CD248 Regulates Wnt Signaling in Pericytes to Promote Angiogenesis and Tumor Growth in Lung Cancer.

The tumor microenvironment plays a central role in cancer initiation and progression. CD248 is expressed in tumor-associated stromal cells, particularly fibroblasts and pericytes. Exploring the function of CD248 has the potential to provide biological insights into tumor-supportive stroma and potential therapeutic targets. Here, we investigated the role of stromal CD248 in lung cancer. In orthotopic lung cancer transplantation models, tumor volume, density of vessels and pericytes, and functionality of tumor vessels were all lower in mice lacking Cd248 (Cd248LacZ/LacZ) compared with Cd248 wild-type or haploinsufficient mice. Two angiogenic factors, OPN and SERPINE1, were decreased in Cd248LacZ/LacZ pericytes, and supplementation with both factors rescued their proliferation and endothelial cell tube formation-promoting ability. Mechanistically, Wnt/ß-catenin signaling induced Opn and Serpine1 expression and was suppressed in Cd248LacZ/LacZ pericytes. CD248 interacted with Wnt pathway repressors IGFBP4 and LGALS3BP, leading to increased Wnt/ß-catenin signaling. Correspondingly, administration of a ß-catenin inhibitor in Cd248+/LacZ mice mimicked the effect of Cd248 loss and blocked the growth of transplanted lung tumor cells that were resistant to this inhibitor in vitro. In addition, CD248+ pericytes coexpressed OPN and SERPINE1 and correlated with increased tumor size in human lung cancer. Additionally, high expression of CD248, OPN, and SERPINE1 was associated with poor survival in lung cancer patients. In summary, CD248 derepresses Wnt signaling and upregulates OPN and SERPINE1 in pericytes, resulting in enhanced angiogenesis and lung cancer growth. This novel axis of CD248-Wnt signaling-angiogenic factors in pericytes provides a potential target for lung cancer therapy. SIGNIFICANCE: These findings demonstrate that CD248 maintains pericyte function in lung cancer through the Wnt signaling pathway and present CD248 as a potential therapeutic target.

Persistent elevation of hepatocyte growth factor activator inhibitors in cholangiopathies affects liver fibrosis and differentiation.

UNLABELLED: Alteration of cell surface proteolysis has been proposed to play a role in liver fibrosis, a grave complication of biliary atresia (BA). In this study we investigated the roles of hepatocyte growth factor activator inhibitor (HAI)-1 and -2 in the progression of BA. The expression levels of HAI-1 and -2 were significantly increased in BA livers compared with those in neonatal hepatitis and correlated with disease progression. In BA livers, HAI-1 and -2 were coexpressed in cells involved in ductular reactions. In other selective cholangiopathies, ductular cells positive for HAI-1 or HAI-2 also increased in number. Inflammatory cytokines, growth factors, and bile acids differentially up-regulated expression of HAI-1 and -2 transcripts in fetal liver cells and this induction could be antagonized by a cyclooxygenase-2 inhibitor. Conditioned media from cell lines stably overexpressing HAI-1 or HAI-2 enhanced the fibrogenic activity of portal fibroblasts and stellate cells, suggesting that both proteins might be involved in liver fibrosis. Because HAI-1 and -2 colocalized in ductular reactions sharing similar features to those observed during normal liver development, we sought to investigate the role of HAI-1 and -2 in cholangiopathies by exploring their functions in fetal liver cells. Knockdown of HAI-1 or HAI-2 promoted bidirectional differentiation of hepatoblast-derived cells. In addition, we showed that the hepatocyte growth factor activator, mitogen-activated protein kinase kinase 1, and phosphatidylinositol 3-kinase signaling pathways were involved in hepatic differentiation enhanced by HAI-2 knockdown. CONCLUSION: HAI-1 and -2 are overexpressed in the liver in cholangiopathies with ductular reactions and are possibly involved in liver fibrosis and hepatic differentiation; they could be investigated as disease markers and potential therapeutic targets.

Gene targeting and expression analysis of mouse Tem1/endosialin using a lacZ reporter.

TEM1 (endosialin) expression is increased in the stroma and tumor vasculature of several common human cancers. The exact physiological role of TEM1 is still unknown since Tem1-deficient mice are viable and show only a lower rate of abdominal site-specific tumor invasion in tumor transplantation experiments. Previous studies have reported Tem1 expression in mouse embryos and adults, but did not determine the timing or location of the earliest expression, and did not examine all organ systems. Using the highly sensitive Bluo-Gal staining method for detecting temporal and spatial Tem1-lacZ activity in lacZ knock-in (+/lacZ) mice, we found that Tem1 gene expression was initially detectable in the dorsal aortic wall, the heart, the umbilical vessels, the first branchial arch, and the cephalic mesenchyme at E9.5. From E10.5 to E14.5, Tem1 gene expression was additionally seen mainly in the genital tubercle, the mesonephros, the whisker follicles, the mesenchymal tissues around the eye, and the lung. Remarkably, the kidney expressed abundant Tem1-lacZ starting from E16.5. Postnatally, Tem1 expression decreased in most organs but elevated expression persisted in the renal glomerulus and the uterus, where the expression pattern varied at different estrous cycle stages. Co-localization studies indicated that most vimentin-positive cells co-expressed Tem1-lacZ, while a large portion of CD31- or desmin-positive cells were also positive for Tem1-lacZ. Taken together, our observations suggest that Tem1 is expressed throughout embryonic and adult development in several types of mesenchymal cells closely related to blood vessels.