Molecular and cytogenetic changes involved in the immortalization of nasopharyngeal epithelial cells by telomerase
Molecular and cytogenetic changes involved in the immortalization of nasopharyngeal epithelial cells by telomerase
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DOI：
10.1002/ijc.22032
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发表时间：
2006-10-01
影响因子：
6.4
通讯作者：
Tsao, S. W.
中科院分区：
文献类型：
--
作者：
Li, H. M.;Man, C.;Tsao, S. W.
鼻咽癌（NPC）是香港和中国南方省份的一种常见疾病。EBV感染被认为在鼻咽癌的发展中起关键作用。以往关于EBV基因转化机制的研究大多是在鼻咽癌或正常咽上皮细胞中进行的，可能不能代表癌前鼻咽上皮细胞。建立具有代表性的细胞系统将有助于阐明EBV感染在鼻咽癌发病中的作用。仅使用端粒酶，我们能够从原发性非恶性鼻咽活检中建立永生化的鼻咽上皮细胞系。端粒酶永生化的鼻咽上皮细胞在核型上大部分是二倍体。有趣的是，这种新永生化的鼻咽上皮细胞系，被称为NP460hTert，含有先前在癌前和恶性鼻咽上皮细胞中发现的遗传改变。其中包括p16（INK4A）基因座纯合缺失导致p16失活和RASSF1A表达下调。p16（INK4A）位点的缺失似乎是端粒酶使鼻咽上皮细胞不朽的最关键事件，并在RASSF1A下调之前发生。此外，通过常规细胞遗传学、谱核型分析（SKY）和阵列CGH对NP460hTert细胞的细胞遗传学变化进行了详细分析，发现在p16（INK4A）位点缺失之前，所有NP460hTert细胞在11p15染色体上增加了17q21-q25片段。17q的增益已经在NPC中报告过了。此外，在永生化NP460hTert细胞中观察到NF-kappa B在后期群体倍增时的活化，并可能在永生化NP上皮细胞的存活中发挥作用。在包括鼻咽癌在内的各种人类癌症中普遍表达的Id1在永生化的NP460hTert细胞中也上调。因此，建立永生化的鼻咽上皮细胞系，包含癌前和癌性鼻咽上皮细胞中常见的遗传改变，可能为检查鼻咽癌发生的早期事件提供有价值的细胞系统，特别是阐明EBV感染在鼻咽癌发展中的作用。(c) 2006 Wiley-Liss, Inc。
Nasopharyngeal carcinoma (NPC) is a common disease in Hong Kong and southern provinces of China. EBV infection is believed to play a critical role in the development of NPC. Previous studies on the transformation mechanism of EBV genes were mostly performed in either NPC or normasopharyngeal epithelial cells which may not be representative of premalignant nasopharyngeal epithelial cells. Establishment of a representative cell system would greatly facilitate the elucidation of the role of EBV infection in the development of NPC. Using telomerase alone, we were able to establish an immortalized nasopharyngeal epithelial cell line from primary nonmalignant nasopharyngeal biopsies. The telomerase-immortalized nasopharyngeal epithelial cells are largely diploid in karyotype. Interestingly, this newly immortalized nasopharyngeal epithelial cell line, referred as NP460hTert, harbors genetic alterations previously identified in premalignant and malignant nasopharyngeal epithelial cells. These include inactivation of p16 by homozygous deletion of the p16(INK4A) locus and downregulation of RASSF1A expression. The deletion of the p16(INK4A) locus appears to be the most crucial event for the immortalization of nasopharyngeal epithelial cells by telomerase and precedes RASSF1A downregulation. In addition, detailed analysis of the cytogenetic changes by conventional cytogenetics, spectral karyotyping (SKY) and array-based CGH revealed a gain of a 17q21-q25 fragment on 11p15 chromosome in all NP460hTert cells which occurred before deletion of the p16(INK4A) locus. Gain of 17q has been previously reported in NPC. In addition, activation of NF-kappa B was observed in immortalized NP460hTert cells at the later population doublings, and may play a role in the survival of immortalized NP epithelial cells. Id1 which is commonly expressed in various human cancers, including NPC, was also upregulated in the immortalized NP460hTert cells. Thus, the establishment of an immortalized nasopharyngeal epithelial cell line harboring common genetic alterations present in premalignant and cancerous nasopharyngeal epithelial cells may provide a valuable cell system to examine for early events involved in NPC carcinogenesis, particularly in elucidating the role of EBV infection in NPC development. (c) 2006 Wiley-Liss, Inc.