title: GLI1 is regulated through Smoothened-independent mechanisms in neoplastic pancreatic ducts and mediates PDAC cell survival and transformation.
abstract: Pancreatic ductal adenocarcinoma (PDAC) is characterized by the deregulation of the hedgehog signaling pathway. The Sonic Hedgehog ligand (Shh), absent in the normal pancreas, is highly expressed in pancreatic tumors and is sufficient to induce neoplastic precursor lesions in mouse models. We investigated the mechanism of Shh signaling in PDAC carcinogenesis by genetically ablating the canonical bottleneck of hedgehog signaling, the transmembrane protein Smoothened (Smo), in the pancreatic epithelium of PDAC-susceptible mice. We report that multistage development of PDAC tumors is not affected by the deletion of Smo in the pancreas, demonstrating that autocrine Shh-Ptch-Smo signaling is not required in pancreatic ductal cells for PDAC progression. However, the expression of Gli target genes is maintained in Smo-negative ducts, implicating alternative means of regulating Gli transcription in the neoplastic ductal epithelium. In PDAC tumor cells, we find that Gli transcription is decoupled from upstream Shh-Ptch-Smo signaling and is regulated by TGF-beta and KRAS, and we show that Gli1 is required both for survival and for the KRAS-mediated transformed phenotype of cultured PDAC cancer cells.
authors.affiliation: Helen Diller Family Comprehensive Cancer Center, University of California at San Francisco, San Francisco, California 94143, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Nolan-Stevaux
authors.forename: Janet
authors.initials: J
authors.lastname: Lau
authors.forename: Morgan L
authors.initials: ML
authors.lastname: Truitt
authors.forename: Gerald C
authors.initials: GC
authors.lastname: Chu
authors.forename: Matthias
authors.initials: M
authors.lastname: Hebrok
authors.forename: Martin E
authors.initials: ME
authors.lastname: Fernández-Zapico
authors.forename: Douglas
authors.initials: D
authors.lastname: Hanahan
mesh_terms: D000818:Animals; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D002478:Cells, Cultured; D015972:Gene Expression Regulation, Neoplastic; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010183:Pancreatic Ducts / Q000378:metabolism* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000072086:Smoothened Receptor; D016212:Transforming Growth Factor beta / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1
chemical_list: C498520:Gli1 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D043562:Receptors, G-Protein-Coupled; C465570:Shh protein, mouse; C491022:Smo protein, mouse; D000072086:Smoothened Receptor; D016212:Transforming Growth Factor beta; D000071676:Zinc Finger Protein GLI1; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras)