Expression profiling and differential screening between hepatoblastomas and the corresponding normal livers:: Identification of high expression of the PLK1 oncogene as a poor-prognostic indicator of hepatoblastomas
Expression profiling and differential screening between hepatoblastomas and the corresponding normal livers:: Identification of high expression of the PLK1 oncogene as a poor-prognostic indicator of hepatoblastomas
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DOI：
10.1038/sj.onc.1207782
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发表时间：
2004-08-05
期刊：
影响因子：
8
通讯作者：
Nakagawara, A
中科院分区：
文献类型：
--
作者：
Yamada, S;Ohira, M;Nakagawara, A
肝母细胞瘤是儿童最常见的肝脏恶性肿瘤之一。最近的证据表明，Wnt信号通路的异常，如β-catenin基因的频繁突变，可能在肝母细胞瘤的发生中起作用。然而，导致肿瘤的确切机制一直难以捉摸。为了寻找新的肝母细胞瘤相关基因以揭示肿瘤发生的分子机制，我们进行了大规模的cDNA克隆，并对其在肝母细胞瘤和相应的正常肝脏中的表达进行了差异筛选。我们用寡核苷酸封顶的方法构建了四个全长丰富的cDNA文库，其中包括两个高水平甲胎蛋白(AFP)的肝母细胞瘤，一个不产生AFP的肝母细胞瘤，以及一个与该肿瘤对应的正常肝组织。在随机挑选并测序成功的10431个基因中，有847个(8.1%)是功能未知的基因。有趣的是，肝母细胞瘤和正常肝的两个亚组之间的表达谱非常不同。半定量RT-PCR分析表明，1188个基因中有86个在肝母细胞瘤和相应的正常肝组织中有差异表达，但其中只有11个在肿瘤中高水平表达。值得注意的是，PLK1癌基因在肝母细胞瘤中的表达水平高于正常婴儿的肝脏。实时荧光定量RT-PCR法检测74例肝母细胞瘤和29例非肿瘤性肝细胞瘤组织中PLK1mRNA的表达，结果显示PLK1高表达的肝母细胞瘤患者的预后明显低于低表达的肝母细胞瘤患者(5年生存率分别为55.9%和87.0%，P=0.042)，提示PLK1的表达水平可作为预测肝母细胞瘤预后的新指标。因此，我们鉴定的差异表达基因可能成为开发肝母细胞瘤新的诊断和治疗策略的有用工具。
Hepatoblastoma is one of the most common malignant liver tumors in young children. Recent evidences have suggested that the abnormalities in Wnt signaling pathway, as seen in frequent mutation of the beta-catenin gene, may play a role in the genesis of hepatoblastoma. However, the precise mechanism to cause the tumor has been elusive. To identify novel hepatoblastoma-related genes for unveiling the molecular mechanism of the tumorigenesis, a large-scale cloning of cDNAs and differential screening of their expression between hepatoblastomas and the corresponding normal livers were performed. We constructed four full-length-enriched cDNA libraries using an oligo-capping method from the primary tissues which included two hepatoblastomas with high levels of alpha-fetoprotein (AFP), a hepatoblastoma without production of AFP, and a normal liver tissue corresponded to the tumor. Among the 10431 cDNAs randomly picked up and successfully sequenced, 847 (8.1%) were the genes with unknown function. Of interest, the expression profile among the two subsets of hepatoblastoma and a normal liver was extremely different. A semiquantitative RT-PCR analysis showed that 86 out of 1188 genes tested were differentially expressed between hepatoblastomas and the corresponding normal livers, but that only 11 of those were expressed at high levels in the tumors. Notably, PLK1 oncogene was expressed at very high levels in hepatoblastomas as compared to the normal infant's livers. Quantitative real-time RT-PCR analysis for the PLK1 mRNA levels in 74 primary hepatoblastomas and 29 corresponding nontumorous livers indicated that the patients with hepatoblastoma with high expression of PLK1 represented significantly poorer outcome than those with its low expression (5-year survival rate: 55.9 vs 87.0%, respectively, p = 0.042), suggesting that the level of PLK1 expression is a novel marker to predict the prognosis of hepatoblastoma. Thus, the differentially expressed genes we have identified may become a useful tool to develop new diagnostic as well as therapeutic strategies of hepatoblastoma.