DEPTOR Is A Direct P53 Target That Suppresses Cell Growth And Chemosensitivity

DEP-domain containing mTOR-interacting protein(DEPTOR),a natural mTOR inhibitor,plays essential roles in several pathways,such as cell growth,metabolism,apoptosis,and immunity.Given the vital role of DEPTOR in modulating the mTOR signaling,a diversity of transcriptional control of DEPOTR expression has been reported,which are cell-and context-specific variables.However,whether there exists a general regulation of DEPTOR expression has largely remained unknown.If a transcription factor can be found that can target and regulate DEPTOR expression in general,it may benefit the researches of DEPTOR related signalings and diseases.In this study,by using immunoblotting,chromatin immunoprecipitation(Ch IP)assay,q RT-PCR,dual-luciferase reporter assay,gene knockdown/knockout,and other biochemistry and molecular biology related technologies,we found that DEPTOR is a target of tumor suppressor p53 which can inhibit cell growth and chemosensitivity.Our conclusion is supported by the following evidences:(1)DEPTOR expression is positively correlated with p53 activity in both in vitro cultured cancer cells and in vivo mice organs;(2)p53 directly binds to and activates DEPTOR promoter,which was verified by dual-luciferase reporter assay and Ch IP assay;(3)Depletion the p53 binding sequence of DEPTOR promoter by CRISPR-Cas9 technology decreases DEPTOR expression and promotes cell growth and survival via activating AKT signaling;(4)Inhibition of AKT by small molecular inhibitor or genetic knockdown suppresses DEPTOR promoter depletion-mediated cell growth and survival superiorities;(5)Activating p53 by genotoxic stress agent doxorubicin induces DEPTOR expression and subsequently represses cell chemosensitivity to doxorubicin treatment.In summary,we reported that p53 directly binds to the DEPTOR promoter and activates its transcription.p53-mediated DEPTOR expression inhibits cell growth and viability by inhibiting AKT under normal conditions.Under stress,activation of p53 by genotoxin(e.g.doxorubicin)can significantly increase DEPTOR expression and activate AKT by alleviating the feedback inhibition of S6K1 to IRS1,thereby inducing chemical resistance to doxorubicin.