Effect of hypoxia on<i> HIF-1a</i> and<i> NOS3</i> expressions in CD34<SUP>+</SUP> cells of JAK2V617F-positive myeloproliferative neoplasms

Purpose: Myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic stem-cell diseases with excessive proliferation of one or more blood cell lines. In this study, we evaluated the effect of different oxygen concentrations on HIF-1a and NOS3 gene expression to determine the effect of the bone marrow microenvironment on JAK2V617F positive Philadelphia chromosome negative (Ph-) MPNs.Patients and methods: Peripheral blood mononuclear cells (MNC) of 12 patients with Ph- MPN were collected. The presence of JAK2V617F allele status was determined with allele-specific nested PCR analysis. MPN CD34+ and CD34depleted populations were isolated from MNC by magnetic beads. Separate cell cultures of CD34+/depleted populations were managed at different oxygen concentrations including anoxia (-0%), hypoxia (-3%), and normoxia (-20%) conditions for 24 h. HIF-1a and NOS3 gene expression changes were examined in each population related to JAK2V617F status with real time RT-PCR.Result: It was revealed that relative HIF-1a and NOS3 expressions were significantly increased in response to decreased oxygen concentration in all samples. Relative HIF-1a and NOS3 expressions were found to be higher especially in CD34+ and CD34depleted populations carrying JAK2V617F mutations compared to MPN patients carrying wild-type JAK2.Conclusion: JAK2V617F might have specific role in HIF-1a and NOS3 regulations with respect to low oxygen concentrations in Ph- MPN. Further evaluations might reveal the effect of JAK2V617F on Ph- MPN pathogenesis in bone marrow microenvironment.