Mechanism of p110γ-mediated growth suppression

p110γ介导的生长抑制机制

基本信息

批准号：
13680798
负责人：
SASAKI Takehiko
金额：
$ 2.3万
依托单位：
Tokyo Metropolitan Institute of Medical Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680798/
关键词：
phosphoinositide signal transduction cell growth PI3-kinase

项目摘要

Phosphoinositide 3-kinases (PI3Ks) constitute a family of evolutionarily conserved lipid kinases that regulate a vast array of fundamental cellular responses, including proliferation, transformation, differentiation and protection from apoptosis. We found that genetic inactivation of p110γ, the catalytic subunit of PI3Kγ, leads to development of invasive colorectal adenocarcinomas in mice. In humans, p110γ protein expression is lost in primary colorectal adenocarcinomas from patients and colon cancer ceil lines. Overexpression of p110γin human colon cancer cells resulted in suppression of their growth.To elucidate the underlying mechanism for the tumor suppressive effect of p110γ, we studied the ability of various p110γ mutants to suppress growth of human colorectal cancer cell lines in vitro. I found that overexpression of a kinase-dead mutant of p110γ (R947P) in HCT116 and DLD1 inhibited cell growth as assessed by colony formation assay and focus assay. These results suggest that P13 … More K activity is dispensable for the tumor suppressive effect of p110γ. As the growth suppressive effects did not depend on its enzymatic activity, we next examined which domain structure is sufficient and/or necessary for the effects. Recent structural studies have revealed that p110γpossesses five distinct domains, namely, N-terminal PH domain, Ras-binding domain, C2-domain, kinase domain and Helical domain. Expression of either the Ras-binding domain or the kinase domain led to growth suppression in the colon cancer cells. However, two Ras-binding mutants that cannot bind to Ras suppressed cell growth and wild type p110γ showed the effects in a DLD1 cell line that lacks endogenous Ki-Ras expression. In addition, expression of truncated mutants that lack the C-terminus kinase domain with intact Ras-binding domain had no effect on cell growth. Taken together, these results demonstrate that the kinase domain is necessary and sufficient for the growth suppression of the colon cancer cells by p110γ. Notably, the conclusion that the kinase activity is dispensable for the effects, provides a novel paradigm for p110γfunction and predict a unique signaling cascade that suppresses tumorigenesis. Less

磷酸肌醇3-激酶（PI3KS）构成了一种家族保守的脂质激酶，估计了巨大的damer反应，包含的泛滥，转化，差异化，差异化和对PI3Kγ的保护，导致侵入性结肠菌文化纯净腺素磷酸菌菌的促进。在p110γ的肿瘤抑制作用中，丢失了一级结肠直肠疾病，研究了各种p110γ的能力HCT116中的p110γ（R947p）的死亡突变体抑制了通过颜色和焦点刺激的细胞生长。 /最近的结构研究所必需的p110γPOSSESSS，五个不同的域ding域，C2域，激酶结构域和螺旋结构域。细胞。将RAS抑制的RAS结合毒素和野生YPEP110γ显示出缺乏内源性Ki-Ras表达的DLD1细胞系中的作用。 RAS结合结构域对细胞生长没有影响，表明激酶结构域是必要的，足以通过P110γ抑制结肠癌细胞。预测抑制肿瘤发生的IQUENTION级联。