mTORC2 Is Required for Proliferation and Survival of TSC2-Null Cells
mTORC2 Is Required for Proliferation and Survival of TSC2-Null Cells
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DOI：
10.1128/mcb.01061-10
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发表时间：
2011-06-01
影响因子：
5.3
通讯作者：
Krymskaya, Vera P.
中科院分区：
文献类型：
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作者：
Goncharova, Elena A.;Goncharov, Dmitry A.;Krymskaya, Vera P.
肿瘤抑制因子结节性硬化症复合体2（TSC 2）的突变失活组成性激活mTORC 1，增加细胞增殖，并诱导在结节性硬化症（TS）和肺淋巴管平滑肌瘤病（LAM）中观察到的病理表现。虽然mTORC 1在TSC 2依赖性生长中的作用已被广泛表征，但对mTORC 2的作用知之甚少。我们的数据表明，mTORC 2通过RhoA GT3和Bcl 2蛋白调节TSC 2缺失细胞的增殖和存活。TSC 2-null细胞增殖不仅受到TSC 2的再表达或小干扰RNA（siRNA）诱导的Rheb、mTOR或raptor下调的抑制，而且受到针对rictor的siRNA的抑制。Rictor的siRNA可抑制RhoA GT3活性和P-Ser 473 Akt的增加。重要的是，组成型活性V14 RhoA逆转了由针对Rictor的siRNA、siRNA TSC 1、TSC 2的再表达或辛伐他汀诱导的生长抑制。虽然RhoA的siRNA对生长抑制具有适度的作用，但RhoA的下调显著增加了TSC 2无效细胞凋亡。抑制RhoA活性下调抗凋亡Bcl 2和上调促凋亡Bim，博克，和彪马。在体外和体内，辛伐他汀单独或与雷帕霉素联合抑制细胞生长，诱导TSC 2-null细胞凋亡，消除TSC 2-null肿瘤生长，提高动物存活率，并通过抑制细胞生长和促进凋亡预防肿瘤复发。我们的数据表明，mTORC 2依赖性激活的RhoA是所需的TSC 2无效的细胞生长和存活，并表明，靶向mTORC 2和mTORC 1的促凋亡辛伐他汀和细胞生长抑制剂雷帕霉素的组合显示出联合治疗干预与TSC 2功能障碍的疾病的希望。
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.