Abstract 5540: Crosstalk between Wnt and AMPK pathway in Asian gastric cancer by metformin.
Authors: Chang Hae Ryung , Nam Seungyoon , Jung Hae Rim , Kwon ChangHyuk , Seo Hye-Hyun , Sung Frances S. , Park Hee Seo , Park Taesung , Kim Yon Hui 
Published: August 2014

Stomach cancer is the most prevalent cancer in Eastern Asia(1). Given the diverse route to oncognesis, it is highly attractive to develop targeted therapy based on each patient's biology(2). Several molecular targeting agents that show survival advantage in other cancer types are being under clinical investigation in gastric cancer (GC) (3-6). These agents focus on a few known oncogenic genes, yet its true efficacy of their biologically targeted therapies in gastric cancer is still unknown. To identify high-quality therapeutic targets, we utilized PATHOME (pathway and genome information), a computational method to identify therapeutic target through sub-pathway employing simple statistic-based approach (unpublished).

PATHOME design had two stages: 1) discovery stage aimed at selecting target signaling pathway, and 2) validation stage aimed at identifying small number of reproducible genes from sub-pathways by using independent dataset to provide a novel theragnostic strategy in GC patients. Four sets of GEO database datasets were used: GSE13861 (84 Korean GC), GSE15081 (56 Japanese GC) for the discovery stage, and GSE36968 (25 Korean GC), and GSE27342 (160 Chinese GC) were added for validation. Using Vogelstein et al. as the gold standard, DAVID and GSEA vs. PATHOME were applied for comparison of potency in prediction of signaling pathways(7). Previous study showed that the energy sensing mechanism by AMPKα is involved in Asian GC(8). Metformin is a drug used to treat diabetes, which affects AMPKα in the cell. We treated GC cell line with metformin and saw the expression level of proteins that were selected by PATHOME to test its predictability of biological context.

13 up-regulated genes were identified using 3 datasets (GSE 13861, GSE 15081 and GSE36968), and 5 (GENE1, GENE2, GENE3, GENE4 and GENE5) from all 4 datasets using PATHOME. Transcription factor binding site analysis showed that two of the 5 genes contained GENE6 binding sites. Implications of AMPKα as a potential therapeutic target has been published(9). Metformin is shown to increase PRKAA2 level, which encodes AMPKα, also inhibits HNF4α(8). To see if metformin has any effect on the genes with HNF4α binding site, we observed the expression level of GENE4 and related proteins. Metformin treated GC cell lines (NCI-N87 and AGS) result in decreased viability compared to untreated cells. On Western-blot analysis, metformin treated cells show a decrease of GENE4, GENE6, but not GENE7 or GENE8.

Utilizing PATHOME, which showed greater consistency compared to DAVID and GSEA in terms of cancer-related pathways, we showed Wnt pathway to have a potential impact on GC in East Asia. Therefore, our approach has simplified insight of multiplexed signals apply in molecular targeted therapies. We report a cross-talk between AMPKα and Wnt pathway in gastric cancer, which is known to be involved in other cancer types. This finding will lead to other potential drug targets for GC.

Citation Format: Hae Ryung Chang, Seungyoon Nam, Hae Rim Jung, ChangHyuk Kwon, Hye-Hyun Seo, Frances S. Sung, Hee Seo Park, Taesung Park, Yon Hui Kim. Crosstalk between Wnt and AMPK pathway in Asian gastric cancer by metformin. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5540. doi:10.1158/1538-7445.AM2013-5540