Abstract 5150: Adipose-derived stem cell disruption of gap junction intercellular communication in obesity-associated endometrial cancer
Authors: Lin Li-Ling , Polusani Srikanth , Huang Guangcun , Lin Chun-Lin , Wang Chiou-Miin , Lucio Nicholas , Kolonin Mikhail , Daquinag Alexes , Osmulski Pawel , Nicholson Bruce , Kost Edward , Huang Tim , Kirma Nameer B. 
Published: August 2019

Abstract
Endometrial cancer is the most common gynecologic cancer. It is divided into two major types, a less aggressive endometrioid type and a more aggressive serous type. Recent clinical observations underscore obesity as a major risk factor for endometrial cancer. In this study, we hypothesized that obesity can result in long term epigenetic modifications in the endometrial compartment, leading to the promotion of endometrial cancer. We examined the role of adipose-derived stem cells (ASCs), which are adipocyte progenitors, in the endometrial tumor microenvironment. By staining for ASCs in a tumor tissue microarray, we observed ASC infiltration that was specific to samples from obese patients, correlating with body mass index (R2=0.77, p&lt;0.001). Using a co-culture system to simulate ASC microenvironmental effects and transcriptomic analysis, we showed that exposure of immortalized endometrial epithelial cells (EECs) to ASC secreted factors led to the repression of cell-cell communication pathways, most notably gap junctions and related factors tight junction proteins TJP and PKC genes. This gene repression was associated with induction of DNA Methylation in the promoter of the major GJ gene GJA1 (encoding connexin 43, Cx43) in the ASC-exposed EECs. Importantly, we further demonstrated this DNA hypermethylation in the promoters of the GJA1, TJP2 and PKC genes in primary endometrial tumors from obese patients compared to non-obese patients. We assessed the effects of epigenetic regulation on gap junction intercellular communication (GJIC) and cell-cell interactions using cellular calcein dye transfer assays and atomic force microscopy (for nano-scale assessment of cell-cell adhesion) by treating endometrial cancer cells with a demethylating agent (DAC). DAC treatment resulted in increased level of cell-cell adhesiveness and communication via gap junction coupling. Specific reactivation of GJA1 (Cx43) by expression vector in endometrial cancer cells led to decreased cellular motility. Because we found that PAI-1 is a major adipokine in the ASC secretome, inhibition of PAI-1 in ASC-exposed EECs led to a cell population expression profile with lower GJ expression, based on single-cell PCR studies. Collectively, the data demonstrate multi-scale regulation of cellular communication via paracrine actions and direct cell-cell coupling via gap junctions by epigenetic silencing influenced by ASCs. This leads to disruption of cellular homeostasis and enhanced motility, promoting endometrial cancer in obese patients.
Citation Format: Li-Ling Lin, Srikanth Polusani, Guangcun Huang, Chun-Lin Lin, Chiou-Miin Wang, Nicholas Lucio, Mikhail Kolonin, Alexes Daquinag, Pawel Osmulski, Bruce Nicholson, Edward Kost, Tim Huang, Nameer B. Kirma. Adipose-derived stem cell disruption of gap junction intercellular communication in obesity-associated endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5150.