Collagen-based three-dimensional culture microenvironment promotes epithelial to mesenchymal transition and drug resistance of human ovarian cancer<i>in vitro</i>

Abstract

Ovarian cancer (OvCa) is a leading cause of mortality from gynecologic malignancy due to its disseminated peritoneal metastasis. The tumor microenvironment dominates epithelial-mesenchymal transition (EMT) development and impacts cancer metastasis as well as mediates drug resistance. Tumour cell interaction with the collagen I matrix is critical in OvCa development. To better understand the role of the collagen matrix and the underlying mechanisms in the early stage of OvCa invasion, we developed a three-dimensional (3D) culture model <i>in vitro</i> by embedding OvCa cells within collagen I to recreate the architecture of a solid tumour. Our results showed that tumour spheroids formed in the 3D collagen model displayed good viability and decreased growth rates, which partly recapitulated the growth behavior of <i>in vivo</i> tumour cells. Collagen I enhanced the OvCa cell motility/invasion capability by up-regulating the expression of MMPs and α5β1 integrin. Moreover, highly invasive OvCa cells in collagen showed the overexpression of mesenchymal markers (<i>N</i>-cadherin, vimentin and fibronectin) and transcriptional factors (Snail and Slug). EMT-associated TGF-β1/Smad4 and Wnt5b/β-catenin signaling pathways were significantly up-regulated accordingly. Additionally, a remarkably enhanced drug resistance to chemotherapeutics was also detected in the 3D cultures. Collectively, the bioengineered 3D collagen models could recapitulate the <i>in vivo</i> tumour-like microenvironment and reflect some biological characteristics of human OvCa more accurately. The collagen I matrix promoted local invasion <i>via</i> EMT and enhanced the multidrug resistance in OvCa. This system might serve as a comprehensive <i>in vitro</i> model to better understand the manifold mechanisms of OvCa metastasis and also provide a robust tool for screening new anti-ovarian cancer therapeutics.