ESTRO 2025 - Abstract Book

S4010

Radiobiology - Tumour radiobiology

ESTRO 2025

3382

Digital Poster Identification of Twist1 and Mylk overexpression in migratory phenotypes of pancreatic cancer Manuela Feyereisen 1 , Francheska Cadacio 1 , Günter Schneider 2,3 , Roland M. Schmid 2 , Daniela Schilling 1,4 , Stephanie E. Combs 1,4,5 , Sophie Dobiasch 1,4,5 1 Department of Radiation Oncology, TUM School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany. 2 Medical clinic and polyclinic II, TUM School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany. 3 Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany. 4 Institute of Radiation Medicine (IRM), Helmholtz Zentrum Munich, Neuherberg, Germany. 5 Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site Munich, Munich, Germany Purpose/Objective: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant diseases, with a 5-year survival rate of less than 10%. It is characterized by early development of metastases and high resistance to standard therapies, including radiotherapy. Own preliminary work showed a high variation of intrinsic radiosensitivity among different murine and human PDAC cell lines. Furthermore, a tendency towards a migratory phenotype in radioresistant murine PDAC cell lines was observed. This project aims to further characterize migration and invasion baseline as well as after irradiation and to identify genes associated with high migration capacities to subsequently target those genes pharmacologically. Material/Methods: Murine PDAC cell lines derived from genetically engineered mice with various genetic backgrounds were used for the experiments. Migration and invasion were characterized baseline (0 Gy) and after 2 Gy, 4 Gy, and 8 Gy by uncoated or matrigel-coated transwell assays (Corning), respectively. Migration was additionally validated by wound healing assay (Ibidi). We used RT2 Profiler PCR arrays to quantify 252 genes associated with cell-cell interactions, cell- matrix interactions, or epithelial-to-mesenchymal transition (Qiagen). Protein expression was analyzed by Western Blot using antibodies against Twist1, RhoA, Mylk, Vimentin (Santa Cruz Biotechnology), Limk1 and E-cadherin (Cell Signaling). Colony formation assays were performed with different concentrations of the indirect Twist1 inhibitor Harmine or direct Mylk inhibitor ML-7 hydrochloride (MedChemExpress) in combination with irradiation to determine cell survival and potential radiosensitization effects. Results: The different cell lines showed baseline significant heterogeneous migratory and invasive capacities in the transwell assay. In addition, there were differences in migration and invasion after irradiation. Data from the wound healing assay validated the results of the transwell migration assay. Different gene expression patterns were identified by the RT2 Profiler PCR array within the murine cell lines and after radiation. Significantly enhanced Twist1 and Mylk gene expression was associated with a migratory phenotype, which was confirmed on the protein level by Western Blot. We observed a concentration-dependent reduction of clonogenic survival after inhibitor treatment with Harmine (5μM, 10μM, 20μM) or ML-7 hydrochloride (2.5μM, 5μM, 10μM). Conclusion: Twist1 and Mylk expression was shown to be associated with high migratory capacities in murine PDAC cell lines. A potential effect on migration and radiosensitivity by targeting Twist1 or Mylk will be investigated further. Combination therapy of targeted pharmacological inhibition and irradiation might improve treatment options for patients with PDAC and might be a strategy to prevent the development of metastases.

Keywords: Migration, PDAC, Radiosensitization