to Retinoblastoma Progression Through SNHG16/miR-183-5p/NRAS Regulatory Network

Purpose

The oncogene of wild type neuroblastoma RAS viral oncogene homolog (NRAS) has been found to involve in the tumorigenesis of cancers. However, the role of NRAS in retinoblastoma (RB) progression remains largely unknown.

Methods

The expression levels of NRAS, miR-183-5p and small nucleolar RNA host gene 16 (SNHG16) were measured using quantitative real-time polymerase chain reaction assay or Western blot assay, respectively. Cell proliferation and apoptosis were analyzed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay or flow cytometry, respectively. Transwell assay was used to determine cell migration and invasion abilities. The interaction between miR-183-5p and NRAS or SNHG16 was analyzed using bioinformatics analysis and dual-luciferase reporter assay.

Results

NRAS was elevated in RB tissues and cell lines, knockdown of NRAS could inhibit proliferation, migration and invasion but induced apoptosis in vitro and suppressed tumor growth in vivo. NRAS was confirmed to be a target of miR-183-5p and was negatively regulated by miR-183-5p in RB cells. Moreover, overexpressed NRAS reversed miR-183-5p mediated inhibition on RB cell progression. Besides that, SNHG16 directly interacted with miR-183-5p and reduced miR-183-5p expression in RB cells. The suppression of RB cell progression induced by SNHG16 silencing could be partially attenuated by the inhibition of miR-183-5p. Besides that, SNHG16 could regulate NRAS expression through competitively binding to miR-183-5p in RB cells.

Conclusion

NRAS functioned as an oncogene to contribute to RB progression by SNHG16/miR-183-5p/NRAS regulatory network, indicating a novel and promising therapeutic target for RB.

Huaier Suppresses Breast Cancer Progression via linc00339/miR-4656/CSNK2B Signaling Pathway

Huaier, as known as Trametes robiniophila Murr, is a traditional Chinese medicine. Various studies have demonstrated that Huaier could inhibit cancer progression and improve the prognosis of patients. In the present study, we comprehensively screened the expression profiles of lncRNAs, miRNAs, and mRNAs in Huaier-treated breast cancer cells. Using bioinformatic analysis, hub genes were identified and functionally annotated. Weighted gene coexpression network analysis was applied to construct the molecular network influenced by Huaier. Linc00339 was then found to play a critical role in Huaier-mediated cancer suppression. To validate the effects of linc00339 and identify the downstream targets, we performed in vitro and in vivo experiments. Finally, we identified that Huaier could inhibit the proliferation of breast cancer cells through modulating linc00339/miR-4656/CSNK2B signaling pathway.

Long noncoding RNA VCAN-AS1 contributes to the progression of gastric cancer via regulating p53 expression

Gastric cancer (GC) is one of the most frequent malignancies worldwide. Long noncoding RNAs (lncRNAs) are found to be largely implicated in various cancers, including GC. However, the function of lncRNA VCAN antisense RNA 1 (VCAN-AS1) in GC remains unclear. Herein, we observed a low level of VCAN-AS1 in normal gastric tissues through NCBI and UCSC, and that VCAN-AS1 upregulation in GC tissues was related to poor prognosis by TCGA. Furthermore, VCAN-AS1 was found markedly enhanced in GC tissues and cell lines, while its upregulation was related with clinical outcomes of GC patients. Besides this, silencing VCAN-AS1 represses cell proliferation, migration, and invasion but enhances apoptosis. More important, we discovered that VCAN-AS1 expression was negatively correlated with wild-type p53 levels in GC tissues and that p53 was negatively modulated by VCAN-AS1 in GC cells. Furthermore, p53 suppression reversed the repression of VCAN-AS1 silence on the biological processes of AGS cells. Intriguingly, we identified that both VCAN-AS1 and TP53 can bind with eIF4A3, one of the core proteins in the exon junction complex. Also, we confirmed that VCAN-AS1 negatively regulates TP53 expression by competitively binding with eIF4A3. Our findings disclosed that VCAN-AS1 contributes to GC progression through interacting with eIF4A3 to downregulate TP53 expression, indicating that VCAN-AS1 is a novel therapeutic strategy for GC treatment.

MicroRNAs associated with microvascular invasion in hepatocellular carcinoma and their prognostic impacts in patients undergoing hepatic resection

Although microvascular invasion (McVI) has prognostic value for patients with hepatocellular carcinoma (HCC) who have undergone hepatic resection, few studies have investigated the relationship between McVI and the aberrant expression of microRNAs (miRNAs). The present study identified the miRNAs that were selectively expressed in HCC with McVI and investigated their prognostic value. Clinical data and the miRNA expression profiles of 372 patients with HCC were extracted from The Cancer Genome Atlas database. miRNAs that were differentially expressed between patients with McVI and those without vascular invasion (VI) were identified and investigated as potential prognostic factors for HCC. The results demonstrated that McVI was a significant predictor of shortened recurrence-free survival (RFS). The 3 year RFS rate in patients with HCC accompanied by McVI was 28.2 and 49.3% in HCC without VI (P<0.001). miRNA-141/-582/-9 were upregulated, while miRNA-675 was downregulated in patients with McVI when compared with HCC patients without VI. Log₂ fold-changes of miRNA-141/-582/-675/-9 were 0.80 [false discovery rate (FDR), 0.005], 0.55 (FDR, 0.045), -0.99 (FDR, 0.005) and 1.22 (FDR, <0.001), respectively. Kaplan-Meier analysis indicated that the overexpression of miR-141/-582/-9 was significantly associated with poor RFS and a poor overall survival. A text mining analysis revealed that these miRNAs were significantly associated with multifaceted hallmarks of cancer, including 'invasion and metastasis'. In conclusion, the overexpression of miRNA-141/-582/-9 was associated with McVI and a poor survival in patients undergoing hepatic resection for HCC.

Targeting Nuclear Exporter Protein XPO1/CRM1 in Gastric Cancer

Gastric cancer remains an unmet clinical problem in urgent need of newer and effective treatments. Here we show that the nuclear export protein, Exportin 1 (XPO1, chromosome region maintenance 1 or CRM1), is a promising molecular target in gastric cancer. We demonstrate significant overexpression of XPO1 in a cohort of histologically diverse gastric cancer patients with primary and metastatic disease. XPO1 RNA interference suppressed gastric cancer cell growth. Anti-tumor activity was observed with specific inhibitor of nuclear export (SINE) compounds (selinexor/XPOVIO), second-generation compound KPT-8602/eltanexor, KPT-185 and +ve control Leptomycin B in three distinct gastric cancer cell lines. SINE compounds inhibited gastric cancer cell proliferation, disrupted spheroid formation, induced apoptosis and halted cell cycle progression at the G1/S phase. Anti-tumor activity was concurrent with nuclear retention of tumor suppressor proteins and inhibition of colony formation. In combination studies, SINE compounds enhanced the efficacy of nab-paclitaxel in vitro and in vivo. More significantly, using non-coding RNA sequencing studies, we demonstrate for the first time that SINE compounds can alter the expression of non-coding RNAs (microRNAs and piwiRNAs). SINE treatment caused statistically significant downregulation of oncogenic miR-33b-3p in two distinct cell lines. These studies demonstrate the therapeutic significance of XPO1 in gastric cancer that warrants further clinical investigation.

The biogenesis and biological functions of circular RNAs and their molecular diagnostic values in cancers

BACKGROUND

In addition to non-coding RNAs (lncRNAs) and microRNAs (miRNAs), circular RNAs (circRNAs) are endogenous RNAs with various functions, which have recently become a research hotspot. CircRNAs are a kind of closed circular RNA molecule widely existing in transcriptomes. Due to lack of free ends, they are not easily cleaved by RNase R, thus avoiding degradation. They are more stable than linear RNAs.

METHODS

Data were collected through PubMed. The following search terms were used: "circular RNA," "circRNA," "cancer," "mechanism," "biogenesis," "biomarker," "diagnosis." Only articles published in English were included.

RESULTS

Most circRNAs express tissue/developmental stage specificity. Moreover, circRNAs are involved in the regulation of a variety of biological activities. In this review, we discuss the formation, classification, and biological functions of circRNAs, especially their molecular diagnostic values in common cancers, including gastric cancer (hsa_circ_002059, circ_LARP4, hsa_circ_0000190, hsa_circ_0000096, circ-SFMBT2, and circ_PVT1), hepatocellular carcinoma (circ_104075, circRNA_100338, circ_MTO1, and circZKSCAN1), colorectal cancer (hsa_circ_0136666 and hsa_circ_0000523), lung cancer (hsa_circ_0006427, circ_100876, and circ_ABCB10), breast cancer (hsa_circ_0089105, circAGFG1, and circEPSTI1), bladder cancer (circFNDC3B and circTFRC), and esophageal squamous cell carcinoma (circ_100876 and circ-DLG1).

CONCLUSION

CircRNAs not only play important roles in tumorigenesis, but also may become new diagnostic biomarkers.

Significantly different expression levels of microRNAs associated with vascular invasion in hepatocellular carcinoma and their prognostic significance after surgical resection

BACKGROUND

Although gross vascular invasion (VI) has prognostic significance in patients with hepatocellular carcinoma (HCC) who have undergone hepatic resection, few studies have investigated the relationship between gross VI and aberrant expression of microribonucleic acids (miRNAs and miRs). Thus, the objective of this study was to identify miRNAs selectively expressed in HCC with gross VI and investigate their prognostic significance.

MATERIALS AND METHODS

Eligible two datasets (accession number: GSE20594 and GSE67140) were collected from the National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) database to compare miRNAs expression between HCC with and without gross VI. Differentially expressed miRNAs were externally validated using expression data from The Cancer Genome Atlas (TCGA) database. Prognostic significance and predicted functions of selected miRNAs for HCC were also investigated.

RESULTS

Thirty-five miRNAs were differentially expressed between HCC with and without gross VI in both datasets. Among them, three miRNAs were validated using TCGA database. miR-99a, miR-100, and miR-148a were downregulated to a greater extent in patients with HCC and gross VI than in those with HCC but no gross VI. Receiver operating characteristic (ROC) curve analysis showed discriminatory power of these miRNAs in predicting gross VI. Multivariate survival analysis revealed that types of surgery, advanced tumor node metastasis (TNM) stage, and low expression of miR-100-5p were independently associated with tumor recurrence. It also revealed that types of surgery, advanced TNM stage, low expression of miR-100-5p and miR-148a-3p were independent risk factors for overall survival (OS) after hepatic resection for HCC. A text mining analysis revealed that these miRNAs were linked to multifaceted hallmarks of cancer, including "invasion and metastasis."

CONCLUSIONS

Low expressions of miR-100-5p and miR-148a-3p were associated with gross VI and poor survival of patients after hepatic resection for HCC.

Genome-wide long non-coding RNAs identified a panel of novel plasma biomarkers for gastric cancer diagnosis

BACKGROUND

Although long non-coding RNAs (lncRNAs) are regarded as useful plasma-based biomarkers for cancer detection, the potential diagnostic value of lncRNAs in gastric cancer (GC) remains unclear.

METHODS

To screen promising lncRNAs biomarkers for GC, we performed genome-wide lncRNA microarray assay between five GC cases plasma and matched healthy controls plasma. The expression of candidate plasma-related lncRNAs were validated in two-phase validation of 446 subjects. The receiver operating characteristic curve was constructed for evaluating diagnostic accuracy. We also determined the origin and stability of plasma lncRNAs, and investigated biological effects of candidate lncRNAs on cellular phenotypes.

RESULTS

A total of 3878 lncRNAs were expressed differentially in GC plasma, among which the top 10 up-regulated lncRNAs were selected for further validation. A two-stage validation revealed that plasma levels of three lncRNAs (FAM49B-AS, GUSBP11, and CTDHUT) were significantly higher in GC plasma as compared with healthy controls (P < 0.05), and the combined area under curve of these lncRNAs was 0.818 (95% CI 0.772-0.864). Moreover, these lncRNAs were stable and detectable in human plasma, and also enriched in extracellular fluid. The expression levels of all three lncRNAs dropped significantly on day 10 after radical surgery compared with preoperative levels (P < 0.05). Also, lncRNA FAM49B-AS significantly promoted GC cell viability and invasion.

CONCLUSIONS

Plasma lncRNA FAM49B-AS, GUSBP11 and CTDHUT have a strong potential to serve as noninvasive biomarkers for GC diagnosis.

Disregulation of miR-216a and miR-217 in Gastric Cancer and Their Clinical Significance

OBJECTIVE

The majority of gastric cancer (GC) diagnoses occur at the middle or late stage of the disease, indicating that finding novel biomarkers that could be detectable at earlier stage is urgently needed. Accumulating studies have shown that microRNAs, a class of tiny single-stranded RNAs, play important roles in multiple biological processes including cancer development. The present study aimed to evaluate the effect of miR-216a and miR-217 in GC.

MATERIAL AND METHODS

The real-time quantitative reverse-transcription PCR was exploited to identify and compare the expression levels of miR-216a and miR-217 in 37 pairs of samples of gastric cancer tissue and adjacent normal tissue. Superimposed on this, the potential relationship between miR-216a/217 levels and clinicopathological parameters in patients suffering GC was explored.

RESULTS

The results obtained from this study showed that the miR-216a is significantly upregulated in gastric cancer tissues, compared with adjacent normal tissues, but the altered expression of miR-217 was not significant. For miR-216a/217, no significant correlations were detected between expression levels of these miRNAs and clinical and pathological characteristics of patients.

CONCLUSION

This prospective study proposes that upregulation of miR-216a might represent an important mechanism for the development of gastric cancer.

[Advances in serum biomarkers for early diagnosis of gastric cancer]

Early diagnosis is the key to improve the prognosis of gastric cancer. How to screen out high-risk subjects of gastric cancer in population is a hot spot. Serum-based early detection of gastric cancer is suitable for high-risk population screening, which is more convenient and safer. This article reviews the diagnostic value of serum biomarkers for gastric cancer, including serum DNA methylation, various RNAs, pepsinogen, gastrin, osteopontin, MG7-Ag and CA724. Until now, there is still lack of ideal biomarkers for gastric cancer, and searching for specific RNAs may be promising for early diagnosis and screening of gastric cancer.

The functions and oncogenic roles of CCAT1 in human cancer

In various human cancers, long non-coding RNAs (lncRNAs), a novel class of RNAs longer than 200 nucleotides without protein-coding potential, are implicated in a variety of biological processes, such as cell proliferation, invasion, metastasis, and apoptosis through regulation of gene expression at various levels including chromatin, splicing, transcriptional and post-transcriptional levels. However, the mechanisms underlying these are still elusive. Colon cancer-associated transcript 1(CCAT1) has received increased attention among those lncRNAs. Studies have shown high expression pattern and oncogenic role of CCAT1 in different types of cancer, and aberrant expression of CCAT1 has been involved in tumor-genesis, progression, metastasis, and patient survival via regulating different target genes and signaling pathways. In this review, we first introduce the concept, identification, and biological function of CCAT1; we then describe the mechanisms by which CCAT1 regulate the cancer proliferation and progression. In the last, we discuss emerging insights into the role of CCAT1 as potential biomarker and therapeutic target for novel treatment paradigms in cancer.

Long non-coding RNA DLX6-AS1 silencing inhibits malignant phenotypes of gastric cancer cells

It has been revealed that long non-coding RNAs (lncRNAs) serve a key role in various malignancies, including gastric cancer (GC). In the present study, the expression and function of lncRNA distal-less homeobox 6 antisense 1 (DLX6-AS1) in GC was investigated. The data revealed that the expression of DLX6-AS1 was significantly upregulated in GC tissues compared with adjacent paired noncancerous tissues. Furthermore, the expression of DLX6-AS1 was higher in advanced GC tissue samples (III/IV) compared with the expression in early-stage samples (I/II). Furthermore, the current study demonstrated that a high expression of DLX6-AS1 was significantly associated with advanced clinical stage, lymph node metastasis and distant metastasis. Compared with patients with a low DLX6-AS1 expression, DLX6-AS1 expression in patients with GC was associated with decreased survival. In vitro experimental data indicated that DLX6-AS1 was upregulated in GC cell lines and that the inhibition of DLX6-AS1 markedly reduced GC cell proliferation, colony formation, cell cycle progression, migration and invasion. Further investigation revealed that knockdown of DLX6-AS1 inhibited EMT in GC cells. In summary, the present study demonstrated that lncRNA DLX6-AS1 was upregulated and serves an oncogenic role in GC, indicating that DLX6-AS1 may be a novel therapeutic target for GC treatment.

Long non-coding SNHG1 in cancer

OBJECTIVES

Long non-coding RNAs (lncRNAs) consist of a cluster of RNAs having >200 nucleotides lacking protein-coding function. Recent studies indicate that lncRNAs are involved in various cellular processes and their aberrant expression may lead to tumour development and progression. They may also serve as oncogenes or tumour suppressor genes in other diseases. In this review, we emphasize current investigations involving clinical management, tumour progression and the molecular mechanism of SNHG1 in human cancer.

MATERIALS AND METHODS

We investigate and summarize recent studies regarding the biologic functions and mechanisms of lncRNA SNHG1 in tumorigenesis. Related studies were obtained through a systematic search of google scholar, PubMed, Embase and Cochrane Library.

RESULTS

SNHG1 is a novel oncogenic lncRNA aberrantly expressed in different diseases including colorectal, liver, lung, prostate, gastric and esophageal cancers as well as ischemic stroke, nasopharyngeal carcinoma, laryngeal squamous cell carcinoma, neuroblastoma, renal cell carcinoma and osteosarcoma. Upregulation of SNHG1 was significantly associated with advanced tumour stage, tumour size, TNM stage and decreased overall survival. Furthermore, aberrant expression of SNHG1 contributes to cell proliferation, metastasis, migration and invasion of cancer cells.

CONCLUSION

SNHG1 likely acts as a useful tumour biomarker for cancer diagnosis, prognosis and treatment.

SUMO1P3 is associated clinical progression and facilitates cell migration and invasion through regulating miR-136 in non-small cell lung cancer

Long non-coding RNA small ubiquitin-like modifier 1 pseudogene 3 (SUMO1P3) is located on chromosome 1q23.2, and has been suggested to serve as oncogenic lncRNA in many kinds of human malignancy. The role of SUMO1P3 in non-small cell lung cancer (NSCLC) was still unknown. In our study, we analyzed The Cancer Genome Atlas (TCGA) database, and observed SUMO1P3 expression was increased in both lung squamous cell carcinoma and lung adenocarcinoma. Then, we confirmed that SUMO1P3 expression was significantly increased in NSCLC cancer tissues and cell lines. Meanwhile, the expression levels of SUMO1P3 expression in metastatic lymph node specimens were strikingly elevated in comparison to primary NSCLC tissue specimens. Then, we found high SUMO1P3 expression was correlated with late clinical stage, lymph node metastasis, distant metastasis and poor differentiated degree. In the survival analysis of TCGA, we observed that SUMO1P3 expression had no association with overall survival and disease free survival in NSCLC patients. There was a statistically negative correlation between SUMO1P3 expression and miR-136 expression in NSCLC tissues. Moreover, miR-136 directly bound to SUMO1P3, and SUMO1P3 negatively regulated miR-136 expression in NSCLC cells. Furthermore, SUMO1P3 promoted NSCLC cell migration and invasion via regulating miR-136. In conclusion, SUMO1P3 functions as metastasis-associated lncRNA in NSCLC.

Upregulated circ RNA hsa_circ_0000337 promotes cell proliferation, migration, and invasion of esophageal squamous cell carcinoma

Background

As a new class of endogenous ncRNAs, circRNAs have been recently verified to be involved in the carcinogenesis and progression of human cancers. In the current study, we attempted to explore the potential function of a candidate circRNA (hsa_circ_0000337) in esophageal squamous cell carcinoma (ESCC).

Patients and methods

The altered expression of hsa_circ_0000337 was validated in clinical samples from 48 patients with ESCC. The human esophageal carcinoma cell lines KYSE-150 and TE-1, and the normal human esophageal epithelial cell line (HET-1A) were applied for functional analysis of hsa_circ_0000337. Cell proliferation was measured using the Cell Counting Kit-8 assay and the colony formation assay. Cell invasion and migration were detected by Transwell and wound healing assays, respectively. We further performed bioinformatic analysis and luciferase reporter assays to explore the role of hsa_circ_0000337 as a miRNA sponge.

Results

hsa_circ_0000337 was significantly upregulated in ESCC tissues compared to adjacent normal-appearing tissues (P<0.0001). In our in vitro experiment, the expression of hsa_circ_0000337 was higher in TE-1 compared to the normal human esophageal epithelial cell line HET-1A (P<0.001), but was not significantly different in KYSE-150 (P>0.05). Knockdown of hsa_circ_0000337 significantly inhibited cell proliferation, migration, and invasion in TE-1 and KYSE-150 cell lines. Bioinformatics predicted and luciferase reporter assay verified that hsa_circ_0000337 could bind to miR-670-5p, a ncRNA involved in carcinogenesis. It is estimated that 21 genes are regulated by miR-670-5p.

Conclusion

hsa_circ_0000337 was found to be an upregulated circRNA that is related to ESCC and promotes the progression of disease by regulating cell proliferation, migration, and invasion. These findings suggest that this circRNA could be a promising diagnostic biomarker and potential therapeutic target.

MIR-1265 regulates cellular proliferation and apoptosis by targeting calcium binding protein 39 in gastric cancer and, thereby, impairing oncogenic autophagy

Increasing evidence indicates that microRNAs (miRNAs) play an important role in various tumors by regulating downstream target genes and diverse signaling pathways. Herein, we confirmed miR-1265 expression in gastric cancer (GC) using the Cancer Genome Atlas (TCGA) database and assessed the level of miR-1265 expression in clinical specimens and cell lines. We found that miR-1265 expression was negatively correlated with tumor size. Further functional analysis revealed that miR-1265 suppresses cellular proliferation and autophagy while inducing apoptosis in GC cells. A luciferase reporter assay was used to identify an miR-1265 targeted gene, calcium binding protein 39 (CAB39), which is an essential upstream regulator in the AMPK-mTOR signaling pathway. Upregulation or downregulation of CAB39 expression reversed the effects of miR-1265 overexpression or inhibition, respectively. Notably, the knockdown of autophagy-related gene 12 (ATG12) impaired the effects of miR-1265 inhibition or CAB39 overexpression in GC. MiR-1265 also suppressed the growth of GC cells in vivo and that of human gastric organoids. Altogether, our results show that miR-1265 suppresses GC progression and oncogenic autophagy by reducing CAB39 expression and regulating the AMPK-mTOR signaling pathway. Therefore, miR-1265 may represent a potential therapeutic target for GC.

Potential ceRNA networks involved in autophagy suppression of pancreatic cancer caused by chloroquine diphosphate: A study based on differentially‑expressed circRNAs, lncRNAs, miRNAs and mRNAs

Autophagy has been reported to be involved in the occurrence and development of pancreatic cancer. However, the mechanism of autophagy‑associated non‑coding RNAs (ncRNAs) in pancreatic cancer remains largely unknown. In the present study, microarrays were used to detect differential expression of mRNAs, microRNAs (miRNAs), long ncRNAs (lncRNAs) and circular RNAs (circRNAs) post autophagy suppression by chloroquine diphosphate in PANC‑1 cells. Collectively, 3,966 mRNAs, 3,184 lncRNAs and 9,420 circRNAs were differentially expressed. Additionally, only two miRNAs (hsa‑miR‑663a‑5p and hsa‑miR‑154‑3p) were underexpressed in the PANC‑1 cells in the autophagy‑suppression group. Furthermore, miR‑663a‑5p with 9 circRNAs, 8 lncRNAs and 46 genes could form a prospective ceRNA network associated with autophagy in pancreatic cancer cells. In addition, another ceRNA network containing miR‑154‑3p, 5 circRNAs, 2 lncRNAs and 11 genes was also constructed. The potential multiple ceRNA, miRNA and mRNA associations may serve pivotal roles in the autophagy of pancreatic cancer cells, which lays the theoretical foundation for subsequent investigations on pancreatic cancer.

Comprehensive Analysis of Aberrantly Expressed ceRNA network in gastric cancer with and without H.pylori infection

Objective: This study mainly focused on revealing ceRNA network in gastric cancer (GC) with Hp infection after comparing with GC without Hp infection and exploring the biological function and prognostic relevance of related molecules.

Methods: The RNA expression profile data of GC patients with or without Hp infection were extracted from TCGA GDC data portal, including 20 GC cases with Hp infection and 168 GC cases without Hp infection. Differentially expressed lncRNAs, miRNAs and mRNAs were unveiled by package edgeR of R, and lncRNA-miRNA-mRNA ceRNA network was constructed by integrating the miRNA target information and the expression data of lncRNAs, miRNAs and mRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of aberrantly expressed mRNAs were performed to identify the related biological functions and pathologic pathways, and protein-protein interaction (PPI) network was constructed by STRING database. The overall survival (OS) of aberrantly expression lncRNAs and miRNAs were analyzed by package survival of R. A total of 30 gastric cancer tissues were used to validate the bioinformatics analysis results by real-time PCR.

Results: Among the 32 differentially expressed miRNAs, 27 differentially expressed lncRNAs and 257 differentially expressed mRNAs were identified by comparing GC patients with and without Hp infection. Totally 10 miRNA, 11 lncRNA, 219 mRNA were included to build ceRNA network. GO and KEGG analysis revealed that differentially expressed mRNAs involved in the ceRNA network were mainly involved in extracellular exosomes, structural molecular activities, proteolysis and P13K-Akt signaling pathways. And PPI analysis obtained six hub genes of NTS, APOC3, OTX2, KRT13, CALCA, GNG4. Survival analysis showed that four lncRNAs (LINC01254, LINC01287, LINC01524, U95743.1) and four miRNAs (miR-302a, miR-302b, miR-1286, miR-378g) were associated with overall survival of GC with Hp infection. The real-time PCR results showed that, the levels of LINCO1254, LINCO1287, LINCO1524, U95743.1 were significantly higher in Hp positive GC patients than Hp negative patients (P=0.02, 0.048, 0.04, 0.036, respectively).

Conclusion: Using TCGA database for data mining, we have successfully constructed a ceRNA regulatory network of GC with Hp infection, consisting of 10 lncRNAs, 11 miRNAs and 219 mRNAs. These findings might provide critical clues for the regulatory role of ceRNA network in the development of GC with Hp infection.

Retracted Article: Long noncoding RNA PTPRG-AS1 regulates growth of glioma cells by sponging miR-185-5p

Previous studies have found that long noncoding RNA (lncRNA) protein tyrosine phosphatase, receptor type, G, antisense (PTPRG-AS1) was upregulated in glioma cells. Our study aimed to explore the detailed molecular mechanisms of PTPRG-AS1 involved in glioma progression. qRT-PCR assay was performed to measure the expressions of PTPRG-AS1 and microRNA-185-5p (miR-185-5p). Cell viability, migration, invasion, and apoptosis were determined by CCK-8 assay, colony formation assay, transwell assay, and flow cytometry assay. Autophagy was evaluated using GFP-LC3 puncta analysis and western blot. Luciferase reporter and RIP assays were employed to explore the association between PTPRG-AS1 and miR-185-5p. Our data showed PTPRG-AS1 was upregulated in glioma cells and tissues. Besides, high expression of PTPRG-AS1 was positively associated with a low survival rate. Upregulation of PTPRG-AS1 promoted proliferation, migration, invasion, colony formations, and autophagy, and inhibited cell apoptosis in U373-MG cells. By contrast, PTPRG-AS1 downregulation had the inverse effect in SHG44 cells. PTPRG-AS1 negatively regulated the expression of miR-185-5p in U373-MG and SHG44 cells and the expression of miR-185-5p was decreased in glioma tissues and cells. In addition, miR-185-5p overexpression suppressed proliferation, metastasis, colony formations, and autophagy, while inducing cell apoptosis in SHG44 cells. As expected, miR-185-5p depletion exhibited the inverse effect in U373-MG cells. Enhanced expression of miR-185-5p attenuated the effect of PTPRG-AS1 upregulation on U373-MG cells, while silencing of miR-185-5p undermined the effect of downregulation of PTPRG-AS1 on SHG44 cells. Our data disclosed that LncRNA PTPRG-AS1 was upregulated in glioma cells and tissues. PTPRG-AS1 regulated glioma proliferation, invasion, migration, apoptosis and autophagy by sponging miR-185-5p in vitro. A new signaling pathway PTPRG-AS1/miR-185-5p was first observed in glioma.

Previous studies have found that long noncoding RNA (lncRNA) protein tyrosine phosphatase, receptor type, G, antisense (PTPRG-AS1) was upregulated in glioma cells.

Biological function and molecular mechanism of piRNA in cancer

Cancer is the second leading cause of death globally. piRNAs, which are a novel type of identified small noncoding RNA (ncRNA), play a crucial role in cancer genomics. In recent years, a relatively large number of studies have demonstrated that several piRNA are aberrantly expressed in various kinds of cancers including gastric cancer, bladder cancer, breast cancer, colorectal cancer and Lung cancer and may probably serve as a novel therapeutic target and biomarker for cancer treatment. The present review summarized current advances in our knowledge of the roles of piRNAs in cancer.

LONG-NONCODING RNAs in gastroesophageal cancers

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

Retracted Article: Long non-coding RNA XIST promotes proliferation, autophagy and inhibits apoptosis by regulating microRNA-30c/ATG5 axis in gastric cancer

Background: Gastric cancer (GC) is a great threat to human health and life. Long non-coding RNA X inactive-specific transcript (XIST) and microRNA-30c (miR-30c) function as crucial players in the tumorigenesis of GC. Bioinformatics analysis suggests that miR-30c has a chance to interact with XIST and autophagy related 5 (ATG5). Moreover, ATG5 has been identified as a target of miR-30c in human intestinal epithelial cells. Hence, whether XIST could regulate cell proliferation, apoptosis and autophagy by miR-30c/ATG5 axis was further investigated in GC. Methods: The levels of XIST, miR-30c and ATG5 mRNA were measured by RT-qPCR assay. ATG5, p62, LC3-I, and LC3-II protein expression was detected by western blot assay. The relationships of XIST, miR-30c and ATG5 were examined by luciferase, RNA immunoprecipitation (RIP) and RNA pull down assays. Cell proliferation was assessed by MTS assay. Cell apoptotic rate was determined using flow cytometry. ATG5 protein expression in tissues was measured by immunohistochemistry (IHC) assay. Results: XIST was highly expressed in GC tissues and cell lines. XIST knockdown suppressed proliferation, autophagy and promoted apoptosis in GC cells. XIST inhibited miR-30c expression by direct interaction in GC cells. Furthermore, miR-30c depletion abrogated XIST deficiency-mediated anti-proliferation, pro-apoptosis and anti-autophagy effects in GC cells. Additionally, ATG5 was a target of miR-30c and XIST promoted ATG5 expression by sequestering miR-30c from ATG5 in GC cells. Conclusion: XIST knockdown suppressed proliferation, autophagy and induced apoptosis through regulating miR-30c/ATG5 axis in GC cells, hinting at the potential value of XIST in the management of GC.

Emerging role of long non-coding RNA in the development of gastric cancer

Gastric cancer is a common, worldwide malignancy and has a poor prognosis due to late diagnosis. Long non-coding RNAs (lncRNAs) are a significant subtype of RNA molecules with a length longer than 200 nucleotides (nt) that rarely encode proteins. In recent decades, deregulation of lncRNAs has been shown to be involved in tumorigenesis and tumor progression in various human carcinomas, including gastric cancer. Accumulating evidence has shown that some lncRNAs may function as diagnostic biomarkers or therapeutic targets for gastric cancer. Thus, exploring the specific functions of lncRNAs will help both gain a better understanding of the pathogenesis and develop novel treatments for gastric cancer. In this review, we highlight the expression and functional roles of lncRNAs in gastric cancer, and analyze the potential applications of lncRNAs as diagnostic markers and therapeutic targets.

Long noncoding RNA TUG1 promotes cell proliferation and migration of renal cell carcinoma via regulation of YAP

OBJECTIVES

Recently, long noncoding RNAs (lncRNAs) have captured much attention for their important roles in human diseases. Deregulation of lncRNA taurine-upregulated gene 1 (TUG1) has been reported to regulate cancer progression in many cancer types. However, how TUG1 contributes to renal cell carcinoma (RCC) remains elusive; we were eager to resolve the questions.

METHODS

Tumor tissues and the matched adjacent normal tissues were collected from patients with RCC. Messenger RNA (mRNA) levels of TUG1, yes-associated protein (YAP), and microRNA (miR)-9 levels were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The regulation of YAP by TUG1 was investigated using Western blot analysis, RT-qPCR, and immunofluorescence. The oncogenic roles of TUG1 and YAP were studied using a cell proliferation assay and a wound healing assay. The interaction of TUG1-miR-9-YAP was analyzed in RCC cell lines.

RESULTS

In the current study, we observed a positive correlation between TUG1 expression and YAP expression in RCC using the Gene Expression Omnibus database and tumor tissues collected from 58 patients with RCC. The TUG1 elevation enhanced YAP expression but did not alter the Hippo-signaling pathway activity or YAP protein distribution in cells. In addition, we found that TUG1 could bind to miR-9; therefore, TUG1 could positively control YAP expression via downregulation of miR-9 level. Furthermore, we observed that inhibition of cell proliferation and cell migration induced by TUG1 silencing could be reversed by overexpression of YAP in RCC cell lines.

CONCLUSIONS

Our findings indicated a pivotal role of TUG1 in driving RCC progression via regulation of miR-9/YAP, suggesting a potential therapeutic targeting role of TUG1 in RCC.

Long non-coding RNAs in the gastric juice of gastric cancer patients

Differently from other digestive malignancies, gastric cancer (GC) carcinogenesis seems more heterogeneous and unclear. This entails failing in identification of reliable serum tumor markers for screening early GC (EGC) as well as persisting ominous prognosis of this disease. Recently, investigation of human noncoding genome, especially long noncoding molecules (lncRNAs), has provided promising data. As for GC, however, since the current information on GC-specific lncRNAs is still scarce and comes largely from analyses performed on tissue or serum of affected patients, we decided to review the current literature dealing with expression of such molecules in the gastric juice (GJ) of GC patients. In the case of GC, in fact, several cytological and molecular works have already demonstrated GJ to be an interesting biological material for improving clinicopathologic and prognostic knowledge of this cancer. For this review, we burrowed into the literature on lncRNAs expressed in GJ of GC patients. PubMed, Science Direct, Scopus, Web of Science, Google Scholar and ResearchGate were the search engines entertained. As of 2018, only seven studies have been reported. LINC00152, AA174084, UCA1, RMRP, ABHD11-AS1, LINC00982 and H19 were the GJ lncRNAs examined. Following our review, we can conclude that, due to their high specificity and reliability, GJ lncRNAs should deserve a prominent role in the field of GC research: importantly, they could be used for screening EGC, ameliorating the existing methods of staging (which are still far from being completely accurate), improving the prognostic capacity of the current diagnostic armamentarium and, finally, providing new and valuable therapeutic targets.

Knockdown of SUMO1P3 represses tumor growth and invasion and enhances radiosensitivity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common types of malignant tumors with high recurrence and metastasis rates. Radiotherapy represents a major therapeutic option for HCC patients. However, the efficacy of radiotherapy has been limited due to the development of intrinsic radioresistance of the tumor cells. Small ubiquitin-like modifier 1 pseudogene 3 (SUMO1P3), one member of SUMO pseudogene family, is a novel identified lncRNA that was originally identified to be upregulated in gastric cancer. However, the detailed roles of SUMO1P3 in HCC development remain to be elucidated. Here, the expression of SUMO1P3 in HCC tissues and cells was examined by qRT-PCR. Cell proliferation, colony formation ability, invasion ability, apoptosis, and radiosensitivity were detected by MTT assay, colony formation assay, cell invasion assay, flow cytometry analysis, and survival fraction assay, respectively. We found that SUMO1P3 was significantly upregulated in HCC tissues and cells. Besides, SUMO1P3 was highly expressed in HCC patients with higher TNM stage. Furthermore, SUMO1P3 knockdown markedly suppressed cell proliferation, colony formation ability, and cell invasiveness, promoted apoptosis, and enhanced radiosensitivity of HCC cells. We concluded that the knockdown of SUMO1P3 repressed tumor growth, invasion, promoted apoptosis, and enhanced radiosensitivity in HCC, providing evidence that SUMO1P3 might be a potential novel biomarker and a therapeutic target for HCC.

Identification and functional characterization of long non-coding RNAs in human gastric cancer

Abnormal regulation of long non-coding RNAs (lncRNAs) appears to be a primary feature of numerous types of human cancer. However, the association between the dysregulation of lncRNAs and functional alterations in gastric cancer (GC) remains unclear. In previous studies, we applied microarray and bioinformatics analyses to screen for key lncRNAs from the tumor tissues and matched adjacent non-tumor tissues of 10 patients with GC. There were seven key lncRNAs demonstrated to be significantly different between carcinoma tissues and adjacent non-tumor tissues. In the present study, the expression of these seven selected lncRNAs were validated in 82 patients with GC to further investigate the association between lncRNAs and GC clinical characterization. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results demonstrated that RP5-919F19, MCPH1 antisense RNA 1 (CTD-2541M15) and urothelial carcinoma-associated 1 (UCA1) exhibited consistent upregulation in cancer compared with adjacent non-tumor tissues, whereas AP000459, LOC101928316, tumor suppressor candidate 8 (LINC01071) and maternally expressed 3 (MEG3) showed consistent downregulation. The results from the microarray and RT-qPCR experiments achieved 100% agreement. A correlation analysis indicated that RP5-919F19, LOC101928316 and MEG3 were significantly associated with tumor differentiation degree, RP5-919F19, UCA1 and MEG3 were significantly associated with lymph node metastasis, and RP5-919F19, CTD-2541M15 and UCA1 were significantly associated with tumor-node-metastasis stage (P<0.05). In addition, it was identified that the differential expression of LINC01071 and LOC101928316 significantly correlated with the age and gender of the GC patients, respectively (P<0.05). The results suggest that the lncRNAs RP5-919F19, LOC101928316, CTD-2541M15, UCA1 and MEG3 are closely associated with the invasion and metastasis of GC, which reveals these indicators as potential specificity biomarkers for the diagnosis, prognosis and classification of GC. Thus, these lncRNAs merit further study as novel candidate biomarkers for the clinical diagnosis of GC and as potential targets for therapy.

Long non-coding RNAs in melanoma

Melanoma is the most lethal cutaneous cancer with a highly aggressive and metastatic phenotype. While recent genetic and epigenetic studies have shed new insights into the mechanism of melanoma development, the involvement of regulatory non-coding RNAs remain unclear. Long non-coding RNAs (lncRNAs) are a group of endogenous non-protein-coding RNAs with the capacity to regulate gene expression at multiple levels. Recent evidences have shown that lncRNAs can regulate many cellular processes, such as cell proliferation, differentiation, migration and invasion. In the melanoma, deregulation of a number of lncRNAs, such as HOTAIR, MALAT1, BANCR, ANRIL, SPRY-IT1 and SAMMSON, have been reported. Our review summarizes the functional role of lncRNAs in melanoma and their potential clinical application for diagnosis, prognostication and treatment.

Comprehensive analysis of differentially expressed non-coding RNAs and mRNAs in gastric cancer cells under hypoxic conditions

Hypoxia commonly occurs in solid cancers, especially in gastric cancer due to its rapid growth. The ability of gastric cancer cells to survive and progress under hypoxic conditions has been known for decades, but the mechanisms underlying this characteristic remain poorly understood. As cancer cells undergo changes in their genetic profile under certain conditions, we investigated the expression profile of non-coding RNAs (circRNAs, lncRNAs, and miRNAs) and mRNAs in gastric cancer MKN-28 cells under hypoxic conditions via sequencing and subsequent bioinformatic analyses. In addition, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate the results. We identified a number of significantly differentially expressed circRNAs, lncRNAs, miRNAs, and mRNAs in hypoxia-exposed MKN-28 cells relative to the normoxia control, and results of qRT-PCR were consistent with sequencing data. Pathway enrichment analyses revealed the principal functions of the significantly deregulated genes. Furthermore, examination of co-expression and competing endogenous RNA (ceRNAs) networks illustrated the complex regulatory pathways among non-coding RNAs and mRNAs, implicating these pathways in gastric cancer. In conclusion, our findings provide a novel perspective on non-coding RNAs and mRNAs and lay the foundation for future research on the potential roles of non-coding RNAs in gastric cancer under hypoxic conditions.

Therapeutic targeting of noncoding RNAs in hepatocellular carcinoma: Recent progress and future prospects

Due to the high mortality rate and unsatisfactory treatment options available, hepatocellular carcinoma (HCC) remains one of the most common malignancies and a leading cause of cancer-associated mortality. Novel therapeutic targets for HCC are urgently required. Advanced RNA sequencing technology enables the identification of considerable amounts of noncoding RNAs (ncRNAs), including small noncoding RNAs and long noncoding RNAs, which exhibit no protein-coding activities. In this respect, ncRNAs and their regulatory processes are important factors in liver tumorigenesis. The present review focuses on the characteristics and biological roles of ncRNAs in HCC. Potential therapeutic applications of ncRNAs in HCC are also evaluated.

Long noncoding RNAs as auxiliary biomarkers for gastric cancer screening: A pooled analysis of individual studies

Background

Long non-coding RNAs (lncRNAs) are highlighted as novel cancer biomarkers with great promise. Herein, we focused on summarizing the overall diagnostic performance of lncRNAs for gastric cancer (GC).

Methods

Publications fulfilling the search criteria were selected from the online databases. Study quality was assessed according to the Quality Assessment for Studies of Diagnostic Accuracy (QUADAS) checklist. The summary receiver operator characteristic (SROC) curve was plotted using a bivariate meta-analysis model. Statistical analysis was performed based on the platforms of STATA 12.0 and Meta-Disc 1.4 software.

Results

Fifteen studies with 1252 patients and 1283 matched controls were included. The pooled sensitivity and specificity for lncRNA expression profile in differentiating GC patients from cancer-free individuals were 0.68 (95%CI: 0.61-0.74) and 0.79 (95%CI: 0.72-0.84), respectively, corresponding to an area under curve (AUC) of 0.80. Moreover, the stratified analyses demonstrated that plasma-based lncRNA profiling harbored higher accuracy than that tissue-based assay (specificity: 0.80 versus 0.75; AUC: 0.84 versus 0.77).

Conclusions

LncRNA profiling hallmarks a moderate diagnostic value in the management of GC and that lncRNA expression patterns may potentially be utilized as auxiliary biomarkers in confirming GC.

Downregulated long non-coding RNA TCONS_00068220 upregulates apoptosis in gastric cancer cells

Long non-coding RNAs (lncRNAs) are emerging as a fundamental class of biological effect or molecules that perform pivotal functions in the regulation of the genome. With advances in bioinformatics and genomics, extensive identification and characterization of lncRNAs is now possible. They regulate cellular growth, differentiation and apoptosis. Dysregulation of lncRNAs has been associated with numerous types of human cancer. In the present study, the expression profile of differentially expressed genes (DEGs) and lncRNAs in gastric cancer (GC) samples and normal tissue samples was evaluated with bioinformatics. The biological functions of the predicted lncRNA TCONS_00068220 were focused on; the DEGs co-expressed with TCONS_00068220 were enriched in cancer-associated pathways. TCONS_00068220 was demonstrated to be upregulated in GC tissues and cell lines compared with normal controls. In addition, an increased rate of apoptosis was observed in NCI-N87 cells following transfection with small interfering RNA against TCONS_00068220. These data suggest that TCONS_00068220 may be associated with the pathogenesis of GC, and it may serve as a potential therapeutic target.

LncRNA-UCA1 enhances MMP-13 expression by inhibiting miR-204-5p in human chondrocytes

Osteoarthritis (OA) is a common degenerative disease characterized by degeneration of articular cartilage. Increasing studies showed that long noncoding RNAs (lncRNAs) play important roles in the cartilage damage. However, little is known about the role of UCA1 in the osteoarthritis. The expression level of UCA1 was upregulated in the OA cartilage. Overexpression of UCA1 suppressed the miR-204-5p expression in the chondrocytes. The expression of miR-204-5p was downregulated in the OA cartilage. Moreover, the expression of miR-204-5p was negatively correlated with the UCA1 expression in the OA cartilage. Elevated expression of UCA1 promoted the chondrocytes cell proliferation and overexpression of miR-204-5p suppressed chondrocytes cell proliferation. In addition, overexpression of UCA1 decreased the expression of the type II collagen and type IV collagen expression in the chondrocytes. Elevated expression of miR-204-5p promoted the type II collagen and type IV collagen expression in the chondrocytes. We idetified MMP-13 was a direct target gene of miR-204-5p in the chondrocytes. Overexpression of UCA1 enhanced the MMP-13 expression in the chondrocytes. Elevated expression of UCA1 regulated the chondrocytes cell proliferation and collagen expression through inhibiting the miR-204-5p expression.These results suggested that UCA1 played as an important regulator of survival and matrix synthesis of chondrocytes partly through suppressing the miR-204-5p expression.

MicroRNA-133a Inhibits Proliferation of Gastric Cancer Cells by Downregulating ERBB2 Expression

Gastric cancer is the fourth most common type of cancer and the second highest leading cause of cancer-related deaths worldwide. It has already been established that miR-133a is involved in gastric cancer. In this study, we investigated the molecular mechanisms by which miR-133a inhibits the proliferation of gastric cancer cells. We analyzed the proliferative capacity of human gastric cancer cells SNU-1 using an MTT assay. Cell apoptosis was determined using flow cytometry. The expression levels of ERBB2, p-ERK1/2, and p-AKT in SNU-1 cells were determined using Western blot analysis. To confirm that ERBB2 is a direct target of miR-133a, a luciferase reporter assay was performed. Results showed that miR-133a overexpression inhibited SNU-1 cell proliferation and increased apoptosis. ERBB2 was a direct target of miR-133a, and it was negatively regulated by miR-133a. Interestingly, ERBB2 silencing has a similar impact to miR-133a overexpression, in that it significantly induced apoptosis and inhibited ERK and AKT activation. Our study showed that miR-133a inhibits the proliferation of gastric cancer cells by downregulating the expression of ERBB2 and its downstream signaling molecules p-ERK1/2 and p-AKT. Therefore, miR-133a might be used as a therapeutic target for treating gastric cancer.

miR-218 suppresses gastric cancer cell cycle progression through the CDK6/Cyclin D1/E2F1 axis in a feedback loop

Studies in several cancers have suggested that miR-218 has anti-tumor activities, but its function is yet to be elucidated. In this study, we investigated the regulation and function of miR-218 (miR-218-5p) in the cell cycle progression of gastric cancer (GC). We found that miR-218 could suppress proliferation of gastric cancer cells, induce cell cycle arrest at the G1 phase and inhibit tumor growth and metastasis in vivo. We also demonstrated that miR-218 specifically targeted the 3'-UTR regions of CDK6 and cyclin D1 and inhibited the expression of these molecules, which in turn repressed the pRb/E2F1 signaling pathway. Overexpression of CDK6 and Cyclin D1 reversed miR-218-mediated inhibition of pRB/E2F1 signaling and attenuated the miR-218-induced cell cycle arrest. More importantly, miR-218 expression was significantly reduced and inversely correlated with the levels of CDK6 and Cyclin D1 in gastric cancer tissues. Decreased miR-218 expression was also correlated with advanced clinical stage, lymph node metastasis, and poor prognosis in gastric cancer patients. Furthermore, we showed that miR-218 expression was directly activated by E2F1 through the transactivation of miR-218 host genes, SLIT2 and SLIT3, revealing a negative feedback regulation of miR-218 expression. Taken together, our results describe a regulatory loop miR-218-CDK6/CyclinD1-E2F1 whose disruption may contribute to cell cycle progression in gastric cancer and indicate the potential application of miR-218 in cancer therapy.

MicroRNA-30a-5p inhibits the proliferation and invasion of gastric cancer cells by targeting insulin-like growth factor 1 receptor

MicroRNAs (miRs) are a class of small non-coding RNAs of 18–25 nucleotides in length that serve as key regulators in the development and progression of human cancers. Recently, miR-30b-5p, as a member of the miR-30 family, has been reported to act as a tumor suppressor in gastric cancer. However, the expression and function of miR-30a-5p in gastric cancer, as well as the corresponding underlying mechanism, remain unknown. In the present study, it was demonstrated that the expression of miR-30a-5p was significantly reduced in gastric cancer tissues (n=43) compared with normal gastric tissues (n=10; P<0.01). Similarly, miR-30a-5p was significantly downregulated in the gastric cancer cell lines AGS, HGC27, BGC823 and SGC7901, when compared with the normal gastric mucosa epithelial cell line GES-1 (P<0.01). In addition, overexpression of miR-30a-5p significantly inhibited the proliferation and invasion of AGS cells (P<0.01). Insulin-like growth factor 1 receptor (IGF-1R) was identified as a novel target of miR-30a-5p, and the protein expression of IGF-1R was negatively regulated by miR-30a-5p in AGS cells (P<0.01). Furthermore, overexpression of IGF-1R significantly reversed the inhibitory effect of miR-30a-5p on the proliferation and invasion of AGS cells (P<0.01), indicating that IGF-1R was involved in miR-30a-5p-mediated proliferation and invasion of AGS cells. It was also observed that the expression of IGF-1R mRNA was upregulated in gastric cancer tissues compared with normal gastric tissues (P<0.01), and its levels of expression were reversely correlated with that of miR-30a-5p in gastric cancer tissues (R²=0.3892; P<0.01). Collectively, these data suggest that miR-30a-5p inhibits the growth and metastasis of gastric cancer by directly targeting IGF-1R. Therefore, the miR-30a-5p/IGF-1R axis may be a potential therapeutic target in the treatment of gastric cancer.

NEAT1: A novel cancer-related long non-coding RNA

Aberrant overexpression of the long non-coding RNA NEAT1 (nuclear paraspeckle assembly transcript 1) has been documented in different types of solid tumours, such as lung cancer, oesophageal cancer, colorectal cancer and hepatocellular carcinoma, in which its high levels are associated with poor prognosis. In contrast, NEAT1 is downregulated in acute promyelocytic leukaemia where it promotes leucocyte differentiation. In this review, we provide an overview of current evidence concerning the oncogenic role and potential clinical utilities of NEAT1. Further investigations are warranted to elucidate the upstream and downstream mechanisms of NEAT1 overexpression.

Long noncoding RNA linc-ITGB1 promotes cell migration and invasion in human breast cancer

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer-related death in women globally. Its high morbidity and mortality, as well as its elevated tendency to metastasize to other organs, warrant the urgency to find new biomarkers for breast cancer diagnosis and treatment. The specific roles of long noncoding RNA linc-ITGB1 on cell proliferation and metastasis in breast cancer were explored in this study. The expression of linc-ITGB1 was significantly upregulated in both clinical breast cancer tissues and cultured breast cancer cell lines. The linc-ITGB1 knockdown with specific short hairpin RNA (shRNA) decreased cell proliferation and colony formation in vitro. Tumor growth in vivo was also inhibited by linc-ITGB1 depletion. In addition, linc-ITGB1 depletion caused cell accumulation in the G0/G1 phase. Breast cancer cell lines with linc-ITGB1 depletion exhibited decreased migration and invasion abilities compared with the control cells. Furthermore, the linc-ITGB1 knockdown decreased the expression of mesenchymal markers N-cadherin and vimentin while increasing the expression of the epithelial marker E-cadherin. Key cell cycle regulators Cdc25C and Cyclin B1 were also decreased by the linc-ITGB1 knockdown. These data suggest that linc-ITGB1 promotes breast cancer progression by inducing cell cycle arrest and interrupting the epithelial-to-mesenchymal transition process.

Curcumin suppresses the proliferation of gastric cancer cells by downregulating H19

Curcumin, a major phytochemical in turmeric, inhibits the proliferation of many types of solid cancer cells by enhancing p53 expression. However, the long non-coding RNA H19 directly inhibits p53 activation and thus promotes gastric cancer progression. The aim of this study was to assess the role of H19 in curcumin-induced proliferative inhibition of gastric cancer. The gastric cancer cell line SGC-7901 was treated with curcumin at different concentrations and time points. The effect of curcumin on proliferation was assessed using cell counting kit-8 assays and flow cytometry with Ki67 staining. In addition, H19 expression was quantified by reverse transcription-quantitative polymerase chain reaction, and apoptosis was evaluated by flow cytometric detection of Annexin V and propidium iodide double staining. The protein expression of p53, B-cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax) and c-Myc in curcumin-treated cells was detected by western blotting. The present study demonstrated that curcumin inhibited the proliferation of SGC7901 cells and suppressed H19 expression in a concentration-dependent manner, while p53 expression was enhanced. Ectopic expression of H19 in SGC7901 cells reversed curcumin-induced proliferative inhibition and downregulated p53 expression. Furthermore, while curcumin induced cell apoptosis and enhanced the expression ratio of Bax/Bcl-2, which are downstream molecules of p53, ectopic expression of H19 inhibited curcumin-induced cell apoptosis. In addition, curcumin decreased the expression of the c-Myc oncogene, and exogenous c-Myc protein reversed the curcumin-induced downregulation of H19 expression. These results suggested that curcumin inhibits the proliferation of gastric cancer cells by downregulating the c-Myc/H19 pathway. Therefore, curcumin may be considered a novel therapeutic strategy to inhibit gastric cancer cell growth.

Significance of microRNA 21 in gastric cancer

Despite promising developments of treatment, the mortality due to gastric cancer remains high and the mechanisms of gastric cancer initiation and the development also remains elusive. It has been reported that patients with positive serologic tests for H. pylori have a higher risk of the development of gastric cancer. microRNAs (miRNAs) are short non-coding RNA molecules consisting of 21-25 nucleotides (nt) in length. The miRNAs silence their cognate target genes by inhibiting mRNA translation or degrading the mRNA molecules by binding to their 3'-untranslated (UTR) regions and plays a very important role in cancer biology. Recent evidences indicate that miR-21 is overexpressed in tumour tissue, including gastric cancer and plays a vital role in tumour cell proliferation, apoptosis, invasion and angiogenesis. Elevated levels of miR-21 is associated with downregulation of tumour suppressor genes, such as programmed cell death 4 (PDCD4), tissue inhibitor of metalloproteinase 3, phosphatase and tensin homolog (PTEN), tropomyosin 1, ras homolog gene family member B, and maspin. Silencing of miR-21 through the use of a miR-21 inhibitor affected cancer cell viability, induced cell cycle arrest and increased chemosensitivity to anticancer agents indicating that miR-21 functions as an oncogene. Although an increased expression level of miR-21 has been observed in gastric cancer, studies related to the role of miR-21 in gastric cancer progression is very limited. The main thrust of this mini review is to explain the potency of miR-21 as a prognostic and/or diagnostic biomarker and as a new target for clinical therapeutic for interventions of gastric cancer progression.

Long noncoding RNA MALAT1 promotes uveal melanoma cell growth and invasion by silencing of miR-140

Increasing evidences have demonstrated that long noncoding RNAs (LncRNAs) play a significant role in the development of tumor. However, the role of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in uveal melanoma remains unknown. In this study, we demonstrated that the expression of MALAT1 was upregulated in the uveal melanoma tissues compared to normal tissues. Among them, MALAT1 was upregulated in 72% (18/25) uveal melanoma tissues compared to their paired normal tissues. Knockdown of MALAT1 suppressed uveal melanoma cell proliferation, colony information, invasion and migration. Moreover, we showed that knockdown of MALAT1 promoted miR-140 expression and suppressed Slug and ADAM10 expression in the MUM-2C cell. In addition, we demonstrated that miR-140 was downregulated in the uveal melanoma tissues compared to normal tissues and cell lines. The expression level of MALAT1 was inversely correlated with the expression level of miR-140 in uveal melanoma tissues. These results suggested that MALAT1 served as an oncogenic LncRNA in the development of uveal melanoma.

Gastric biomarkers: a global review

BACKGROUND

Gastric cancer is an aggressive disease with a poor 5-year survival and large global burden of disease. The disease is biologically and genetically heterogeneous with a poorly understood carcinogenesis at the molecular level. Despite the many prognostic, predictive, and therapeutic biomarkers investigated to date, gastric cancer continues to be detected at an advanced stage with resultant poor clinical outcomes.

MAIN BODY

This is a global review of gastric biomarkers with an emphasis on HER2, E-cadherin, fibroblast growth factor receptor, mammalian target of rapamycin, and hepatocyte growth factor receptor as well as sections on microRNAs, long noncoding RNAs, matrix metalloproteinases, PD-L1, TP53, and microsatellite instability.

CONCLUSION

A deeper understanding of the pathogenesis and biological features of gastric cancer, including the identification and characterization of diagnostic, prognostic, predictive, and therapeutic biomarkers, hopefully will provide improved clinical outcomes.

Noncoding RNAs in gastric cancer: Research progress and prospects

Noncoding RNAs (ncRNAs) have attracted much attention in cancer research field. They are involved in cellular development, proliferation, differentiation and apoptosis. The dysregulation of ncRNAs has been reported in tumor initiation, progression, invasion and metastasis in various cancers, including gastric cancer (GC). In the past few years, an accumulating body of evidence has deepened our understanding of ncRNAs, and several emerging ncRNAs have been identified, such as PIWI-interacting RNAs (piRNAs) and circular RNAs (circRNAs). The competing endogenous RNA (ceRNA) networks include mRNAs, microRNAs, long ncRNAs (lncRNAs) and circRNAs, which play critical roles in the tumorigenesis of GC. This review summarizes the recent hotspots of ncRNAs involved in GC pathobiology and their potential applications in GC. Finally, we briefly discuss the advances in the ceRNA network in GC.

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

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

Roles of long noncoding RNAs in gastric cancer and their clinical applications

PURPOSE

Gastric cancer ranks as the most common cancer in the world. However, the progresses of its diagnosis and treatment are still not satisfactory. The purpose of this study is to summarize the roles of lncRNAs associated with gastric cancer.

METHODS

We searched lncRNAs associated with gastric cancer in PubMed.

RESULTS

Long noncoding RNAs (lncRNAs), transcripts larger than 200 nucleotides, regulate gene expression at various levels. They are playing important roles in the occurrence and development of gastric cancer. They are involved in signaling pathways, crosstalk with microRNAs, and affecting metastasis by regulating epithelial-to-mesenchymal transition. By acting as oncogenes or tumor suppressors, lncRNAs contribute to gastric cancer occurrence and development. Several lncRNAs including HOTAIR, HULC, LINC00152, MALAT2, H19, GHET1, and GACAT3 have been demonstrated having oncogene activities, while other lncRNAs including LEIGC, GAS5, and FER1L4 have been thought as tumor suppressors.

CONCLUSIONS

Several lncRNAs from tissue, blood, and gastric juice have shown potential values in gastric cancer diagnosis or prognosis evaluation.

Role of competing endogenous RNAs in development of gastric cancer

Gastric cancer is one of the most common digestive system tumors and the second cause of malignancy related death, and it is caused by multiple factors such as genetic susceptibility, environment and living habits. It is reported that members of competitive endogenous RNAs, including microRNAs and long non-coding RNAs, play an important role in gastric cancer development. This article reviews the role of competing endogenous RNAs in the development of gastric cancer.

Upregulated long intergenic noncoding RNA KRT18P55 acts as a novel biomarker for the progression of intestinal-type gastric cancer

Background

Long noncoding RNAs (lncRNAs) with dysregulated expression levels have been investigated in numerous types of different cancer. Whether lncRNAs can predict the progression of gastric cancer (GC) still remains largely unclear. The aim of our study was to investigate whether KRT18P55, a novel intergenic lncRNA, can be a predictive biomarker for GC.

Methods

To determine the expression levels of KRT18P55 in GC, we evaluated it in five GC cell lines (SGC-7901, MGC-803, BGC-823, AGS, and HG27) and 97 GC tissue samples in comparison with a normal control by quantitative polymerase chain reaction. In addition, the association with patient clinicopathological characteristics was analyzed to identify the clinical significance of KRT18P55. We also used publicly accessible data from The Cancer Genome Atlas (TCGA) to further verify the expression levels and clinical significance of KRT18P55. Furthermore, a receiver operating characteristic curve was also conducted to evaluate the diagnostic value of KRT18P55 for GC.

Results

A significant upregulation was observed in GC cell lines (P<0.01) and tissue samples (P<0.01). This finding was consistent with the results of 29 pairs of GC tissue samples from TCGA (P<0.01). Additionally, we indicated that the increased expression of KRT18P55 was related to the progression of intestinal type (P=0.032), which was also supported by results of independent GC cohorts from TCGA (P<0.01). However, we did not find significant difference in prognosis between patients with high and low expression of KRT18P55 (P>0.05). Finally, KRT18P55 showed potential diagnostic value for GC with an area under the receiver operating characteristic curve of 0.733 (P<0.01).

Conclusion

Upregulated KRT18P55 was a novel biomarker for the progression of GC, especially for the intestinal type.