J Cancer 2013; 4(5):383-390. doi:10.7150/jca.6545

Research Paper

Plasma Fibronectin Promotes Tumor Cell Survival and Invasion through Regulation of Tie2

Lynn M. Knowles1, Gunjan Malik1, Jan Pilch1,2 ✉

1. Department of Urology, University of Pittsburgh School of Medicine, Shadyside Medical Center, 5200 Centre Avenue, Pittsburgh, PA 15232, USA.
2. Prostate and Urological Cancers Program, University of Pittsburgh Cancer Institute, 5150 Centre Avenue, Pittsburgh, PA 15232, USA.

Abstract

Our previous research has shown that plasma fibronectin promotes lung metastasis by facilitating tumor cell invasion in clotted plasma. To evaluate the role of clotted plasma for tumor cell survival, we treated B16F1 cells embedded in a 3-dimensional matrix of fibrin with tumor necrosis factor α (TNFα), a cytokine with anti-tumor activity. Under these conditions, TNFα caused significant cytotoxicity, which was prevented when we added plasma fibronectin to the fibrin clot. Fibronectin-mediated TNFα resistance was dependent on PI3-kinase, which also mediated the pro-adhesive and pro-invasive effects of plasma fibronectin on tumor cells. To further investigate the role of plasma fibronectin in tumor cell signaling, we performed a gene array that showed specific upregulation of Tie2 in B16F1 cells embedded in fibrin-fibronectin compared to fibrin. Importantly, inhibition of Tie2 resulted in decreased tumor cell invasion, reduced colony formation and increased tumor cell death in response to TNFα. Together, our findings indicate that plasma fibronectin induces tumor cell invasion and protects tumor cells from the cytotoxic effects of inflammatory mediators through up-regulation of Tie2.

Keywords: Plasma fibronectin, Metastasis, Fibrin, Tie2.

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How to cite this article:
Knowles LM, Malik G, Pilch J. Plasma Fibronectin Promotes Tumor Cell Survival and Invasion through Regulation of Tie2. J Cancer 2013; 4(5):383-390. doi:10.7150/jca.6545. Available from http://www.jcancer.org/v04p0383.htm