title: Niclosamide blocks glucagon phosphorylation of Ser552 on β-catenin in primary rat hepatocytes via PKA signalling.
abstract: Recently, it has been found that glucagon is able to activate the β-catenin signalling pathway leading to increased cyclin D1 and c-Myc expression in liver. Therefore the main aim of the present study is to determine whether the effect of glucagon activating β-catenin signalling leading to increased target gene expression is mediated through cAMP activation of PKA (protein kinase A). Primary rat hepatocytes were incubated with insulin, glucagon or adrenaline (epinephrine) and a range of inhibitors of PI3K (phosphoinositide 3-kinase), Wnt, mitochondrial uncoupler (niclosamide) or PKA inhibitors to dissect out the pathway leading to increased Ser(552) phosphorylation on β-catenin following glucagon exposure. In primary rat hepatocytes, we found that short exposure to glucagon or adrenaline caused a rapid increase in Ser(552) phosphorylation on β-catenin that leads to increased cyclin D1 and c-Myc expression. A range of PI3K and Wnt inhibitors were unable to block the effect of glucagon phosphorylating β-catenin. Interestingly, both niclosamide and the PKA inhibitor H89 blocked the glucagon effect on β-catenin signalling, leading to a reduction in target gene expression. Likewise, niclosamide inhibited cAMP levels and the direct addition of db-cAMP (dibutyryl-cAMP sodium salt) also resulted in Ser(552) phosphorylation of β-catenin. We have identified a new pathway via glucagon signalling that leads to increased β-catenin activity that can be reversed with the antihelminthic drug niclosamide, which has recently shown promise as a potential treatment of T2D (Type 2 diabetes). This novel finding could be useful in liver cancer treatment, particularly in the context of T2D with increased β-catenin activity.
authors.affiliation: Department of Pharmacology, UNSW Australia, Sydney, NSW 2052, Australia.
authors.forename: Md Kamrul H
authors.initials: MK
authors.lastname: Chowdhury
authors.affiliation: Department of Pharmacology, UNSW Australia, Sydney, NSW 2052, Australia.
authors.forename: Lindsay E
authors.initials: LE
authors.lastname: Wu
authors.affiliation: Victor Chang Cardiac Research Institute, Sydney, NSW 2010, Australia.
authors.forename: James L J
authors.initials: JL
authors.lastname: Coleman
authors.affiliation: Victor Chang Cardiac Research Institute, Sydney, NSW 2010, Australia.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Smith
authors.affiliation: Department of Pharmacology, UNSW Australia, Sydney, NSW 2052, Australia.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Morris
authors.affiliation: Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Shepherd
authors.affiliation: Department of Pharmacology, UNSW Australia, Sydney, NSW 2052, Australia g.smith@unsw.edu.au.
authors.forename: Greg C
authors.initials: GC
authors.lastname: Smith
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000378:metabolism; D005934:Glucagon / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism*; D008297:Male; D009534:Niclosamide / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D016271:Proto-Oncogene Proteins c-myc; D051176:beta Catenin; D003994:Bucladesine; D009534:Niclosamide; D005934:Glucagon; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: H89; Type 2 diabetes; cancer; glucagon; niclosamide; protein kinase A (PKA); β-catenin