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T. Kimura

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    O12 - Lung Cancer Biology II (ID 87)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Biology
    • Presentations: 1
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      O12.07 - Pulmonary fibroblasts increase EMT signaling and decrease sensitivity to chemotherapy in non-small cell lung cancer cells via TGF-beta and IL-6 signaling (ID 265)

      10:30 - 12:00  |  Author(s): T. Kimura

      • Abstract
      • Presentation
      • Slides

      The tumor microenvironment is a key factor in tumor progression. A specific subset of stromal cells, termed cancer associated fibroblasts (CAFs), modulate the behavior of adjacent cancer cells by secreting various growth factors and cytokines. The purpose of this study was to clarify the roles of transforming growth factor (TGF)-β and interleukin (IL)-6 in the communication between CAFs and non-small-cell lung cancer (NSCLC) cells.

      Fibroblasts obtained during surgical exploration were co-cultured with human lung adenocarcinoma cell lines. We defined fibroblasts obtained from tumors as CAFs and those from normal lung tissue as lung normal fibroblasts (LNFs). Immunohistochemistry was used to examine the fibroblast distribution, as well as TGF-β and IL-6 expression in 60 tumor specimens obtained from patients with NSCLC after undergoing induction chemotherapy or chemoradiotherapy (ITx).

      The expression levels of myofibroblast markers were higher in CAFs than LNFs after 5 passages in the absence of continuing interaction with carcinoma cells, and we used at least 2 pairs of those CAFs and LNFs in the following experiments. Conditioned medium (CM) from both types of fibroblasts induced epithelial mesenchymal transition (EMT) and acquisition of cancer stemness in lung cancer cells (A549 and NCI-H358), indicating it to be biologically active. Phenotypic changes of cancer cells by CM from CAFs were greater than those induced by CM from LNFs. These CAF-induced changes were inhibited by addition of the TGF-β inhibitor SB431542 or IL-6 receptor neutralizing antibody (IL6-R-Ab). The concentrations of TGF-β1 and IL-6 were higher in CM from CAFs as compared to that from LNFs. Subcutaneous co-injection of lung cancer cells and CAFs in mice enhanced tumor growth when compared with cancer cells alone, which was attenuated by administration of SB431542 or IL-6R-Ab. These findings suggested that CAFs may be more activated in our experimental system as compared to LNFs, and stimulate tumor progression via TGF-β and IL-6 signaling. In addition, decreased expression of epithelial markers and upregulation of mesenchymal markers were detected in surgically resected specimens after ITx as compared with biopsy specimens obtained before treatment. The disease-free survival rate of patients with EMT marker-positive tumors was significantly lower than that of those with EMT marker-negative tumors, indicating that EMT changes are associated with insensitivity to ITx. Furthermore, an increased diffuse distribution pattern of SMA-positive activated fibroblasts was significantly correlated with the expression of EMT markers. Also, though SMA-stained fibroblasts expressed IL-6 in the surgical specimens, TGF-β was expressed in cancer cells as well as CAFs after ITx. Together, our results suggest that tumor stromatic tissues including CAFs increase in response to ITx, while CAFs secrete TGF-β and IL-6, inducing EMT in cancer cells.

      The TGF-β and IL-6 axis induces EMT and stimulates tumor progression, while TGF-β and IL-6 may play roles to contribute to communication between CAFs and NSCLC cells for tumor progression. Targeting CAFs as a therapeutic strategy against cancer is an intriguing concept that would benefit from further study.

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