Fundamental control of grade-specific colorectal cancer morphology by Src regulation of ezrin-centrosome engagement

The phenotypic spectrum of colorectal cancer (CRC) is remarkably diverse with seemingly endless variations of cell shape, mitotic figures, and multicellular configurations. Despite this morphological complexity, histological grading of collective phenotype patterns provides robust prognostic stratification in CRC. While mechanistic understanding is incomplete, previous studies show that the cortical protein ezrin controls diversification of cell shape, mitotic figure geometry and multicellular architecture, in three-dimensional (3D) organotypic CRC cultures. Because ezrin is a substrate of Src tyrosine kinase that is frequently overexpressed in CRC, we investigated Src regulation of ezrin and morphogenic growth in 3D CRC cultures. Here we show that Src perturbations disrupt CRC epithelial spatial organization. Aberrant Src activity suppresses formation of the cortical ezrin cap that anchors interphase centrosomes. In CRC cells with normal centrosome number, these events lead to mitotic spindle misorientation, perturbation of cell cleavage, abnormal epithelial stratification, apical membrane misalignment, multi-lumen formation and evolution of cribriform multicellular morphology, a feature of low-grade cancer. In isogenic CRC cells with centrosome amplification, aberrant Src signalling promotes multipolar mitotic spindle (MMS) formation, pleomorphism and morphological features of high-grade cancer. Translational studies in archival human CRC revealed associations between Src intensity, MMS frequency and high-grade cancer morphology. Collectively, our study reveals Src regulation of CRC morphogenic growth via ezrin-centrosome engagement and uncovers combined perturbations underlying transition to high-grade CRC morphology. This article is protected by copyright. All rights reserved.