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Akt Inhibition Overcomes Rapamycin Resistance By Enhancing The Repressive Function Of Pras40 On Mtorc1/4e-Bp1 Axis, Wenting Mi, Qing Ye, Side Liu, Qing-Bai She

Markey Cancer Center Faculty Publications

The mTORC1 inhibitors, rapamycin and its analogs, are known to show only modest antitumor activity in clinic, but the underlying mechanisms remain largely elusive. Here, we found that activated AKT signaling is associated with rapamycin resistance in breast and colon cancers by sustained phosphorylation of the translational repressor 4E-BP1. Treatment of tumor cells with rapamycin or the AKT inhibitor MK2206 showed a limited activity in inhibiting 4E-BP1 phosphorylation, cap-dependent translation, cell growth and motility. However, treatment with both drugs resulted in profound effects in vitro and in vivo. Mechanistic investigation demonstrated that the combination treatment was required to effectively …