Abstract 54: Cancer-associated fibroblasts induce epithelial-mesenchymal-transition and stemness in non-small-cell lung cancer

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Abstract The tumor microenvironment is composed of different types of stromal cells and a key component of tumor progression. It has been hypothesized that these stromal components are functionally organized to promote the survival of cancer cells. A specific subset of stromal cells, termed cancer-associated fibroblasts (CAFs), secretes factors that promote tumorigensis. To investigate whether CAFs constitute a specific microenvironment conductive for lung cancer progression, we performed in vitro and in vivo experiments using CAFs derived from primary lung cancer in conjunction with the human lung adenocaricinoma cell lines. We first showed that conditioned medium (CM) from human CAFs was biologically active. When human lung adenocarcinoma cell lines (A549 and NCI-H358) were cultured with CM from CAFs, epithelial cells became spindle and scattered as well as decreased cell surface E-cadherin. Further CM increased N-cadherin and vimentin expression, which is a hallmark of an epithelial-mesenchymal-transition (EMT). Coculture experiments using traswell plates with inserts of pore size 3 μm also showed EMT change in cancer cells. CM led cancer cells to enhance expression of stem cell markers such as CD44 and CD133 mRNA levels by ten times. It also triggered the acquisitions of cancer stemness such the ability of resistance to cisplatin or gefitinib as well as sphere formation. These phenotype changes associated with EMT and stemness were inhibited by the addition of TGF-β inhibitor, SB431542 (10 μM). The s.c. coinjection of human lung adenocarcinoma cell lines and human CAFs to the mice result in a high rate of tumor formation compared with the injection of these cell lines without CAFs. A decreased expression of epithelial markers and upregulation of angiogenesis and proliferative index were detected in specimens from mice with coinjection of these cells. TGF β inhibitor attenuated the tumor formation enhanced by coinjection with CAFs. The compound was injected i.p. at 0.2 mg/kg (1 per day, 5 per week for 2 weeks) after coinjection. These results indicate that the paracrine interplay between CAFs and cancer cells mediated by TGF-β signaling leads to an EMT driven gain of cancer stem cell properties and suggest that the CAFs contribute a specific niche for tumor progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 54. doi:1538-7445.AM2012-54