mTORC2 Is Required for Proliferation and Survival of TSC2-Null Cells

被引:109
作者
Goncharova, Elena A.
Goncharov, Dmitry A.
Li, Hua
Pimtong, Wittaya
Lu, Stephen
Khavin, Irene
Krymskaya, Vera P. [1 ,2 ,3 ]
机构
[1] Univ Penn, Translat Res Labs, Dept Med, Pulm Allergy & Crit Care Div, Philadelphia, PA 19104 USA
[2] Univ Penn, Abramson Canc Ctr, Philadelphia, PA 19104 USA
[3] Univ Penn, Cardiovasc Inst, Philadelphia, PA 19104 USA
关键词
TUBEROUS SCLEROSIS COMPLEX; RAPAMYCIN ANALOG CCI-779; COA REDUCTASE INHIBITORS; SIMVASTATIN INDUCES APOPTOSIS; S6 KINASE ACTIVATION; SMOOTH-MUSCLE-CELLS; NF-KAPPA-B; MAMMALIAN TARGET; BCL-2; EXPRESSION; DOWN-REGULATION;
D O I
10.1128/MCB.01061-10
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Mutational inactivation of the tumor suppressor tuberous sclerosis complex 2 (TSC2) constitutively activates mTORC1, increases cell proliferation, and induces the pathological manifestations observed in tuberous sclerosis (TS) and in pulmonary lymphangioleiomyomatosis (LAM). While the role of mTORC1 in TSC2-dependent growth has been extensively characterized, little is known about the role of mTORC2. Our data demonstrate that mTORC2 modulates TSC2-null cell proliferation and survival through RhoA GTPase and Bcl2 proteins. TSC2-null cell proliferation was inhibited not only by reexpression of TSC2 or small interfering RNA (siRNA)-induced downregulation of Rheb, mTOR, or raptor, but also by siRNA for rictor. Increased RhoA GTPase activity and P-Ser473 Akt were inhibited by siRNA for rictor. Importantly, constitutively active V14RhoA reversed growth inhibition induced by siRNA for rictor, siRNA TSC1, reexpression of TSC2, or simvastatin. While siRNA for RhoA had a modest effect on growth inhibition, downregulation of RhoA markedly increased TSC2-null cell apoptosis. Inhibition of RhoA activity downregulated antiapoptotic Bcl2 and upregulated proapoptotic Bim, Bok, and Puma. In vitro and in vivo, simvastatin alone or in combination with rapamycin inhibited cell growth and induced TSC2-null cell apoptosis, abrogated TSC2-null tumor growth, improved animal survival, and prevented tumor recurrence by inhibiting cell growth and promoting apoptosis. Our data demonstrate that mTORC2-dependent activation of RhoA is required for TSC2-null cell growth and survival and suggest that targeting both mTORC2 and mTORC1 by a combination of proapoptotic simvastatin and cytostatic rapamycin shows promise for combinational therapeutic intervention in diseases with TSC2 dysfunction.
引用
收藏
页码:2484 / 2498
页数:15
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