Abstract 7344: NRG1 knock out in cancer cell lines decreases their aggressiveness

Abstract Introduction: Neuregulin-1 (NRG1) is a growth factor which can bind to the ErbB/human epidermal growth factor receptors (HERs), especially to HER3, and activate the downstream signalling pathways. The NRG1 gene has the potential to form oncogenic gene fusions with diverse gene partners leading to the emergence of cancer. Several therapeutic approaches targeting more or less directly NRG1’s signalling pathway exist, but patients tend to respond poorly to treatments or rapidly develop resistances. A better understanding of the NRG1- and NRG1-fusion-dependent cell biology could allow us to propose new treatment options to these patients. Here our objective is to study NRG1-dependent cell biology parameters in various cancer cell lines, with or without genetic alterations of NRG1. Methods: A CRISPR-Cas9-based deletion of NRG1 was obtained in the A549 and SW1573 Non-Small Cell Lung Cancer (NSCLC) cell lines which highly express wild type NRG1, in the HCC95 NSCLC cell line which has an amplification of NRG1, and in the MDA-MB-175 breast cancer cell line which bears a complex PPP6R3-TENM4-NRG1 fusion. The modified cell lines were grown as either or both polyclonal and monoclonal populations and were characterized using classic cell biology techniques such as western blot and flow cytometry to monitor protein expression, confluence assay and Cell-Trace CFSE to study proliferative capacities, scratch wound assay and Boyden chamber to monitor migratory capacities, and soft agar and clonogenic assay to study stemness characteristics. Results: The NRG1-deficient A549 clones (n=5) clustered into two distinct behavioural groups. One of them showed a loss of HER3 expression, a 3-fold increased sensitivity to afatinib, and up to 2-fold decreased migratory capacities. As for the other group, there was an induced expression of mesenchymal markers and a loss of FGFR1 expression. For other parameters, all A549 clones behaved in a similar manner as control clones. Preliminary results in NRG1-deficient HCC95 (n=2) suggest they have slightly reduced proliferative capacities and NRG1-deficient MDA-MB-175 (n=2) have a 2-fold higher sensitivity to several treatments including afatinib. All clones for the SW1573 cell line (n=4) exhibited no difference within all performed experiments. Conclusion: Overall, NRG1-deficiency decreases cancer cells’ aggressiveness, although in a cell-specific manner. Upcoming transcriptomic assay of our different models will give us a better insight in NRG1-related molecular modifications. Further analyses of all models are ongoing (clones of MDA-MB-175 and HCC95, 3D bioprinting experiments, in vivo tumour growth⋯) and results will be included in the poster. Citation Format: Marie Issenmann, Clarisse Thiollier-Schmitt, Manon Barre, Emeline Cros-Perrial, Michael Duruisseaux, Lars Petter Jordheim. NRG1 knock out in cancer cell lines decreases their aggressiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7344.