Abstract 2423: A Cdh3 - Lam332 signaling axis by a unique subset of leader cells controls breast tumor organoid protrusion dynamics and directed collective migration

Abstract

Abstract Carcinoma dissemination can occur when heterogeneous tumor and tumor stromal cells clusters migrate together via collective migration. Cells at the front lead and direct collective migration, yet how these leader cells form and interact with the microenvironment to direct migration are not fully appreciated. From live videos of primary mouse and human breast tumor organoids in a 3D microfluidic system that mimics the native breast tumor microenvironment, we developed 3D computational models. These hypothesize that for leader cells to polarize to the leading edge and lead directed collective migration they need to generate high protrusive forces and overcome extracellular matrix (ECM) resistance. From scRNAseq of migrating primary tumor organoids, we identify significant K14+ “leader” cell heterogeneity that differs depending upon the environmental signal. We isolate a unique Cadherin-3 (Cdh3) positive leader cell subpopulation that is necessary and sufficient to lead collective migration. Cdh3 controls leader cell protrusion dynamics through controlling the local production of Laminin-332 which is required for integrin/focal adhesion function. Loss of Cdh3 expression in mouse and human primary breast tumor organoids and invasive breast tumor cell lines significantly impairs directed collective migration. In the absence of leader cell Cdh-Cdh3 intercellular adhesions there is reduced cellular β-catenin levels and Laminin 332 production. In syngeneic, orthotopic transplant mouse models, Cdh3 depletion in tumor cells resulted in decreased laminin 332 production at the invasive edge of primary tumors and decreased lung metastasis. Chromatin Immunoprecipitation experiments revealed that in contacted cells β-catenin and TCF4 are present on Lam α3, β3, and γ2 promoter regions. Laminin 332 production by leader cells was required for optimal Integrin/FA function and cellular protrusion stability. These results indicated that in leader cells local Cdh3-Cdh3/β-catenin regulated Laminin 332 production controls protrusion dynamics and overcomes resistance to ECM to lead directed collective tumor migration. Our findings highlight how a unique subset of leader cells in breast tumors interact with the microenvironment to direct collective migration. Citation Format: Yanyang Cao, Priscilla Y. Hwang, Maria Clarke, Jose Almeida, Amit Pathak, Gregory D. Longmore. A Cdh3 - Lam332 signaling axis by a unique subset of leader cells controls breast tumor organoid protrusion dynamics and directed collective migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2423.