Cleavage of β-catenin by calpain in prostate and mammary tumor cells
Cleavage of β-catenin by calpain in prostate and mammary tumor cells
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DOI：
10.1158/0008-5472.can-04-1048
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发表时间：
2004-10-15
期刊：
影响因子：
11.2
通讯作者：
Day, ML
中科院分区：
文献类型：
--
作者：
Rios-Doria, J;Kuefer, R;Day, ML
β-连环蛋白基因的NH 2-末端调节结构域的突变导致蛋白质的异常稳定和积累以及TCF/LEF依赖性转录的增加。虽然这些突变在某些癌症中很常见，但在前列腺癌和乳腺癌中并不常见。我们发现，通过快速尸检组织获取程序获得的转移性前列腺癌标本表达β-连环蛋白的新的M，75，000蛋白水解片段（β-cat（75））。β-Cat（75）也在多种前列腺癌和乳腺癌细胞系中表达，并且与钙依赖性蛋白酶calpain的活性密切相关。在前列腺癌cDNA微阵列中，发现与正常前列腺相比，转移性疾病中的m-钙蛋白酶RNA水平显著增加。我们在细胞培养物和体外显示了β-cat（75）的钙蛋白酶依赖性生成。分子图谱显示，钙蛋白酶切割去除了β-连环蛋白的NH 2-末端调节结构域。用离子霉素处理MCF-7细胞导致β-cat（75）在细胞核中的积累和TCF依赖性转录活性增加。缺乏NH 2-末端132个氨基酸并具有转化潜力的类似β-连环蛋白片段的过表达激活了TCF依赖性转录。由于前列腺癌和乳腺癌中β-连环蛋白突变诱导的激活频率较低，钙蛋白酶对β-连环蛋白的蛋白水解裂解可能代表了一种新的机制，通过这种机制，该蛋白在肿瘤发生过程中被激活。
Mutations in the NH2-terminal regulatory domain of the beta-catenin gene lead to aberrant stabilization and accumulation of the protein and increased TCF/LEF-dependent transcription. Although these mutations are common in some cancers, they are infrequent in prostate and breast cancer. We have found that metastatic prostate cancer specimens, obtained through a rapid autopsy tissue procurement program, expressed a novel M, 75,000 proteolytic fragment of beta-catenin (beta-cat(75)). beta-Cat(75) was also expressed in multiple prostate and breast cancer cell lines and was closely associated with the activity of the calcium-dependent protease, calpain. In a prostate cancer cDNA microarray, m-calpain RNA levels were found to be significantly increased in metastatic disease compared with normal prostate. We showed calpain-dependent generation of beta-cat(75) in cell culture and in vitro. Molecular mapping revealed that calpain cleavage removed the NH2-terminal regulatory domain of the beta-catenin protein. Treatment of MCF-7 cells with ionomycin led to increased accumulation of beta-cat(75) in the nucleus and TCF-dependent transcriptional activity. Overexpression of a similar beta-catenin fragment that lacks the NH2-terminal 132 amino acids and has transforming potential activated TCF-dependent transcription. Given the low frequency of mutation-induced activation of beta-catenin in prostate and breast cancers, proteolytic cleavage of beta-catenin by calpain may represent a novel mechanism by which the protein is activated during tumorigenesis.