被撤回的出版物: Nonsteroidal Anti-Inflammatory Drug Flufenamic Acid Is a Potent Activator of AMP-Activated Protein Kinase (Retracted article. See vol. 295, pg. 670, 2020)

Flufenamic acid (FFA) is a nonsteroidal anti-inflammatory drug (NSAID). It has anti-inflammatory and antipyretic properties. In addition, it modulates multiple channel activities. The mechanisms underlying the pharmacological actions of FFA are presently unclear. Given that AMP-activated protein kinase (AMPK) has both anti-inflammatory and channel-regulating functions, we examined whether FFA induces AMPK activation. 1) Exposure of several different types of cells to FFA resulted in an elevation of AMPK alpha phosphorylation at Thr172. This effect of FFA was reproduced by functionally and structurally similar mefenamic acid, tolfenamic acid, niflumic acid, and meclofenamic acid. 2) FFA-induced activation of AMPK was largely abolished by the treatment of cells with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (an intracellular Ca2+ chelator) or depletion of extracellular Ca2+, whereas it was mimicked by stimulation of cells with the Ca2+ ionophore 5-(methylamino)-2-({(2R,3R,6S,8S,9R,11R)-3,9,11-trimethyl-8-[(1S)-1-methyl-2-oxo-2-(1H-pyrrol-2-yl)ethyl]-1,7-dioxaspiro[5.5]undec-2-yl}methyl)-1,3-benzoxazole-4-carboxylic acid (A23187) or ionomycin. 3) FFA triggered a rise in intracellular Ca2+, which was abolished by cyclosporine, a blocker of mitochondrial permeability transition pore. Cyclosporine also abolished FFA-induced activation of AMPK. 4) Inhibition of Ca2+/calmodulin-dependent kinase kinase beta (CaMKK beta) with 7-oxo-7Hbenzimidazo[2,1-a]benz[de]isoquinoline-3-carboxylic acid acetate (STO-609) or down-regulation of CaMKK beta with short interfering RNA largely abrogated FFA-induced activation of AMPK. 5) FFA significantly suppressed nuclear factor-kappa B activity and inducible nitric-oxide synthase expression triggered by interleukin-1 beta and tumor necrosis factor alpha. This suppression was also largely abrogated by STO-609. Taken together, we conclude that FFA induces AMPK activation through the Ca2+-CaMKK beta pathway. Activation of AMPK is a presently unrecognized important mechanism underlying the pharmacological effects of FFA.