Angiotensin II Receptor Type 1 Antagonists Modulate Vascular Smooth Muscle Cell Proliferation and Migration via AMPK/mTOR

The aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) in the vascular wall are crucial pathological events involved in cardiovascular impairments including hypertension, heart failure, and atherosclerosis. At the molecular level, the mammalian target of rapamycin (mTOR)-ribosomal protein S6 kinase beta-1 (p70S6K) signaling pathway is essential to potentiate VSMC proliferation and migration. Although angiotensin II receptor type 1 ­(AT1-R) antagonists such as valsartan and telmisartan have a significant cardiovascular protective effect, the molecular basis of this class of drugs in VSMC proliferation and migration remains elusive. By using cultured VSMCs, adenosine monophosphate-activated protein kinase (AMPK) α2 knockout mice, and hypertensive rat models, this study investigated whether AT1-R antagonists can inhibit the mTOR-p70S6K signaling pathway in VSMCs and the vascular wall. Valsartan activated AMPK, which in turn suppressed reactive oxygen species production and consequently attenuated VSMC proliferation and migration. In vivo, a clinical dose of telmisartan significantly inhibited the mTOR-p70S6K signaling pathway in the vascular wall of wild-type but not AMPKα2–/– mice. Furthermore, spontaneously hypertensive rats had significantly elevated phosphorylation of mTOR and p70S6K in the aorta compared to Wistar-Kyoto rats, which were reduced by telmisartan administration. These data suggest that AT1-R antagonists inhibit VSMC proliferation and migration via their regulation of AMPK, mTOR, and p70S6K, which contribute to the cardioprotective effects of these drugs.