Project description:To efficiently identify genetic susceptibility variants for gastric cancer, including rare coding variants, we performed an exome chip-based array study. We found that a linkage disequilibrium (LD) block containing 2 significant variants in PSCA gene increased the risk and two blocks that included 15 suggested variants including TRIM31, TRIM 40, TRIM 10, and TRIM26 regions, and included one suggested variant and OR2H2 gene showed protective associations with gastric cancer susceptibility. In addition, the PLEC region (rs200893203), FBLN2 region (rs201192415), and EPHA2 region (rs3754334) were associated with increased susceptibility We performed an exome chip-based array study in 329 gastric cancer cases and 683 controls.
Project description:To efficiently identify genetic susceptibility variants for gastric cancer, including rare coding variants, we performed an exome chip-based array study. We found that a linkage disequilibrium (LD) block containing 2 significant variants in PSCA gene increased the risk and two blocks that included 15 suggested variants including TRIM31, TRIM 40, TRIM 10, and TRIM26 regions, and included one suggested variant and OR2H2 gene showed protective associations with gastric cancer susceptibility. In addition, the PLEC region (rs200893203), FBLN2 region (rs201192415), and EPHA2 region (rs3754334) were associated with increased susceptibility
Project description:Deregulated gene expression is a hallmark of cancer, however most studies to date have analyzed short-read RNA-sequencing data with inherent limitations. Here, we combine PacBio long-read isoform sequencing (Iso-Seq) and Illumina paired-end short read RNA sequencing to comprehensively survey the transcriptome of gastric cancer (GC), a leading cause of global cancer mortality. We performed full-length transcriptome analysis across 10 GC cell lines covering four major GC molecular subtypes (chromosomal unstable, Epstein-Barr positive, genome stable and microsatellite unstable). We identify 60,239 non-redundant full-length transcripts, of which >66% are novel compared to current transcriptome databases. Novel isoforms are more likely to be cell-line and subtype specific, expressed at lower levels with larger number of exons, with longer isoform/coding sequence lengths. Most novel isoforms utilize an alternate first exon, and compared to other alternative splicing categories are expressed at higher levels and exhibit higher variability. Collectively, we observe alternate promoter usage in 25% of detected genes, with the majority (84.2%) of known/novel promoter pairs exhibiting potential changes in their coding sequences. Mapping these alternate promoters to TCGA GC samples, we identify several cancer-associated isoforms, including novel variants of oncogenes. Tumor-specific transcript isoforms tend to alter protein coding sequences to a larger extent than other isoforms. Analysis of outcome data suggests that novel isoforms may impart additional prognostic information. Our results provide a rich resource of full-length transcriptome data for deeper studies of GC and other gastrointestinal malignancies.
Project description:We leveraged massively parallel sequencing approach to comprehensively characterize the spectrum of somatic mutations and genomic rearrangements in two intestinal-type gastric adenocarcinomas from patients with and without active Helicobacter pylori infections. The tumours exhibited distinct patterns of genomic changes with more than 16,000 somatic substitutions on average, focal amplifications and rearrangements in the non-active infected tumour and a 7-fold enrichment of micro-deletions in the infected tumour. Paired-end sequences from large insert libraries revealed the structure and origins of large amplicons, including one involving the oncogene KRAS. The mutational frequencies of the tumours revealed patterns of H. pylori infection and mutagenesis and a unique exome signature, providing insights into mechanisms that define the mutational landscape of gastric cancer. For the tumour with active infection, we also reconstructed the genome of the pathogenic H. pylori strain from the raw sequence reads, demonstrating the power of whole-genome shotgun sequencing for simultaneously characterizing the tumour and its associated carcinogen genome.