ABSTRACT
PURPOSE: To investigate the clinical relevance of macrophages in liver metastasis of colorectal cancer and their influence on angiogenesis and patient survival. Moreover to evaluate specific blood monocytes as markers of disease recurrence.Experimental design: In a mouse model with spontaneous liver metastasis, the angiogenic characteristics of tumor- and metastasis (MAM)-associated macrophages were evaluated. Macrophages and the vasculature from 130 primary tumor (pTU) and 123 patients with liver metastasis were assessed. In vivo and in human samples, the clinical relevance of macrophage VEGFR1 expression was analyzed. Blood samples from patients (n = 157, 80 pTU and 77 liver metastasis) were analyzed for assessing VEGFR1-positive (VEGFR1+) cells as suitable biomarkers of disease recurrence. RESULTS: The number of macrophages positively correlated with vascularization in metastasis. Both in the murine model as well as in primary isolated human cells, a subpopulation of MAMs expressing VEGFR1 were found highly angiogenic. While VEGFR1 expression in pTU patients did not predict prognosis; high percentage of VEGFR1+ cells in liver metastasis was associated with worse patient outcome. Interestingly, VEGFR1+-circulating monocytes in blood samples from patients with liver metastasis not only predicted progression but also site of recurrence. CONCLUSIONS: Our findings identify a new subset of proangiogenic VEGFR1+ MAMs in colorectal cancer that support metastatic growth and may become a liquid biomarker to predict disease recurrence in the liver.
Subject(s)
Colorectal Neoplasms/metabolism , Colorectal Neoplasms/pathology , Macrophages/metabolism , Neovascularization, Pathologic/metabolism , Vascular Endothelial Growth Factor Receptor-1/metabolism , Animals , Biomarkers, Tumor , Cell Line, Tumor , Cell Proliferation , Colorectal Neoplasms/etiology , Colorectal Neoplasms/mortality , Disease Models, Animal , Fluorescent Antibody Technique , Humans , Immunohistochemistry , Liver Neoplasms/secondary , Macrophages/drug effects , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Mice, Knockout , Prognosis , Recurrence , Xenograft Model Antitumor AssaysABSTRACT
The consumption of bovine milk and meat is considered a risk factor for colon- and breast cancer formation, and milk consumption has also been implicated in an increased risk for developing Multiple Sclerosis (MS). A number of highly related virus-like DNAs have been recently isolated from bovine milk and sera and from a brain sample of a MS patient. As a genetic activity of these Acinetobacter-related bovine milk and meat factors (BMMFs) is unknown in eukaryotes, we analyzed their expression and replication potential in human HEK293TT cells. While all analyzed BMMFs show transcriptional activity, the MS brain isolate MSBI1.176, sharing homology with a transmissible spongiform encephalopathy-associated DNA molecule, is transcribed at highest levels. We show expression of a replication-associated protein (Rep), which is highly conserved among all BMMFs, and serological tests indicate a human anti-Rep immune response. While the cow milk isolate CMI1.252 is replication-competent in HEK293TT cells, replication of MSBI1.176 is complemented by CMI1.252, pointing at an interplay during the establishment of persistence in human cells. Transcriptome profiling upon BMMF expression identified host cellular gene expression changes related to cell cycle progression and cell viability control, indicating potential pathways for a pathogenic involvement of BMMFs.
