Milk Fat Globule-EGF Factor 8 is Required for Recovery of Pancreas From Cerulein-Induced Pancreatitis

Abstract

Gastric cancer (GC) is a male-predominant cancer associated with Helicobacter pylori (HP). Epidemiological studies suggest that female hormones reduce GC risk and our previous work demonstrated that ovariectomized female mice have increased GC risk. We examined the effect of 17 beta-estradiol (E2) on HP-induced gastric cancer in hypergastrinemic 8 week-old male and female INS-GAS mice inoculated with HP SS1 or vehicle-only. At 16 weeks post-infection (WPI), mice were treated with E2, Tamoxifen, E2 and Tamoxifen or placebo pellets for 12 weeks. Gastric histopathology was evaluated before and after treatment. At 28 WPI, stomachs were evaluated by HP quantitative culture, promoter CpG methylation of 24 tumor suppressors/oncogenes, and gene expression, and serum inflammatory cytokines measured by Luminex. At 16 WPI, HP infection induced robust gastric pathology in mice of both genders (P<0.001). After 12 weeks of E2 treatment, gastric pathology was significantly reduced in infected E2 males compared to infected placebo males (P<0.001). Tamoxifentreated and dual-treated infected males also showed reduction in gastric pathology compared to infected placebo males (both P<0.01) indicating that Tamoxifen may act agonistically in the stomach. In contrast, Tamoxifen treatment in females did not alter pathology in females. By microarray assessment, infected E2 males differentially expressed 412 probes compared to infected placebo males (Q<0.05). Cancer (115/412 probes) and inflammatory response (38/412) were among the top five differentially expressed biological functions using Ingenuity pathway analysis. Serum keratinocyte chemoattractant (KC) was decreased in infected E2 males and infected placebo females (P<0.05, P<0.001 respectively) compared to infected placebo males. Infected E2 males had significantly higher amounts of IL-6 and IL-10 compared to infected placebo males (P<0.01, P<0.05, respectively). MIP1a and MIP1b was significantly lower in infected placebo males compared to infected placebo females (both P<0.01) but these cytokines in infected E2 males did not differ from females. Both KC and MIP1a/b are strong neutrophil activators that were deregulated by E2 in infected males and trended toward the levels in infected females. IL-6 and IL-10 increased in infected E2 males to levels similar to that noted in infected females. Initial CpG methylation results indicate increased promoter methylation in 4 of 24 genes caused by HP infection in male mice. Studies are underway to elucidate the effect of E2 on methylation status. Our results demonstrate that E2 treatment can prevent the progression of HP-induced pathology by shifting the inflammatory response in males to one that resembles a female inflammatory response.