Abstract LB-328: Loss of TFF1 leads to activation of RAGE in mouse and human gastric tumorigenesis
Authors: Bhat Nadeem S. , Soutto Mohammed , Chen Zheng , Zhu Shoumin , Naz Huma , Gomaa Ahmed , Wang Sen , Hudson Barry I. , Wael El-Rifai 
Published: August 2019

Abstract
Background: The receptor for advanced glycation end products (RAGE) is a central signaling molecule in the innate immune system and is highly expressed in various cancers including gastric cancer. RAGE is a pattern recognition receptor that binds to multiple ligands leading to its activation and onset of pro-inflammatory response. Trefoil factor 1 (TFF1) is a small secreted protein expressed in the gastrointestinal tract which plays a key role in protection of gastric mucosal membrane and provides protection from injury and damage, therefore acts as tumor suppressor gene. In this study we investigated the role of TFF1 in regulation and degradation of RAGE receptor in vivo and in vitro.
Material and Results: Using quantitative real-time PCR, we observed significant increase of RAGE expression in gastric tissue from Tff1 knockout from non-dysplastic lesion; this increase of expression of RAGE was more notable in dysplastic samples, as compared to normal tissues (p&lt;0.001). The Tff1-KO mice tissues with gastritis and low grade dysplasia (LGD) and high grade dysplasia (HGD) showed significantly progressive higher expression of RAGE, as compared to normal tissues (p&lt;0.001). Analysis of human tissue samples demonstrated significant overexpression of RAGE, as compared to normal gastric tissues (p=0.01). Furthermore, we analyzed paired tumor and normal samples, and we found a significant up-regulation of RAGE mRNA expression in tumors compared to their corresponding normal samples (p=0.01). We also detected an inverse relationship between TFF1 and RAGE levels in mouse and human tissue samples. We next determined the levels of RAGE ligands, S100A2 and A4. The results showed significant increase in expression levels of S100A2 and A4 in human and mouse neoplastic gastric lesions, as compared to normal tissue samples (P&lt;.01). To determine a causal relationship between TFF1 and RAGE, we used in vitro cell models. Using Western blot and RT-PCR analysis, the reconstitution of TFF1 in AGS cells showed a decrease in expression levels of RAGE, S100A2, and A4, as compared to control cells. Treatment of cancer cell lines (AGS, MKN28, and MKN45) with RAGE inhibitor Azeliragon led to significant reduction in cell viability with IC50 range AGS= 1.65µM, MKN28=1.22µM, MKN45= 1.37µM .
Conclusion: Our data demonstrate, for the first time, that high levels of RAGE and its ligands S100A2 and A4 are mechanistically related to TFF1 levels. RAGE inhibitors demonstrated a therapeutic efficacy in pre-clinical in vitro models. Additional in vitro and in vivo studies are planned to determine the functional, mechanistic and therapeutic outcomes of RAGE in gastric tumorigenesis.
Citation Format: Nadeem S. Bhat, Mohammed Soutto, Zheng Chen, Shoumin Zhu, Huma Naz, Ahmed Gomaa, Sen Wang, Barry I. Hudson, El-Rifai Wael. Loss of TFF1 leads to activation of RAGE in mouse and human gastric tumorigenesis [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 LB-328.