Abstract 765: Tumor extracellular matrix drivesEMT and cellular reprogrammingin Wilms tumor.

Abstract Introduction: The extracellular matrix (ECM) is a dynamic component of the tumor microenvironment (TME) that orchestrates cancer progression, invasion, metastasis, and therapy resistance. Wilms tumor (WT), a pediatric renal malignancy, presents an altered ECM architecture. We investigated how WT ECM influences cellular behavior and transcriptional programs compared to normal kidney ECM. Methods: Spatial transcriptomics and immunohistochemistry mapped ECM localization in WT and normal kidneys. Decellularization protocols were established to completely remove cellular materials while preserving the fibrillar ECM architecture and embedded soluble matrix proteins, as validated by second-harmonic generation imaging and ECM-associated proteins profiling using a cancer biomarker antibody array. Moreover, cancer and normal cells were cultured on decellularized ECM (dECM) scaffolds of WT and normal kidney for 21 days. Cellular dynamics were monitored via two-photon microscopy, and transcriptional changes were assessed by bulk RNA sequencing. Results: WT ECM exhibited disorganized collagen networks and elevated levels of inflammatory markers, cytoskeletal proteins, and epithelial-mesenchymal transition (EMT) regulators. Cancer cells cultured on WT dECM upregulated EMT-related genes (e.g., FOXC2, TGFB2) and ECM remodeling enzymes (e.g., ADAMTS5), while downregulating cell cycle and integrin-associated genes. Normal cells seeded on WT dECM also adopted cancer-like transcriptional profiles, including increased expression of survival and proliferation genes (e.g., AKT3, BCL2) and decreased integrin-related gene expression. Conclusion: WT ECM is structurally and molecularly distinct from normal kidney ECM and actively promotes EMT, stemness, and tumor-supportive reprogramming. These findings underscore the ECM as a crucial driver of cancer progression and highlight ECM-targeted strategies as a promising therapeutic approach for combating aggressive cancers. Citation Format: Wilson Yeung, Matthew E. Thornton, Hripsime Chomoyan, David Koos, Justin Sunwoo, Brendan H. Grubbs, Roger E. De Filippo, Stefano Da Sacco, Laura Perin, Astgik Petrosyan. Tumor extracellular matrix drivesEMT and cellular reprogrammingin Wilms tumor 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 765.