Ascites-induced shift along epithelial-mesenchymal spectrum in ovarian cancer cells: enhancement of their invasive behavior partly dependant on αv integrins.

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence. The presence of ascites, which acts as a dynamic reservoir of active molecules and cellular components, correlates with the OC peritoneal metastasis and is associated with poor prognosis. Since epithelial-mesenchymal transition (EMT) is involved in different phases of OC progression, we have investigated the effect of the unique ascitic tumor microenvironment on the EMT status and the behavior of OC cells. The exposure of three OC cell lines to ascites leads to changes in cellular morphologies. Within ascites, OC cells harboring an initial intermediate epithelial phenotype are characterized by marked dislocation of epithelial markers (E-cadherin, ZO-1 staining) while OC cells initially harboring an intermediate mesenchymal phenotype strengthen their mesenchymal markers (N-cadherin, vimentin). Ascites differentially triggers a dissemination phenotype related to the initial cell features by either allowing the proliferation and the formation of spheroids and the extension of colonies for cells that present an initial epithelial intermediate phenotype, or favoring the migration of cells with a mesenchymal intermediate phenotype. In an ascitic microenvironment, a redeployment of αv integrins into cells was observed and the ascites-induced accentuation of the two different invasive phenotypes (i.e. spheroids formation or migration) was shown to involve αv integrins. Thus, ascites induces a shift toward an unstable intermediate state of the epithelial-mesenchymal spectrum and confers a more aggressive cell behavior that takes on a different pathway based on the initial epithelial-mesenchymal cell features.

Identification of proteins undergoing expression level modifications in WI-38 SV40 fibroblasts overexpressing methionine sulfoxide reductase A.

Methionine sulfoxide reductase A overexpressing WI-38 SV40 human fibroblasts have been previously shown to exhibit higher resistance to oxidative stress by decreasing intracellular reactive oxygen species content and oxidative damage to proteins [C.R. Picot, I. Petropoulos, M. Perichon, M. Moreau, C. Nizard, B. Friguet, Overexpression of MsrA protects WI-38 SV40 human fibroblasts against H(2)O(2)-mediated oxidative stress, Free Radic Biol Med 39 (2005) 1332-1341]. In order to get further insight into the molecular mechanisms underlying this resistance to oxidative stress, proteins that are differentially expressed in methionine sulfoxide reductase A overexpressing cells were identified by 2D gel and Western blot quantitative analyses. Five proteins were shown to be differentially expressed and were identified by mass spectrometry, some of them were related to either cellular protection against oxidative stress, apoptosis or premature ageing.