Fisetin-induced PTEN expression reverses cellular senescence by inhibiting the mTORC2-Akt Ser473 phosphorylation pathway in vascular smooth muscle cells

Cellular senescence is caused by a wide range of intracellular and extracellular stimuli and influences physiological functions, leading to the progression of age-related diseases. Many studies have shown that cellular senescence is related to phosphatase and tension homolog deleted on chromosome ten (PTEN) loss and mammalian target of rapamycin (mTOR) activation. Although it has been reported that mTOR complex 1 (mTORC1) is major anti-aging target in several cell types, the functions and mechanisms of mTOR complex 2 (mTORC2) during aging have not been elucidated in vascular smooth muscle cells (VSMCs). Therefore, the aim of this study was to reveal the relationship between PTEN and mTORC2 during VSMC senescence. We found adriamycin-induced VSMC senescence was accompanied by reduced PTEN protein expression and upregulation of the mTORC2-Akt (Ser 473) pathway and that fisetin treatment reduced VSMC senescence by increasing PTEN and decreasing mTORC2 protein levels. Furthermore, PTEN played a primary role in the anti-aging effect of fisetin, and fisetin-activated PTEN directly regulated the mTORC2-Akt (Ser 473) signaling pathway, and attenuated senescence phenotypes such as senescence-associated β-galactosidase (SA-β-gal) and the p53-p21 signaling pathway in VSMCs. In mouse aortas, fisetin delayed aging by regulating the PTEN-mTORC2-Akt (Ser473) signaling pathway. These results suggest PTEN and mTORC2 are associated with cellular senescence in VSMCs and that the mTORC2-Akt (Ser 473) signaling pathway be considered a new target for preventing senescence-related diseases.