Fig. 7: H. pylori induces micronuclei but not apoptosis in gastric epithelial cells and its presence is associated with specific mutational patterns in gastric cancer.

a, b Micronuclei formation as quantified in binucleated AGS cells that had been subjected to cytochalasin B treatment to prevent cytokinesis, and had additionally been infected for 16 h with the indicated WT or RfaE mutant strains of H. pylori. Representative images are shown in a; arrows point to micronuclei. Frequencies of binucleated (BN) cells with micronuclei are quantified in b and pooled from three independent experiments. Data are presented as mean values +/− SEM. P-values were calculated by one-way ANOVA with Dunn’s multiple comparisons correction. Scale bar represents 15 μm. c, d Annexin V staining for apoptosis of AGS cells infected with WT H. pylori, or treated with 5 μm staurosporine (STA) for 6 or 24 h. Representative FACS plots are shown in c, and the quantification of Annexin V-positive cells of three independent experiments is shown in d. Data are presented as mean values +/− SEM. P-values were calculated by two-way ANOVA with Tukey’s multiple comparisons correction. e Mutational signature of H. pylori in gastric cancer as determined on 291 gastric cancer samples available through the Cancer Genome Atlas (TCGA). The H. pylori status was annotated based on the presence of at least one unambiguous H. pylori-specific read detected in the transcriptome, whole genome or exome of either the tumor or adjacent tissue of a total of 267 among the 291 patients. The gastric cancer subtype was assigned based on the previous description⁴² of CNVs, presence of EBV transcripts, methylation of signature genes and microsatellite instability; the color code on the right indicates the four subtypes chromosomally instable (CIN), microsatellite instable (MSI), EBV-positive (EBV), and genomically stable (GS). The heatmap shows the 232 genes found to be differentially mutated between H. pylori-positive and -negative cases (p < 0.05 as determined by Student’s t-test); the majority of differentially mutated genes are found in the MSI subtype. Genes are listed in Supplementary Table 1. ns, not significant; *p < 0.05, **p < 0.01.