Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
Exp Hematol Oncol. 2012 Jun 21;1(1):15. doi: 10.1186/2162-3619-1-15.
JAK2V617F, a gain-of-function mutant form of tyrosine kinase JAK2, is found in the majority of patients with Ph- myeloproliferative neoplasms (MPNs), a group of chronic hematological diseases that often lead to acute leukemia. The current study is intended to find other gene mutations that collaborate with JAK2V617F to cause leukemic transformation.
Total RNA and genomic DNA were isolated from two JAK2V617F-positive cell lines, namely, erythroleukemic HEL and megakaryoblastic leukemic SET-2 cells. Candidate genes were amplified by PCR and further sequenced.
Homozygous mutations of the TP53 gene which encodes tumor suppressor p53 were found in HEL and SET-2 cells. While HEL cells, which have homozygous JAK2V617F, contain a rare M133K p53 mutation, SET-2 cells, which have a heterozygous JAK2V617F mutation, contain a common R248W p53 alteration. Western blot analyses revealed high levels of p53 expression in both cells. M133K and R248W are located in the DNA binding domain of p53. Structural analyses revealed that they potentially disrupt the interaction of p53 with DNA, thereby causing loss of p53 function.
JAK2V617F and p53 mutations coexist in leukemia cells. We believe that JAK2V617F is able to drive leukemic transformation when the function of tumor suppressor p53 is lost. The interplay of JAK2V617F with p53 may affect the progression of MPNs.
JAK2V617F 是一种酪氨酸激酶 JAK2 的功能获得性突变形式，存在于大多数 Ph-骨髓增殖性肿瘤（MPN）患者中，MPN 是一组常导致急性白血病的慢性血液病。本研究旨在寻找与 JAK2V617F 协同导致白血病转化的其他基因突变。
从两个 JAK2V617F 阳性细胞系，即红白血病 HEL 和巨核细胞白血病 SET-2 细胞中分离总 RNA 和基因组 DNA。通过 PCR 扩增候选基因，并进一步测序。
在 HEL 和 SET-2 细胞中发现了编码肿瘤抑制因子 p53 的 TP53 基因的纯合突变。虽然具有纯合 JAK2V617F 的 HEL 细胞含有罕见的 M133K p53 突变，但具有杂合 JAK2V617F 突变的 SET-2 细胞含有常见的 R248W p53 改变。Western blot 分析显示这两个细胞中 p53 表达水平较高。M133K 和 R248W 位于 p53 的 DNA 结合域。结构分析表明，它们可能破坏了 p53 与 DNA 的相互作用，从而导致 p53 功能丧失。
JAK2V617F 和 p53 突变共存于白血病细胞中。我们认为，当肿瘤抑制因子 p53 的功能丧失时，JAK2V617F 能够驱动白血病转化。JAK2V617F 与 p53 的相互作用可能会影响 MPN 的进展。
