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Advance in the relationship between checkpoint with fork head associated and ring finger gene and carcinomas of digestive tract
Yu-Jia Gao, Yan Xin
Yu-Jia Gao, Doctor from China Medical University, the Sixth Department of Internal Medicine, Cancer Hospital of Liaoning Province, Shenyang 110042, Liaoning Province, China
Yan Xin, the Fourth Laboratory of Cancer Institute, the First Affiliated Hospital of China Medical University, Shengyang 110001, Liaoning Province, China
Supported by: National Natural Science Foundation of China, No. 30371607, and the Specialized Research Fund for the Doctoral Program of Education Ministry, No. 20040159021.
Correspondence to: Professor Yan Xin, the Fourth Laboratory of Cancer Institute, the First Affiliated Hospital, China Medical University, 155 Nanjing North Street, Heping District, Shengyang 110001, Liaoning Province, China. yxin@mail.cum.edu.cn
Received: April 1, 2007 Revised: April 10, 2007 Accepted: April 13, 2007 Published online: May 28, 2007
CHFR (checkpoint with fork head associated and ring finger), a novel checkpoint gene, was frequently inactivated in human cancers. In response to mitotic stress, it causes a delay in chromosome condensation during prophase. Studies have showed that the direct target of the CHFR pathway was Plk1. In vitro-translated Plk1 is ubiquitinated, in a CHFR-dependent manner, both in Xenopus interphase extracts as well as in a purified system reconstituted with recombinant proteins. In addition, by excluding Cyclin B1 from the nucleus, regulating Aurora-A level and acting with the P38 stress kinases, CHFR blocks entry to mitosis prophase in mammalian cells. Besides, USP7 can remove ubiquitin moiety from the autoubiquitinated CHFR both in vivo and in vitro, which results in the accumulation of CHFR in the cells. Thus, USP7-mediated deubiquitination of CHFR leads to its accumulation, which might be a key regulatory step for CHFR activation. CHFR expression is frequently silenced by aberrant methylation in the carcinomas of digestive tract. In this article, we reviewed the progress of research on the structure of CHFR gene and effect of CHFR protein as well as its relation to the carcinomas of digestive tract.
Key Words: Mitosis prophase; Cell cycle checkpoint; Checkpoint with fork head associated and ring finger gene; Carcinoma of digestive tract
Citation: Gao YJ, Xin Y. Advance in the relationship between checkpoint with fork head associated and ring finger gene and carcinomas of digestive tract. Shijie Huaren Xiaohua Zazhi 2007; 15(15): 1745-1749
Matsusaka et al[17]研究表明CHFR蛋白是在哺乳动物细胞中预前期检查点的一个重要成份, 并且P38应激激酶似乎是这个检查点的下游效应物. 作为检查点机制的部分, CHFR要求他的泛素连接酶活性, 但他的底物不需被蛋白酶体降解. 在微管毒素存在的条件下, 这个预前期检查点主要由P38应激激酶所介导并且需要CHFR蛋白. P38α和β激酶抑制剂能废除预前期检查点并且一个P38α激酶的活化形式能返回早前期细胞到间歇期.
2.5 由USP7/HAUSP所致的CHFR去泛素化调节其稳定性和活性
Oh et al[18]鉴定了USP7(也被称为HAUSP), 一种分解多聚泛素链和/或泛素前体并能与CHFR相互作用的蛋白. 他在体内外能去除自动泛素的CHFR的泛素部分. 导致CHFR在细胞内的积累. 这一研究结果表明USP7介导的CHFR去泛素化致其累积可能对于CHFR激活是一个关键的调节步骤, 并且在CHFR介导的细胞周期进程和肿瘤抑制的调解方面可能发挥着重要作用.
3 CHFR在消化道肿瘤中的表达及特点
3.1 食管癌
Shibata et al[4]的研究表明15个食管癌细胞株中的4个(26.7%)和43例原发癌中的7例(16.3%)CHFR检测点基因启动区的异常超甲基化. 因用甲基转移酶抑制剂5-aza-dc处理后诱导CHFR基因表达的恢复, 表明CHFR启动区的异常甲基化与mRNA表达丢失密切相关. Hamilton et al[19]的研究发现CHFR被甲基化在对食管癌放化疗没反应的患者中占32%, 但在有反应的患者中只有8%, 这种甲基化的差异很可能是由于灭活CHFR的肿瘤细胞使细胞增殖失调, 变得较难被放化疗的毒素作用杀灭所致.
3.2 胃癌
已有研究发现, CHFR在人正常组织中普遍表达, 而在人肿瘤组织中表达缺失. Kang et al[20]用RT-PCR、重亚硫酸盐PCR和序列分析方法对人胃癌细胞株和原发胃癌组织中CHFR的甲基化状态及CHFR表达进行了研究, 发现在12个胃癌细胞株中的8例(66.7%)和43例原发性胃癌中的19例(44.2%)显示CHFR甲基化, 而正常组织中没有检出CHFR甲基化, 表明CHFR甲基化在人胃癌中是频发事件. 有CHFR甲基化的胃癌细胞株显示其mRNA表达下调或缺失. 在几个胃癌细胞株中被抑制的CHFR表达经5-aza-dc处理后可恢复. 联合5-aza-dc和TSA, 可协同提高CHFR的表达, 提示CHFR表达的丟失是由DNA甲基化改变和组蛋白脱乙酰作用所调节. 此外发现TSA独自并不足以诱导CHFR表达, 表明异常甲基化是导致CHFR转录沉默的主要原因. Milne et al[21]研究结果显示, 在174例胃癌中CHFR蛋白表达缺失率为33%, 且弥漫型胃癌表达缺失率显著高于肠型胃癌(P = 0.001). Morioka et al[22]研究发现, 53例胃癌中出现CHFR基因异常甲基化16例(30%), 而正常组织中没有检测到异常甲基化. Koga et al[23]发现, 9个胃癌细胞株中有3个启动子异常甲基化致CHFR表达沉默. CHFR mRNA的表达水平与用微管抑制剂作用的胃癌细胞系的50%抑制浓度密切相关, R = 0.889, P = 0.005. 并且, 在46例胃癌患者中, 24例(52%)呈现CHFR异常甲基化, 有CHFR甲基化的患者对微管抑制剂治疗有反应的为7例(占29%), 其中6例(86%)显示一些消退或不进展, 而没有CHFR甲基化的5例肿瘤患者中有4例(80%)显示进展恶化, 提示CHFR甲基化有望在临床上作为一个预测微管抑制剂治疗效果的新标志物. 但Yoshida et al[24]发现, 41例胃癌标本中15例(36.6%)显示CHFR的DNA甲基化. 在单独用泰素治疗的12例患者中, CHFR的甲基化状态与对泰素的反应没有联系. 有CHFR甲基化的5例患者中, 仅1例(20.0%)对泰素治疗显示部分缓解(PR), 而没有甲基化的7例患者中3例(42.9%)显示PR. 在29例用多西他赛和S-1联合治疗的患者中, CHFR甲基化状态与对联合治疗的反应没有明确的联系. 其中19例显示PR, 然而哪个抗肿瘤药物有效并不清楚. 而在无效的10例患者中, 有CHFR甲基化, 这被认为是与对多西他赛高度敏感有关, 在10例患者中6例(60%)被检测到. 结果表明CHFR的DNA甲基化状态在胃癌中对预测多西他赛或泰素的反应不是一个好的标志物. 其与以前研究结果不一致的原因可能是: (1)Satoh et al[25]检测CHFR是在胃癌细胞株中; (2)他们在原发胃癌中调查CHFR甲基化, 但在许多病例的转移灶中对化疗的反应进行了评估. 在转移胃癌病变中, CHFR可能被再次活化. 12例单独用泰素治疗的患者中4例达PR, 其中3例没有DNA甲基化占75%, 这表明即使CHFR被表达, 泰素也是有效的. Homma et al[26]观察发现 CHFR超甲基化在L-NIN中比H-NIN的频率低(P<0.05). CHFR甲基化和hMLH1甲基化同时发生(P<0.01); CHFR和hMLH1二者的超甲基化与年龄显著相关. CHFR超甲基化在小凹型和普通型胃肿瘤中分别占50%(2/4)、40%(40/16), 而在肠化生型胃肿瘤中占0%(0/8). 胃癌发生的分子通路取决于组织的背景, 并且由于先天和后天改变, 胃癌显示了不同的生物学行为[27]. 总之, 研究表明尽管CHFR甲基化与CIN没有联系, 但某些小凹型和普通型的胃肿瘤是由于在正常的胃黏膜或不完全的肠化生黏膜中与老年人有关的CHFR和hMLH1超甲基化的产生.
3.3 大肠癌
Bertholon et al[28]报道, 21个结肠癌细胞株中有12个(57%)显示CHFR表达完全缺失. 22例原发性结肠癌中有8例(36%)可检测到CHFR基因启动子区CpG岛异常甲基化, 提示CHFR基因异常甲基化和表达缺失在结肠癌中是频发事件. Derks et al[29]观察发现在18例结直肠癌中CHFR基因异常甲基化占55.6%, CHFR的启动子甲基化与许多染色体异常不相关. Brandes et al[30]报道, 在61例原发性结肠癌标本中, 19例(31%)可检出CHFR启动子异常甲基化. 此外, MSI表型阳性的大肠癌细胞株均伴有CHFR基因启动子甲基化. Hibi et al[31]观察了58例人结直肠癌组织CHFR基因的甲基化状态. 发现25例(43.1%)显示CHFR基因异常甲基化, 且低分化结直肠癌CHFR基因甲基化检出率较高分化结直肠癌多见(P = 0.0041). Morioka et al[32]研究发现, 在98例原发性结直肠癌中25例(26%)显示CHFR基因异常甲基化. 且早期结直肠癌CHFR甲基化出现率(30.7%, 23/75)显著高于进展期(8.7%, 2/23)(P = 0.035), 提示CHFR可能至少与部分结直肠癌的发生有关, CHFR甲基化可能是结直肠癌发生、发展早期阶段的一种特殊现象.
3.4 肝癌、胆管癌和胰腺癌
Sakai et al[33]研究发现, 在原发性肝癌中35%(22/62)发现CHFR基因启动子甲基化, 而在对应的正常肝组织中没有发现, 提示CHFR甲基化在肝细胞癌中是一个频繁的事件. 另外, CHFR的甲基化与肝细胞癌侵袭性的生长模式(P = 0.047)和临床病理分期(P = 0.037)显著相关. CHFR甲基化状态可能是一个新的评估肝细胞癌恶性程度的分子标志物. Tozawa et al[34]报道, 在原发性胆管癌中CHFR甲基化频率为16.2%(6/37). Takahashi et al[35]检测了胆囊癌中24个已知或怀疑为抑癌基因的异常甲基化状况, 发现其甲基化频率为0%-80%, 其中CHFR甲基化属低频率组(2%-14%). 迄今关于CHFR基因异常甲基化与胰腺癌发生、发展的关系尚未见报道.
Mizuno K, Osada H, Konishi H, Tatematsu Y, Yatabe Y, Mitsudomi T, Fujii Y, Takahashi T. Aberrant hypermethylation of the CHFR prophase checkpoint gene in human lung cancers.Oncogene. 2002;21:2328-2333.
[PubMed] [DOI]
Corn PG, Summers MK, Fogt F, Virmani AK, Gazdar AF, Halazonetis TD, El-Deiry WS. Frequent hypermethylation of the 5' CpG island of the mitotic stress checkpoint gene Chfr in colorectal and non-small cell lung cancer.Carcinogenesis. 2003;24:47-51.
[PubMed] [DOI]
Shibata Y, Haruki N, Kuwabara Y, Ishiguro H, Shinoda N, Sato A, Kimura M, Koyama H, Toyama T, Nishiwaki T. Chfr expression is downregulated by CpG island hypermethylation in esophageal cancer.Carcinogenesis. 2002;23:1695-1699.
[PubMed] [DOI]
Corn PG, Heath EI, Heitmiller R, Fogt F, Forastiere AA, Herman JG, Wu TT. Frequent hypermethylation of the 5' CpG island of E-cadherin in esophageal adenocarcinoma.Clin Cancer Res. 2001;7:2765-2769.
[PubMed] [DOI]
Toyota M, Sasaki Y, Satoh A, Ogi K, Kikuchi T, Suzuki H, Mita H, Tanaka N, Itoh F, Issa JP. Epigenetic inactivation of CHFR in human tumors.Proc Natl Acad Sci U S A. 2003;100:7818-7823.
[PubMed] [DOI]
Stavridi ES, Huyen Y, Loreto IR, Scolnick DM, Halazonetis TD, Pavletich NP, Jeffrey PD. Crystal structure of the FHA domain of the Chfr mitotic checkpoint protein and its complex with tungstate.Structure. 2002;10:891-899.
[PubMed] [DOI]
Hammet A, Pike BL, McNees CJ, Conlan LA, Tenis N, Heierhorst J. FHA domains as phospho-threonine binding modules in cell signaling.IUBMB Life. 2003;55:23-27.
[PubMed] [DOI]
Swenson KI, Winkler KE, Means AR. A new identity for MLK3 as an NIMA-related, cell cycle-regulated kinase that is localized near centrosomes and influences microtubule organization.Mol Biol Cell. 2003;14:156-172.
[PubMed] [DOI]
Kang D, Chen J, Wong J, Fang G. The checkpoint protein Chfr is a ligase that ubiquitinates Plk1 and inhibits Cdc2 at the G2 to M transition.J Cell Biol. 2002;156:249-259.
[PubMed] [DOI]
Shtivelman E. Promotion of mitosis by activated protein kinase B after DNA damage involves polo-like kinase 1 and checkpoint protein CHFR.Mol Cancer Res. 2003;1:959-969.
[PubMed] [DOI]
Summers MK, Bothos J, Halazonetis TD. The CHFR mitotic checkpoint protein delays cell cycle progression by excluding Cyclin B1 from the nucleus.Oncogene. 2005;24:2589-2598.
[PubMed] [DOI]
Oh YM, Yoo SJ, Seol JH. Deubiquitination of Chfr, a checkpoint protein, by USP7/HAUSP regulates its stability and activity.Biochem Biophys Res Commun. 2007;357:615-619.
[PubMed] [DOI]
Hamilton JP, Sato F, Greenwald BD, Sunthara-lingam M, Krasna MJ, Edelman MJ, Doyle A, Berki AT, Abraham JM, Mori Y. Promoter methylation and response to chemotherapy and radiation in esophageal cancer.Clin Gastroenterol Hepatol. 2006;4:701-708.
[PubMed] [DOI]
Kang HC, Kim IJ, Park JH, Shin Y, Park HW, Ku JL, Yang HK, Lee KU, Choe KJ, Park JG. Promoter hypermethylation and silencing of CHFR mitotic stress checkpoint gene in human gastric cancers.Oncol Rep. 2004;12:129-133.
[PubMed] [DOI]
Morioka Y, Hibi K, Sakai M, Koike M, Fujiwara M, Kodera Y, Ito K, Nakao A. Aberrant methylation of the CHFR gene in digestive tract cancer.Anticancer Res. 2006;26:1791-1795.
[PubMed] [DOI]
Koga Y, Kitajima Y, Miyoshi A, Sato K, Sato S, Miyazaki K. The significance of aberrant CHFR methylation for clinical response to microtubule inhibitors in gastric cancer.J Gastroenterol. 2006;41:133-139.
[PubMed] [DOI]
Yoshida K, Hamai Y, Suzuki T, Sanada Y, Oue N, Yasui W. DNA methylation of CHFR is not a predictor of the response to docetaxel and paclitaxel in advanced and recurrent gastric cancer.Anticancer Res. 2006;26:49-54.
[PubMed] [DOI]
Satoh A, Toyota M, Itoh F, Sasaki Y, Suzuki H, Ogi K, Kikuchi T, Mita H, Yamashita T, Kojima T. Epigenetic inactivation of CHFR and sensitivity to microtubule inhibitors in gastric cancer.Cancer Res. 2003;63:8606-8613.
[PubMed] [DOI]
Homma N, Tamura G, Honda T, Jin Z, Ohmura K, Kawata S, Motoyama T. Hypermethylation of Chfr and hMLH1 in gastric noninvasive and early invasive neoplasias.Virchows Arch. 2005;446:120-126.
[PubMed] [DOI]
Tamura G. Genetic and epigenetic alterations of tumor suppressor and tumor-related genes in gastric cancer.Histol Histopathol. 2002;17:323-329.
[PubMed] [DOI]
Bertholon J, Wang Q, Falette N, Verny C, Auclair J, Chassot C, Navarro C, Saurin JC, Puisieux A. Chfr inactivation is not associated to chromosomal instability in colon cancers.Oncogene. 2003;22:8956-8960.
[PubMed] [DOI]
Brandes JC, van Engeland M, Wouters KA, Weijenberg MP, Herman JG. CHFR promoter hypermethylation in colon cancer correlates with the microsatellite instability phenotype.Carcinogenesis. 2005;26:1152-1156.
[PubMed] [DOI]
Morioka Y, Hibi K, Sakai M, Koike M, Fujiwara M, Kodera Y, Ito K, Nakao A. Aberrant methylation of the CHFR gene is frequently detected in non-invasive colorectal cancer.Anticancer Res. 2006;26:4267-4270.
[PubMed] [DOI]
Sakai M, Hibi K, Kanazumi N, Nomoto S, Inoue S, Takeda S, Nakao A. Aberrant methylation of the CHFR gene in advanced hepatocellular carcinoma.Hepatogastroenterology. 2005;52:1854-1857.
[PubMed] [DOI]