Abstract 1730: Unraveling the oncogenic potential of KDM2A with gastric organoids
Authors: Dhar Shilpa S. , Brown Calena , Zod Constantin , Ajani Jaffer A. , Lee Min Gyu 
Published: March 2024

Abstract
Background: Gastric adenocarcinoma (GAC), prevalent and often lethal, imposes a serious global health challenge. Therefore, it is critical to identify novel oncogenes (drivers) that can be therapeutically targeted. Of epigenetic modifications, histone lysine methylation is a hallmark of epigenetic and transcriptional regulation of gene expression. Therefore, investigating the involvement of histone methylation modifiers in GAC is paramount to gaining a comprehensive understanding of the disease but also to discover novel targets. Our analysis of the GAC genome indicates that these epigenetic modifiers are amplified in GAC.
Objective and Hypothesis: The overall objective is to define the oncogenic role of KDM2A in GAC pathogenesis and progression. The central hypothesis is that KDM2A promotes GAC by upregulating the expression of oncogenic proteins via the activation of epigenomic signatures/pathways.KDM2A (FBXL11) is a histone lysine demethylase that demethylates H3K36me2 and represses target genes involved in various biological processes, including cell proliferation, DNA damage repair, and stem cell maintenance. Previously, we reported that KDM2A was necessary for the tumorigenic and metastatic capabilities of non-small lung cancer cells through transcriptionally repressing the expression of DUSP3 and HDAC3, which led to activation of ERK signaling and upregulation of cell cycle-associated genes.
Results: Our analysis of the GAC genome indicates that KDM2A is one of the top demethylases frequently amplified and overexpressed (14%). In addition, KDM2A expression was significantly higher in GAC samples than in normal tissues, and high expression of KDM2A was associated with poor survival in GAC patients. To examine the effect of KDM2A knockdown on characteristics of GAC, we used gastric organoids generated from KDM2Aflox/flox mouse stomach. We expressed wild-type (Flag-KDM2A) and catalytic mutant (Flag-KDM2A-mut) in these organoids. Ectopic expression of KDM2A wild-type, but not mutant, increased the proliferation of organoids. We showed that KDM2A knockdown decreased the proliferation and invasion of two GAC cells, GA0518 and AGS. In addition, we determine the effect of overexpression of KDM2A on cell proliferation by comparing the control organoids to KDM2A overexpressed using IHC staining of Ki-67 (a proliferation marker) and other activated oncogenic signaling PI3KCA/mTOR/AKT, EGFR. We showed that GA5018 cells were very sensitive to the KDM2A inhibitor (daminozide) alone and in combination with erlotinib (EGFRi inhibitor) and RAD001 (RAD1 mTOR inhibitor).
Significance and Innovation: In contrast to advances in cellular signaling pathways in GAC pathogenesis, how GAC development is epigenetically regulated remains largely unknown. Our results from using organoids indicate that KDM2A is an oncoprotein.
Citation Format: Shilpa S. Dhar, Calena Brown, Constantin Zod, Jaffer A. Ajani, Min Gyu Lee. Unraveling the oncogenic potential of KDM2A with gastric organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1730.