Running title: Tumor growth and spread in hrg-deficiency Key words: Histidine-rich glycoprotein, tumor-associated macrophages, angiogenesis, metastasis, immune response

Histidine-rich glycoprotein (HRG) is a 75 kDa heparin-binding plasma protein implicated in the regulation of tumor growth and vascularization. In this study, we show that hrg mice challenged with fibrosarcoma or pancreatic carcinomas grow larger tumors with increased metastatic properties. Compared with wild type mice, fibrosarcomas in hrg mice were more hypoxic, necrotic and less perfused, indicating enhanced vessel abnormalization. HRG-deficiency was associated with a suppressed anti-tumor immune response, with both increased infiltration of M2-marker-expressing macrophages and decreased infiltration of dendritic cells and cytotoxic T cells. Analysis of transcript expression in tumor-associated as well as peritoneal macrophages from hrg mice revealed an increased expression of genes associated with a pro-angiogenic and immunoinhibitory phenotype. In accordance, expression arrays performed on HRG-treated peritoneal macrophages showed induction of genes involved in extracellular matrix biology and immune responsiveness. In conclusion, our findings demonstrate that macrophages are a direct target of HRG. HRG loss influences macrophage gene regulation, leading to excess stimulation of tumor angiogenesis, suppression of tumor immune response, and increased tumor growth and metastatic spread.