Chromosomal Instability Induces Cellular Invasion in Epithelial Tissues

Most sporadic carcinomas with high metastatic activity show an increased rate of changes in chromosome structure and number, known as chromosomal instability (CIN). However, the role of CIN in driving invasiveness remains unclear. Using an epithelial model in Drosophila, we present evidence that CIN promotes a rapid and general invasive behavior. Cells with an abnormal number of chromosomes delaminate from the epithelium, extend actin-based cellular protrusions, form membrane blebs, and invade neighboring tissues. This behavior is governed by the activation of non-muscle Myosin II by Rho kinase and by the expression of the secreted EGF/Spitz ligand. We unravel fundamental roles of the mitogen-activated protein kinase pathways mediated by the Fos proto-oncogene and the Capicua tumor suppressor gene in the invasive behavior of CIN-induced aneuploid cells. Our results support the proposal that the simple production of unbalanced karyotypes contributes to CIN-induced metastatic progression.