Spatial heterogeneity in tumor adhesion qualifies collective cell migration

Collective cell migration, a canon of most invasive solid tumors, is an emergent property of the interactions between cancer cells and their surrounding extracellular matrix (ECM). However, tumor populations invariably consist of cells expressing variable levels of adhesive proteins that mediate such interactions, disallowing an intuitive understanding of how tumor invasiveness at a multicellular scale is influenced by spatial heterogeneity of cell-cell and cell-ECM adhesion. Here, we have used a Cellular Potts model-based multiscale computational framework that is constructed on the histopathological principles of glandular cancers. In earlier efforts on homogenous cancer cell populations, this framework revealed the relative ranges of interactions, including cell-cell and cell-ECM adhesion that drove collective, dispersed, and mixed multimodal migrations. Here, we constitute a tumor core of two separate cell subsets showing distinct intra-subset cell-cell or cell-ECM adhesion strengths. These two subsets of cells are arranged to varying extents of spatial intermingling, which we call the heterogeneity index (HI). Our simulations show that for a given two intra-subset cell-cell adhesions for two subsets of cells, low and high inter-subset cell adhesion favors migration of high HI and low HI intermingled populations, respectively. In addition, for the most explored values of cell-ECM adhesion strengths, populations with high HI values collectively migrate better than those with lower HI values. We then asked how spatial migration is regulated by progressively intermingled cellular subsets that were epithelial, i.e., showed high cell-cell but poor cell-ECM adhesion, and mesenchymal, i.e., with reversed adhesion strengths to the former. Here too, inter-subset adhesion plays an important role in contextualizing the proportionate relationship between HI and migration. We also observe an exception to this relationship for cases of heterogeneous cell-ECM adhesion where sub-maximal HI patterns with higher outer localization of cells with stronger ECM adhesion collectively migrate better than their relatively higher HI counterparts. Our simulations also reveal how adhesion heterogeneity qualifies migrative dynamics through collective cellular unjamming, when either cell-cell or -ECM adhesion type is varied but incorporates dispersion when both adhesion types are simultaneously altered.