Proinvasive Properties of Ovarian Cancer Ascites-Derived Membrane Vesicles

Abstract

Malignant ovarian ascites are rich in cellular components, membranebound vesicles, and soluble proteins. This study focused on the structure of membrane-bound vesicles and their ability to promote invasion in cultured malignant ovarian epithelium. Membrane vesicles were derived from women with stage I-IV malignant ovarian ascites and from nonmalignant gynecologic ascites. Isolated vesicles were characterized by immunofluorescence and Western blot analysis. Using gel zymography for matrix metalloproteinase (MMP) detection and a colorimetric assay for urokinase-type plasminogen activator (uPA) analysis, we analyzed the proteinase activities of MMP-2, MMP-9, and uPA from the prepared vesicles, whole cells isolated from ascites, and the cell-free ultracentrifuged supernatant. The invasiveness of established cultured malignant ovarian epithelium on addition of ascites-derived vesicles was tested using a Matrigel-based invasion assay. Fractionation of malignant ascites revealed that extracellular matrix-degrading proteinases including MMPs and uPA are localized preferentially in membrane vesicles. All malignant vesicles tested, regardless of cancer stage, stimulated invasion. Furthermore, the combination of ovarian cancer cells and membrane vesicles resulted in greater uPA activation than that of cells or vesicles alone. Membrane vesicles from malignant ascites were also found to contain activated MMP-2, MMP-9, and uPA. Our data suggest that vesiclestimulated proteinase activation leads to increased extracellular matrix degradation, which may facilitate tumor cell invasion and metastasis.

Tumour-derived exosomes and their role in cancer-associated T-cell signalling defects

“…Our findings, as well as those of other investigators, have demonstrated that membrane vesicles isolated from ovarian cancer patients' peripheral blood and malignant effusions appear to be identical, in terms of general protein composition and presence of specific marker proteins (Taylor et al 1980(Taylor et al , 2003Graves et al, 2004). However, to date, it is unclear whether the shed tumourderived membrane vesicles are the same or distinct from tumourderived 'exosomes.'…”

The Rho/ROCK pathway for lysophosphatidic acid-induced proteolytic enzyme expression and ovarian cancer cell invasion

“…The main reasons for the low survival rate of patients with ovarian cancer are caused by the lack of effective early detection and treatment, as well as the highly metastatic nature of the disease (Gardner et al, 1995). The pathogenesis of this disease involves widespread dissemination of malignant ovarian epithelium throughout the entire peritoneal cavity (Graves et al, 2004). Various proteolytic enzymes, including urokinase-type plasminogen activator (uPA) and matrix metalloproteinase (MMP)-2 and MMP-9, are suggested as critical mediators for ovarian cancer metastasis (Kobayashi et al, 1992;Moser et al, 1994;Young et al, 1996;Fishman et al, 1997Fishman et al, , 2001.…”

Ascites induces modulation of α6β1 integrin and urokinase plasminogen activator receptor expression and associated functions in ovarian carcinoma

“…These data indicate that enhancement of a6 integrin and uPA/uPAR in ovarian cancer cells occurs specifically in the presence of ascites without affecting normal ovarian epithelial cell function. Proinvasive properties of ovarian cancer ascitesderived membrane vesicles have been reported recently (Graves et al, 2004).…”