Abstract 2827: Heat shock factor 1 regulates the cellular toxicity-induced autophagy in pancreatic ductal adenocarcinoma

Abstract Background: Heat shock factor 1 (HSF1) is a master transcriptional regulator of the proteotoxic stress response and has been known to be hyperactivated in pancreatic ductal adenocarcinoma (PDAC). Recent research has shown that ion-induced cellular toxicity (ferroptosis or cuproptosis) triggers autophagy—a critical mechanism that maintains cellular homeostasis. HSF1 has been established to mediate autophagy in a context-dependent manner. It has been reported that HSF1 prevents copper-induced toxicity in PDAC; however, it remains unclear whether HSF1 mediates autophagy as a mechanism of stress adaptation in response to aforementioned cellular toxicity. Objective: The objective of this study is to investigate the molecular mechanism of the role of HSF1 in cellular ion toxicity-induced autophagy. Methods: Human PDAC cell line MIA PaCa-2 was used for this study. A CellTiter Blue Cell Viability Assay was used to determine the IC50 of Erastin, a well-known ferroptosis inducer, and Elesclomol/copper, a copper ionophore, in human PDAC cells. An HSF1 overexpressed (HSF1_WT) MIA PaCa-2 cell was used to test ion-induced toxicity in comparison to the control (LacZ) MIA PaCa-2 cells. Western blotting was used to detect the protein HSF1, autophagy markers, and internal loading control. Results: In human MIA PaCa-2 cells, Elesclemol/copper and Erastin induced cell death. Elesclomol/copper and Erastin induced increased autophagy marker microtubule-associated protein 1A/1B-light chain 3β (LC3β) lipidation and decreased the expression of total HSF1 protein in a dose-dependent manner. The overexpression of HSF1 prevented the Erastin-induced LC3β lipidation. Conclusion: HSF1 plays a role in the induction of autophagy, which functions as a stress-adaptive mechanism in the tumor cell in response to the toxicities induced by ferroptosis and cuproptosis inducers. Citation Format: Rejina Shrestha, Shruti Ghai, Ahmad Hegazi, Kuo-Hui Su. Heat shock factor 1 regulates the cellular toxicity-induced autophagy in pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2827.