Hypermethylation of p16 and p15 genes and RB protein expression in acute leukemia
Hypermethylation of p16 and p15 genes and RB protein expression in acute leukemia
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DOI：
10.1016/s0145-2126(99)00158-7
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发表时间：
2000-01-01
影响因子：
2.7
通讯作者：
Hayashi, Y
中科院分区：
文献类型：
--
作者：
Guo, SX;Taki, T;Hayashi, Y
p16和p15均由位于染色体9 p21上的基因编码，是细胞周期蛋白依赖性激酶4/6（CDK 4/6）的抑制剂和RE功能的上游调节剂，并建立RB/p16肿瘤抑制途径，其在人类肿瘤中经常被废除，或者通过RE或p16肿瘤抑制蛋白的失活，或者通过细胞周期蛋白D1或CDK 4癌蛋白的改变。在血液恶性肿瘤中，p16/p15基因座的缺失已被证明对淋巴恶性肿瘤具有高度特异性，更具体地说，对T细胞急性淋巴细胞白血病（T-ALL）具有高度特异性。然而，在ALL的其他子集中，p16和p15缺失是相对罕见的事件。为了研究这些基因是否由于5'端CpG岛甲基化而失活，我们用Southern印迹、PCR和Western印迹分析了35个白血病细胞系和29例儿童急性髓细胞白血病（AML）患者。我们在24个ALL细胞系中的12个（50%）、10个AML细胞系中的5个（50%）和29个AML患者中的11个（38%）中发现了p16甲基化。p16基因甲基化的白血病细胞系p16蛋白表达缺失。p15基因甲基化在29个ALL细胞系中的10个（34%）、10个AML细胞系中的6个（60%）、29个AML患者中的15个（52%）中没有p15纯合缺失。这些结果揭示了在B-ALL和AML中频繁的p16和p15基因甲基化，尽管在这些白血病中p16和p15缺失和突变的频率较低。在RE蛋白表达的研究中，我们发现16个白血病细胞系中有4个不表达RE。在所有表达RE的细胞系中均发现p16基因失活。细胞周期蛋白D1基因在所有细胞系中均未扩增或重排。提示p16和p15基因失活是急性白血病最常见的遗传事件之一，在RB/p16通路中起重要作用。(C)1999 Elsevier Science Ltd.保留所有权利。
Both p16 and p15, encoded by genes located on chromosome 9p21, are inhibitors of cyclin-dependent kinases 4/6 (CDK4/6) and upstream regulators of RE function, and set up the RB/p16 tumor suppressive pathway, which is abrogated frequently in human neoplasms, either through inactivation of the RE or p16 tumor-suppressor protein, or alteration of the cyclin D1 or CDK4 oncoproteins. In hematological malignancies, deletion of p16/p15 locus has been shown to be highly specific to lymphoid malignancies, and more particularly to T-cell acute lymphoblastic leukemia (T-ALL). However, in the other subsets of ALL, deletions of p16 and p15 are relatively rare events. To investigate whether these genes are inactivated by methylation of the 5' CpG islands, we examined 35 leukemia cell lines and 29 childhood acute myeloid leukemia (AML) patients by Southern blot, polymerase chain reaction (PCR) and Western blot analyses. We found methylation of p16 in 12 (50%) of 24 ALL cell lines, 5 (50%) of 10 AML cell lines without homozygous deletion of p16, and 11 (38%) of 29 AML patients. Those leukemia cell lines subjected to p16 methylation were found to have lost p16 protein expression. The p15 gene was methylated in 10 (34%) of 29 ALL cell lines, 6 (60%) of 10 AML cell lines without homozygous deletion of p15, and 15 (52%) of 29 AML patients. These results revealed the frequent methylation of p16 and p15 genes in B-ALL and AML despite a low frequency of p16 and p15 deletions and mutations in these leukemias. In the study for expression of RE protein, we found no expression of RE in 4 of 16 leukemia cell lines. Inactivation of the p16 gene was found in all the cell lines with expression of RE. Neither amplification nor rearrangement of cyclin D1 gene was found in any cell lines. These results suggest that inactivation of p16 and p15 genes is one of the most common genetic events in acute leukemia, and plays an important role for the RB/p16 pathway in the pathogenesis of acute leukemia. (C) 1999 Elsevier Science Ltd. All rights reserved.