Epigenetic silencing of miR-338-3p contributes to tumorigenicity in gastric cancer by targeting SSX2IP

Role of Some microRNA/ADAM Proteins Axes in Gastrointestinal Cancers as a Novel Biomarkers and Potential Therapeutic Targets—A Review

Gastrointestinal (GI) cancers are some of the most common cancers in the world and their number is increasing. Their etiology and pathogenesis are still unclear. ADAM proteins are a family of transmembrane and secreted metalloproteinases that play a role in cancerogenesis, metastasis and neoangiogenesis. MicroRNAs are small single-stranded non-coding RNAs that take part in the post-transcriptional regulation of gene expression. Some ADAM proteins can be targets for microRNAs. In this review, we analyze the impact of microRNA/ADAM protein axes in GI cancers.

CASP9 As a Prognostic Biomarker and Promising Drug Target Plays a Pivotal Role in Inflammatory Breast Cancer

Background

Inflammatory breast cancer (IBC) is one of the most rare and aggressive subtypes of primary breast cancer (BC). Our study aimed to explore hub genes related to the pathogenesis of IBC, which could be considered as novel molecular biomarkers for IBC diagnosis and prognosis. Material and Methods. Two datasets from gene expression omnibus database (GEO) were selected. Enrichment analysis and protein-protein interaction (PPI) network for the DEGs were performed. We analyzed the prognostic values of hub genes in the Kaplan-Meier Plotter. Connectivity Map (CMap) and Comparative Toxicogenomics Database (CTD) was used to find candidate small molecules capable to reverse the gene status of IBC.

Results

157 DEGs were selected in total. We constructed the PPI network with 154 nodes interconnected by 128 interactions. The KEGG pathway analysis indicated that the DEGs were enriched in apoptosis, pathways in cancer and insulin signaling pathway. PTEN, PSMF1, PSMC6, AURKB, FZR1, CASP9, CASP6, CASP8, BAD, AKR7A2, ZNF24, SSX2IP, SIGLEC1, MS4A4A, and VSIG4 were selected as hub genes based on the high degree of connectivity. Six hub genes (PSMC6, AURKB, CASP9, BAD, ZNF24, and SSX2IP) that were significantly associated with the prognosis of breast cancer. The expression of CASP9 protein was associated with prognosis and immune cells infiltration of breast cancer. CASP9- naringenin (NGE) is expected to be the most promising candidate gene-compound interaction for the treatment of IBC.

Conclusion

Taken together, CASP9 can be used as a prognostic biomarker and a novel therapeutic target in IBC.

Variations in Fibrinogen-like 1 (FGL1) Gene Locus as a Genetic Marker Related to Fat Deposition Based on Pig Model and Liver RNA-Seq Data

The goal of this study was to evaluate the effects of mutations in the FGL1 gene associated with pig productive traits to enrich the genetic marker pool for further selection and to support the studies on FGL1 in the context of the fat deposition (FD) process. The variant calling and χ2 analyses of liver RNA-seq data were used to indicate genetic markers. FGL1 mutations were genotyped in the Złotnicka White (n = 72), Polish Large White (n = 208), Duroc (n = 72), Polish Landrace (PL) (n = 292), and Puławska (n = 178) pig breeds. An association study was performed using a general linear model (GLM) implemented in SAS® software. More than 50 crucial mutations were identified in the FGL1 gene. The association study showed a significant effect of the FGL1 on intramuscular fat (IMF), loin eye area, backfat thickness at the lumbar, ham mass (p = 0.0374), meat percentage (p = 0.0205), and loin fat (p = 0.0003). Alternate homozygotes and heterozygotes were found in the PL and Duroc, confirming the selective potential for these populations. Our study supports the theory that liver FGL1 is involved in the FD process. Moreover, since fat is the major determinant of flavor development in meat, the FGL1 rs340465447_A allele can be used as a target in pig selection focused on elevated fat levels.

Distinct transcriptomic profile of small arteries of hypertensive patients with chronic kidney disease identified miR-338-3p targeting GPX3 and PTPRS

OBJECTIVE

Hypertension is associated with vascular injury, which contributes to end-organ damage. MicroRNAs regulating mRNAs have been shown to play a role in vascular injury in hypertensive mice. We aimed to identify differentially expressed microRNAs and their mRNA targets in small arteries of hypertensive patients with/without chronic kidney disease (CKD) to shed light on the pathophysiological molecular mechanisms of vascular remodeling.

METHODS AND RESULTS

Normotensive individuals and hypertensive patients with/without CKD were recruited ( n  = 15-16 per group). Differentially expressed microRNAs and mRNAs were identified uniquely associated with hypertension (microRNAs: 10, mRNAs: 68) or CKD (microRNAs: 68, mRNAs: 395), and in both groups (microRNAs: 2, mRNAs: 32) with a P less than 0.05 and a fold change less than or greater than 1.3 in subcutaneous small arteries ( n  = 14-15). One of the top three differentially expressed microRNAs, miR-338-3p that was down-regulated in CKD, presented the best correlation between RNA sequencing and reverse transcription-quantitative PCR (RT-qPCR, R2  = 0.328, P  < 0.001). Profiling of human aortic vascular cells showed that miR-338-3p was mostly expressed in endothelial cells. Two of the selected top nine up-regulated miR-338-3p predicted targets, glutathione peroxidase 3 ( GPX3 ) and protein tyrosine phosphatase receptor type S ( PTPRS ), were validated with mimics by RT-qPCR in human aortic endothelial cells ( P  < 0.05) and by a luciferase assay in HEK293T cells ( P  < 0.05).

CONCLUSION

A distinct transcriptomic profile was observed in gluteal subcutaneous small arteries of hypertensive patients with CKD. Down-regulated miR-338-3p could contribute to GPX3 and PTPRS up-regulation via the canonical microRNA targeting machinery in hypertensive patients with CKD.

GRAPHICAL ABSTRACT

http://links.lww.com/HJH/C27.

Identification of circRNA-miRNA-Immune-Related mRNA Regulatory Network in Gastric Cancer

The pathogenesis of gastric cancer (GC) is still not fully understood. We aimed to find the potential regulatory network for ceRNA (circRNA–miRNA–immune-related mRNA) to uncover the pathological molecular mechanisms of GC. The expression profiles of circRNA, miRNA, and mRNA in gastric tissue from GC patients were downloaded from the Gene Expression Omnibus (GEO) datasets. Differentially expressed circRNAs, miRNAs, and immune-related mRNAs were filtered, followed by the construction of the ceRNA (circRNA–miRNA–immune-related mRNA) network. Functional annotation and protein–protein interaction (PPI) analysis of immune-related mRNAs in the network were performed. Expression validation of circRNAs and immune-related mRNAs was performed in the new GEO and TCGA datasets and in-vitro experiment. A total of 144 differentially expressed circRNAs, 216 differentially expressed miRNAs, and 2,392 differentially expressed mRNAs were identified in GC. Some regulatory pairs of circRNA–miRNA–immune-related mRNA were obtained, including hsa_circ_0050102–hsa-miR-4537–NRAS–Tgd cells, hsa_circ_0001013–hsa-miR-485-3p–MAP2K1–Tgd cells, hsa_circ_0003763–hsa-miR-145-5p–FGF10–StromaScore, hsa_circ_0001789–hsa-miR-1269b–MET–adipocytes, hsa_circ_0040573–hsa-miR-3686–RAC1–Tgd cells, and hsa_circ_0006089–hsa-miR-5584-3p–LYN–neurons. Interestingly, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN had potential diagnostic value for GC patients. In the KEGG analysis, some signaling pathways were identified, such as Rap1 and Ras signaling pathways (involved NRAS and FGF10), Fc gamma R-mediated phagocytosis and cAMP signaling pathway (involved RAC1), proteoglycans in cancer (involved MET), T-cell receptor signaling pathway (involved MAP2K1), and chemokine signaling pathway (involved LYN). The expression validation of hsa_circ_0003763, hsa_circ_0004928, hsa_circ_0040573, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN was consistent with the integrated analysis. In conclusion, the identified ceRNA (circRNA–miRNA–immune-related mRNA) regulatory network may be associated with the development of GC.

Molecular interactions of miR-338 during tumor progression and metastasis

Background

Cancer, as one of the main causes of human deaths, is currently a significant global health challenge. Since the majority of cancer-related deaths are associated with late diagnosis, it is necessary to develop minimally invasive early detection markers to manage and reduce mortality rates. MicroRNAs (miRNAs), as highly conserved non-coding RNAs, target the specific mRNAs which are involved in regulation of various fundamental cellular processes such as cell proliferation, death, and signaling pathways. MiRNAs can also be regulated by long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). They are highly stable in body fluids and have tumor-specific expression profiles, which suggest their suitability as efficient non-invasive diagnostic and prognostic tumor markers. Aberrant expression of miR-338 has been widely reported in different cancers. It regulates cell proliferation, migration, angiogenesis, and apoptosis in tumor cells.

Main body

In the present review, we have summarized all miR-338 interactions with other non-coding RNAs (ncRNAs) and associated signaling pathways to clarify the role of miR-338 during tumor progression.

Conclusions

It was concluded that miR-338 mainly functions as a tumor suppressor in different cancers. There were also significant associations between miR-338 and other ncRNAs in tumor cells. Moreover, miR-338 has a pivotal role during tumor progression using the regulation of WNT, MAPK, and PI3K/AKT signaling pathways. This review highlights miR-338 as a pivotal ncRNA in biology of tumor cells.

hsa_circ_0001018 promotes papillary thyroid cancer by facilitating cell survival, invasion, G1/S cell cycle progression, and repressing cell apoptosis via crosstalk with miR-338-3p and SOX4

We identified a novel interactome, circ_0001018/miR-338-3p/SOX4, in papillary thyroid cancer (PTC), and we intended to confirm the regulatory relationship between the three and to study the effects of the three in PTC. The bioinformatics method was used to screen out the circular RNA and mRNA of interest. A cellular fractionation assay and fluorescence in situ hybridization (FISH) assay were conducted to prove that circ_0001018 and CCT4 (the host gene of circ_0001018) mRNA primarily localized in the cytoplasm of PTC cell lines. By qRT-PCR analysis, the expression of circ_0001018 and SOX4 mRNA was found upregulated while the expression of miR-338-3p was found downregulated in PTC tissues and cells. circ_0001018 silence significantly inhibited the tumor growth in xenografted nude mice. A series of cytological experiments such as a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2′-deoxyuridine (EdU) assay, cell cycle profiling, wound healing, a transwell assay, and cell apoptosis were conducted and showed that circ_0001018 and SOX4 promoted cell proliferation, migration, and invasion, inhibited cell apoptosis, and reduced the cell cycle arrest at the G₁ phase in PTC cells. Compared with circ_0001018 and SOX4, miR-338-3p held the opposite function. The regulatory relationship between circ_0001018 and miR-338-3p, and between miR-338-3p and SOX4 mRNA, was validated using a luciferase reporter gene assay and/or RNA immunoprecipitation (RIP assay). Our findings showed that circ_0001018 acted as the tumor promoter via sponging miR-338-3p to elevate SOX4 expression level in PTC. Importantly, this novel circ_0001018/miR-338-3p/SOX4 axis has the potential to be considered as a therapy target for PTC.

The role of microRNA-338-3p in cancer: growth, invasion, chemoresistance, and mediators

Cancer still remains as one of the leading causes of death worldwide. Metastasis and proliferation are abnormally increased in cancer cells that subsequently, mediate resistance of cancer cells to different therapies such as radio-, chemo- and immune-therapy. MicroRNAs (miRNAs) are endogenous short non-coding RNAs that can regulate expression of target genes at post-transcriptional level and capable of interaction with mRNA-coding genes. Vital biological mechanisms including apoptosis, migration and differentiation are modulated by these small molecules. MiRNAs are key players in regulating cancer proliferation and metastasis as well as cancer therapy response. MiRNAs can function as both tumor-suppressing and tumor-promoting factors. In the present review, regulatory impact of miRNA-338-3p on cancer growth and migration is discussed. This new emerging miRNA can regulate response of cancer cells to chemotherapy and radiotherapy. It seems that miRNA-338-3p has dual role in cancer chemotherapy, acting as tumor-promoting or tumor-suppressor factor. Experiments reveal anti-tumor activity of miRNA-338-3p in cancer. Hence, increasing miRNA-338-3p expression is of importance in effective cancer therapy. Long non-coding RNAs, circular RNAs and hypoxia are potential upstream mediators of miRNA-338-3p in cancer. Anti-tumor agents including baicalin and arbutin can promote expression of miRNA-338-3p in suppressing cancer progression. These topics are discussed to shed some light on function of miRNA-338-3p in cancer cells.

Potential therapeutic approaches of microRNAs for COVID-19: Challenges and opportunities

The coronavirus disease 2019 (COVID-19) emerges as current outbreak cause by Novel Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2). This infection affects respiratory system and provides uncontrolled systemic inflammatory response as cytokine storm. The main concern about SARS-CoV-2 pandemic is high viral pathogenicity with no specific drugs. MicroRNAs (miRs) as small non-coding RNAs (21–25 ​nt) regulate gene expression. The SARS-CoV-2 encoded-miRs affect human genes that involved in transcription, translation, apoptosis, immune response and inflammation. Also, they alter self-gene regulation and hijacked host miRs that provide protective environment to maintain its latency. On the other hand, Host miRs play critical role in viral gene expression to restrict infection. Over expression/inhibition of miRs might result in cell cycle irregularity, impaired immune response or cancer. In this manner, exact role of each miR should be specified. Mimic encoded-miRs like antagomirs showed successful result in phases of clinical trial prevent from negative effects of viral encoded-miRs. Products of mimic miRs are inexpensive corresponds to synthesis of primer; they are short and nanoscale in size. Although SARS-CoV-2 genome is undergoing evaluation, detection of exact molecular pathogenesis open up opportunities to for vaccine development. Salivaomics can evaluate SARS-CoV-2 genome, transcriptome, proteome and biomarkers like miRs in oral related and cancer disease. In this review, we studied the challenge and opportunities of miRs in therapeutic approach for SARS-CoV-2 infection, then overviewed the role of miRs in saliva droplet during SARS-CoV-2 infection and related cancer.

Implications of SARS-CoV-2 Mutations for Genomic RNA Structure and Host microRNA Targeting

The SARS-CoV-2 virus is a recently-emerged zoonotic pathogen already well adapted to transmission and replication in humans. Although the mutation rate is limited, recently introduced mutations in SARS-CoV-2 have the potential to alter viral fitness. In addition to amino acid changes, mutations could affect RNA secondary structure critical to viral life cycle, or interfere with sequences targeted by host miRNAs. We have analysed subsets of genomes from SARS-CoV-2 isolates from around the globe and show that several mutations introduce changes in Watson-Crick pairing, with resultant changes in predicted secondary structure. Filtering to targets matching miRNAs expressed in SARS-CoV-2-permissive host cells, we identified ten separate target sequences in the SARS-CoV-2 genome; three of these targets have been lost through conserved mutations. A genomic site targeted by the highly abundant miR-197-5p, overexpressed in patients with cardiovascular disease, is lost by a conserved mutation. Our results are compatible with a model that SARS-CoV-2 replication within the human host is constrained by host miRNA defences. The impact of these and further mutations on secondary structures, miRNA targets or potential splice sites offers a new context in which to view future SARS-CoV-2 evolution, and a potential platform for engineering conditional attenuation to vaccine development, as well as providing a better understanding of viral tropism and pathogenesis.

Expression and prognostic utility of SSX2IP in patients with nasopharyngeal carcinoma

Cell adhesion affects carcinogenesis, tumor progression, and metastasis. We datamined a published transcriptome (GSE12452) of nasopharyngeal carcinoma (NPC) and identified SSX2IP as a significantly upregulated gene in NPC carcinogenesis among genes associated with cell adhesion (GO:0007155). Consequently, we assessed SSX2IP protein expression and its prognostic significance in 124 patients with NPC using immunohistochemistry and the H-score method. The status of SSX2IP immunoexpression correlated with clinical and pathological characteristics, as well as oncological outcomes. High levels of SSX2IP expression were significantly associated with more advanced primary tumor and TNM stages. Kaplan-Meier and log-rank analyses revealed that high levels of SSX2IP expression, and advanced tumor stage and lymph node metastasis were significantly associated with lower rates of local recurrence-free survival (LRFS), distant metastasis-free survival (DMeFS), and disease-specific (DSS) survival. Multivariate analysis showed that high levels of SSX2IP expression significantly predicted DSS (hazard ratio [HR], 4.290; 95% confidence interval [CI], 2.271-8.102; p < 0.001), DMeFS (HR, 4.159' 95% CI, 2.072-8.345; p < 0.001), and LRFS (HR, 3.007' 95% CI,: 1.418-6.378; p = 0.004). We associated high levels of SSX2IP immunoexpression with aggressive pathological features and worse oncological outcomes, suggesting its potential therapeutic value for patients with NPC.

Circulating MACC1 Transcripts in Glioblastoma Patients Predict Prognosis and Treatment Response

Glioblastoma multiforme is the most aggressive primary brain tumor of adults, but lacks reliable and liquid biomarkers. We evaluated circulating plasma transcripts of metastasis-associated in colon cancer-1 (MACC1), a prognostic biomarker for solid cancer entities, for prediction of clinical outcome and therapy response in glioblastomas. MACC1 transcripts were significantly higher in patients compared to controls. Low MACC1 levels clustered together with other prognostically favorable markers. It was associated with patients’ prognosis in conjunction with the isocitrate dehydrogenase (IDH) mutation status: IDH1 R132H mutation and low MACC1 was most favorable (median overall survival (OS) not yet reached), IDH1 wildtype and high MACC1 was worst (median OS 8.1 months), while IDH1 wildtype and low MACC1 was intermediate (median OS 9.1 months). No patients displayed IDH1 R132H mutation and high MACC1. Patients with low MACC1 levels receiving standard therapy survived longer (median OS 22.6 months) than patients with high MACC1 levels (median OS 8.1 months). Patients not receiving the standard regimen showed the worst prognosis, independent of MACC1 levels (low: 6.8 months, high: 4.4 months). Addition of circulating MACC1 transcript levels to the existing prognostic workup may improve the accuracy of outcome prediction and help define more precise risk categories of glioblastoma patients.

CircHIPK3 overexpression accelerates the proliferation and invasion of prostate cancer cells through regulating miRNA-338-3p

Objective: Circular RNA is a type of endogenous RNA molecule with a stable closed-loop structure which is ubiquitous in mammals. Circular RNA HIPK3 (circHIPK3) is highly expressed in hepatocellular carcinoma and promotes the growth of hepatoma cells. However, its role in prostate cancer (PCa) has not been reported. This study aims to explore whether circHIPK3 could affect the proliferative and invasive potentials of PCa cells by regulating miRNA-338-3p.

Methods: Expression levels of circHIPK3 and miRNA-338-3p in PCa tissues and cells were determined by RT-qPCR. The regulatory effects of circHIPK3 and miRNA-338-3p on proliferative and invasive potentials of PCa cells were evaluated by CCK-8 and transwell assay, respectively. We verified the binding between miRNA-338-3p and ADAM17, as well as miRNA-338-3p and circHIPK3 through dual-luciferase reporter gene assay. Rescue experiments were conducted to clarify whether circHIPK3 affected the proliferative and invasive potentials of PCa cells by regulating miRNA-338-3p.

Results: Expression level of circHIPK3 in PCa tissues was remarkably higher than that of paracancerous tissues. Knockdown of circHIPK3 inhibited the proliferative and invasive rates of PC-3 and DU145 cells. Dual-luciferase reporter gene assay indicated that circHIPK3 could bind to miRNA-338-3p. Moreover, miRNA-338-3p expression was downregulated in PCa tissues. miRNA-338-3p expression was negatively correlated with lymph node metastasis and distant metastasis. miRNA-338-3p overexpression markedly reduced proliferative and invasive abilities of PC-3 and DU145 cells. Furthermore, ADAM17 was confirmed to be the target gene of miRNA-338-3p. Overexpression of ADAM17 enhanced proliferative and invasive abilities of PC-3 and DU145 cells. Finally, rescue experiments indicated that miRNA-338-3p knockdown in PC-3 and DU145 cells partially reversed the regulatory effects of circHIPK3 on proliferative and invasive potentials.

Conclusion: Overexpression of circHIPK3 promotes the proliferative and invasive potentials of PCa cells through sponging miRNA-338-3p to regulate ADAM17 expression, thus accelerating the malignant progression of PCa.

Derivation of preoligodendrocytes from human-induced pluripotent stem cells through overexpression of microRNA 338

MicroRNAs (miRNAs) control gene expression at the posttranscriptional level and have a critical role in many biological processes such as oligodendrocyte differentiation. Recent studies have shown that microRNA 338 (miR-338) is overexpressed during the oligodendrocyte development process in the central nervous system; this finding indicates a potentially important role for miR-338 in oligodendrocyte development. To evaluate this assumption, we studied the effect of miR-338 overexpression on promoting the differentiation of oligodendrocyte progenitor cells (OPCs), derived from human-induced pluripotent stem cells (hiPSC), into preoligodendrocyte. hiPSCs were differentiated into OPCs after treating for 16 days with basic fibroblast growth factor (BFGF), epidermal growth factor (FGF), and platelet-derived growth factor (PDGF)-AA. Bipolar OPCs appeared and the expression of OPC-related markers, including Nestin, Olig2, Sox10, PDGFRα, and A2B5 was confirmed by real-time polymerase chain reaction (PCR) and immunofluorescence. Then, OPCs were transduced by miR-338 expressing lentivirus or were treated with triiodothyronine (T3) for 6 days. Data obtained from real-time PCR and immunofluorescence experiment indicated that preoligodendrocyte markers such as Sox10, O4, and MBP were expressed at higher levels in transduced cells with miR-338 in comparison with the T3 group. So, the overexpression of miR-338 in iPSC-derived OPCs can promote their differentiation into preoligodendrocyte which can be used in cell therapy of myelin-related diseases.

Molecular alterations of cancer cell and tumour microenvironment in metastatic gastric cancer

The term metastasis is widely used to describe the endpoint of the process by which tumour cells spread from the primary location to an anatomically distant site. Achieving successful dissemination is dependent not only on the molecular alterations of the cancer cells themselves, but also on the microenvironment through which they encounter. Here, we reviewed the molecular alterations of metastatic gastric cancer (GC) as it reflects a large proportion of GC patients currently seen in clinic. We hope that further exploration and understanding of the multistep metastatic cascade will yield novel therapeutic targets that will lead to better patient outcomes.

miR-338-3p functions as a tumor suppressor in gastric cancer by targeting PTP1B

Gastric cancer (GC) is one of the most common malignant tumors and peritoneal metastasis is the primary cause for advanced GC’s mortality. Protein-tyrosine phosphatase 1B (PTP1B) functions as an oncogene and involves in carcinogenesis and cancer dissemination. However, the function and regulation of PTP1B in GC remain poorly understood. In this study, we found that PTP1B was upregulated in GC tissues and overexpression of PTP1B in vitro promoted cell migration and prevented apoptosis. Then, we predicted that PTP1B was a target of miR-338-3p and we revealed an inverse correlation between miR-338-3p levels and PTP1B protein levels in GC tissues. Next, we verified that PTP1B was inhibited by miR-338-3p via direct targeting to its 3′-untranslated regions. Moreover, overexpression of miR-338-3p in vitro attenuated GC cell migration and promoted apoptosis, and these effects could be partially reversed by reintroduction of PTP1B. Finally, we established an orthotopic xenograft model and a peritoneal dissemination model of GC to demonstrate that miR-338-3p restrained tumor growth and dissemination in vivo by targeting PTP1B. Taken together, our results highlight that PTP1B is an oncogene and is negatively regulated by miR-338-3p in GC, which may provide new insights into novel molecular therapeutic targets for GC.

MiR-152-5p as a microRNA passenger strand special functions in human gastric cancer cells

Gastric cancer (GC) is one of the most common malignancies with high mortality rate. MiR-152 may exert the function of tumor suppressor by regulating its target gene, including PIK3CA. Nevertheless, all of the described functions are referred explicitly to miR-152-3p, while miR-152-5p as a passenger strand is poorly realized and entirely ignored. We previously selected miR-152-5p as a candidate using cell migration inhibition screening for GC cells and predicted that miR-152-5p might also target PIK3CA. In this study, we found an abnormal proportion of miR-152-3p / miR-152-5p in GC (gastric cancer) tissues and cells and demonstrated that miR-152-5p had poorer stability in GC cells, revealing the possibility that miR-152-5p is abnormally "suppressed" in gastric cancer. We also investigated and confirmed the role of miR-152-5p in GC by a series of experiments, and found that miR-152-5p modulated cell viability, migration, invasion, and cell-cycle progression of human GC cells, and also inhibited tumor growth and metastasis in vivo partially by targeting PIK3CA. More interestingly, it was proved that miR-152-3p and miR-152-5p had synergistic effects on the inhibition of PIK3CA in GC cells. The results of this study suggest that miR-152-5p may act as a tumor suppressor in SGC-7901 gastric cancer cells via targeting PIK3CA. Further, the study provides a novel insight into the roles of miRNA* during carcinogenesis.

LncRNA Snhg1, a non-degradable sponge for miR-338, promotes expression of proto-oncogene CST3 in primary esophageal cancer cells

Competing endogenous RNA (ceRNA) is a newly proposed mechanism that describes a crosstalk among lncRNAs, mRNAs and their shared miRNAs. In this study, the role of miR-338-3p (miR-338) in the progression of esophageal cancer and its involve in the ceRNA regulatory circuit lncRNA-Snhg1/CST3 were explored. MiR-338 displayed a 30% decreased expression in esophageal squamous cell carcinoma tissues compared with the adjacent. Then, proto-oncogene CST3 was predicted and validated as a target gene of miR-338. Gain-and-loss-function experiments indicated that miR-338 suppressed expression of CST3 protein (also Cystatin C, CysC), promoted expression of apoptotic proteins caspase-8/3, attenuated esophageal carcinoma cell growth and induced its apoptosis. In addition, lncRNA-Snhg1 was significantly upregulated in esophageal carcinoma tissues and promoted esophageal carcinoma cell growth. Furthermore, our results from bioinformatics, luciferase reporter gene and RNA pull-down assays indicated that Snhg1 could be directly bound by miR-338. Snhg1 acted as a non-degradable sponge to relieve the suppression on CST3 caused by miR-338. In conclusion, lncRNA-Snhg1 promoted cell proliferation by acting as a non-degradable sponge for the tumor suppressor miR-338 in esophageal cancer cells.

Epigenetic Mechanisms and Events in Gastric Cancer-Emerging Novel Biomarkers

Gastric cancer is one of the most common malignancy worldwide. The various genetic and epigenetic events have been found to be associated with its carcinogenesis. The epigenetic is a heritable and transient/reversible change in the gene expression that is not accompanied by modification in the DNA sequence. This event is characterized by the alteration in the promoter CpG island of the gene or histone modification. These events are associated with silencing of critical tumor suppressor gene and activation of oncogenes leading to carcinogenesis. The DNA methylation is a chemical change in the DNA sequence that most commonly occurs at cytosine moiety of CpG dinucleotide and histone, primarily on N- terminal tail that ultimately effect the interaction of DNA with chromatin modifying protein.Hypermethylation of tumor suppressor genes and global hypomethylation of oncogenes are widely studied epigenetic modifications. There are large number of publish reports regarding epigenetic events involving gastric cancer. These changes are potentially useful in identifying markers for early diagnosis and management of this lethal malignancy. Also, role of specific miRNAs and long non coding RNAs in regulation of gene expression is gaining interest and is a matter of further investigation. In this review, we aimed to summarize major epigenetic events (DNA methylation) in gastric cancer along with alteration in miRNAs and long non coding RNAs which plays an important role in pathology of this poorly understood malignancy.

GATA1 activated lncRNA (Galont) promotes anoxia/reoxygenation-induced autophagy and cell death in cardiomyocytes by sponging miR-338

The hypernomic autophagy is associated with various cardiovascular diseases. Long noncoding RNAs (lncRNAs) are emerging as important regulators in gene expression, which have been involved in multiple physiological and pathological processes. However, the function of lncRNAs and how they functioned in the autophagy in cardiomyocytes were rarely reported. In this study, we report that a lncRNA, named GATA1 activated lncRNA (Galont), can directly interact with miR-338 and promote ATG5-mediated autophagic cell death in murine cardiomyocytes. First, we found that Galont was upregulated by anoxia/reoxygenation (A/R) stimulus, and it was able to promote autophagy and cell death in cardiomyocytes exposure to A/R. Then, miR-338 was identified as a novel suppressor in autophagy and autophagic cell death. Our results from bioinformatic analysis and luciferase reporter gene assay indicated that ATG5 is a target gene of miR-338. Furthermore, RNA pull-down assays demonstrated that Galont directly interacted with miR-338, and thus promoted ATG5 expression and autophagic cell death. Our findings reveal a novel regulatory circuit in the autophagy in cardiomyocytes, which consists of Galont, miR-338 and ATG5.

MicroRNA-338-3p Suppresses Proliferation of Human Liver Cancer Cells by Targeting SphK2

Recent studies have revealed abnormal expression of miRNAs in various tumors. Although microRNA-338-3p (miR-338-3p) plays an important role in many types of tumors, its influence on liver cancer (LC) is unknown. In this study, we found that expression of miR-338-3p was decreased in LC cells and tissues. Colony formation and cell proliferation were suppressed by enhanced expression of miR-338-3p in LC cells. Moreover, miR-338-3p targeted sphingosine kinase 2 (SphK2). Silencing of SphK2 had an identical influence as overexpression of miR-338-3p in LC cells. Overexpression of SphK2 without the 3′-untranslated region remarkably enhanced the growth suppression triggered by miR-338-3p in LC cells. These findings indicate that miR-338-3p influences the development of LC by targeting SphK2, suggesting that miR-338-3p can be targeted as an innovative therapeutic strategy for LC.

Chondromodulin‑I suppresses tumorigenesis of human osteosarcoma cells

Osteosarcoma is the most common type of bone cancer, and accounts for ~3% of cancers that occurring in children. Chondromodulin‑I (ChM-I) is a 25 kDa glycoprotein that is expressed mainly in cartilage. ChM-I demonstrates anti‑angiogenic activity and has been suggested to inhibit endothelial cells from invading cartilage, and then has been shown to be an inhibitor of tumorigenesis. However, it remains unclear if ChM‑I has any direct anti‑tumorigenesis role on osteosarcoma. Therefore, the present study aimed to identify whether ChM‑I has any direct inhibit effect on human osteosarcoma cells. A bromodeoxyuridine incorporation assay was performed on the Saos‑2 human osteosarcoma cell line treated with or without recombinant human ChM‑I, to evaluate its impact on DNA synthesis. An adenovirus carrier for the expression of ChM‑I was constructed and transfected into tumor cells in vitro to evaluate the effect of ChM‑I on tumor cells. Additionally, ChM‑I was knocked down by using small interfering RNA to downregulate the expression of ChM‑I. Cell invasion, migration and cell‑colony formation assays, and xenograft tumor experiments were performed to evaluate the effects of ChM‑I on tumor cells in vitro and in vivo. The results demonstrated that ChM‑I could suppress DNA synthesis of human osteosarcoma cells, and it also exerted an inhibitory effect on the proliferation and colony formation abilities of human osteosarcoma cells. In addition, ChM‑I inhibited cell invasion and migration in vitro and suppressed osteosarcoma cell growth significantly in vivo. In conclusion, ChM‑I directly suppressed the proliferation and growth of osteosarcoma cells in an anchorage‑independent manner, and may therefore be a promising drug for the treatment of osteosarcoma.

MicroRNA-338-3p targets SOX4 and inhibits cell proliferation and invasion of renal cell carcinoma

MicroRNA (miR)-338-3p has been reported to be involved in tumor progression and development in various types of cancer. However, the biological function of miR-338-3p and its related molecular pathways involved in the progression of renal cell carcinoma (RCC) are unknown. The present study aimed to investigate the biological role and underlying mechanism of miR-338-3p in RCC cells. It was demonstrated that miR-338-3p expression level was significantly downregulated (P<0.05) in RCC tissues and cell lines. Clinical association analysis indicated that low expression of miR-338-3p was significantly associated with advanced TNM stage and lymph node metastasis (P<0.05). Function assays revealed that restoration of miR-338-3p in RCC cells significantly inhibited cell proliferation, colony formation, migration and invasion (P<0.05). Notably, sex-determining region Y-box 4 (SOX4) was identified as a direct target of miR-338-3p in RCC cells through a luciferase reporter assay, reverse transcription-quantitative polymerase chain reaction and western blot analysis. Furthermore, SOX4 overexpression partially rescued miR-338-3p-mediated inhibition of cell proliferation, colony formation, migration and invasion in RCC cells. These results suggested that miR-338-3p functioned as a tumor suppressor in RCC cells by modulating SOX4, suggesting that miR-338-3p may have a potential use in the treatment of RCC.

MicroRNAs and clinical implications in hepatocellular carcinoma

AIM

To assess the role of some circulating miRNAs (miR-23a, miR-203, miR338, miR-34, and miR-16) as tumor markers for diagnosis of hepatocellular carcinoma (HCC).

METHODS

One hundred and seventy-one subjects were enrolled, 57 patients with HCC, 57 patients with liver cirrhosis (LC) and 57 healthy subjects as control group. Severity of liver disease was assessed by Child Pugh score. Tumor staging was done using Okuda staging system. Quantification of Micro RNA (miR-23a, miR-203, miR338, miR-34, and miR-16) was performed.

RESULTS

All studied miRNA showed significant difference between HCC and cirrhotic patients in comparison to healthy control. miR-23a showed statistically significant difference between HCC and cirrhotic patients being higher in HCC group than cirrhotic. miR-23a is significantly higher in HCC patients with focal lesion size equal or more than 5 cm, patients with multiple focal lesions and Okuda stage III. At cutoff value ≥ 2¹⁰, miR-23a showed accuracy 79.3% to diagnose HCC patients with sensitivity 89.47% and specificity about 64.91%. At cut off level ≥ 200 ng/mL, serum alpha fetoprotein had 73.68% sensitivity, 52.63% specificity, 43.75% PPV, 80% NPV for diagnosis of HCC.

CONCLUSION

MicroRNA 23a can be used as a screening test for early detection of HCC. Also, it is related to larger size of tumour, late Okuda staging and multiple hepatic focal lesions, so it might be a prognostic biomarker.

miR-338-3p inhibits the invasion of renal cell carcinoma by downregulation of ALK5

Background

The current study aims to elucidate the role of miRNA-338-3p (miR-338-3p) in the invasion of renal cell carcinoma (RCC).

Methods

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-338-3p in human RCC cell lines with high metastatic potential (Caki-1) and low metastatic potential (786-O), respectively. The Caki-1 and 786-O cells were transfected with miR-338-3p mimic or inhibitor. Wound healing assay, Transwell assay and western blotting were performed to analyze the invasive ability and expression of activin receptor-like kinase 5 (ALK5) in the RCC cell lines. During the 36-month follow-up, we detected the expressions of miR-338-3p and ALK5 in 22 RCC cases with metastasis and 60 cases achieving a remission.

Results

miR-339-3p was significantly downregulated in the Caki-1 cells as compared with the 786-O cells. The transfection with miR-338-3p inhibitor caused an increased invasive ability of both two cell lines. However, the transfection with miR-338-3p mimic caused a reduction of the invasiveness. In RCC cells, the expression of ALK5 was negatively correlated to miR-338-3p. Upregulation of ALK5 partially counteracted the miR-338-3p-induced invasiveness of RCC cells. We subsequently found the negative correlations between miR-338-3p and metastasis/ALK5 expression could be also observed in human RCC tissues.

Conclusion

Taken together, these results indicate that miR-338-3p acts as a novel tumor suppressor to inhibit the invasion of RCC by regulating ALK5 expression.

MiR-338-3p regulates neuronal maturation and suppresses glioblastoma proliferation

Neurogenesis is a highly-regulated process occurring in the dentate gyrus that has been linked to learning, memory, and antidepressant efficacy. MicroRNAs (miRNAs) have been previously shown to play an important role in the regulation of neuronal development and neurogenesis in the dentate gyrus via modulation of gene expression. However, this mode of regulation is both incompletely described in the literature thus far and highly multifactorial. In this study, we designed sensors and detected relative levels of expression of 10 different miRNAs and found miR-338-3p was most highly expressed in the dentate gyrus. Comparison of miR-338-3p expression with neuronal markers of maturity indicates miR-338-3p is expressed most highly in the mature neuron. We also designed a viral “sponge” to knock down in vivo expression of miR-338-3p. When miR-338-3p is knocked down, neurons sprout multiple primary dendrites that branch off of the soma in a disorganized manner, cellular proliferation is upregulated, and neoplasms form spontaneously in vivo. Additionally, miR-338-3p overexpression in glioblastoma cell lines slows their proliferation in vitro. Further, low miR-338-3p expression is associated with increased mortality and disease progression in patients with glioblastoma. These data identify miR-338-3p as a clinically relevant tumor suppressor in glioblastoma.

MicroRNA-338-3p suppresses cell proliferation and induces apoptosis of non-small-cell lung cancer by targeting sphingosine kinase 2

Background

Lung cancer is the major cause of cancer-related death worldwide, and 80% patients of lung cancer are non-small-cell lung cancer (NSCLC) cases. MicroRNAs are important gene regulators with critical roles in diverse biological processes, including tumorigenesis. Studies indicate that sphingosine kinase 2 (SphK2) promotes tumor progression in NSCLC, but how this occurs is unclear. Thus, we explored the effect of miR-338-3p targeting SphK2 on proliferation and apoptosis of NSCLC cells.

Methods

Expression of miR-338-3p and SphK2 in NSCLC A549 and H1299 cell lines was measured using qRT-PCR and Western blot. CCK-8 and colony formation assays were used to assess the effect of miR-338-3p on NSCLC cell line proliferation. Flow cytometry was used to study the effect of miR-338-3p on NSCLC apoptosis. Luciferase reporter assay and Western blot were used to confirm targeting of SphK2 by miR-338-3p. Finally, in vivo tumorigenesis studies were used to demonstrate subcutaneous tumor growth.

Results

miR-338-3p expression in 34 NSCLC clinical samples was downregulated and this was correlated with TNM stage. miR-338-3p significantly suppressed proliferation and induced apoptosis of NSCLC A549 and H1299 cells in vitro. SphK2 was a direct target of miR-338-3p. Overexpression of miR-338-3p significantly inhibited SphK2 expression and reduced luciferase reporter activity containing the SphK2 3′-untranslated region (3′-UTR) through the first binding site. SphK2 lacking 3′-UTR restored the effects of miR-338-3p on cell proliferation inhibition. miR-338-3p significantly inhibited tumorigenicity of NSCLC A549 and H1299 cells in a nude mouse xenograft model.

Conclusions

Collectively, miR-338-3p inhibited cell proliferation and induced apoptosis of NSCLC cells by targeting and down-regulating SphK2, and miR-338-3p could inhibit NSCLC cells A549 and H1299 growth in vivo, suggesting a potential mechanism of NSCLC progression. Therapeutically, miR-338-3p may serve as a potential target in the treatment of human lung cancer.

miRNA-338-3p/CDK4 signaling pathway suppressed hepatic stellate cell activation and proliferation

BACKGROUND

Activated hepatic stellate cell (HSC) is the main fibrogenic cell type in the injured liver. miRNA plays an important role in activation and proliferation of HSC.

METHODS

Our previous study examined the expression profiles of microRNAs in quiescent and activated HSC. Real-time PCR and western blot were used to detect the expression of Collagen type I (Col 1) and Alpha-Smooth Muscle Actin (α-SMA). CCK-8 and Edu assay was used to measure the proliferation rate of HSC. Luciferase reporter gene assay was used to tested the binding between miR-338-3p and Cyclin-dependent kinase 4 (CDK4).

RESULTS

We found overexpression of miR-338-3p could inhibit Col 1 and α-SMA, two major HSC activation markers, whereas miR-338-3p inhibitor could promote them. Besides, miR-338-3p overexpression could suppress the growth rate of HSC. Further, we found that CDK4, a pleiotropic signaling protein, was a direct target gene of miR-338-3p. Moreover, we found that overexpression of CDK4 could block the effects of miR-338-3p.

CONCLUSIONS

We found miR-338-3p is an anti-fibrotic miRNA which inhibits cell activation and proliferation. Our findings suggest that miR-338-3p/CDK4 signaling pathway participates in the regulation of HSC activation and growth and may act as a novel target for further anti-fibrotic therapy.

MiR-338-3p inhibits the growth and invasion of non-small cell lung cancer cells by targeting IRS2

MicroRNA-338-3p (miR-338-3p) has recently been reported to have anti-cancer efficacy in several types of cancers. However, its biological function and underlying mechanism involved in modulation of human non-small cell lung cancer (NSCLC) remain largely unknown. The present study was designed to investigate the function and underlying mechanism of miR-338-3p in human NSCLC tissues and cell lines. We demonstrated that miR-338-3p was significantly decreased in NSCLC tissues and cell lines, and negatively correlated with advanced and tumor-node-metastasis (TNM) stage and lymph node metastasis (both P<0.01). Transient overexpression of miR-338-3p by transfecting with miR-338-3p mimic significantly suppressed NSCLC cell proliferation, migration, invasion and induced apoptosis and cell cycle at G1 phase. Additionally, insulin receptor substrate 2 (IRS2), a known oncogene, was identified as a potential target gene of miR-338-3p. Subsequent investigations found a negative correlation between the expression of miR-338-3p and IRS2 in NSCLC tissues. Furthermore, overexpression of IRS2 reversed the effects of miR-338-3p in NSCLC cells on cell proliferation, cycle, apoptosis, migration, invasion. These findings suggested that miR-338-3p might act as a tumor suppressor by directly targeting IRS2 in NSCLC.

Anticancer bioactive peptide-3 inhibits human gastric cancer growth by targeting miR-338-5p

BACKGROUND

Cancer incidence and mortality have been increasing in China, making cancer the leading cause of death since 2010 and a major public health concern in the country. Cancer stem cells have been studied in relation to the treatment of different malignancies, including gastric cancer. Anticancer bioactive peptide-3 (ACBP-3) can induce the apoptosis of gastric cancer stem cells (GCSCs) and reduce their tumorigenicity. In the present study, for the first time, we used a miRNA microarray and bioinformatics analysis to identify differentially expressed miRNAs in ACBP-3-treated GCSCs and GCSC-derived tumors in a xenograft model and functionally verified the identified miRNAs. miR-338-5p was selected based on its significant upregulation by ACBP-3 both in cultured GCSCs and in tumor tissues.

RESULTS

miR-338-5p was downregulated in GCSCs compared with normal gastric epithelial cells, and the ectopic restoration of miR-338-5p expression in GCSCs inhibited cell proliferation and induced apoptosis, which correlated with the upregulation of the pro-apoptotic Bcl-2 proteins BAK and BIM. We also found that ACBP-3-treated GCSCs could respond to lower effective doses of cisplatin (DDP) or 5-fluorouracil (5-FU), possibly because ACBP-3 induced the expression of miR-338-5p and the BAK and BIM proteins and promoted GCSC apoptosis.

CONCLUSIONS

Our data indicate that miR-338-5p is part of an important pathway for the inhibition of human gastric cancer stem cell proliferation by ACBP-3 combined with chemotherapeutics. ACBP-3 could suppress GCSC proliferation and lower the required effective dose of cisplatin or 5-fluorouracil. Therefore, this study provides not only further evidence for the remarkable anti-tumor effect of ACBP-3 but also a possible new approach for the development of GCSC-targeting therapies.

MiR-338-3p targets pyruvate kinase M2 and affects cell proliferation and metabolism of ovarian cancer

MiR-338-3p is down-regulated in cancer, which inhibits cancer cell proliferation, metastasis, and increases chemosensitivity, but its functions in ovarian cancer remains unknown. The present study aims to identify the miR-338-3p targeted genes and to investigate the associated regulatory mechanisms in ovarian cancer cell proliferation and metabolism. Our results demonstrated miR-338-3p expression was down-regulated in most of ovarian cancer tissues and cell lines. Restoration of miR-338-3p expression in ovarian cancer cells could inhibit cell proliferation, lactate production and lactate production of ovarian cancer cells. PKM2 was verified as a target gene of miR-338-3p by luciferase assay. Further study indicated miR-338-3p controlled ovarian cancer cell metabolism by inhibiting PKM2 expression. It is summarized that the regulatory role of miR-338-3p on PKM2 expression in ovarian cancer may play important roles in cell metabolism.

Effects of microRNA‑338‑3p on morphine‑induced apoptosis and its underlying mechanisms

The aim of the present study was to investigate the effects of microRNA-338-3p (miR-338-3p) on morphine (MP)-induced apoptosis, and its underlying mechanisms. Freshly‑isolated mouse peritoneal macrophages were cultured in vitro and treated with MP following transfection with miR‑338‑3p mimic, inhibitor or controls. miR‑338‑3p expression levels increased significantly following MP treatment (P<0.01). This increase was enhanced following transfection with miR‑338‑3p mimic (P<0.05) and abrogated following transfection with miR‑338‑3p inhibitor (P<0.05). The apoptotic rate increased significantly in groups treated with MP (P<0.05); however, this increase was abrogated by transfection with miR‑338‑3p inhibitor (P<0.05). Bioinformatics software predicted that sex determining region Y‑box 4 (SOX4) was the target gene of miR‑338‑3p and this was verified using a dual‑luciferase reporter gene system. SOX4 mRNA and protein expression levels decreased significantly following MP treatment (P<0.05); however, this decrease was abrogated following transfection with miR‑338‑3p inhibitor (P<0.05). Caspase‑3 protein expression levels increased markedly following MP treatment (P<0.05); however, this increase was inhibited by transfection with miR‑338‑3p inhibitor (P<0.05). Therefore, decreased expression of miR‑338‑3p may suppress MP‑induced apoptosis, potentially via the upregulation of SOX4 expression and the caspase‑3‑dependent apoptotic signaling pathway.

MicroRNA-338-3p suppresses metastasis of lung cancer cells by targeting the EMT regulator Sox4

Metastasis remains the leading cause of the majority of cancer-related mortality. MicroRNAs (miRNAs) have frequently emerged as tumor metastatic regulator by acting on multiple signaling pathways. In the present study, we demonstrated that miR-338-3p was significantly downregulated in highly metastatic NSCLC cell lines and clinical metastatic tissues. Then, we found that introduction of miR-338-3p significantly suppressed the migration and invasion of lung cancer cells both in vitro and in vivo, suggesting that miR-338-3p may be a novel tumor suppressor. Further studies indicated that the EMT-related transcription factor Sox4 was one direct target gene of miR-338-3p, evidenced by the direct binding of miR-338-3p with the 3'untranslated region (3'UTR) of Sox4. Furthermore, miR-338-3p could decrease the expression of Sox4 both at mRNA and protein levels. Notably, the EMT marker E-cadherin or vimentin, a downstream regulator of Sox4, was also down-regulated or up-regulated upon miR-338-3p treatment. Additionally, over-expressing or silencing Sox4 could elevate or inhibit the migration and invasion of lung cancer cells, parallel to the effect of miR-338-3p on the lung cancer cells. Meanwhile, knockdown of Sox4 reversed the enhanced migration and invasion mediated by miR-338-3p. These results indicated that miR-338-3p suppressed the migration and invasion of NSCLC cells through targeting Sox4 involving in the EMT process. Thus, our finding provides new insight into the mechanism of NSCLC progression. Therapeutically, miR-338-3p may serve as a potential target in the treatment of human lung cancer.

Helicobacter pylori-induced inflammation and epigenetic changes during gastric carcinogenesis

The sequence of events associated with the development of gastric cancer has been described as “the gastric precancerous cascade”. This cascade is a dynamic process that includes lesions, such as atrophic gastritis, intestinal metaplasia and dysplasia. According to this model, Helicobacter pylori (H. pylori) infection targets the normal gastric mucosa causing non-atrophic gastritis, an initiating lesion that can be cured by clearing H. pylori with antibiotics or that may then linger in the case of chronic infection and progress to atrophic gastritis. The presence of virulence factors in the infecting H. pylori drives the carcinogenesis process. Independent epidemiological and animal studies have confirmed the sequential progression of these precancerous lesions. Particularly long-term follow-up studies estimated a risk of 0.1% for atrophic gastritis/intestinal metaplasia and 6% in case of dysplasia for the long-term development of gastric cancer. With this in mind, a better understanding of the genetic and epigenetic changes associated with progression of the cascade is critical in determining the risk of gastric cancer associated with H. pylori infection. In this review, we will summarize some of the most relevant mechanisms and focus predominantly but not exclusively on the discussion of gene promoter methylation and miRNAs in this context.

Dysregulation of non-coding RNAs in gastric cancer

Gastric cancer (GC) is one of the most common cancers in the world and a significant threat to the health of patients, especially those from China and Japan. The prognosis for patients with late stage GC receiving the standard of care treatment, including surgery, chemotherapy and radiotherapy, remains poor. Developing novel treatment strategies, identifying new molecules for targeted therapy, and devising screening techniques to detect this cancer in its early stages are needed for GC patients. The discovery of non-coding RNAs (ncRNAs), primarily microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), helped to elucidate the mechanisms of tumorigenesis, diagnosis and treatment of GC. Recently, significant research has been conducted on non-coding RNAs and how the regulatory dysfunction of these RNAs impacts the tumorigenesis of GC. In this study, we review papers published in the last five years concerning the dysregulation of non-coding RNAs, especially miRNAs and lncRNAs, in GC. We summarize instances of aberrant expression of the ncRNAs in GC and their effect on survival-related events, including cell cycle regulation, AKT signaling, apoptosis and drug resistance. Additionally, we evaluate how ncRNA dysregulation affects the metastatic process, including the epithelial-mesenchymal transition, stem cells, transcription factor activity, and oncogene and tumor suppressor expression. Lastly, we determine how ncRNAs affect angiogenesis in the microenvironment of GC. We further discuss the use of ncRNAs as potential biomarkers for use in clinical screening, early diagnosis and prognosis of GC. At present, no ideal ncRNAs have been identified as targets for the treatment of GC.

MicroRNA-338-3p functions as tumor suppressor in breast cancer by targeting SOX4

MicroRNA-338-3p (miR‑338-3p), a recently discovered miRNA, has been reported to be downregulated and play tumor suppressor roles in gastric cancer, ovarian cancer, colorectal carcinoma and lung cancer by targeting several genes. However, the role and potential mechanism of miR‑338-3p in breast cancer (BC) is still unclear. In the present study, we investigated the roles and mechanisms of miR‑338-3p in human breast cancer. miR‑338-3p expression was determined by qRT-PCR in human BC cell lines, and clinical significantly of miR‑338-3p expression was further evaluated. Furthermore, the function of miR‑338-3p in breast cancer also was investigated by several in vitro approaches and in nude mouse models. Luciferase assay and western blot analysis were performed to validate the potential targets of miR‑338-3p after the preliminary screening by employing open access software. It was found that miR‑338-3p was significantly downregulated in both BC tissues and cell lines and the low expression of miR‑338-3p was inversely correlated with lymph node metastatic and TNM stage status (P<0.01). Function assay showed that the overexpression of miR‑338-3p in BC cells significantly inhibited cell proliferation, colony formation, migration and invasion, and induced cell apoptosis and cell cycle arrest at G1/G0 stage, as well as suppressed tumor growth in the nude mouse model. Luciferase assay and western blot analysis identified sex-determining region Y-box 4 (SOX4) as a direct and functional target of miR‑338-3p. These findings revealed that miR‑338-3p may act as a tumor suppressor in breast cancer by targeting SOX4, suggesting miR‑338-3p as a novel strategy for breast cancer treatment.

Mineralocorticoid receptor suppresses cancer progression and the Warburg effect by modulating the miR-338-3p-PKLR axis in hepatocellular carcinoma

Hormones and their corresponding receptors are vital in controlling metabolism under normal physiologic and pathologic conditions, but less is known about their roles in the metabolism of cancer. Using a small interfering RNA screening approach, we examined the effects of silencing 20 well-known hormone receptors on the Warburg effect, specifically by measuring the production of lactate in four established hepatocellular carcinoma (HCC) cell lines. We found that silencing a variety of hormone receptors had effects on the production of this metabolite. Unexpectedly silencing of mineralocorticoid receptor (MR) significantly increased lactate production in all these HCC cell lines. Subsequent in vitro and in vivo studies showed that gain- and loss-of-function of MR significantly influenced HCC cellular proliferation, cell cycle distribution, and apoptosis. Furthermore, mechanistic studies revealed that MR as a transcriptional factor directly regulated the expression of miR-338-3p, suppressing the Warburg effects of HCC cells by targeting a key enzyme of glycolysis: pyruvate kinase, liver and red blood cells. Moreover, MR expression was significantly down-regulated in 81% of HCC patient tissues, caused by both chromosome deletion and histone deacetylation. Low expression of MR in tumor tissues was associated with poor patient prognosis. The expression level of miR-338-3p was found to positively correlate with the expression of MR in HCC tissues and to inversely correlate with expression of the enzyme pyruvate kinase, liver and red blood cells.

CONCLUSION

MR affects HCC development by modulating the miR-338-3p/pyruvate kinase, liver and red blood cells axis with an ability to suppress the Warburg effect.

Methylation of miR-155-3p in mantle cell lymphoma and other non-Hodgkin's lymphomas

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin's lymphoma (NHL). In cancers, tumor suppressive microRNAs may be silenced by DNA hypermethylation. By microRNA profiling of representative EBV-negative MCL cell lines before and after demethylation treatment, miR-155-3p was found significantly restored. Methylation-specific PCR, verified by pyrosequencing, showed complete methylation of miR-155-3p in one MCL cell line (REC-1). 5-aza-2′-deoxycytidine treatment of REC-1 led to demethylation and re-expression of miR-155-3p. Over-expression of miR-155-3p led to increased sub-G1 apoptotic cells and reduced cellular viability, demonstrating its tumor suppressive properties. By luciferase assay, lymphotoxin-beta (LT-β) was validated as a miR-155-3p target. In 31 primary MCL, miR-155-3p was found hypermethylated in 6(19%) cases. To test if methylation of miR-155-3p was MCL-specific, miR-155-3p methylation was tested in an additional 191 B-cell, T-cell and NK-cell NHLs, yielding miR-155-3p methylation in 66(34.6%) including 36(27%) non-MCL B-cell, 24(53%) T-cell and 6(46%) of NK-cell lymphoma. Moreover, in 72 primary NHL samples with RNA, miR-155-3p methylation correlated with miR-155-3p downregulation (p = 0.024), and LT-β upregulation (p = 0.043). Collectively, miR-155-3p is a potential tumor suppressive microRNA hypermethylated in MCL and other NHL subtypes. As miR-155-3p targets LT-β, which is an upstream activator of the non-canonical NF-kB signaling, miR-155-3p methylation is potentially important in lymphomagenesis.

Epigenetic silencing of microRNA-149 in cancer-associated fibroblasts mediates prostaglandin E2/interleukin-6 signaling in the tumor microenvironment

Tumor initiation and growth depend on its microenvironment in which cancer-associated fibroblasts (CAFs) in tumor stroma play an important role. Prostaglandin E2 (PGE2) and interleukin (IL)-6 signal pathways are involved in the crosstalk between tumor and stromal cells. However, how PGE2-mediated signaling modulates this crosstalk remains unclear. Here, we show that microRNA (miR)-149 links PGE2 and IL-6 signaling in mediating the crosstalk between tumor cells and CAFs in gastric cancer (GC). miR-149 inhibited fibroblast activation by targeting IL-6 and miR-149 expression was substantially suppressed in the CAFs of GC. miR-149 negatively regulated CAFs and their effect on GC development both in vitro and in vivo. CAFs enhanced epithelial-to-mesenchymal transition (EMT) and the stem-like properties of GC cells in a miR-149-IL-6-dependent manner. In addition to IL-6, PGE2 receptor 2 (PTGER2/EP2) was revealed as another potential target of miR-149 in fibroblasts. Furthermore, H. pylori infection, a leading cause of human GC, was able to induce cyclooxygenase-2 (COX-2)/PGE2 signaling and to enhance PGE2 production, resulting in the hypermethylation of miR-149 in CAFs and increased IL-6 secretion. Our findings indicate that miR-149 mediates the crosstalk between tumor cells and CAFs in GC and highlight the potential of interfering miRNAs in stromal cells to improve cancer therapy.

miR‑338‑3p suppresses tumor growth of ovarian epithelial carcinoma by targeting Runx2

miR‑338‑3p, a recently discovered miRNA, has been shown to play important roles in tumorigenesis and metastasis in various cancers. However, the exact roles and mechanisms of miR‑338‑3p remain unknown in human ovarian epithelial carcinoma (EOC). The relationship between miR‑338‑3p expression pattern and clinicopathological features of patients with EOC were determined by real-time quantitative RT-PCR. Furthermore, the role of miR‑338‑3p and possible molecular mechanisms in EOC was investigated by several in vitro approaches and in a nude mouse model. We first showed that the expression of miR‑338‑3p was significantly downregulated in EOC tissues compared to those in adjacent normal tissues, and the value was negatively related to advanced FIGO stage, high histological grading and lymph node metastasis (P<0.01). An in vitro analysis revealed that the overexpression of miR‑338‑3p in EOC cells significantly inhibited cell proliferation, colony formation, migration and invasion, inducing cell apoptosis and enhancing caspase-3, -8, and -9 activities. Bioinformatic analysis and dual luciferase assays identified Runx2 as a direct target of miR‑338‑3p. We also found that enforced expression of miR‑338‑3p markedly inhibited the in vivo tumorigenicity in a nude mouse xenograft model system. Furthermore, overexpression of miR‑338‑3p inhibited phosphorylation of PI3K and AKT, which contributed to suppression of ovarian cancer cell growth. These findings revealed that miR‑338‑3p may act as a tumor suppressor that blocks the growth of human ovarian epithelial carcinoma through PI3K/AKT signaling pathways by targeting Runx2.

Contribution of Intronic miR-338-3p and Its Hosting Gene AATK to Compensatory β-Cell Mass Expansion

The elucidation of the mechanisms directing β-cell mass regeneration and maintenance is of interest, because the deficit of β-cell mass contributes to diabetes onset and progression. We previously found that the level of the microRNA (miRNA) miR-338-3p is decreased in pancreatic islets from rodent models displaying insulin resistance and compensatory β-cell mass expansion, including pregnant rats, diet-induced obese mice, and db/db mice. Transfection of rat islet cells with oligonucleotides that specifically block miR-338-3p activity increased the fraction of proliferating β-cells in vitro and promoted survival under proapoptotic conditions without affecting the capacity of β-cells to release insulin in response to glucose. Here, we evaluated the role of miR-338-3p in vivo by injecting mice with an adeno-associated viral vector permitting specific sequestration of this miRNA in β-cells. We found that the adeno-associated viral construct increased the fraction of proliferating β-cells confirming the data obtained in vitro. miR-338-3p is generated from an intron of the gene coding for apoptosis-associated tyrosine kinase (AATK). Similarly to miR-338-3p, we found that AATK is down-regulated in rat and human islets and INS832/13 β-cells in the presence of the cAMP-raising agents exendin-4, estradiol, and a G-protein-coupled Receptor 30 agonist. Moreover, AATK expression is reduced in islets of insulin resistant animal models and selective silencing of AATK in INS832/13 cells by RNA interference promoted β-cell proliferation. The results point to a coordinated reduction of miR-338-3p and AATK under insulin resistance conditions and provide evidence for a cooperative action of the miRNA and its hosting gene in compensatory β-cell mass expansion.

The functional sites of miRNAs and lncRNAs in gastric carcinogenesis

Gastric cancer is one of the most common malignant diseases and has one of the highest mortality rates worldwide. Its molecular mechanisms are poorly understood. Recently, the functions of non-coding RNAs (ncRNAs) in gastric cancer have attracted wide attention. Although the expression levels of various ncRNAs are different, they may work together in a network and contribute to gastric carcinogenesis by altering the expression of oncogenes or tumor suppressor genes. They affect the cell cycle, apoptosis, motility, invasion, and metastasis. Dysregulated microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), including miR-21, miR-106, H19, and ANRIL, directly or indirectly regulate carcinogenic factors or signaling pathways such as PTEN, CDK, caspase, E-cadherin, Akt, and P53. Greater recognition of the roles of miRNAs and lncRNAs in gastric carcinogenesis can provide new insight into the mechanisms of tumor development and identify targets for anticancer drug development.

MicroRNA-338-3p inhibits cell proliferation in hepatocellular carcinoma by target forkhead box P4 (FOXP4)

MicroRNAs (miRNAs) are a class of small, non-coding RNAs, which have demonstrated to important gene regulators, and have critical roles in diverse biological processes including cancer cell proliferation. Previous studies suggested microRNA-338-3p (miR-338-3p) was down-regulated and play tumor suppressor roles in gastric cancer, colorectal carcinoma and lung cancer. However, the role of miR-338-3p in hepatocellular carcinoma (HCC) is still unclear. In this study, we analyzed the expression of miR-338-3p in HCC tissues and HCC cell lines. We find that miR-338-3p was downregulated in HCC tissues and cell lines. Then functional studies demonstrate ectopic miR-338-3p expression significantly suppressed the in vitro proliferation and colony formation of HCC cells and cause to cell cycle arrest. Using bio-informatic method and report assay we identified a novel miR-338-3p target, FOXP4 in HCC cells. Furthermore, knockdown of FOXP4 have the similar effects in HCC corrected with miR-338-3p. These findings suggest that miR-338-3p regulates survival of HCC cells partially through the downregulation of FOXP4. Therefore, targeting with the miR-338-3p/FOXP4 axis might serve as a novel therapeutic application to treat HCC patients.

MiR-338-3p inhibits hepatocarcinoma cells and sensitizes these cells to sorafenib by targeting hypoxia-induced factor 1α

Hypoxia is a common feature of solid tumors and an important contributor to anti-tumor drug resistance. Hypoxia inducible factor-1 (HIF-1) is one of the key mediators of the hypoxia signaling pathway, and was recently proven to be required for sorafenib resistance in hepatocarcinoma (HCC). MicroRNAs have emerged as important posttranslational regulators in HCC. It was reported that miR-338-3p levels are associated with clinical aggressiveness of HCC. However, the roles of miR-338-3p in HCC disease and resistance to its therapeutic drugs are unknown. In this study, we found that miR-338-3p was frequently down-regulated in 14 HCC clinical samples and five cell lines. Overexpression of miR-338-3p inhibited HIF-1α 3'-UTR luciferase activity and HIF-1α protein levels in HepG2, SMMC-7721, and Huh7 cells. miR-338-3p significantly reduced cell viability and induced cell apoptosis of HCC cells. Additionally, HIF-1α overexpression rescued and HIF-1α knock-down abrogated the anti-HCC activity of miR-338-3p. Furthermore, miR-338-3p sensitized HCC cells to sorafenib in vitro and in a HCC subcutaneous nude mice tumor model by inhibiting HIF-1α. Collectively, miR-338-3p inhibits HCC tumor growth and sensitizes HCC cells to sorafenib by down-regulating HIF-1α. Our data indicate that miR-338-3p could be a potential candidate for HCC therapeutics.

KDM5B is overexpressed in gastric cancer and is required for gastric cancer cell proliferation and metastasis

Epigenetic alterations such as aberrant expression of histone-modifying enzymes have been implicated in tumorigenesis. KDM5B (also known as JARID1B) is a newly identified histone demethylase that regulates chromatin structure or gene expression by removing methyl residues from trimethylated lysine 4 on histone H3. Recent observations have shown oncogenic activity of KDM5B. However, the role of KDM5B in gastric cancer carcinogenesis remains unclear. In this study, we aimed to investigate the role of KDM5B in gastric cancer. Immunohistochemical analysis, western blotting, and qRT-PCR were used to measure the levels of KDM5B in gastric cancer cell lines, 45 pairs of gastric cancer tissues and the adjacent nonneoplastic tissues. KDM5B and shKDM5B were transfected into gastric cancer cells to investigate its role on regulating cell proliferation which was measured by MTT and colony formation assay. Cell's migration and invasion were measured by Transwell and Matrigel analysis in vitro. PCNA expression was measured by immunofluorescence staining and immunohistochemical analysis. The in vivo tumorigenesis and metastasis assays were performed in SCID mice. In clinical gastric cancer samples, we found that KDM5B expression was significantly up-regulated in cancer lesions compared with paired normal gastric tissues. By silencing or overexpressing KDM5B in gastric cancer cells, we found that KDM5B could promote cell growth and metastasis in vitro. An in vivo assay showed that KDM5B not only dramatically promoted gastric cancer cell xenograft formation and growth but also promoted gastric cancer cell metastasis in a liver metastasis model. Moreover, we demonstrated that KDM5B promoted gastric cancer metastasis via regulation of the Akt pathway. Our study provided evidence that KDM5B functions as a novel tumor oncogene in gastric cancer and may be a potential therapeutic target for gastric cancer management.

microRNA-338-3p functions as a tumor suppressor in human non‑small‑cell lung carcinoma and targets Ras-related protein 14

microRNAs (miRNAs) have been demonstrated to be important gene regulators with critical roles in diverse biological processes, including tumorigenesis. Accumulating evidence suggests that miR‑338-3p exerts a tumor suppressor role and is downregulated in tumors, including gastric cancer and colorectal carcinoma. However, the role of miR‑338-3p in lung cancer, particularly non‑small‑cell lung carcinoma (NSCLC), has remained elusive. In the present study, the expression levels of miR‑338-3p in NSCLC tissues were compared with those of matched normal tissues by use of polymerase chain reaction analysis. miR-338-3p was shown to be downregulated in NSCLC tissues, and the expression levels of miR‑338‑3p were significantly correlated with NSCLC cancer differentiation, pathological stage and lymph‑node metastasis. Ectopic miR-338-3p expression significantly suppressed the in vitro proliferation and colony formation of NSCLC cells and enhanced apoptosis. Of note, ectopic miR‑338-3p expression significantly inhibited Ras‑related protein 14 (RAB14) mRNA and protein expression, and reduced luciferase reporter activity containing the RAB14 3'-untranslated region through the first binding site. These findings suggested that miR‑338-3p regulated the survival of NSCLC cells partially through the downregulation of RAB14. Therefore, targeting the miR‑338-3p/RAB14 interaction may serve as a novel therapeutic application to treat NSCLC patients.