Integrin beta 3 regulates cellular senescence by activating the TGFβ pathway

Cellular senescence is an important in vivo mechanism that prevents the propagation of damaged cells. However, the precise mechanism(s) regulating senescence are not well characterized. Here, we find that ITGB3 (integrin beta 3 or β3) is epigenetically regulated by the Polycomb protein CBX7. β3 expression accelerates the onset of senescence in human primary fibroblasts, by activating the TGFβ pathway in a cell autonomous and non-cell autonomous manner. β3 levels are dynamically increased during oncogeneinduced senescence (OIS) through CBX7 epigenetic regulation. DNA-damage and therapy-induced senescence (TIS) also induce β3 expression. In fact, downregulation of β3 levels override OIS and TIS, independently of its ligand-binding activity. Moreover, cilengitide, a αvβ3 antagonist, has the ability to block the SASP without affecting proliferation. Finally, we show an increase in β3 levels during aging in mice and humans. Altogether, our data show that integrin β3 subunit is a marker and regulator of senescence.