Genetic alterations of P16INK4A and P14ARF genes in human bladder cancer
Genetic alterations of P16INK4A and P14ARF genes in human bladder cancer
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DOI：
10.1097/01.ju.0000067626.37837.3e
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发表时间：
2003-08-01
影响因子：
6.6
通讯作者：
Huang, CH
中科院分区：
文献类型：
--
作者：
Chang, LL;Yeh, WT;Huang, CH
目的：位于9p21基因簇上的生长抑制基因p161NK4a和p14ARF分别在Rb和P53的生长调控通路中发挥重要作用。P161NK4a是一种细胞周期蛋白依赖性激酶抑制因子，作用于Rb上游。P14ARF通过阻断MDM2对P53活性的抑制来抑制细胞生长，从而促进P53介导的细胞周期停滞和细胞凋亡。为阐明9p21染色体区域在膀胱癌发生中的作用，分析了p161NK4a和p14ARF基因的突变情况。材料与方法：收集44例膀胱癌患者的53例移行细胞癌标本。采用Southern杂交、聚合酶链式反应-单链构象多态性分析和甲基化特异性聚合酶链式反应分析等方法分析p16INK4a和p14ARF基因的遗传改变。结果：p161NK4a和p14ARF基因纯合性缺失率分别为23%(12/53)和43%(23/53)。大多数缺失仅发生在E1beta-p14ARF区域。P16INK4a和p14ARF基因同时缺失的病例仅2例。在p14ARF+p161NK4a基因外显子2检测到1个突变。P161NK4a基因甲基化阳性率为60%(24/40)。然而，在任何情况下都没有检测到p14ARF基因甲基化。比较逆转录-聚合酶链式反应结果显示，大多数肿瘤组织中p14ARF和p161NK4a基因表达下调与基因突变有关。结论：p14ARF是膀胱癌9p21区域高甲基化的主要靶点，而p161NK4a是9p21区域高甲基化的热点。P14ARF和p161NK4a基因的频繁失活可能是膀胱癌发生发展过程中P53和Rb生长调控通路功能障碍的重要机制。
Purpose: The growth suppressive genes p161NK4a and p14ARF located on the 9p21 gene cluster have active roles in the Rb and p53 growth control pathways, respectively. p161NK4a is a cyclin dependent kinase inhibitor functioning upstream of Rb. p14ARF restrains cell growth by abrogating Mdm2 inhibition of p53 activity, thereby, facilitating p53 mediated cell cycle arrest and apoptosis. To elucidate specific targets and aberrations affecting the 9p21 chromosomal region in bladder cancer tumorigenesis alterations in the p161NK4a and p14ARF genes were analyzed.Materials and Methods: A total of 53 transitional cell carcinomas from 44 patients with bladder cancer were collected. Genetic alterations of p16INK4a and p14ARF genes were analyzed by Southern hybridization, polymerase chain reaction (PCR)-single strand conformational polymorphism analysis and methylation specific PCR. In addition, mRNA expression status was detected by reverse transcriptase-PCR.Results: Homozygous deletion of p161NK4a and p14ARF genes was observed in 23% (12 of 53 samples) and 43% (23 of 53), respectively. Most deletions occurred exclusively on the E1beta-p14ARF region. Concomitant deletion of p16INK4a and p14ARF genes was found in only 2 samples. One mutation was detected in exon 2 of p14ARF plus p161NK4a genes. Aberrant methylation of p161NK4a gene was found in 60% (24 of 40 tumors). However, no p14ARF gene methylation was detected in any case. The result of comparative reverse transcriptase-PCR showed that suppressed mRNA expression correlated with genetic alterations of p14ARF and p161NK4a genes in most tumor samples examined.Conclusions: Results indicate that p14ARF is a primary target of homozygous deletion, whereas p161NK4a is the hot spot of hypermethylation on the 9p21 region in bladder cancer. The frequent inactivation of the p14ARF and p161NK4a genes may be an important mechanism for the dysfunction of p53 and Rb growth regulatory pathways during bladder cancer development.