Investigation Of Salicylate Hepatic Responses In Comparison With Chemical Analogues Of The Drug
Authors: Amy R. Cameron, Lisa Logie, Kashyap Patel, Sandra Bacon, Calum Forteath, Jean Harthill, Adam Roberts, Calum Sutherland, Derek Stewart, Benoit Viollet, Kei Sakamoto, Gordon McDougall, Marc Foretz, Graham Rena
Abstract:
The hydroxybenzoic acid salicylate exhibits potential anti-hyperglycemic effects attributed to its influence on mitochondrial uncoupling, activation of AMP-activated protein kinase (AMPK), and inhibition of NF-κB signaling. In this study, we aimed to assess the significance of these effects in controlling hepatocyte glucose production by comparing salicylate with inactive hydroxybenzoic acid analogs of the drug. Our experiments in rat H4IIE hepatoma cells revealed that salicylate uniquely activated AMPK, while mTOR signaling reduction was observed across various analogs. In a subset of analogs, salicylate alone decreased promoter activity of the gluconeogenic enzyme glucose 6-phosphatase and suppressed basal glucose production in mouse primary hepatocytes. Both salicylate and 2,6 dihydroxybenzoic acid inhibited TNFα-induced IκB degradation. However, genetic knockout experiments demonstrated that salicylate's effect on IκB degradation was independent of AMPK. Previous studies also indicated AMPK-independent glucose regulation, and our findings revealed that direct inhibition of NF-κB or mTOR signaling did not suppress glucose production, suggesting additional factors beyond these signaling pathways play a role in salicylate's response. Notably, H4IIE cells displayed high sensitivity to uncoupling with modest doses of salicylate, similar to the anti-hyperglycemic agent 2,4-dinitrophenol, while two non-anti-hyperglycemic salicylate analogs had no discernible effect. This supports earlier literature indicating that salicylates exert anti-hyperglycemic effects, at least partially, through uncoupling mechanisms.
Keywords
Salicylate; AMPK; mTOR signalling; NF-κB signalling; Gluconeogenesis
Citaion: Amy R. Cameron, Lisa Logie, Kashyap Patel, Sandra Bacon, Calum Forteath, Jean Harthill, Adam Roberts, Calum Sutherland, Derek Stewart, Benoit Viollet, Kei Sakamoto, Gordon McDougall, Marc Foretz, Graham Rena Investigation Of Salicylate Hepatic Responses In Comparison With Chemical Analogues Of The Drug doi:10.1016/j.bbadis.2016.04.015.
Received: 15 January 2016, Revised: 17 April 2016, Accepted: 22 April 2016, Available online: 27 April 2016
Copyright: © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Conclusion
In this work, we have investigated responses to SA in hepatocytes. Comparison with a panel of SA analogues suggests that mitochondrial uncoupling and AMPK activation but not other signalling pathways correlate well with published anti-hyperglycaemic effects.
Acknowledgements
We thank Dr. Craig Beall (Exeter) for assistance on Seahorse experiments. GR gratefully acknowledges support from MRC (MR/K012924/1), the Cunningham Trust, and the Diabetes UK RW & JM Collins studentship (12/0004625), which is supporting CF. SB was supported by a Ph.D. studentship from the Rank Prize Funds, with additional support provided by the University of Dundee. KP was supported by a Wellcome Trust Clinical Ph.D. studentship. The research was also supported by Tenovus Scotland (GR), by the UK Medical Research Council (KS and GR), by the Région Ile de France-CORDDIM (MF), and by the Société Francophone du Diabète (MF). DS and GMcD acknowledge funding from The Scottish Government's Rural and Environment Science and Analytical Services Division.
