Expression, regulation, and function of αV integrins in hepatocellular carcinoma: An in vivo and in vitro study

The expression of αV integrins by neoplastic cells contributes to the promotion of local invasion and metastasis. The most characteristic extracellular ligands of αV integrins are vitronectin and fibronectin. Hepatocytes are the main source of vitronectin, and the capacity to synthesize and secrete vitronectin is usually retained in hepatocellular carcinoma. The aim of this study was to explore the expression, regulation, and functional role of αV integrins in hepatocellular carcinoma. We first analyzed the expression of αV integrins and their ligands fibronectin and vitronectin in 80 cases of hepatocellular carcinoma. αV integrin chain was detected in 44 cases and vitronectin in 50. Twenty-four of the 44 αV-positive tumors contained large amounts of vitronectin. These cases presented more frequently with adverse histoprognostic factors, including infiltrative growth pattern (62.5%), lack of capsule (71%), presence of capsular invasion (57%), and satellite nodules (50%). We then used HepG2 and Hep3B cell lines as in vitro models to study αV integrin regulation and function. HepG2 and Hep3B cells expressed αV integrin chain and used αVβ1 and αVβ5 for adhesion and migration on vitronectin. Tumor necrosis factor (TNF) α and transforming growth factor (TGF) β significantly increased the expression levels of αV integrins and stimulated the adhesion and migration of both HepG2 and Hep3B cell lines on vitronectin. The effects of growth factors on cell adhesion and migration were reproduced by incubation with conditioned medium from rat liver myofibroblasts. In conclusion, our results support the existence of an αV integrin/vitronectin connection in hepatocellular carcinoma and suggest that this connection may be an adverse prognostic factor

Contribution of endothelial cells to organogenesis: a modern reappraisal of an old Aristotelian concept

It is well established that many tissue-derived factors are involved in blood vessel formation, but evidence is now emerging that endothelial cells themselves represent a crucial source of instructive signals to non-vascular tissue cells during organ development. Thus, endothelial cell signalling is currently believed to promote fundamental cues for cell fate specification, embryo patterning, organ differentiation and postnatal tissue remodelling. This review article summarizes some of the recent advances in our understanding of the role of endothelial cells as effector cells in organ formation

Liver sinusoidal endothelial cells - gatekeepers of hepatic immunity.

Liver sinusoidal endothelial cells (LSECs) line the low shear, sinusoidal capillary channels of the liver and are the most abundant non-parenchymal hepatic cell population. LSECs do not simply form a barrier within the hepatic sinusoids but have vital physiological and immunological functions, including filtration, endocytosis, antigen presentation and leukocyte recruitment. Reflecting these multifunctional properties, LSECs display unique structural and phenotypic features that differentiate them from the capillary endothelium present within other organs. It is now clear that LSECs have a critical role in maintaining immune homeostasis within the liver and in mediating the immune response during acute and chronic liver injury. In this Review, we outline how LSECs influence the immune microenvironment within the liver and discuss their contribution to immune-mediated liver diseases and the complications of fibrosis and carcinogenesis