It is increasingly clear that inflammatory diseases and cancers are influenced by cleavage products of the pro-hormone chromogranin A (CgA), such as the 21-amino acids long catestatin (CST). The goal of this review is to provide an overview of the anti-inflammatory effects of CST and its mechanism of action. We discuss evidence proving that CST and its precursor CgA are crucial for maintaining metabolic and immune homeostasis. CST could reduce inflammation in various mouse models for diabetes, colitis and atherosclerosis. In these mouse models, CST treatment resulted in less infiltration of immune cells in affected tissues, although in vitro monocyte migration was increased by CST. Both in vivo and in vitro, CST can shift macrophage differentiation from a pro- to an anti-inflammatory phenotype. Thus, the concept is emerging that CST plays a role in tissue homeostasis by regulating immune cell infiltration and macrophage differentiation. These findings warrant studying the effects of CST in humans and make it an interesting therapeutic target for treatment and/or diagnosis of various metabolic and immune diseases.

Highlights d Hypoxia/HIF signaling converts collective invasion to blebbing-amoeboid migration d Calpain-2 cleaves talin-1, inactivates b1 integrins, and induces amoeboid conversion d Amoeboid movement occurs with reduced oxidative metabolism and glycolysis d Calpain-2 inhibition prevents amoeboid transition and HIFinduced 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 deactivating 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. IntroductionCancer cell invasion initiates a multistep cascade to metastasis, which converts local neoplasia into a life-threatening systemic disease. 1-3 Invading cancer cells migrate away from the primary tumor and penetrate blood and lymph vessels, followed by systemic spreading and metastatic colonization of distant organs. 1,3 For tissue invasion, cancer cells deploy a range of collective and individual cell 3 migration strategies. Collective invasion of multicellular groups occurs when cells are held together by cell-cell adhesion, whereas single-cell migration lacks cell-cell cohesion and connectivity. 4 Mesenchymal single-cell migration depends on effective integrin-mediated adhesion to the extracellular matrix (ECM), which supports spindle-like cell elongation and directs matrix metalloproteases (MMPs) for ECM remodeling and path generation. 5 Amoeboid movement of roundish or ellipsoid cells engages only weak adhesion to the ECM, lacks ECM remodeling and, instead deploys kinetic deformation of the cell body for passage through 3D tissue. 6 Besides the cell shape and the strength of ECM interactions, protrusion types differ between amoeboid migration modes. Amoeboid-moving leukocytes and cancer cells develop actin-rich pseudopodia and filopodia at the leading edge, which generate protrusive...