Genetic variants in the IL1A gene region contribute to intestinal-type gastric carcinoma susceptibility in European populations

TAS2R38 polymorphisms, Helicobacter pylori infection and susceptibility to gastric cancer and premalignant gastric lesions

BACKGROUND

Gastric cancer is worldwide the fourth more common cancer type by incidence, and the third by mortality. We analyzed three missense variants of TAS2R38 gene: rs713598 (A49P), rs1726866 (V262A), and rs10246939 (I296V). These variants and their combination in haplotypes (proline, alanine and valine/tasters or alanine, valine and isoleucine/nontasters) and diplotypes are responsible for individual differences in bitter perception. The single-nucleotide polymorphisms and the related phenotypes are known to be associated with susceptibility to Gram-negative bacterial infections, such as Helicobacter pylori , and with risk of various cancer types. An association between intermediate tasters (as defined by TAS2R38 diplotypes) and increased risk of gastric cancer was reported in a Korean population.

METHODS

We analyzed 2616 individuals of Latin American origin, representing the whole spectrum of lesions from gastritis to gastric cancer.

RESULTS

Comparing cancer cases vs. noncancers we observed a decrease in risk associated with heterozygous carriers of rs10246939 ( P  = 0.006) and rs1726866 ( P  = 0.003) when compared with homozygotes of the more common allele. Also, the analysis of diplotypes/phenotypes reflected the same association, with super-tasters showing a borderline increased risk of developing gastric cancer compared to medium-tasters [odds ratio (OR) = 1.63; 95% confidence interval (CI), 1.04-2.56; P  = 0.033]. Also, nontasters showed an increased risk when compared to medium-tasters although not reaching statistical significance (OR = 1.58; 95% CI, 0.80-2.87; P  = 0.203). We also tested the interactions between the TAS2R38 genotypes and H. pylori cagA status in a subset of samples and found no interaction.

CONCLUSION

In conclusion, our results suggest only a modest contribution of TAS2R38 gene genetic variability in gastric cancer etiology.

Pyroptosis-related genes play a significant role in the prognosis of gastric cancer

BACKGROUND

Pyroptosis is an inflammatory form of programmed cell death, which has been shown to be related to the prognosis of many tumors. However, its role in gastric cancer (GC) is not fully understood.

AIM

To evaluate the expression of pyroptosis-related genes in GC and its correlation with prognosis.

METHODS

We constructed prognostic multigene markers of differentially expressed genes associated with pyroptosis by least absolute contraction and selection operator Cox regression. The risk model was analyzed by Kaplan-Meier curve, two-sided log-rank test and functional enrichment analysis.

RESULTS

Sixty-three pyroptosis-related genes were differentially expressed in tumor tissues and adjacent nontumor tissues. Based on these differentially expressed genes, 5 gene signature were constructed and all GC patients were classified into two risk groups. Kaplan-Meier survival curve showed that the overall survival (OS) of patients in the high-risk group was significantly lower than that of the low-risk group. Multivariate Cox regression analyses showed that the risk score was an independent risk factor for OS. Receiver operating characteristic curve analysis confirmed the predictive ability of the model. External validation indicated increased OS in the low-risk group. The immune function and immune cell scores of the high-risk group were generally higher than those of the low-risk group.

CONCLUSION

Pyroptosis-related genes play a significant role in tumor immune microenvironment. This novel model, which contains 5 pyroptosis-related genes, is an independent predicting factor for OS in GC patients, and may help to evaluate the prognosis of GC.

Identification of pyroptosis-related subtypes, development of a prognostic model, and characterization of tumour microenvironment infiltration in gastric cancer

As a new programmed death mode, pyroptosis plays an indispensable role in gastric cancer (GC) and has strong immunotherapy potential, but the specific pathogenic mechanism and antitumor function remain unclear. We comprehensively analysed the overall changes of pyroptosis-related genes (PRGs) at the genomic and epigenetic levels in 886 GC patients. We identified two molecular subtypes by consensus unsupervised clustering analysis. Then, we calculated the risk score and constructed the risk model for predicting prognostic and selected nine PRGs related genes (IL18RAP, CTLA4, SLC2A3, IL1A, KRT7,PEG10, IGFBP2, GPA33, and DES) through LASSO and COX regression analyses in the training cohorts and were verified in the test cohorts. Consequently, a highly accurate nomogram for improving the clinical applicability of the risk score was constructed. Besides, we found that multi-layer PRGs alterations were correlated with patient clinicopathological features, prognosis, immune infiltration and TME characteristics. The low risk group mainly characterized by increased microsatellite hyperinstability, tumour mutational burden and immune infiltration. The group had lower stromal cell content, higher immune cell content and lower tumour purity. Moreover, risk score was positively correlated with T regulatory cells, M1 and M2 macrophages. In addition, the risk score was significantly associated with the cancer stem cell index and chemotherapeutic drug sensitivity. This study revealed the genomic, transcriptional and TME multiomics features of PRGs and deeply explored the potential role of pyroptosis in the TME, clinicopathological features and prognosis in GC. This study provides a new immune strategy and prediction model for clinical treatment and prognosis evaluation.

Interaction between Helicobacter pylori and host genetic variants in gastric carcinogenesis

Helicobacter pylori (H. pylori) is the definite carcinogen of gastric cancer. H. pylori infection induces chronic inflammation, causes DNA damage and aberrant methylation of genes and these pathways are involved in H. pylori-related gastric carcinogenesis. Polymorphisms of the genes involved in these pathways could alter susceptibility to gastric cancer. In this mini review, we focused on the role of polymorphisms in these genes on the susceptibility to gastric cancer, with a particular emphasis on their possible interactions with H. pylori infection. We found that many studies on this theme did not simultaneously report H. pylori infection and the interactions remained inconclusive.

Polymorphisms in host immune response associated genes and risk of nasopharyngeal carcinoma development in Portugal

BACKGROUND

Host genetic susceptibility markers in immune response associated genes may contribute to identify individuals with high risk of developing viral infection and viral-associated cancers. We aimed to characterize different polymorphisms in immune response associated genes and evaluate its association with nasopharyngeal carcinoma (NPC) development.

METHODS

We have developed a hospital-based case-control study selecting 134 patients with NPC (cases) and 732 healthy individuals (controls) from the Northern Region of Portugal. Eight single nucleotide polymorphisms (SNP) were selected: -56C>T IFNGR1 (rs2234711), +4854G>T IL1A (rs17561), +3954C>T IL1B (rs1143634), +1902A>G IL4RA (rs1801275), -1082G>A IL10 (rs1800896), +2018T>C IL1RN (rs419598), HLA-A locus A>T (rs2530388), HCGA9 locus A>T (rs6457110). All polymorphisms were analysed by real-time methodology using TaqMan(®) SNP Genotyping Assays.

RESULTS

The overall analysis revealed no statistical significant differences between genotypes distributions in all of studied polymorphisms (p>0.05). However, the results for HCGA9 rs6457110 polymorphism showed a tendency for an increased risk of NPC development among TT carriers with an almost of 2-fold increased risk (OR=1.86; 95%CI 1.00-3.65).

CONCLUSIONS

This is the first study to characterize these polymorphisms in NPC patients in Portugal. Our study indicates that HCGA9 rs6457110 polymorphism might represent a risk marker for NPC development in our population and that other SNPs should be further studied in larger populations to clarify the evidences. This data reinforces the need for more studies, especially in NPC low-prevalent populations.

Finding gastric cancer related genes and clinical biomarkers for detection based on gene-gene interaction network

BACKGROUND/OBJECTIVE

Gastric cancer (GC) is the second leading cause of death resulted from cancer globally. The most common cause of GC is the infection of Helicobacter pylori, approximately 11% of cases are caused by genetic factors. The objective of this study was to develop an effective computational method to meaningfully interpret these GC-related genes and to predict potential prognostic genes for clinical detection.

METHODS

We employed the shortest path algorithm and permutation test to probe the genes that have relationship with known GC genes in gene-gene interaction network. We calculated the enrichment scores of gene ontology and pathways of gastric cancer related genes to characterize these genes in terms of molecular features. The optimal features that primly representing the gastric cancer related genes were selected using Random Forest classification and incremental feature selection. Random Forest classification was also used for the prediction of the novel gastric cancer related genes based on the selected features and the identification of novel prognostic genes based on the expression of genes.

RESULTS

Based on the shortest path analysis of 36 known GC genes, 39 genes occurring in shortest path were identified as GC-related genes. In subsequent classification, 4153 gene ontology terms and 157 pathway terms were identified as the optimal features to depict these gastric cancer related genes. Based on them, a total of 886 genes were predicted as related genes. These 886 genes could serve as expression biomarkers for clinical detection and they achieved a 100% accuracy for distinguishing gastric cancer from a case-control dataset, better than any of 886 random selected genes did.

CONCLUSION

By analyzing the features of known GC-related genes, we employed a systematic method to predict gastric cancer related genes and novel prognostic genes for accurate clinical detection.

Associations of Il-1 Family-Related Polymorphisms With Gastric Cancer Risk and the Role of Mir-197 In Il-1f5 Expression

To explore whether the roles of IL-1 family single nucleotide polymorphisms (SNPs) of the microRNA binding sites (miR-SNPs) in the 3' untranslated region (3'-UTR) of their target genes in the progression of gastric cancer (GC) and verify the relationship between miR-197 with chronic inflammatory gene-IL1-F5 by microRNA target prediction, a case-control study which consisted of 500 cases and 500 frequency-matched healthy controls was conducted. Single nucleotide polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or allele-specific PCR (AS-PCR). Association between SNPs and GC risk was evaluated by adjusted odds ratios (ORs) and 95% confidence intervals (CIs) in unconditional logistic regression analyses. Quantitative real-time (qRT) PCR assay and Western Blot analyses were performed to analyze the miR-197 expression and the IL1-F5 expression. The variant homozygote and heterozygote genotype of rs9005 in IL-1RN were significantly associated with increased risks of GC (ORadjusted [95%CI]: 1.71[1.04-2.81] and ORadjusted[95%CI]: 1.36 [1.04-1.78]). Compared with the wild heterozygote genotype, the variant heterozygote genotype of rs2472188 and rs2515401 in IL-1F5 polymorphisms were significantly associated with increased GC risks (ORadjusted [95%CI]: 1.51[1.15-1.99] and ORadjusted[95%CI]: 1.36[1.04-1.76]), but no significant differences existed in other 7 IL-1 family SNPs (rs2856836 in IL-1A, rs3732131 in IL-1R1, rs1135354 and rs3771157 in IL-18RA, rs3180235, rs957201 and rs2515402 in IL-1F5) with GC. The recombinant plasmid-pGenesil-1-miR-197 could upregulate the expression of miR-197 and downregulate the expression of IL-1F5 in human gastric cancer cell lines SGC-7901 and BGC-823 cells after transfection, and the miR-197 inhibitor could facilitate the expression of IL1-F5 after transfecting the same cell lines. These results suggested that SNPs in the IL-1 family genes play important roles in the development of GC and the IL-1F5 might be the target gene of miR-197, and miR-197 might negatively regulate its expression.

Genetic variation and gastric cancer risk: a field synopsis and meta-analysis

BACKGROUND

Data on genetic susceptibility to sporadic gastric carcinoma have been published at a growing pace, but to date no comprehensive overview and quantitative summary has been available.

METHODS

We conducted a systematic review and meta-analysis of the evidence on the association between DNA variation and risk of developing stomach cancer. To assess result credibility, summary evidence was graded according to the Venice criteria and false positive report probability (FPRP) was calculated to further validate result noteworthiness. Meta-analysis was also conducted for subgroups, which were defined by ethnicity (Asian vs Caucasian), tumour histology (intestinal vs diffuse), tumour site (cardia vs non-cardia) and Helicobacter pylori infection status (positive vs negative).

RESULTS

Literature search identified 824 eligible studies comprising 2 530 706 subjects (cases: 261 386 (10.3%)) and investigating 2841 polymorphisms involving 952 distinct genes. Overall, we performed 456 primary and subgroup meta-analyses on 156 variants involving 101 genes. We identified 11 variants significantly associated with disease risk and assessed to have a high level of summary evidence: MUC1 rs2070803 at 1q22 (diffuse carcinoma subgroup), MTX1 rs2075570 at 1q22 (diffuse), PSCA rs2294008 at 8q24.2 (non-cardia), PRKAA1 rs13361707 5p13 (non-cardia), PLCE1 rs2274223 10q23 (cardia), TGFBR2 rs3087465 3p22 (Asian), PKLR rs3762272 1q22 (diffuse), PSCA rs2976392 (intestinal), GSTP1 rs1695 11q13 (Asian), CASP8 rs3834129 2q33 (mixed) and TNF rs1799724 6p21.3 (mixed), with the first nine variants characterised by a low FPRP. We also identified polymorphisms with lower quality significant associations (n=110).

CONCLUSIONS

We have identified several high-quality biomarkers of gastric cancer susceptibility. These data will form the backbone of an annually updated online resource that will be integral to the study of gastric carcinoma genetics and may inform future screening programmes.