The Role of miR-375-3p and miR-200b-3p in Gastrointestinal Stromal Tumors.

Deregulated microRNA (miRNA) expression profiles and their contribution to carcinogenesis have been observed in virtually all types of human cancer. However, their role in the pathogenesis of rare mesenchymal gastrointestinal stromal tumors (GISTs) is not well defined, yet. In this study, we aimed to investigate the role of two miRNAs strongly downregulated in GIST-miR-375-3p and miR-200b-3p-in the pathogenesis of GIST. To achieve this, miRNA mimics were transfected into GIST-T1 cells and changes in the potential target gene mRNA and protein expression, as well as alterations in cell viability, migration, apoptotic cell counts and direct miRNA-target interaction, were evaluated. Results revealed that overexpression of miR-375-3p downregulated the expression of KIT mRNA and protein by direct binding to KIT 3'UTR, reduced GIST cell viability and migration rates. MiR-200b-3p lowered expression of ETV1 protein, directly targeted and lowered expression of EGFR mRNA and protein, and negatively affected cell migration rates. To conclude, the present study identified that miR-375-3p and miR-200b-3p have a tumor-suppressive role in GIST.

miR-20b and miR-451a Are Involved in Gastric Carcinogenesis through the PI3K/AKT/mTOR Signaling Pathway: Data from Gastric Cancer Patients, Cell Lines and Ins-Gas Mouse Model.

Gastric cancer (GC) is one of the most common and lethal gastrointestinal malignancies worldwide. Many studies have shown that development of GC and other malignancies is mainly driven by alterations of cellular signaling pathways. MicroRNAs (miRNAs) are small noncoding molecules that function as tumor-suppressors or oncogenes, playing an essential role in a variety of fundamental biological processes. In order to understand the functional relevance of miRNA dysregulation, studies analyzing their target genes are of major importance. Here, we chose to analyze two miRNAs, miR-20b and miR-451a, shown to be deregulated in many different malignancies, including GC. Deregulated expression of miR-20b and miR-451a was determined in GC cell lines and the INS-GAS mouse model. Using Western Blot and luciferase reporter assay we determined that miR-20b directly regulates expression of PTEN and TXNIP, and miR-451a: CAV1 and TSC1. Loss-of-function experiments revealed that down-regulation of miR-20b and up-regulation of miR-451a expression exhibits an anti-tumor effect in vitro (miR-20b: reduced viability, colony formation, increased apoptosis rate, and miR-451a: reduced colony forming ability). To summarize, the present study identified that expression of miR-20b and miR-451a are deregulated in vitro and in vivo and have a tumor suppressive role in GC through regulation of the PI3K/AKT/mTOR signaling pathway.

The Role of VEGFA, COX2, HUR and CUGBP2 in Predicting the Response to Neoadjuvant Therapy in Rectal Cancer Patients.

Background and objectives: The effectiveness of neoadjuvant therapy, which is commonly used for stage II-III rectal cancer (RC) treatment, is limited. Genes associated with the pathogenesis of RC could determine response to this treatment. Therefore, the aim of this study was to investigate the potential predictive value of VEGFA, COX2, HUR and CUGBP2 genes and the associations between post-treatment changes in gene expression and the efficacy of neoadjuvant therapy. Materials and Methods: Biopsies from RC and healthy rectal tissue of 28 RC patients were collected before neoadjuvant therapy and 6-8 weeks after neoadjuvant therapy. The expression levels of VEGFA, COX2, HUR, CUGBP2 genes were evaluated using a quantitative real-time polymerase chain reaction. Results: The results reveal a significantly higher expression of VEGFA, COX2 and HUR mRNA in RC tissue compared to healthy rectal tissue (p < 0.05), and elevated VEGFA gene expression in pre-treatment tissues was associated with a better response to neoadjuvant therapy based on T-stage downstaging (p < 0.05). The expression of VEGFA, HUR and CUGBP2 genes significantly decreased after neoadjuvant therapy (p < 0.05). Responders to treatment demonstrated a significantly stronger decrease of VEGFA and COX2 expression after neoadjuvant therapy than non-responders (p < 0.05). Conclusions: The findings of this study suggest that the pre-treatment VEGFA gene expression might have predictive value for the response to neoadjuvant therapy, while the post-treatment decrease in VEGFA and COX2 gene expression could indicate the effectiveness of neoadjuvant therapy in RC patients.

Identification of long intergenic non-coding RNAs (lincRNAs) deregulated in gastrointestinal stromal tumors (GISTs).

Long intergenic non-coding RNAs (lincRNAs) are >200 nucleotides long non-coding RNAs, which have been shown to be implicated in carcinogenic processes by interacting with cancer associated genes or other non-coding RNAs. However, their role in development of rare gastrointestinal stromal tumors (GISTs) is barely investigated. Therefore, the aim of this study was to define lincRNAs deregulated in GIST and find new GIST-lincRNA associations. Next-generation sequencing data of paired GIST and adjacent tissue samples from 15 patients were subjected to a web-based lincRNA analysis. Three deregulated lincRNAs (MALAT1, H19 and FENDRR; adjusted p-value < 0.05) were selected for expression validation in a larger group of patients (n = 22) by RT-qPCR method. However, only H19 and FENDRR showed significant upregulation in the validation cohort (adjusted p < 0.05). Further, we performed correlation analyses between expression levels of deregulated lincRNAs and GIST-associated oncogenes or GIST deregulated microRNAs. We found high positive correlations between expression of H19 and known GIST related oncogene ETV1, and between H19 and miR-455-3p. These findings expand the knowledge on lincRNAs deregulated in GIST and may be an important resource for the future studies investigating lincRNAs functionally relevant to GIST carcinogenesis.

Evidence for PTGER4, PSCA, and MBOAT7 as risk genes for gastric cancer on the genome and transcriptome level.

Genetic associations between variants on chromosome 5p13 and 8q24 and gastric cancer (GC) have been previously reported in the Asian population. We aimed to replicate these findings and to characterize the associations at the genome and transcriptome level. We performed a fine-mapping association study in 1926 GC patients and 2012 controls of European descent using high dense SNP marker sets on both chromosomal regions. Next, we performed expression quantitative trait locus (eQTL) analyses using gastric transcriptome data from 143 individuals focusing on the GC associated variants. On chromosome 5p13 the strongest association was observed at rs6872282 (P = 2.53 × 10-04 ) and on chromosome 8q24 at rs2585176 (P = 1.09 × 10-09 ). On chromosome 5p13 we found cis-eQTL effects with an upregulation of PTGER4 expression in GC risk allele carrier (P = 9.27 × 10-11 ). On chromosome 8q24 we observed cis-eQTL effects with an upregulation of PSCA expression in GC risk allele carrier (P = 2.17 × 10-47 ). In addition, we found trans-eQTL effects for the same variants on 8q24 with a downregulation of MBOAT7 expression in GC risk allele carrier (P = 3.11 × 10-09 ). In summary, we confirmed and refined the previously reported GC associations at both chromosomal regions. Our data point to shared etiological factors between Asians and Europeans. Furthermore, our data imply an upregulated expression of PTGER4 and PSCA as well as a downregulated expression of MBOAT7 in gastric tissue as risk-conferring GC pathomechanisms.

MiRNA profiling of gastrointestinal stromal tumors by next-generation sequencing.

Deregulation of miRNAs has been observed virtually in all major types of cancer, whereas the miRNA signature in GIST is not well characterized yet. In this study the first high-throughput miRNA profiling of 15 paired GIST and adjacent normal tissue samples was performed using small RNA-seq approach and differentially expressed miRNAs as well as isomiRNAs were defined. Highly significantly deregulated miRNAs were selected for validation by Taq-Man low-density array in replication group of 40 paired samples. Validated miRNAs were further subjected to enrichment analysis, which revealed significantly enriched KEGG pathways in the main GIST associated pathways. Further, we used an integrated analysis of miRNA-mRNA correlations for KIT and PDGFRA target genes and found a significant correlation between all of the enriched miRNAs and their target gene KIT. Results of the phenotype analysis showed miR-509-3p to be up-regulated in epithelioid and mixed cell types compared to spindle type, whereas miR-215-5p showed negative correlation with risk grade of GIST. These data reveal a detailed miRNA profile of GIST and highlight new candidates that may be important in the development of malignant disease.

Common Genetic Variants of PSCA, MUC1 and PLCE1 Genes are not Associated with Colorectal Cancer.

BACKGROUND: Polymorphisms of genes encoding PSCA, PLCE1 and MUC1 have been associated with the risk of different cancers in genome wide association studies (GWAS). Up to date there are limited data on the role of these genetic alterations in colorectal cancer (CRC) development. The aim of this study was to evaluate potential associations between single nucleotide polymorphisms (SNPs) of genes encoding PSCA, PLCE1 and MUC1 and the presence of CRC in European populations. MATERIALS AND METHODS: Gene polymorphisms were analyzed in 574 European subjects (controls: n=382; CRC: n=192). PSCA C>T (rs2294008), PSCA G>A (rs2976392), MUC1 A>G (rs4072037) and PLCE1 A>G (rs2274223) SNPs were genotyped by RT-PCR. RESULTS: The distribution of genotypes for all four SNPs was in line with the Hardy-Weinberg equilibrium (rs2294008, P=0.153; rs2976392, P=0.269; rs4072037, P=0.609; rs2274223, P=0.858). The distribution of genotypes and alleles of PSCA C>T, PSCA G>A, MUC1 A>G and PLCE1 A>G SNPs was similar among controls and CRC patient groups (P>0.05). GG genotype of MUC1 SNP was more frequent in CRC patients (24.0%) than in controls (20.2%); however, this association failed to reach significance (OR-1.45, P=0.15). Overall, in the present study SNPs of PSCA (rs2294008, rs2976392), MUC1 (rs4072037) and PLCE1 (rs2274223) genes were not associated with the presence of CRC. CONCLUSIONS: Gene polymorphisms of PSCA, PLCE1 and MUC1 genes are not associated with the presence of CRC in European subjects.

Lack of association between miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608 gene polymorphisms and colorectal cancer.

Colorectal cancer (CRC) is one of the most common cancers worldwide with high mortality rates. MicroRNAs (miRNAs) have an established role in the development of different cancers. Single nucleotide polymorphisms (SNPs) in miRNA related genes were linked with various gastrointestinal malignancies. However, the data on association between miRNA SNPs and CRC development are inconsistent. The aim of the present study was to evaluate the association between miRNA-related gene polymorphisms (miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608) and the presence of CRC in European population. Gene polymorphisms were analyzed in 621 subjects (controls: n = 428; CRC: n = 193). MiR-27a T>C (rs895819), miR-146a G>C (rs2910164), miR-196a-2 C>T (rs11614913), miR-492 G>C (rs2289030) and miR-608 C>G (rs4919510) SNPs were genotyped by RT-PCR. Overall, all genotypes and alleles of miRNA SNPs were distributed equally between control and CRC groups. We observed a tendency for miR-146a C allele to be associated with lower risk of CRC when compared to G allele, however, the difference did not reach the adjusted P-value (odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.49-0.95, P = 0.025). In conclusion, gene polymorphisms of miR-27a, miR-146a, miR-196a-2, miR-492, miR-492a and miR-608 were not associated with the presence of CRC in European subjects.

Gene polymorphisms of micrornas in Helicobacter pylori-induced high risk atrophic gastritis and gastric cancer.

BACKGROUND AND AIMS: MicroRNAs (miRNAs) are known for their function as translational regulators of tumor suppressor or oncogenes. Single nucleotide polymorphisms (SNPs) in miRNAs related genes have been shown to affect the regulatory capacity of miRNAs and were linked with gastric cancer (GC) and premalignant gastric conditions. The purpose of this study was to evaluate potential associations between miRNA-related gene polymorphisms (miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608) and the presence of GC or high risk atrophic gastritis (HRAG) in European population. METHODS: Gene polymorphisms were analyzed in 995 subjects (controls: n = 351; GC: n = 363; HRAG: n = 281) of European descent. MiR-27a T>C (rs895819), miR-146a G>C (rs2910164), miR-196a-2 C>T (rs11614913), miR-492 G>C (rs2289030) and miR-608 C>G (rs4919510) SNPs were genotyped by RT-PCR. RESULTS: Overall, SNPs of miRNAs were not associated with the presence of GC or HRAG. We observed a tendency for miR-196a-2 CT genotype to be associated with higher risk of GC when compared to CC genotype, however, the difference did not reach the adjusted P-value (odds ratio (OR) - 1.46, 95% confidence interval (CI) 1.03-2.07, P = 0.032). MiR-608 GG genotype was more frequent in GC when compared to controls (OR -2.34, 95% CI 1.08-5.04), but significance remained marginal (P = 0.029). A similar tendency was observed in a recessive model for miR-608, where CC + CG vs GG genotype comparison showed a tendency for increased risk of GC with OR of 2.44 (95% CI 1.14-5.22, P = 0.021). The genotypes and alleles of miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608 SNPs had similar distribution between histological subtypes of GC and were not linked with the presence of diffuse or intestinal-type GC. CONCLUSIONS: Gene polymorphisms of miR-27a, miR-146a, miR-196a-2, miR-492, miR-492a and miR-608 were not associated with the presence of HRAG, GC or different histological subtypes of GC in European subjects.