JAK2V617F and p53 mutations coexist in erythroleukemia and megakaryoblastic leukemic cell lines

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.Ph- myeloproliferative neoplasms (MPNs) are clonal hematopoietic disorders in which one or more myeloid lineages are abnormally amplified. These diseases represent a group of chronic conditions including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) [1]. MPNs mainly affect older people with an average age of onset of 55 years. Complications associated with MPNs include development of acute leukemia as well as thrombosis, hemorrhage, and myeloid metaplasia. The major molecular lesion in these diseases is JAK2V617F, which occurs in over 90% of PV and over 50% of ET and PMF [1,2]. JAK2V617F has enhanced tyrosine kinase activity, and it causes constitutive activation of down-stream signal transducers when expressed in cells [3]. Studies have demonstrated that transgenic expression or knock-in of JAK2V617F in mice causes MPN-like phenotypes [4,5]. However, whether or not JAK2V617F is able to drive leukemic transformation is not known.Ma