Abstract 4455: Involvement of the PI3K/AKT signaling pathway in the cancer cell response to tumor treating fields (TTFields)

Abstract Introduction: Tumor treating fields (TTFields) therapy is an approved treatment for glioblastoma (GBM), pleural mesothelioma and non-small cell lung carcinoma (NSCLC), and is under investigation for the treatment of other solid tumors. The current study aimed to uncover cellular response mechanisms of cancer cells to TTFields treatment. Methods: Changes in signaling pathways following TTFields application (150 or 200 kHz; 1.7 V/cm RMS) were analyzed using the Luminex multiplex assay and validated by protein expression in three cancer cell lines: A2780 ovarian cancer cells, H1299 lung cancer cells, and U87-MG GBM cells. The mechanism of action was tested with various tools, including immunofluorescence microscopy, inhibition assay, antibody neutralization assay, and immunoprecipitation. The efficacy of concomitant treatment with TTFields and a potential inhibitor were tested in cell lines and in an orthotopic LL/2 lung cancer mouse model. Results: Increased PI3K/AKT and Focal Adhesion Kinase (FAK) phosphorylation were observed in the cancer cells following short term (2h) treatment with TTFields. Accordingly, FAK inhibition abrogated TTFields-induced AKT phosphorylation. For long term (72h) treatment, the PI3K/AKT pathway was activated via N-cadherin, as evident by the increased cell surface levels and reversal of the AKT phosphorylation when a neutralizing antibody was used to inhibit the N-cadherin-mediated cell-cell contacts. Additionally, pull-down assays with an anti-N-cadherin antibody demonstrated increased recruitment of the p85 regulatory subunit of PI3K to N-cadherin complexes. In accordance with the identified involvement of the PI3K/AKT axis in the response to TTFields, co-treatment with the PI3K inhibitor alpelisib enhanced the effectiveness of TTFields in vitro and in vivo. Conclusions: These findings provide a molecular understanding of the cellular response to TTFields, with early PI3K/AKT activation through FAK cell-surface interactions, and late activation via N-cadherin cell-cell interactions. PI3K inhibition presents a potential therapeutic strategy to sensitize cancer cells to TTFields treatment. Citation Format: Anat Klein-Goldberg, Tali Voloshin, Efrat Zemer-Tov, Rom Paz, Lilach Koren, Kerem Wainer-Katsir, Alexandra Volodin, Bella Koltun, Boris Brant, Yiftah Barsheshet, Tal Kan, Cfir David, Tharwat Haj Khalil, Naama Flint-Brodsly, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. Involvement of the PI3K/AKT signaling pathway in the cancer cell response to tumor treating fields (TTFields) [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 4455.