Abstract 6140: Caspase-3 mediated cleavage of GSDME enhances the antitumor efficacy of HER2-targeted therapy in HER2-positive gastric cancer
Authors: Luo Qiuyun , Xia Zengfei , Yang Jing , Pan Wentao , Luo Fan , Cao Jiaxin , Sun Yuting , Yang Liqiong , Zhang Lin , Qiu Miaozhen , Yang Dajun 
Published: April 2023

Abstract
Background: Gasdermin E (GSDME) is one of the gasdermin family proteins, which induces a new type of programmed cell death - pyroptosis after cleavage by caspase-3. Previous researches have shown that the overexpression of GSDMB, another gasdermin family protein, is associated with poor prognosis in HER2 breast cancer and attributed to HER2-targeted therapy resistance through mediating protective autophagy. However, the role of GSDME in the anti-HER2 treatment of HER2-positive gastric cancer remains unclear. In this study, we sought to explore the function of GSDME in response to anti-HER2 treatment of HER2-positive gastric cancer and investigate the combination treatment strategies.
Methods: GSDME overexpressed vector and siRNA interference were applied to evaluate the function of GSDME in HER2-positive gastric cancer. The correlation between the expression of GSDME and survival in HER2-positive and negative gastric cancer was analyzed in the Kaplan Meier plotter database. Flow cytometry, LDH release assay and western blotting were used to determine apoptosis and pyroptosis. Moreover, the phospho-tyrosine kinase array was applied to explore the synergistic mechanism of combination therapy. GSDME overexpressed NCI-N87 xenograft model was established to evaluate the synergistic antitumor effect in vivo.
Results: We found that anti-HER2 agents upregulated the expression level of GSDME in a dose- and time-dependent manner. The bioinformatics analysis showed that a higher level of GSDME was correlated with poor overall survival both in HER2-negative and HER2-positive gastric cancer. We further demonstrated that GSDME upregulation in response to anti-HER2 treatment is associated with anti-HER2 therapy resistance. In order to validate whether cleavage of GSDME may render the cancer cells more sensitive to anti-HER2 agents, we applied a novel BCL-2/BCL-XL dual target inhibitor APG-1252 to test the combination antitumor effect with anti-HER2 agents. We found that APG-1252 could enhance the antitumor effect of lapatinib by promoting cell apoptosis and pyroptosis. Mechanistically, the combination treatment synergistically inhibited the phosphorylation of AKT/GSK-3β, subsequently inducing depolarization of the mitochondrial membrane and caspase-3-dependent cleavage of GSDME, which consequently triggered cell apoptosis and pyroptosis. Finally, in the HER2-positive GC cells xenotransplantation models, both lapatinib and APG-1252 monotherapy could delay tumor growth, while the combination therapy significantly suppressed tumor growth.
Conclusions: Taken together, our data indicated that anti-HER2 agents could upregulate the expression of GSDME, and the combination of lapatinib and APG-1252 showed a synergistic antitumor effect against HER2-positive gastric cancer through inducing caspase-3/GSDME mediated apoptosis and pyroptosis.
Citation Format: Qiuyun Luo, Zengfei Xia, Jing Yang, Wentao Pan, Fan Luo, Jiaxin Cao, Yuting Sun, Liqiong Yang, Lin Zhang, Miaozhen Qiu, Dajun Yang. Caspase-3 mediated cleavage of GSDME enhances the antitumor efficacy of HER2-targeted therapy in HER2-positive gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6140.