Gliclazide, a K channel blocker, inhibits vascular smooth muscle cell proliferation through the CaMKKβ-AMPK pathway.

Gliclazide, a sulfonylurea that is widely used to treat type II-diabetes, specifically blocks K channels and recombinant smooth muscle (SUR2B/Kir6.1) K channels with high potency. Furthermore, it exerts antioxidant properties and inhibits tumor cell proliferation. In this study, we investigated the inhibitory effect of gliclazide on vascular smooth muscle cell (VSMC) proliferation and tried to identify the underlying signaling pathway. We first investigated the effect of gliclazide-induced AMP-activated protein kinase (AMPK) activation on the proliferation of VSMCs. Gliclazide induced phosphorylation of AMPK in a dose- and time-dependent manner and inhibited VSMC proliferation following stimulation by platelet-derived growth factor (PDGF). However, K channel openers and Kir6.1 siRNA prevented gliclazide-mediated inhibition of VSMC proliferation. Gliclazide also increased the levels of Ca/calmodulin-dependent protein kinase kinase β (CaMKKβ), an upstream kinase of AMPK. These findings suggested that the effects of K channels on AMPK activity were mediated by the regulation of intracellular Ca levels. Oral administration of 2mg/kg gliclazide resulted in the activation of CaMKKβ and AMPK in vivo, suggesting that gliclazide suppressed VSMC proliferation via the CaMKKβ-AMPK signaling pathway. Taken together, our observations indicated that gliclazide-induced AMPK activation may act to prevent diabetes-associated atherosclerosis.