Abstract 2593: Racially diverse primary esophageal cell cultures for evaluating mitigation of bile-induced injury

Abstract

Persistent and symptomatic reflux of gastric and duodenal contents, known as gastroesophageal reflux disease (GERD), is the strongest risk factor for EAC development. GERD and esophagitis occur at similar rates among Blacks and Caucasians; yet, progression to EAC is significantly elevated among Caucasians. Unique protective factors in the epithelium of Blacks may contribute to this disparity. Our research team recently reported that the detoxification enzyme GSTT2 is higher in the esophageal squamous epithelium of Blacks compared to Caucasians with potential linkages to previously identified genomic variants in the GSTT2 locus (a 37 kb deletion and a 17 bp promoter duplication among Caucasians). Thus, the current study seeks to evaluate whether primary esophageal cell cultures isolated from Black or Caucasian cohorts can serve as discerning and relevant model systems to investigate risk factors linked to EAC progression, assess efficacy of mitigating agents and differential responses linked to race. We have shown that cranberry proanthocyanidins (C-PAC) mitigate DNA damage associated with reflux through upregulation of GSTT2 in a rat surgical model of reflux-induced EAC, but whether effects are recapitulated in humans or differentially based on race remains unknown. Herein we isolated normal primary esophageal epithelial cells from Black and Caucasian patients and assessed GSTT2 genotype, GSTT2 protein levels and cellular viability following exposure of the cultures to a bile acid cocktail (BAC) [0.2mM] with and without C-PAC [50µg/ml] treatment. Constitutive levels of GSTT2 were 1.7-fold higher in Blacks than Caucasians, with 71% of Blacks identified as high expressors compared to 33% of Caucasians. Pretreatment (48h) of primary cultures with C-PAC induced GSTT2 levels in all but one Black-derived culture which already expressed high basal levels. GSTT2 induction in normal epithelial cultures by C-PAC was greatest in cells with constitutively low GSTT2 expression; however, upon BAC challenge C-PAC effectively mitigated BAC-induced reductions in GSTT2 levels and subsequent loss of normal cell viability regardless of basal GSTT2 expression or race. C-PAC treatment pre- plus post-BAC imparted no additional benefit over pretreatment alone in preserving viability but did further increase GSTT2 levels. Next steps include expanding our panel of primary cultures and conducting nano LC-MS/MS proteomic profiling of Black and Caucasian-derived cultures treated with vehicle, BAC, C-PAC and BAC + C-PAC, with stratification based on GSTT2 basal expression. Taken together these data support that C-PAC may be used as an efficacious non-toxic agent serving to promote epithelial fitness and resiliency against the biologic and molecular sequelae linked bile acid-induced esophageal injury and progression to EAC. Citation Format: Katherine M. Weh, Danielle K. Turgeon, Amy Howell, Laura A. Kresty. Racially diverse primary esophageal cell cultures for evaluating mitigation of bile-induced injury [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2593.