Abstract 2813: Pyruvate kinase M2 confers radioresistance in head and neck cancer through reprograming the tumor-immune microenvironment via ECM1

Abstract Radiotherapy plays an essential role in cancer treatment, yet radioresistance remains a major barrier to therapeutic efficacy. A better understanding of the predominant pathways determining radiotherapy response could help develop mechanism-informed therapies to improve cancer management. PKM2, an enzyme that regulates the final rate-limiting step of glycolysis, has different functions in the occurrence, progression and metastasis of cancer. However, whether PKM2 plays a vital role in radioresistance is unclear, especially in head and neck squamous cell carcinoma (HNSCC). Here we report the upregulation of PKM2 in primary post-radiotherapy tumor tissues collected from radioresistant HNSCC patients. Using multidisciplinary approaches, we found elevated PKM2 in response to radiation, which confers radioresistance in HNSCC cells via extracellular matrix protein 1 (ECM1). Mechanistically, PKM2 activates STAT5 signaling pathway in HNSCC cells upon radiation, which enhances ECM1 expression. Moreover, ECM1 upregulation mediated by PKM2 prevents effector T cells from migrating to radioresistant head and neck tumors. While depletion of ECM1 overcomes PKM2-mediated radioresistance in orthotopic xenograft mice through altering the profile of chemo-attractants, which in turn remodels the tumor microenvironment to promote more cytotoxic T cells home to tumors. These novel and significant findings not only demonstrate a novel mechanism underpinning the interaction between tumor-derived PKM2 and immune cells in radioresistance but also provide a possible therapeutic strategy to overcome the failure of radiotherapy in HNSCC patients. Citation Format: Fanghui Chen, Yang Fan, Chris Tang, Qin Richard, Zheng Wei, Yong Teng. Pyruvate kinase M2 confers radioresistance in head and neck cancer through reprograming the tumor-immune microenvironment via ECM1 [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 2813.