Mesothelial cells promote early ovarian cancer metastasis through fibronectin secretion
Hilary A. Kenny, … , David Bowtell, Ernst Lengyel
Hilary A. Kenny, … , David Bowtell, Ernst Lengyel
Published September 9, 2014
Citation Information: J Clin Invest. 2014;124(10):4614-4628. https://doi.org/10.1172/JCI74778.
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Research Article

Mesothelial cells promote early ovarian cancer metastasis through fibronectin secretion

Abstract

Ovarian cancer (OvCa) metastasizes to organs in the abdominal cavity, such as the omentum, which are covered by a single layer of mesothelial cells. Mesothelial cells are generally thought to be “bystanders” to the metastatic process and simply displaced by OvCa cells to access the submesothelial extracellular matrix. Here, using organotypic 3D cultures, we found that primary human mesothelial cells secrete fibronectin in the presence of OvCa cells. Moreover, we evaluated the tumor stroma of 108 human omental metastases and determined that fibronectin was consistently overexpressed in these patients. Blocking fibronectin production in primary mesothelial cells in vitro or in murine models, either genetically (fibronectin 1 floxed mouse model) or via siRNA, decreased adhesion, invasion, proliferation, and metastasis of OvCa cells. Using a coculture model, we determined that OvCa cells secrete TGF-β1, which in turn activates a TGF-β receptor/RAC1/SMAD-dependent signaling pathway in the mesothelial cells that promotes a mesenchymal phenotype and transcriptional upregulation of fibronectin. Additionally, blocking α5 or β1 integrin function with antibodies reduced metastasis in an orthotopic preclinical model of OvCa metastasis. These findings indicate that cancer-associated mesothelial cells promote colonization during the initial steps of OvCa metastasis and suggest that mesothelial cells actively contribute to metastasis.

Authors

Hilary A. Kenny, Chun-Yi Chiang, Erin A. White, Elizabeth M. Schryver, Mohammed Habis, Iris L. Romero, Andras Ladanyi, Carla V. Penicka, Joshy George, Karl Matlin, Anthony Montag, Kristen Wroblewski, S. Diane Yamada, Andrew P. Mazar, David Bowtell, Ernst Lengyel

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Figure 6

Tumor cells induce fibronectin expression in mesothelial cells through a TGF-β1–dependent signaling pathway.

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Tumor cells induce fibronectin expression in mesothelial cells through a...
(A) Left: qRT-PCR analysis for CDH1 and VIM. Primary human mesothelial cells were cultured on plastic or cocultured with the indicated OvCa cells for 48 hours followed by cell separation using FACS and extraction of RNA (mean ± SEM; n = 3; 3 independent experiments). *P < 0.05, **P < 0.01, Student’s t test. Right: Immunoblot analysis of fibronectin, E-cadherin, and vimentin in primary human mesothelial cells treated with or without SKOV3ip1 CM. (B and C) Immunoblots for fibronectin. (B) Primary human mesothelial cells were treated with SKOV3ip1 CM for 72 hours, and cell lysates were extracted. (C) Detection of fibronectin secreted by primary human mesothelial cells treated with or without SKOV3ip1 CM and the RHO kinase inhibitor, the RAS signaling activity inhibitor, the RAC-GEF interaction inhibitor, the TGF-βRI kinase inhibitor I, or the TGF-βRII blocking antibody.