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Research on tumor-suppressive activity of apoptosis-related cysteine proteinase ICH-1

凋亡相关半胱氨酸蛋白酶ICH-1的抑癌活性研究

基本信息

批准号：
09680711
负责人：
HIWASA Takaki
金额：
$ 2.3万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09680711/
关键词：
Apoptosis Protease Caspase Cancer Ras がん抑制活性

项目摘要

Although it is generally accepted that caspase family proteases play central roles in induction of apoptosis, their other biological activity remains to be proved. Therefore, we have transfected cDNAs of caspase-1 (ICE), 2 (ICH-1) and 3 (CPP32) into Ha-ras-transformed NIH3T3 cells and investigated the effects after induction of their expression. High expression of these proteases alone did not result in apoptosis-like cell death. However, morphological reversion was frequently observed in clones which overexpressed caspase-2. The reversion was well correlated to the expression level of caspase-2. Moreover, the reverted clones lost the ability of anchorage-independent growth in soft agar medium. These results suggest that caspase-2 possesses the tumor suppressive activity toward Ha-ras-transformed cells. Similar effects of caspase-2 were also observed for v-src-transformed NIH3T3 cells but not for Ki-ras-transformed cells. Thus, caspase-2 may affect a signal transduction pathway which is specific for Src and Ha-Ras. Further western blot analysis showed that the expression level of Ha-Ras was reduced in caspase-2-producing cells. In vitro incubation of cell extract of Ha-ras-transformed cells resulted in degradation of Ha-Ras protein. Th is degradation was completely suppressed in the presence of caspase inhibitors. Taken together, it is plausible that caspase-2 induced reversion of transformed cells by stimulating the degradation of Ha-Ras protein.

虽然人们普遍认为caspase家族蛋白酶在诱导细胞凋亡中起着核心作用，但它们的其他生物学活性仍有待证实。因此，我们将caspase-1（ICE）、2（ICH-1）和3（CPP 32）的cDNA转染Ha-ras转化的NIH 3 T3细胞，并研究诱导其表达后的效果。这些蛋白酶单独的高表达不会导致细胞凋亡样细胞死亡。然而，形态逆转经常观察到过度表达caspase-2的克隆。逆转与caspase-2的表达水平密切相关。此外，回复的克隆丧失了在软琼脂培养基上的非贴壁生长能力。这些结果表明caspase-2对Ha-ras转化细胞具有肿瘤抑制活性。caspase-2对v-src转化的NIH 3 T3细胞也有类似的作用，但对Ki-ras转化的细胞没有作用。因此，caspase-2可能影响Src和Ha-Ras特异性的信号转导途径。进一步的western blot分析表明，Ha-Ras的表达水平在caspase-2产生细胞中降低。Ha-ras转化细胞的细胞提取物的体外孵育导致Ha-Ras蛋白的降解。这种降解在半胱天冬酶抑制剂的存在下被完全抑制。综上所述，caspase-2通过刺激Ha-Ras蛋白的降解诱导转化细胞的逆转是合理的。