ABSTRACT
The alphavbeta3 integrin and its ligand vitronectin are expressed by differentiated epithelial ovarian carcinomas and carcinoma cell lines in culture. Moreover, alphavbeta3/vitronectin interaction influences adhesion and migration of ovarian carcinoma cells in culture. For a better understanding of the behavior of these carcinomas, it appeared necessary to study the characteristics of their normal counterpart, the ovarian surface epithelium (OSE). The present study showed that normal cultured human OSE cells, like the carcinoma cells, have the ability to synthesize vitronectin. The vitronectin receptor, alphavbeta3 integrin, is also expressed by OSE cells and is localized in focal contacts close to paxillin, a focal contact-specific protein, and p125(FAK), a cytoskeletal and signaling molecule. This localization suggested an active participation of the integrin in the adhesion and/or proliferation of OSE cells. Indeed, the use of a blocking antibody demonstrated that alphav integrins promote OSE cell adhesion on vitronectin but not on fibronectin and that these integrins are required for maximal proliferative activity. The results suggest a role of the alphavbeta3/vitronectin system in normal OSE physiology and demonstrate that the expression of this system by well-differentiated ovarian carcinomas reflects the retention of normal cell properties.
Subject(s)
Epithelial Cells/metabolism , Ovary/cytology , Receptors, Vitronectin/biosynthesis , Vitronectin/biosynthesis , Adult , Cell Adhesion , Female , Humans , Middle AgedABSTRACT
Extracellular matrix components and integrin receptors are frequently altered in cancer, including ovarian adenocarcinoma. Vitronectin (Vn) is a matrix protein mainly synthesized by liver cells; it is present in normal ovarian surface epithelium and differentiated ovarian adenocarcinoma, but is frequently undetectable in undifferentiated carcinoma (F. Carreiras et al., 1996, Gynecol Oncol 62:260-267). Wondering about the cellular origin of Vn in ovarian carcinoma, we searched for evidence of Vn synthesis by these tumors. We demonstrated that three human ovarian adenocarcinoma cell lines were able to synthesize Vn, as revealed by the presence of Vn mRNA and the protein. The Vn matrix promotes adhesion of ovarian tumor cells through alphav integrins. Moreover, during in vitro growth, Vn is progressively organized into a particular pattern in combination with the recruitment of alphav into focal contacts. Our results suggest that Vn synthesis may participate in ovarian adenocarcinoma cell biology and raise the possibility that altered expression of Vn in some ovarian carcinomas could result from a defect in Vn synthesis.
Subject(s)
Adenocarcinoma/metabolism , Ovarian Neoplasms/metabolism , Vitronectin/biosynthesis , Adenocarcinoma/pathology , Blotting, Northern , Blotting, Western , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Cell Adhesion , DNA Primers , Female , Fluorescent Antibody Technique , Humans , Immunoblotting , Integrins/physiology , Ovarian Neoplasms/pathology , Precipitin Tests , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Tumor Cells, Cultured/cytology , Tumor Cells, Cultured/metabolism , Vitronectin/genetics , Vitronectin/physiologyABSTRACT
Cell migration of ovarian tumoral cells is essential for cell dissemination and for invasion of the submesothelial extracellular matrix (ECM). We have conducted a study of the migratory properties of an ovarian adenocarcinoma cell line (IGROV1) by using 2 distinct methods for the evaluation of cell migration. We found that in a short-term transfilter migration assay, IGROV1 cells migrated toward vitronectin, fibronectin, type IV collagen and laminin in an integrin-dependent manner. When migration was evaluated in a wound healing assay, the restitution of the wounded area was stimulated solely by added, exogenous vitronectin and was almost totally dependent on alpha(v)beta3 integrin function. Moreover, we demonstrated that alpha(v)beta3 was localized in focal contacts restricted to the leading edge of migrating cells, whereas vitronectin notably localized with actin stress fibers and cortical actin. On the other hand, several kinase inhibitors were found to impede migration of IGROV1 induced by vitronectin. It thus appears that alpha(v)beta3-vitronectin interactions lead to the activation of multiple signaling pathway including activation of protein kinase C, phosphatidyl-inositol-3-phosphate kinase and protein tyrosine kinase. The "alpha(v)beta3-vitronectin system" is therefore essential to the migration of human ovarian carcinoma cells.
