Author of

• 11515

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  P2.05 - Poster Session 2 - Preclinical Models of Therapeutics/Imaging (ID 158)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11527

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    P2.05-012 - An inducible transition cell model reflecting epithelioid versus sarcomatoid differentiation of Malignant Pleural Mesothelioma (ID 1892)

    09:30 - 09:30  |  Author(s): K. Schelch
    • Abstract

    Background
    Malignant pleural mesothelioma (MPM) is an aggressive asbestos-related malignancy characterized by frequent resistance to chemo- and radiotherapy. Signals induced by Fibroblast growth factors (FGF) and their high-affinity receptors (FGFR) have been identified as important drivers for malignant growth in several tumor entities including thoracic malignancies. We have recently demonstrated that FGFR signals stimulate growth and migration in MPM cell models, whereas inhibition of FGFR1 reduced tumor growth and had an antagonistic effect on malignant behavior of MPM cells. In several cell models of biphasic MPM, FGF2 induced phenotypical changes reminiscent of epithelial-mesenchymal-transition (EMT). In this study we analyzed these FGF-induced morphological and functional alterations and the associated signal transduction mechanisms in more detail.

    Methods
    Cells were stimulated with recombinant FGF2 and analyzed by microscopy and ImageJ software. The specific inhibitors PD166866, UO126, MK2206, LY294002 and SB431542 were used to block FGFR1, MEK, AKT, PI3K and TGFbeta receptors, respectively. Alterations in gene expression were determined via whole-genome expression arrays and further evaluated by immunofluorescence. Downstream signaling was investigated by immunoblotting.

    Results
    In M38K and SPC212 cells FGF2 induced morphological alterations that were characterized by a more spindle-shaped appearance and reduced contacts with adjacent cells. This correlated with increased cell migration. With respect to signal transduction, the effects of FGF2 could be blocked by inhibition of FGFR1 or MEK, whereas inhibition of AKT, PI3K or receptors of the TGFbeta/activin family had no effect. Expression arrays of both cell models indicated regulation of several matrix metalloproteinases (MMP1, MMP4), the integrin subunit ITGA6 and the two TGFbeta family-related proteins INHBB and Smad7. Since the phenotypical changes were similar to EMT, genes previously connected to EMT were analyzed. Whereas slug/SNAI2 and ZEB1 were increased, other mesenchymal genes such as vimentin or N-cadherin were already expressed at high levels in the untreated cells, likely due to the mesodermal origin of mesothelial cells. In M38K, E-cadherin was decreased whereas in the more “fibroblastoid-type” SPC212 E-cadherin was generally expressed at very low levels.

    Conclusion
    Our data suggest that FGF2 induces morphological changes that result in a more sarcomatoid cell morphology and expression of some markers connected to EMT. These effects depend on the MAPK pathway and are connected to more aggressive cell behavior, paralleling the higher aggressiveness and worse prognosis of the sarcomatoid and biphasic compared to the epithelioid histological subtype of MPM.