Abstract 4236: Obesity-associated endometrial cancer: Identifying the contributions of TMEM205 expression to the pathogenesis of disease
Authors: Sakaue Takahiko , Zingarelli Roman , Khadraoui Wafa , Saini Uksha , Wallbillich John , Anbazhakan Muralidharan , Warner Ross , Dorayappan Kalpana Deepa Priya , Kalaiyarasan Deepika , Morton Molly , Cosgrove Casey , Suarez Adrian , Maxwell Larry J. , O'Malley David , Cohn David E. , Selvendiran Karuppaiyah 
Published: April 2023

Background & Objective: Endometrial cancer (EC) is the most common gynecologic malignancy in the US. EC is more strongly associated with obesity than any other cancer type, with 57% of cases linked to obesity. As rates of obesity increase, the incidence of EC is also rising with worsening prognosis. The objective of this study is to identify the molecular mechanisms of TMEM205 expression that regulate exosome secretion, and the oncogenic proteins that underlie this transformation. Our findings are critical to understanding the pathways of obesity mediated EC and essential for developing novel strategies for preventing and treating EC.

Methods: The exosomes were then quantified using nanoparticle tracking analyzer (NTA) and their size measured by Transmission electron microscopy (TEM). TMEM205, STAT5, FAS and PIAS3 expression was confirmed by IHC, WB and RT-PCR in patient and high fat diet treated mouse tissue. Endometrial hyperplasia was developed in immunocompetent mice using high fat diet (HFD; 45 kcal% fat diet) for 16 weeks.

Results: To examine the effect of a continuous HFD (45 kcal% fat diet) on adipose, uterine and endometrial tissue, we first investigated body weight and uterine morphology in mice after 24 weeks of treatment. As expected, mice fed a HFD had a significantly higher body weight and increased adipose tissue when compared to control. In addition, mice in the HFD group showed marked enlargement in uterine horn size (hyperplasia) and inflammation with increased cell proliferation in the endometrial layer. The HFD treated mice were associated with increased exosome secretion and expression of the oncogenic proteins TMEM205 and STAT5. Expression of the tumor suppressor gene PIAS3 wasdownregulated in adipose and uterine tissues. L-2265 is a small molecule inhibitor that selectively inhibits TMEM205 and exosome secretion in EC cancer cells. To examine the effect of L-2263 in the context of obesity, we fed mice a HFD and treatment with L-2263 (2mg/kg/) weekly for 3 doses. L-2263 treatment resulted in significantly decreased body weight (BW) and decreased accumulation of adipose tissue relative to control HFD treated mice. Mice in the HFD group showed marked enlargement in uterine horn size (hyperplasia), whereas mice that received L-2263 treatment had normal uterine morphology of mouse age. L-2263 treated mice also demonstrated a significant decrease in the expression of proteins involved in exosome secretion (e.g., TMEM205 and STAT5) and those found in exosomes.

Conclusion: This study provides fundamental insight into the mechanism of obesity-mediated TMEM205 expression and exosome secretion and their contribution to the pathogenesis of EC. This study is also provides pre-clinical evidence for the development of the first in-human studies of exosome-targeted therapies to prevent obesity-mediated EC.

Citation Format: Takahiko Sakaue, Roman Zingarelli, Wafa Khadraoui, Uksha Saini, John Wallbillich, Muralidharan Anbazhakan, Ross Warner, Kalpana Deepa Priya Dorayappan, Deepika Kalaiyarasan, Molly Morton, Casey Cosgrove, Adrian Suarez, Larry J. Maxwell, David O'Malley, David E. Cohn, Karuppaiyah Selvendiran. Obesity-associated endometrial cancer: Identifying the contributions of TMEM205 expression to the pathogenesis of disease. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4236.