Helicobacter pylori infection combined with DENA revealed altered expression of p53 and 14-3-3 isoforms in Gulo−/− mice

Unlike most other mammals, human bodies do not have the ability to synthesize vitamin C inside of their own bodies. Therefore, humans must obtain vitamin C through daily diet. Gulo−/− mice strain is known with deficiency, in which vitamin C intake can be controlled by diet like human, and would be valuable for investigating the molecular mechanism of various diseases. In the present study, we established Gulo−/− mice model and investigated the differentially expressed proteins in stomach tissue of Gulo−/− mice after Helicobacter pylori-infected, and followed by DENA, using immunohistochemistry and proteomic approach. The results of immunohistochemistry analysis of stomach tissue showed that the tumor suppressor, p53 protein, expression was significantly decreased (p < 0.05) but not messenger RNA (mRNA) transcriptional level, and 14-3-3ε, 14-3-3δ, Ki-67 and cleaved caspase 3 expressions were significantly increased (p < 0.05) by H. Pylori infection, and followed by DENA treatment in Gulo−/− mice. Moreover, knockdown of 14-3-3 isoforms (14-3-3ε, 14-3-3σ, 14-3-3ζ and 14-3-3η) were significantly increased sub-G1 phase (characteristics of apoptosis) in AGS cells and, phenotypic changes like cell shrinkage, density and cleaved nuclei were also observed. Proteome analyses showed that 14-3-3σ, 14-3-3η, and tropomyosin alpha-1 chain were down-regulated, and Hspd1 protein and HSC70 were up-regulated after H. Pylori-infection, and followed by DENA. The combined results of immunohistochemistry and proteomic analysis suggest that H. pylori altered the p53 and 14-3-3 isoforms expression and DENA further enhanced the H. pylori effect, which might be involved in carcinogenesis and metastasis of gastric cancer on Gulo−/− mice.