The Effect of Acute and Chronic Infection-Induced by AvrA Protein of Salmonella typhimurium on Radical Oxygen Species, Phosphatase and Tensin Homolog, and Cellular Homolog Expression During the Development of Colon Cancer

Abstract

AIM: The study aimed to analyze the effect of AvrA effector protein of Salmonella typhimurium in inducing colon cancer through increased of radical oxygen species (ROS), phosphatase and tensin homolog (PTEN), and avian myelocytomatosis virus oncogene cellular homolog (c-Myc) expression, in mice model of colorectal cancer. METHODS: This study used Balb/c mice which were divided into four types of groups: Negative control, exposed to azoxymethane (AOM), treatment with AOM, and AvrA (AOM+AvrA), and treatment with AOM and S. typhimurium (AOM + S. typhimurium). Each type consists of a 1-week treatment group and a 12-weeks treatment group, with a final number of eight groups. S. typhimurium-specific protein (AvrA) was isolated and then injected to AOM + AvrA groups (40 μg/50 μl), intraperitoneally. S. typhimurium was administered orally to AOM + S. typhimurium groups. ROS production in peripheral blood mononuclear cells was measured by flow cytometry. PTEN and c-Myc expression in colon tissue were detected through immunohistochemistry. RESULTS: The study showed that ROS production was higher in the 12-week AOM + S. typhimurium treatment group compared with other 12-week treatment groups (p < 0.05). AOM + AvrA and AOM + S. typhimurium groups demonstrated a decrease of PTEN expression and an increase of c-Myc expression in colon tissue, compared to AOM groups, both in 1-week and 12-weeks treatment (p < 0.05). CONCLUSION: AvrA effector protein from S. typhimurium increased ROS production and c-Myc expression while suppressed PTEN expression as markers of colorectal cancer, both in acute and chronic infections.