Evidence for heightened genetic instability in precancerous spasmolytic polypeptide expressing gastric glands

BackgroundSpasmolytic polypeptide-expressing metaplasia (SPEM) is present in more than 90% of resected gastric cancer tissues. However, although widely regarded as a pre-cancerous tissue, its genetic characteristics have not been well studied.MethodsImmunohistochemistry using Trefoil factor 2 (TFF2) antibodies was used to identify TFF2-positive SPEM cells within SPEM glands in the stomach of Helicobacter felis (H. felis) -infected mice and human clinical samples. Laser microdissection was used to isolate specific cells from both the infected mice and the human samples. The genetic instability in these cells was examined by measuring the lengths of microsatellite (MS) markers using capillary electrophoresis. Also, genome-wide genetic variations in the SPEM cells from the clinical sample was examined using deep whole-exome sequencing.ResultsSPEM cells indeed exhibit not only heightened MS instability (MSI), but also genetic instabilities that extend genome-wide. Furthermore, surprisingly, we found that morphologically normal, TFF2-negative cells also contain a comparable degree of genomic instabilities as the co-resident SPEM cells within the SPEM glands.ConclusionThese results, for the first time, clearly establish elevated genetic instability as a critical property of SPEM glands, which may provide a greater possibility for malignant clone selection. More importantly, these results indicate that SPEM cells may not be the sole origin of carcinogenesis in the stomach and strongly suggest the common progenitor of these cells, the stem cells, as the source of these genetic instabilities, and thus, potential key players in carcinogenesis.

Loss of Trefoil Factor 2 Sensitizes Rat Pups to Systemic Infection with the Neonatal PathogenEscherichia coliK1

ABSTRACTGastrointestinal (GI) colonization of 2-day-old (P2) rat pups withEscherichia coliK1 results in translocation of the colonizing bacteria across the small intestine, bacteremia, and invasion of the meninges, with animals frequently succumbing to lethal infection. Infection, but not colonization, is strongly age dependent; pups become progressively less susceptible to infection over the P2-to-P9 period. Colonization leads to strong downregulation of the gene encoding trefoil factor 2 (Tff2), preventing maturation of the protective mucus barrier in the small intestine. Trefoil factors promote mucosal homeostasis. We investigated the contribution of Tff2 to protection of the neonatal rat fromE. coliK1 bacteremia and tissue invasion. Deletion oftff2, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9, sensitized P9 pups toE. coliK1 bacteremia. There were no differences betweentff2−/−homozygotes and the wild type with regard to the dynamics of GI colonization. Loss of the capacity to elaborate Tff2 did not impact GI tract integrity or the thickness of the small-intestinal mucus layer but, in contrast to P9 wild-type pups, enabledE. coliK1 bacteria to gain access to epithelial surfaces in the distal region of the small intestine and exploit an intracellular route across the epithelial monolayer to enter the blood circulation via the mesenteric lymphatic system. Although primarily associated with the mammalian gastric mucosa, we conclude that loss of Tff2 in the developing neonatal small intestine enables the opportunistic neonatal pathogenE. coliK1 to enter the compromised mucus layer in the distal small intestine prior to systemic invasion and infection.