Biomarkers for personalized medicine in GI cancers

Identification of the RP11-21C4.1/SVEP1 gene pair associated with FAT2 mutations as a potential biomarker in gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide. Despite rapid advances in systemic therapy, GC remains the third leading cause of cancer-related deaths. We aimed to identify a novel prognostic signature associated with FAT2 mutations in GC. We analyzed the expression levels of FAT2-mutant and FAT2-wildtype GC samples obtained from The Cancer Genome Atlas (TCGA). The Kaplan–Meier survival curve showed that patients with FAT2 mutations showed better prognosis than those without the mutation. Sixteen long non-coding RNAs (lncRNAs) and 62 messenger RNAs (mRNAs) associated with FAT2 mutations were correlated with the prognosis of GC. We then constructed a 4-mRNA signature and a 5-lncRNA signature for GC. Finally, we identified the most relevant RP11-21 C4.1/SVEP1 gene pair as a prognostic signature of GC that exhibited superior predictive performance in comparison with the 4-mRNA or 5-lncRNA signature by weighted gene correlation network analysis (WGCNA) and Cox proportional hazards regression analysis. In this study, we constructed a prognostic signature of GC by integrative genomics analysis, which also provided insights into the molecular mechanisms linked to FAT2 mutations in GC.

Chromosomal instability of circulating tumor DNA reflect therapeutic responses in advanced gastric cancer

Gastric cancer is characterized by chromosomal instability. In this study, we investigated chromosomal instability quantified by copy number instability (CNI) score of circulating tumor DNA (ctDNA) during the drug treatment in advanced gastric cancer (AGC). A total of 55 pretherapeutic plasmas from 55 AGC patients and 75 plasmas during drug treatment of 26 AGC patients were collected. Plasma ctDNA was extracted and assessed by whole-genome sequencing (WGS) for somatic copy number alteration (SCNA), and according to which we calculated the CNI scores. We next assessed the correlations between chromosomal instability and therapeutic response. The cutoff value of chromosomal instability was defined as the mean + SD of the CNI scores (56.60) in cfDNA of plasmas from 100 healthy people. For 55 enrolled cases, chromosomal instability was observed in 27 (49%) prior to drug treatment, whose response rate (59%, 16/27) was higher than in 28 patients with stable chromosomes (32%, 9/28, P = 0.043). We also observed that CNI scores fluctuated during treatment in 26 patients. Specifically, the CNI scores in 93% (14/15) of patients sensitive to drug treatment reduced to the level of chromosomal stability and the CNI scores in 52% (13/25) of patients resistant to treatment elevated again. For ctDNA with developed resistance, the SCNA patterns were identical to those before treatment, whereas the CNI scores were lower than the pretherapeutic scores. We found that chromosomal instability based on ctDNA could predict and monitor therapeutic response in gastric cancer, although validation in a larger cohort will be necessary.

Elevated limb-bud and heart development (LBH) expression indicates poor prognosis and promotes gastric cancer cell proliferation and invasion via upregulating Integrin/FAK/Akt pathway

The limb-bud and heart development (LBH) gene is a highly conserved, tissue-specific transcription cofactor in vertebrates that regulates multiple key genes in embryonic development. The role of LBH in various cancer types is still controversial, and its specific role and molecular mechanism in the oncogenesis of gastric cancer (GC) remains largely unexplored. In the present study, the prognostic significance and clinicopathological characteristics of LBH in GC was determined. The LBH mRNA expression was first investigated in four independent public datasets (TCGA-STAD, GSE15459, GSE29272, and GSE62254) and then validated with our samples at the protein level. LBH was overexpressed at both the mRNA and protein levels in cancer compared with normal tissues. High LBH expression was correlated with advanced T, N, and M stages. Kaplan–Meier analysis and log-rank test indicated that higher LBH expression was statistically correlated with shorter overall survival (OS) in the public datasets and our study samples. Univariate and multivariate Cox regression analysis showed that LBH was an independent prognostic biomarker for survival in TCGA-STAD, GSE15459, GSE62254 cohorts, and our GC patients. In vitro experiments showed that knockdown of LBH can significantly inhibit the proliferation and invasion of HGC-27 cells, while overexpression of LBH can significantly enhance the proliferation and invasion of BGC-823 cells. Gene Set Enrichment Analysis (GSEA), Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomics (KEGG) indicated that high LBH expression is associated with the PI3K-Akt pathway, focal adhesion, and extracellular matrix (ECM)-receptor interaction. Western blot analysis showed that knockdown of LBH significantly inhibited the expression of integrin α5, integrin β1, p-FAK, and p-Akt. Therefore, results from the present study indicate that LBH is a potential independent prognostic biomarker and promotes proliferation and invasion of GC cells by activating the integrin/FAK/Akt pathway.

Gastric carcinoma in canines and humans, a review

Gastric carcinoma (GC) is the most common neoplasm in the stomach of dogs. Although incidence in the general population is reported to be low, breed-specific GC has a high incidence. Median age at presentation ranges from 8 to approximately 10 years. The disease is mostly located in the lesser curvature and antropyloric region of the stomach. Unfortunately, diagnosis is usually made when the disease is at an advanced stage and, therefore, prognosis is poor. Due to similarities in clinical presentation, diagnosis, histology and prognosis, canine GC may serve as a valuable model for human GC. Extensive pedigrees of canine gastric carcinoma cases could reveal insights for human gastric carcinoma. Putative species differences include the role of Helicobacter in pathogenesis, the wide array of genetic data and screening available for humans, and treatment protocols that are available for human GC.

Function analysis of rs9589207 polymorphism in miR-92a in gastric cancer

MiR-92a was identified as an essential oncogene by promoting the cell proliferation through FBXW7 in gastric cancer (GC). The function of the single nucleotide polymorphism (SNP) located in the mature region of miR-92a (rs9589207) has not been investigated. We found that rs9589207 in miR-92a was involved in the occurrence of GC by acting as a tumor protective factor and was highly associated with tumor size in GC patients instead of tumor number or metastasis in 554 GC patients and 531 cancer-free controls. Besides, the AA genotype in miR-92a could attenuate the promoting function of miR-92a in cell proliferation with an incapacitation in downregulating the expression of FBXW7. In conclusion, rs9589207 in miR-92a was highly associated with a decreased risk of GC in Chinese Han population and might serve as a novel biomarker for the disease.