Increased expression of the INK4a/ARF locus in polycythemia vera.
Increased expression of the INK4a/ARF locus in polycythemia vera.
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DOI：
10.1182/blood.v97.11.3424
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发表时间：
2001-06
期刊：
影响因子：
20.3
通讯作者：
C. Dai;S. B. Krantz
中科院分区：
文献类型：
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作者：
C. Dai;S. B. Krantz
视网膜母细胞瘤（Rb）、细胞周期蛋白依赖性激酶（CDK）和CDK抑制剂基因调节细胞生成，并且失调可产生增加的细胞生长和肿瘤发生。真性红细胞增多症（PV）是一种克隆性骨髓增生性疾病，其造血功能增加的机制尚不清楚。为了研究PV细胞周期调控中可能存在的缺陷，使用RNA酶保护试验（RPA）和11种基因探针在高度纯化的人红系集落形成细胞（ECFC）中筛选Rb和CDK抑制剂基因信使RNA（mRNA）的表达。结果发现，在11例PV患者中，代表p16（INK 4a）和p14（ARF）外显子2的RNA增强了2.8- 15.9倍。PV患者的T细胞或继发性红细胞增多症患者的ECFC和T细胞中没有明显的外显子2 mRNA增加。p27在PV ECFC中也有升高的mRNA表达，但程度较轻。由于INK 4a/ARF基因座编码两种肿瘤抑制因子，p16（INK 4a）和p14（ARF）具有相同的外显子2序列，因此增加的mRNA片段可能代表其中任何一种。为了澄清这一点，mRNA代表独特的第一外显子INK 4a和ARF进行了半定量逆转录-聚合酶链反应分析。这表明来自两种基因的第一外显子的mRNA在红系细胞和粒细胞-巨噬细胞中增加，并且蛋白质印迹分析显示INK 4a蛋白（p16（INK 4a））在PV ECFC中增加。测序结果显示10例PV患者均未发现INK 4a或ARF突变。p16（INK 4a）是一种重要的细胞周期负调控因子，但与其中INK 4a基因失活是最常见的致癌事件之一的广泛的恶性肿瘤相反，在PV中p16（INK 4a）表达显著增加，而与正常ECFC相比，ECFC细胞周期没有显著变化。p16（INK 4a）和p14（ARF）很可能不是PV的致病原因，而是代表细胞对下游增殖调节因子如细胞周期蛋白D、CDK 4/CDK 6、Rb或E2 F的异常的反应。进一步的工作来描绘这些基因在PV中的功能正在进行中。（血。2001;97：3424-3432）
The retinoblastoma (Rb), cyclin-dependent kinase (CDK), and CDK inhibitor genes regulate cell generation, and deregulation can produce increased cell growth and tumorigenesis. Polycythemia vera (PV) is a clonal myeloproliferative disease where the mechanism producing increased hematopoiesis is still unknown. To investigate possible defects in cell-cycle regulation in PV, the expression of Rb and CDK inhibitor gene messenger RNAs (mRNAs) in highly purified human erythroid colony-forming cells (ECFCs) was screened using an RNase protection assay (RPA) and 11 gene probes. It was found that RNA representing exon 2 of p16(INK4a) and p14(ARF) was enhanced by 2.8- to 15.9-fold in 11 patients with PV. No increase of exon 2 mRNA was evident in the T cells of patients with PV, or in the ECFCs and T cells from patients with secondary polycythemia. p27 also had elevated mRNA expression in PV ECFCs, but to a lesser degree. Because the INK4a/ARF locus encodes 2 tumor suppressors, p16(INK4a) and p14(ARF) with the same exon 2 sequence, the increased mRNA fragment could represent either one. To clarify this, mRNA representing the unique first exons of INK4a and ARF were analyzed by semiquantitative reverse transcription-polymerase chain reaction. This demonstrated that mRNAs from the first exons of both genes were increased in erythroid and granulocyte-macrophage cells and Western blot analysis showed that the INK4a protein (p16(INK4a)) was increased in PV ECFCs. Sequencing revealed no mutations of INK4a or ARF in 10 patients with PV. p16(INK4a) is an important negative cell-cycle regulator, but in contrast with a wide range of malignancies where inactivation of the INK4a gene is one of the most common carcinogenetic events, in PV p16( INK4a) expression was dramatically increased without a significant change in ECFC cell cycle compared with normal ECFCs. It is quite likely that p16(INK4a) and p14(ARF) are not the pathogenetic cause of PV, but instead represent a cellular response to an abnormality of a downstream regulator of proliferation such as cyclin D, CDK4/CDK6, Rb, or E2F. Further work to delineate the function of these genes in PV is in progress. (Blood. 2001;97:3424-3432)