Mesothelial vitronectin stimulates migration of ovarian cancer cells

Ovarian carcinomas, the most fatal gynaecological malignancies, are associated with poor prognosis predominantly because of a high recurrence rate. Ovarian cancer cells spread widely throughout the abdominal cavity leading to peritoneal metastasis. The influence of the mesothelial microenvironment on the biological mechanisms leading to cancer cell colonization of the mesothelium is poorly understood. This study aims to investigate whether mesothelial secretions affect the migration of ovarian cancer cells and focuses on the role of the adhesive molecule Vn (vitronectin) and its integrin receptors. An in vitro co-culture model indicated that clusters of IGROV1 and SKOV3 cells adhere to MeT-5A mesothelial cells preferentially at intercellular sites, invade the mesothelial monolayer and alter the integrity of the mesothelium. In addition, mesothelial CM (cell-conditioned medium) induces migration of IGROV1 and SKOV3 cells in Boyden chambers and wound healing assays. Furthermore, blocking molecules directed against vitronectin or its alphav integrin receptor decrease mesothelial-CM-induced migration by approximately 40% and 60-70% for IGROV1 and SKOV3 ovarian cancer cells, respectively, in Boyden chamber assays. Wound healing assays that allow cell migration to be measured over 24 h periods demonstrated that blocking molecules prevent the migration of IGROV1 and SKOV3 cells. Vitronectin is present in CM MeT-5A (mesothelial conditioned medium) and in metastatic peritoneal tissue sections. The expression of vitronectin at the periphery of mesothelial cells and within ovarian cancer cell clusters suggests a potential role for this molecule during intraperitoneal implantation of ovarian cancer cells. Vitronectin could represent a target for the development of anti-adhesive strategies to impede ovarian cancer dissemination.