Leader epithelial cells develop nucleoli of bigger size and in higher numbers compared to follower cells. Stiff matrices and cancer cells further enhance this nucleolar mechano-response in epithelial colonies.

No abstract

Dynamic nucleocytoplasmic transport of E-M factors regulates cellular E-M states; yet, it remains unknown how simultaneously trapping these factors affects epithelia at the macroscale. To explore this question, we performed nuclear export inhibition (NEI) via leptomycin B and Selinexor treatment, which biases nuclear localization of CRM1-associated E-M factors. We examined changes in collective cellular phenotypes across a range of substrate stiffnesses. Following NEI, soft substrates elevate collective migration of MCF10A cells for up to 24 hr, while stiffer substrates reduce migration at all time points. Our results suggest that NEI disrupts migration through competition between intercellular adhesions and mechanoactivation, generally causing loss of cell–cell coordination. Specifically, across substrate stiffnesses, NEI fosters an atypical E-M state wherein MCF10A cells become both more epithelial and more mesenchymal. We observe that NEI fosters a range of these concurrent phenotypes, from more epithelial shYAP MCF10A cells to more mesenchymal MDCK II cells. α-Catenin emerges as a potential link between E-M states, where it maintains normal levels of intercellular adhesion and transmits mechanoactive characteristics to collective behavior. Ultimately, to accommodate the concurrent states observed here, we propose an expanded E-M model, which may help further understand fundamental biological phenomena and inform pathological treatments.

Epithelial-mesenchymal (E-M) phenotypes govern collective cellular behaviors to facilitate diverse tissue functions, including embryogenesis, wound healing, and cancer invasion. Cellular E-M state is regulated by dynamic nucleocytoplasmic transport of corresponding E-M factors; yet, it remains unknown how concurrently trapping these factors affects epithelia at the macroscale. To explore this question, we performed nuclear export inhibition (NEI) via Leptomycin B treatment, which biases nuclear localization of CRM1- associated E-M factors. We examined changes in collective cell migration across a range of substrate stiffnesses. Our results show that NEI fosters an atypical E-M state wherein cells concurrently strengthen intercellular adhesions and develop mechanoactive characteristics. Following NEI, soft substrates elevate collective migration for up to 24 h, while stiffer substrates reduce migration at all timepoints. We demonstrate that excluding Yes-associated protein 1 from NEI shifts affected cells toward an epithelial phenotype. Meanwhile, removing α-catenin maintains NEI’s intercellular adhesion strengthening and mechanoactivation capabilities, but prevents mechanoactive characteristics from reaching collective behavior. Overall, our results show that NEI disrupts epithelial migration through competition between intercellular adhesions, mechanoactivation, and cell-cell coordination. Ultimately, these findings of mechanoactive NEI outcomes for healthy cells could warrant additional investigation in the context of NEI-centered cancer therapies.