Tumor specific modulation of KU70/80 DNA binding activity in breast and bladder human tumor biopsies
Tumor specific modulation of KU70/80 DNA binding activity in breast and bladder human tumor biopsies
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DOI：
10.1038/sj.onc.1204148
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发表时间：
2001-02-08
期刊：
影响因子：
8
通讯作者：
Fazio, VM
中科院分区：
文献类型：
--
作者：
Pucci, S;Mazzarelli, P;Fazio, VM
Ku 70/80异源二聚体是DNA依赖性蛋白激酶（DNA-PK）的调节亚基，其DNA结合活性介导DNA双链断裂修复。虽然Ku 80最近被提出作为参与控制基因组完整性的看守基因，但没有关于Ku 70/80在人类肿瘤中DNA结合活性的数据。异源二聚体DNA结合活性和蛋白质表达进行了测定，通过凝胶电泳迁移率变化分析（EMSA）和蛋白质印迹分析，在核和细胞质提取物从8个乳腺癌，7个膀胱原发性肿瘤和3个转移性淋巴结乳腺癌。同时取同一患者相应的正常组织作为对照。15个肿瘤中有10个显示核Ku结合活性比正常组织高3-10倍，无论膀胱或乳腺起源。相反，在5/15的原发性肿瘤和所有的转移性淋巴结分析，核Ku活性是1.5-4.5倍低于相应的正常组织。细胞质异源二聚体活性在肿瘤和正常组织之间显著不同，在肿瘤组织中显示2-10倍的增加。确定了三种不同的模式，结合Ku表达和活性与肿瘤特征。在低侵袭性乳腺肿瘤中，p70/p80蛋白在肿瘤中表达，而在正常组织中不表达。异源二聚体结合活性与蛋白水平相匹配。在非浸润性膀胱癌中，肿瘤和相应的正常组织之间的蛋白表达没有显着差异，但异源二聚体结合活性在肿瘤样品中增加。在乳腺和膀胱肿瘤中，在晚期和淋巴结转移中，结合活性在肿瘤活检中强烈降低，然而在正常和肿瘤蛋白水平之间仅显示无差异。我们的结果表明，在人类肿瘤组织中Ku 70/80 DNA结合活性的不同调节，可能与肿瘤进展有关。研究结果提供了组织特异性蛋白表达和异二聚体活性的翻译后调节的进一步数据。
The Ku70/80 heterodimer is the regulatory subunit of the DNA-dependent protein kinase (DNA-PK) and its DNA-binding activity mediates DNA double-strand breaks repair. Although Ku80 was recently proposed as a caretaker gene involved in the control of genome integrity, no data are available on Ku70/80 DNA-binding activity in human tumors. Heterodimer DNA-binding activity and protein expression were assayed by electrophoretic-mobility-shift-assay (EMSA) and Western blot analysis, in nuclear and cytoplasmic extracts from eight breast, seven bladder primary tumors and three metastatic nodes from breast cancers. Corresponding normal tissues of the same patients were used as controls. Ten out of 15 tumors showed nuclear Ku-binding activity 3-10 times higher than in the normal tissues, irrespective of bladder or breast origin. Conversely, in 5/15 primary tumors and in all the metastatic nodes analysed, nuclear Ku-activity was 1.5-4.5-fold lower than in the corresponding normal tissues. Cytoplasmic heterodimer activity significantly differed between tumor and normal tissues, displaying a 2-10-fold increase in neoplastic tissues. Three different patterns combining both Ku expression and activity with tumor characteristics were identified. In low aggressive breast tumors p70/p80 proteins were expressed in tumor but not in normal tissues. The heterodimer binding-activity matched the protein levels. In non-invasive bladder carcinomas no significant differences in protein expression between tumor and the corresponding normal tissues were found, however heterodimer binding-activity was increased in tumor samples. In breast and bladder tumors, at the advanced stage and in node metastases, the binding activity was strongly reduced in tumor biopsies, however no differences mere demonstrated between normal and tumor protein levels, Our results suggest a different modulation of Ku70/80 DNA-binding activity in human neoplastic tissues, possibly related to tumor progression. Findings provide further data on tissue-specific protein expression and post-translational regulation of heterodimer activity.