Abstract 5626: Essential role of Slug during the evolution of drug-tolerance in lung adenocarcinoma

Abstract A major obstacle in the efficacy of targeted therapies of oncogene-driven tumors are drug-tolerant persister cells (DTPs) that build the basis for the outgrowth of drug-resistant clones and ultimately limit patient survival. During treatment, DTPs enter a reversible senescent state to survive therapy while cell death is induced in non-DTPs. Here, using RNA-Seq and proteomic analyses, we identified drug-induced TGFβ2 secretion in DTPs derived from different oncogene-driven lung cancer cell lines. As expected, TGFβ2 induces epithelial-to-mesenchymal transition (EMT) that over time promotes the ability of cells to survive targeted therapy. Using CRISPR/Cas9-mediated loss-of-function and reconstitution experiments we show that downstream of TGFβ2, expression of the transcription factor SNAI2 (SLUG) is essential for the outgrowth of DTPs during targeted treatment. Unsupervised RNA-Seq data analyses in combination with Cut&Tag profiling revealed that EMT signaling is in part a SLUG regulated process but that is also independent of direct SLUG binding at the transcription start sites (TSS) of EMT signature genes. In contrast, we observed high occupancy of SLUG at TSS of genes involved in the regulation of cell cycle, being repressed in DTPs and at TSS of genes that regulate sphingolipid metabolism and MAPK signaling, being induced in DTPs. In line with our previous findings, a motif-based analysis of the Cut&Tag data (TOBIAS) furthermore uncovered a tight connection between DTP outgrowth and inflammatory signaling induced through IRF7, IRF4 or STAT1 activation. In vivo, EGFR-mutant SLUG deficient cells showed a significantly prolonged tumor onset and a higher response rate to osimertinib treatment. Overall, we uncover a major role of TGFβ2/SLUG-mediated EMT signaling that may be induced indirectly through SLUG-dependent reprogramming of cell cycle directed and metabolic processes in drug tolerant cells. These insights may offer unique therapeutic opportunities to limit the outgrowth of drug resistant tumors in cancer patients. Citation Format: Jenny Ostendorp, Hannah Lea Tumbrink, Pascal Hunold, Michaela Hoehne, Philipp Jurmeister, Anastasia Dekker, Felix Heisel, Johannes Brägelmann, Frederick Klauschen, Robert Haensel-Hertsch, Martin L. Sos. Essential role of Slug during the evolution of drug-tolerance in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5626.