Fibrin Deposit on the Peritoneal Surface Serves as a Niche for Cancer Expansion in Carcinomatosis Patients

Peritoneal metastasis (PM) is a very serious complication of gastrointestinal and gynecological malignancies which is poorly documented. Modified mesothelial cell layer and their microenvironments can favor fibrin deposition for cancer cell adhesion. Scanning and transmission electron microscopy of peritoneal surface and cancer cell clusters from cancer patients was done. Ascites and its impact on mesothelial cells were assessed by cytokine array. Neprilysin, matrix metalloprotease, epithelial mesenchymal transition (EMT) related molecules (Ecadherin, Snail, Slug, Twist, Vimentin and Fibronectin), tissues factor (TF), endothelial protein C receptors (EPCR) were quantified by qPCR. Fibrin in the simples were stained using anti fibrin F1E1 antibody. Migration ability was assessed by scratch assay. Cell viability and neprilysin activity were analyzed by bioluminescence. Cancer cellsfibrin interaction was investigated by scanning electron microscopy (SEM) and microcinematography (MCG). Mesothelial cells change their morphology after incubation with carcinomatosis peritoneal fluids in vitro. EMT associated with upregulation of neprilysin, matrix metalloproteinase2, tissue factor and cytokines secretions such as interleukin6, and 8, hepatocyte growth factor and granulocyte chemotactic protein2 mRNA and protein were observed. EPCR expression as a natural anticoagulant was decreased. In parallel, carcinomatosis cell clusters extracted from peritoneal fluids were found to be associated with fibrin. Kinetic analysis of cancer cellfibrin interaction in vitro studied by MCG showed that fiber filaments generated from clots inhibited cancer cell adhesion on fibrin clots. These results indicated that fibrin deposit on the peritoneal surface serve as niches for cancer expansion in carcinomatosis patients.