Dihydroartemisinin (DHA), an
anti-malarial drug, has been shown to possess potent anticancer activity, partly by inhibiting the
mammalian target of rapamycin (mTOR) complex 1 (
mTORC1) signaling. However, how DHA inhibits
mTORC1 is still unknown. Here, using
rhabdomyosarcoma (RMS) as a model, we found that DHA reduced cell proliferation and viability in RMS cells, but not those in normal cells, which was associated with inhibition of
mTORC1. Mechanistically, DHA did not bind to mTOR or
FK506 binding protein 12 (
FKBP12). In addition, DHA neither inhibited
insulin-like growth factor-1 receptor (IGF-1R),
phosphoinositide 3-kinase (PI3K), and
extracellular signal-regulated kinase ½ (Erk1/2), nor activated
phosphatase and
tensin homolog (PTEN) in the cells. Rather, DHA activated
AMP-activated protein kinase (AMPK). Pharmacological inhibition of AMPK, ectopic expression dominant negative or
kinase-dead AMPK, or knockdown of AMPKa attenuated the inhibitory effect of DHA on
mTORC1 in the cells. Additionally, DHA was able to induce dissociation of
regulatory-associated protein of mTOR (raptor) from mTOR and inhibit
mTORC1 activity. Moreover, treatment with
artesunate, a
prodrug of DHA, dose-dependently inhibited
tumor growth and concurrently activated AMPK and suppressed
mTORC1 in RMS xenografts. The results indicated that DHA inhibits
mTORC1 by activating AMPK in
tumor cells. Our finding supports that DHA or
artesunate has a great potential to be repositioned for treatment of RMS.