Transcriptional and microbial profile of gastric cancer patients infected with Epstein-Barr virusOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
The study profiled the transcriptional and microbial differences between Epstein-Barr virus (EBV) positive and EBV-negative gastric cancer. EBV is a recognized carcinogen linked to gastric carcinogenesis. Researchers sequenced tumor RNA on Illumina NextSeq, aligned reads to the human genome, and identified differentially expressed genes with DESeq2. Unaligned reads were classified with Kraken2 for the gastric microbiome. They also correlated genes with bacteria using Spearman analysis.
Who was studied?
The study used 41 stomach tumor tissue samples from patients with gastric adenocarcinoma at a university hospital in Belem, Brazil. Eight tumors were EBV-positive and 33 were EBV-negative. Patients ranged in age from 34 to 82 years, and most tumors were the intestinal Lauren subtype located in the noncardia stomach. None of the EBV-positive samples showed Helicobacter pylori co-infection. Each sample yielded roughly six million sequencing reads.
What were the most important findings?
EBV-positive tumors differed sharply in gene expression, with 117 upregulated and 202 downregulated genes. Upregulated genes centered on immune response, inflammation and complement activation, and functional analysis highlighted cytokine signaling, antigen presentation and Th17 responses. The gastric microbiome also shifted. EBV-positive samples had significantly lower diversity by Shannon (p equals 0.038) and Simpson (p equals 0.024) indices. Most bacterial genera declined in EBV-positive tumors, though a small subset was enriched. Overall community composition did not separate significantly (PERMANOVA p equals 0.141).
What are the greatest implications of this study?
The findings suggest EBV shapes both host gene expression and the gastric microbiota in gastric cancer. The virus appears to drive an inflammatory, immunomodulated tumor microenvironment while reducing bacterial diversity. Spearman analysis linked differentially abundant bacteria to genes for cell differentiation, cytokine production and cell death, hinting at host-microbe interplay. These are correlational results from a small cohort, so they identify candidate biomarkers and therapeutic targets rather than proving that microbial shifts cause cancer progression.