title: Combinatorial chemoprevention reveals a novel smoothened-independent role of GLI1 in esophageal carcinogenesis.
abstract: Reflux-induced injury promotes esophageal adenocarcinoma, one of the most rapidly increasing, highly lethal cancers in Western countries. Here, we investigate the efficacy of a combinatorial chemoprevention strategy for esophageal adenocarcinoma and characterize the underlying molecular mechanisms. Specifically, our approach involves the use of ursodeoxycholic acid (Urso) due to its ability to decrease injury-inducing bile salts in combination with Aspirin to mitigate the consequences of injury. We find that Urso-Aspirin combination reduces the risk of adenocarcinoma in vivo in animals with reflux, decreases the proliferation of esophageal adenocarcinoma cells, and downregulates a key cell cycle regulator, CDK2. Mechanistically, using cell growth, luciferase reporter, expression, and chromatin immunoprecipitation assays, we identify GLI1, a Hedgehog-regulated transcription factor, as a novel target of Urso-Aspirin combination. We show that GLI1 is upregulated during esophageal carcinogenesis, and GLI1 can bind to the CDK2 promoter and activate its expression. Although the Urso-Aspirin combination downregulates GLI1, the GLI1 overexpression not only abrogates the effect of this combination on proliferation but it also restores CDK-2 expression. These findings support that the chemopreventive effect of the Urso-Aspirin combination occurs, at least in part, through a novel GLI1-CDK2-dependent mechanism. To further understand the regulation of CDK2 by GLI1, both pharmacologic and RNAi-mediated approaches show that GLI1 is a transcriptional activator of CDK2, and this regulation occurs independent of Smoothened, the central transducer of the Hedgehog canonical pathway. Collectively, these results identify a novel GLI1-to-CDK2 pathway in esophageal carcinogenesis, which is a bona fide target for effective combinatorial chemoprevention with Urso and Aspirin.
authors.affiliation: Division of Gastroenterology and Hepatology, Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN, USA.
authors.forename: Sumera I
authors.initials: SI
authors.lastname: Ilyas
authors.forename: Cathrine J
authors.initials: CJ
authors.lastname: Demars
authors.forename: Andrea
authors.initials: A
authors.lastname: Comba
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Gainullin
authors.forename: Zaheer
authors.initials: Z
authors.lastname: Rizvi
authors.forename: Luciana L
authors.initials: LL
authors.lastname: Almada
authors.forename: Kenneth
authors.initials: K
authors.lastname: Wang
authors.forename: Gwen
authors.initials: G
authors.lastname: Lomberk
authors.forename: Martin E
authors.initials: ME
authors.lastname: Fernández-Zapico
authors.forename: Navtej S
authors.initials: NS
authors.lastname: Buttar
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D001241:Aspirin / Q000008:administration & dosage*; D001471:Barrett Esophagus / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects; D051357:Cyclin-Dependent Kinase 2 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects; D004938:Esophageal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D006801:Humans; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011485:Protein Binding; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D014580:Ursodeoxycholic Acid / Q000008:administration & dosage*; D000071676:Zinc Finger Protein GLI1
chemical_list: D016588:Anticarcinogenic Agents; D015513:Oncogene Proteins; D015534:Trans-Activators; D000071676:Zinc Finger Protein GLI1; D014580:Ursodeoxycholic Acid; D051357:Cyclin-Dependent Kinase 2; D001241:Aspirin