Identification of cervical adeno carcinoma related tumor suppressor using proteomic method

人乳头瘤病毒（HPV）被认为在宫颈癌发生中起因果作用。大约，在95%的宫颈癌组织中，通过从癌组织中提取的翅膀DNA发现HPV感染。HPV 16型是所有子宫颈癌组织中最常见的HPV类型，而HPV 18型是子宫颈癌腺癌中最常见的HPV类型，约占子宫颈癌的10-20%。众所周知，与鳞状细胞癌相比，宫颈腺癌多发生于年轻女性，且预后比鳞状细胞癌差。鉴于两种类型的HPV感染宫颈上皮的年龄相同，HPV 18型被认为比HPV 16型具有更强的转化能力。HPV有两个致癌基因，E6和E7。E7癌蛋白与肿瘤抑制因子pRb相互作用。虽然E6癌蛋白与肿瘤抑制因子p53相互作用，但它也通过泛素介导的途径降解p53，这取决于E6AP的表达，E6AP是细胞内的泛素蛋白连接酶。中川俊介博士是这项研究的成员之一，他发现了一种新的肿瘤抑制蛋白——人类涂鸦蛋白。人类Scribble蛋白是果蝇肿瘤抑制蛋白的人类同源物，具有控制细胞顶基底侧极性的作用。scribble突变的缺失导致上皮极性的破坏和上皮的过度生长。湖南潦草的蛋白质结构与果蝇的同源物几乎相同。人类Scribble基因在果蝇Scribble突变体中的表达恢复了细胞极性丧失和上皮过度生长的表型。这些结果表明，人Scribble具有抑制肿瘤发生的作用。我们试图鉴定一种新的与宫颈腺癌发展相关的肿瘤抑制蛋白。我们发现dbc-1（在乳腺癌-1中缺失）基因的产物，定位于8p21，在乳腺癌中经常缺失，现在是泛素介导的E6癌蛋白降解靶点。DBC1具有Leucine Zipper结构域、E6结合共识基序和Ca结合EF-hand基序。bc -1与低危型E6、11型及高风险型E6s、16、18型均有结合，但与低危型11E6的结合弱于与高风险型16、18E6的结合。我们还发现E6癌蛋白在E6AP存在的情况下降解DBC-1。凋亡过程中DBC-1定位于细胞核，但集中于线粒体。我们的数据提示E6-E6AP对DBC-1的降解可能对参与宫颈癌发生的线粒体凋亡信号通路有一定影响

Human papillomavirus(HPV) is thought to have a causal role in cervical carcinogenesis. Approximately, in 95% of cervical cancer tissues, infection of HPV in found by wing DNA extracted from cancer tissues. HPV type 16 is the type of HPV most frequently identified from allover cervical cancer tissues, while HPV type 18 is the HPV type most frequently found in cervical adeno carcinoma, which represent about 10-20% of cervical cancer. Cervical adenocarcinoma is known to occur in younger women comparing with squamous cell carcinoma and to have poorer prognosis than squamous cell carcinoma. Given that each types of HPV infect to the cervical epithelia at the same age, HPV type 18 is thought to have stronger transforming ability than HPV type 16. HPV has two oncogenes, E6 and E7. E7 oncoprotein interacts with tumor suppressor pRb. While E6 oncoprotein interacts with tumor suppresser p53, it also degrade p53 through the ubiquitin-mediated pathway depending on the expression of E6AP, the cellu … More lar ubiquitin-protein ligase. Dr.Shunsuke Nakagawa, who is a member of this research, identified a new tumor suppressor protein human Scribble. Human Scribble is a human homologue of Drosophila tumor suppressor protein, which has a role in control of cellular apical-basolateral polarity. Loss of scribble mutation leads to the disruption of epithelial polarity and overgrowth of epithelia. Hunan Scribble has almost equivalent protein structure to its Drosophila homologue. The expression of human Scribble in Drosophila scribble mutant recovers phenotype of loss of cellular polarity and overgrowth of epithelia. These results indicate that human Scribble has a role in suppression of tumorgenesis. We tried to identify a new tumor suppressor protein related to the development of cervical adenocarcinoma. We identified the product of dbc-1(deleted in breast cancer-1) gene, which localizes on 8p21 and is frequently deleted among breast cancers, as a now ubiqituin-mediated degradation target of E6 oncoprotein. DBC1 possesses a Leucine Zipper domain, E6 binding consensus motif and a Ca binding EF-hand motif. DBC-1 bound with both low risk type E6, type 11, and with high risk E6s, type 16 and 18, but the binding with low risk 11E6 was weaker than with high risk 16 and 18E6. We also revealed that E6 oncoprotein degrades DBC-1 in the presence of E6AP. DBC-1 localized in nucleus, but concentrated on mitochondria during apoptosis.Our data suggest the possibility that degradation of DBC-1 by E6-E6AP might have some effect on the apoptotic signal pathway in mitochondria, which takes part in the cervical carcinogenesis Less