te Boekhorst, V. | bioRxiv Science

bioRxiv2020

Glycocalyx-mediated Cell Adhesion and Migration

Cell migration is a force-dependent adaptive process mediated by integrin-dependent adhesion as well as other yet poorly defined interactions to the extracellular matrix. Using enzymatic multi-targeted digestion of sugar moieties on the surface of mesenchymal cells and leukocytes after interference with integrin function, we demonstrate that the surface glycocalyx represents an independent adhesion system. The glycocalyx mediates cell attachment to ECM ligand in the 100-500 pN force range and amoeboid migration in 3D environments in vitro and in vivo. Glycan-based adhesions consist of actin-rich membrane deformations and appositions associated with bleb-like and other protrusions forming complex-shaped sub-micron contact sites to ECM fibrils. These data implicate the glycocalyx in mediating generic stickiness to support nanoscale interactions (nanogrips) between the cell surface and ECM, mechano-coupling, and migration.

cell biology↗

bioRxiv2020

Calpain-2 regulates hypoxia/HIF-induced amoeboid reprogramming and metastasis

Hypoxia, through hypoxia inducible factor (HIF), drives cancer cell invasion and metastatic progression in various cancer types, leading to poor prognosis. In epithelial cancer, hypoxia further induces the transition to amoeboid cancer cell dissemination, yet the molecular mechanisms, relevance for metastasis, and effective interventions to combat hypoxia-induced amoeboid reprogramming remain unclear. Here, we identify calpain-2 as key regulator and anti-metastasis target of hypoxia-induced transition from collective to amoeboid dissemination of breast and head and neck (HN) carcinoma cells. Hypoxia-induced amoeboid dissemination occurred through low ECM-adhesive, bleb-based amoeboid movement, which effectively invaded into 3D collagen with low-oxidative and -glycolytic energy metabolism, revealing an microenvironmentally-induced, energy-conserving dissemination route in epithelial cancers. Hypoxia-induced calpain-2 mediated amoeboid conversion by de-activating beta1 integrins, through enzymatic cleavage of the focal adhesion adaptor protein talin-1. Consequently, targeted downregulation of calpain-2 or pharmacological intervention restored talin-1 integrity, beta1 integrin engagement and reverted blebbing-amoeboid to elongated phenotypes under hypoxia. Calpain-2 activity was required for hypoxia-induced blebbing-amoeboid conversion in the orthotopic mouse dermis, and upregulated in invasive HN tumor xenografts in vivo, and attenuation of calpain activity prevented hypoxia-induced metastasis to the lungs. This identifies the calpain-2/talin-1/beta1 integrin axis as mechanosignaling program and promising intervention target of plasticity of cancer cell invasion and metastasis formation in epithelial cancers under hypoxia.

cancer biology↗