Identification of Cellular Damage in Uteri From Hyperinsulinemic Mice Treated With Unopposed Estradiol

Unopposed estradiol and obesity are known risk factors for endometrial adenocarcinoma (EC). Endometrium from women with obesity was found to have an increase in mutations relative to tissue from normal weight women, indicating DNA damage may be accelerated in the setting of obesity. Since obesity is associated with high levels of insulin and anovulatory cycles, we sought to mimic these conditions in a mouse model. We previously found that hyperinsulinemic MKR mice, without the confounder of obesity, have an increased incidence of nuclear atypia in endometrial glands. We hypothesized that hyperinsulinemia and unopposed estradiol have a synergistic effect on inducing abnormal architecture and DNA damage in the endometrium, than either alone. At 8-10 weeks old, cohorts of MKR (n=20) and WT (n=20) mice underwent ovariectomy and placement of either an estradiol (E2) or placebo (P) pellet. Metabolic profiling included insulin tolerance testing and MR for body composition. At 3 months post-implantation, mice received a partial hysterectomy and second pellet replacement. At 6 months, the remaining uterus was bisected into pieces. A blinded histological analysis was conducted by a gynecology pathologist. A marker of DNA damage due to oxidative stress, 8-oxoguanine-DNA-glycosylase (8-OHdG), was quantified by ELISA. Data was analyzed using Kruskal-Wallis test with multiple test correction, or Fischer’s exact test. By 6 months, MKR-E2 treated mice had a 27% lower body weight than MKR-P mice (p