Myofibroblast-derived PDGF-BB promotes Hedgehog survival signaling in cholangiocarcinoma cells.
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.
Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA.
Christian D
CD
Fingas
Steven F
SF
Bronk
Nathan W
NW
Werneburg
Justin L
JL
Mott
Maria E
ME
Guicciardi
Sophie C
SC
Cazanave
Joachim C
JC
Mertens
Alphonse E
AE
Sirica
Gregory J
GJ
Gores
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D000077214:Becaplermin; D001650:Bile Duct Neoplasms / Q000235:genetics / Q000503:physiopathology*; D001653:Bile Ducts, Intrahepatic / Q000503:physiopathology*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000235:genetics / Q000503:physiopathology*; D018920:Coculture Techniques; D053823:Hedgehog Proteins / Q000502:physiology*; D055166:Hepatic Stellate Cells / Q000378:metabolism; D006801:Humans; D008297:Male; D020574:Proto-Oncogene Proteins c-sis / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D000072086:Smoothened Receptor; D014157:Transcription Factors / Q000378:metabolism; D014704:Veratrum Alkaloids / Q000494:pharmacology; D000071676:Zinc Finger Protein GLI1
C400551:GLI1 protein, human; D053823:Hedgehog Proteins; D020574:Proto-Oncogene Proteins c-sis; D043562:Receptors, G-Protein-Coupled; C491023:SMO protein, human; D000072086:Smoothened Receptor; D014157:Transcription Factors; D014704:Veratrum Alkaloids; D000071676:Zinc Finger Protein GLI1; D000077214:Becaplermin; C000541:cyclopamine