A Study On The Correlation Between JAK2V617F Mutation And The Expression Level Of Cytokine Receptors In Myeloproliferative Disorders

Objective:The BCR/ABL negative chronic myeloproliferative disorders ( cMPDs ) mainly consist of polycythemia vera (PV), primary thrombocythemia(ET)and idiopathic myelofibrosis (IMF). Recently, acquired high pathogenic JAK2V617F point mutations were found in almost 90% of PV as well as some ET and IMF patients. JAK2 is a constitutive tyrosine kinase which can activate the JAK-STAT signal transduction pathways. The JAK2V617F point mutation which can cause cMPDs such as PV requires coexpression of the type I cytokine receptors to exert its constitutive activation activity. Without the expression of type I cytokine receptors, the JAK2V617F mutation can not fully display its biological activities. The purpose of this study is to investigate the expression of erythropoietin receptor (EPOR), granulocyte colony-stimulating factor receptor(G-CSFR) and thrombopoietin receptor (C-MPL) in cMPDs, further investigate the molecular biological pathogenesis of BCR/ABL negative cMPDs, and hoping to establish a theory foundation for providing JAK2V617F-positive-cMPDs patients with more specific targeted therapeutic drugs. Methods:The present study included 44 patients with BCR/ABL negative chronic myeloproliferative disorders (16 with PV, 14 with ET and 14 with IMF, respectively), 11patients with chronic myelogenous leukemia(CML) and 20 healthy volunteers as normal control (NC). Quantitative reverse transcription polymerase chain reaction(RT-PCR) was used to detect the JAK2V617F mutation, and the patients were divided into the following groups according to the JAK2V617F positive or not:⑴NC group⑵CML group⑶JAK2V617F- treated group⑷JAK2V617F~+ treated group⑸JAK2V617F- pre-treated group and⑹JAK2V617F~+ pre-treated group. The expression of EPOR mRNA, G-CSFR mRNA and C-MPL mRNA in each experimental group were evaluated by Quantitative real-time PCR).Results:1 Use the quantitative reverse transcription polymerase chain reaction(RT-PCR) to detect JAK2V617F mutation, the results showed that 26 out of 44 BCR/ABL negative cMPDs patients had JAK2V617F point mutation (positive rate is 59.1%), including 9 of 16 PV patients (positive rate is 56.25%), 10 of 14 ET patients (positive rate is 71.43%), 7 of 14 IMF patients (positive rate is 50.0%). By contrast, no JAK2V617F mutation was detected in 11 CML patients and 12 healthy volunteers.2 Use the fluorescent quantitative PCR to evaluate the expression of EPOR mRNA, G-CSFR mRNA and C-MPL mRNA in each experimental group. The results were shown as following:2.1 EPOR mRNAThe relative expression data of EPOR mRNA in each group were tested by normality test and homogeneity test of variance, and these data were confirmed in normal distribution but not with equal variance. One-factor analysis of variance show F=1063.8, P=0.000,indicate the relative expression of EPOR mRNA among each group is not complete the same, so further use the t'test to compare between every two groups. There is significant difference between all the cMPDs patients and normal control group(P<0.05). There is significant difference before and after the treatment of JAK2V617F~+ as well as JAK2V617F- cMPDs patients(P<0.05). There is no significant difference between JAK2V617F- pre-treated group and JAK2V617F+ pre-treated group(P>0.05).2.2 G-CSFR mRNAThe relative expression data of G-CSFR mRNA in each group were tested by normality test and homogeneity test of variance, these data were confirmed in normal distribution and with equal variance. One-factor analysis of variance show F=280.813, P=0.000,indicate the relative expression of G-CSFR mRNA among each group is not complete the same, so further use the LSD-t test to compare between every two groups. There is significant difference when cmpared JAK2V617F~+ pre-treated group and JAK2V617F~- pre-treated group with normal control group (both P<0.05), and then, there is significant difference when compared JAK2V617F~+ pre-treated group with JAK2V617F- treated group and JAK2V617F~+ treated group(both P<0.05). There is no significant difference when compared JAK2V617F- pre-treated group with JAK2V617F~+ pre-treated group (both P>0.05).2.3 C-MPL mRNAThe relative expression data of C-MPL mRNA in each group were tested by normality test and homogeneity test of variance, these data were confirmed in normal distribution and with equal variance. One-factor analysis of variance show F=41.272, P=0.000, indicate the relative expression of C-MPL mRNA among each group is not complete the same, so further use the LSD-t test to compare between every two groups. There is no significant difference when compared JAK2V617F~+ pre-treated group with JAK2V617F~- pre-treated group and normal control group (both P>0.05). There is significant difference before and after the treatment of cMPDs patients (P<0.05).Conclusion:1 JAK2V617F mutation is involved in the the pathogenesis of cMPDs, rather than a occasional occured nonfunctional mutation.2 JAK2V617F mutation may be associated with the Prognosis of cMPDs, but the details need to be elucidated by follow-up survey, observation and statistical analysis with a large number of cases 3 Type I cytokine receptors with JAK2V617F mutation may be associated with the Prognosis of cMPDs together.4 Type I cytokine receptors have a high expression in many malignant hematopoietic disorders, and be associated with the pathogenesis of many kines of malignant diseases, but not the key factor for the pathogenesis of cMPDs.