SIRT1 and Familial prostate cancer: Additionally, shRNA-mediated inhibition of SIRT1 expression induces proliferation and inhibits autophagy of DU145 and PC3 prostate cancer cells by repressing the phosphorylation of p70 ribosomal S6 kinases (S6K) and 4E-binding protein 1 [87], which are downstream effectors of the mammalian target of rapamycin 1 (mTORC1)-mediated protein synthesis regulation [127].