Myofibroblast-derived PDGF-BB promotes hedgehog survival signaling in cholangiocarcinoma cells

Authors


  • Potential conflict of interest: Nothing to report.

  • This work was supported by National Institutes of Health (NIH; Bethesda, MD) grants NIH DK59427 (to G.J.G.), NIH R01 CA 83650, R01 CA 39225 (to A.E.S.), the optical microscopy, clinical, and genetics core of NIH DK84567, and the Mayo Foundation. C.D.F. is a German Research Foundation fellow (Deutsche Forschungsgemeinschaft; grant FI 1630/1-1).

Abstract

Cholangiocarcinoma (CCA) cells paradoxically express the death ligand, tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) and, therefore, are dependent upon potent survival signals to circumvent TRAIL cytotoxicity. CCAs are also highly desmoplastic cancers with a tumor microenvironment rich in myofibroblasts (MFBs). Herein, we examine a role for MFB-derived CCA survival signals. We employed human KMCH-1, KMBC, HuCCT-1, TFK-1, and Mz-ChA-1 CCA cells, as well as human primary hepatic stellate and myofibroblastic LX-2 cells, for these studies. In vivo experiments were conducted using a syngeneic rat orthotopic CCA model. Coculturing CCA cells with myofibroblastic human primary hepatic stellate cells or LX-2 cells significantly decreased TRAIL-induced apoptosis in CCA cells, a cytoprotective effect abrogated by neutralizing platelet-derived growth factor (PDGF)-BB antiserum. Cytoprotection by PDGF-BB was dependent upon Hedgehog (Hh) signaling, because it was abolished by the smoothened (SMO; the transducer of Hh signaling) inhibitor, cyclopamine. PDGF-BB induced cyclic adenosine monophosphate–dependent protein kinase–dependent trafficking of SMO to the plasma membrane, resulting in glioma-associated oncogene (GLI)2 nuclear translocation and activation of a consensus GLI reporter gene-based luciferase assay. A genome-wide messenger RNA expression analysis identified 67 target genes to be commonly up- (50 genes) or down-regulated (17 genes) by both Sonic hedgehog and PDGF-BB in a cyclopamine-dependent manner in CCA cells. Finally, in a rodent CCA in vivo model, cyclopamine administration increased apoptosis in CCA cells, resulting in tumor suppression. Conclusions: MFB-derived PDGF-BB protects CCA cells from TRAIL cytotoxicity by a Hh-signaling–dependent process. These results have therapeutical implications for the treatment of human CCA. (HEPATOLOGY 2011;)

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