Abstract Endometrial carcinoma exhibits the strongest association with obesity of any cancer. Tumor growth is driven by PI3K/AKT activation, and opposed by tumor suppressors, including the tuberous sclerosis complex (TSC) and p27, with inactivation of TSC2 and loss of cytoplasmic misloclization of p27 both being linked to PI3K/AKT signaling. However, little is known about the involvement of p27 in the development of endometrial carcinoma arising in the setting of obesity, expecially its role in early disease progression. We found that p27 was moderatley-to-severely reduced in both “normal” endometrial glands as well as endometrial hyperplasia of obese women. Obese Tsc-2-deficient Eker rats similarly developed endometrial hyperplasia with a high frequency and short latency, and like obese women, endometrial hyperplasia that developed in obese rats exhibited loss of p27. In Eker rats, even a short duration of caloric restriction (2-4 months of age) reduced weight, increased adiponectin and lowered leptin to produce favorable leptin:adiponectin ratio, and reduced circulating insulin levels. Caloric restriction also increased p27 levels, primarily in the nucleus, and significantly decreased endometrial hyperplasia incidence by up to 50%. These data demonstrate that in the setting of obesity, loss of p27 occurs very early in progression to carcinoma. Importantly, p27 can be modulated along with weight by diet, and perhaps other lifestyle interventions that decrease risk for development of carcinoma, suggesting it may be a useful biomarker, and possible determinant of risk for endometrial carcinoma in the setting of obesity. Citation Format: Adrienne S. McCampbell, Megan L. Mittlestedt, Ruhee Dere, Lijun Zhou, Bojana Djordjevic, Pamela T. Soliman, Qian Zhang, Caimiao Wei, Stephen D. Hursting, Karen H. Lu, Cheryl L. Walker, Russell R. Broaddus. p27 as a biomarker and determinant of risk for endometrial carcinoma arising in the setting of obesity. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4102. doi:10.1158/1538-7445.AM2014-4102
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