A Research About The Promoter’s Methylation Of RASSF1A And SOCS-1Gene In The Patients With Myelodysplastic Syndromes

Background:Myelodysplastic syndrome (MDS) is one of the malignant clone acquired disorders, it originated in hematopoietic stem/progenitor cells, have very strong heterogeneity. Its main characteristic is bone marrow failure, refractory cytopenia in peripheral blood cells and high risk to become AML.Its clinical manifestations are anemia, bleeding and infection. Complete blood cell in patients are reduced and easily converted into acute myeloid leukemia cells. MDS is a multifactor disease progression with many genetic changes accumulate, the process of its pathogenesis has not been clear, in recent years, studies have found that changes in the genetics and epigenetics, especially the mutations in oncogenes or inactivation in tumor suppressor gene, play an important role in the tumorigenesis and development. Studies found that DNA methylation is a reversible change, reverse gene promoter region methylation can make silence gene expression again, this is new targets for the treatment of hematologic malignancies. Recently, the tumor suppressor gene RASSF1A and SOCS-1become new hotspot in the field of tumor, a large number of studies have shown that FASS1A and SOCS-1gene promoter region methylation play an important role in a variety of the development of tumor, but its effect on the MDS has not yet been reported at home and abroad.Objective:This study by examining RASSF1A gene and SOCS-1gene expression levels and its promoter region methylation status in patients with myelodysplastic syndrome (MDS) to explore the correlation between the methylation of RASSF1A and SOCS-1gene and the development of MDS.Research the changes in tumor suppressor genes’ methylation state before and after the treatment of decitabine, provides a new targets for demethylation drugs.Methods:30patients with MDS were chosen as study group,15patients with non-malignant hematological diseases were chosen as control group, divide the study group according to the MDS IPSS risk score. Mononuclear cells were isolated using lymphocyte separation medium. Extract the DNA from the bone marrow of patients with blood mononuclear cells and RPMI8226cell lines and U266cell lines according to the manual of genomic DNA extraction kit and use Trizol to extract total RNA. Extract the same amount of DNA from MDS patients before and after treatment of decitabine, use the the Jetta gel system and ImageJ software to analysis the strip of the target gene and the reference gene, se the OD ratio of the target gene and the reference gene to represente the relative content of the PCR product. Methylation specific PCR(MS PCR) was employed to detect the methylation status of the RASSF1A an SOCS-1gene promoter region in30patients with MDS. Expression levels of RASSF1A an SOCS-1gene mRNA was also determined by reverse transcription PCR (RT PCR).Contrast MDS Patients’ methylation status of RASSF1A and SOCS-1gene before and after using decitabine.Results:The methylation rate of RASSF1A gene in study group(73.33%) was much higher than that of the control group(P<0.05), and the methylation rate of RASSF1A gene in medium-high risk MDS patients(81.8%) is obviously higher than that of the low-risk MDS patients(18.2%)(P<0.05); Meanwhile, the mRNA expression level of RASSF1A gene in study group(40%) was significantly lower than the control group(P<0.05).The methylation rate of SOCS-1gene in study group(53.33%) was much higher than that of the control group(P<0.05), and the methylation rate of RASSF1A gene in medium-high risk MDS patients(65.2%) is obviously higher than that of the low-risk MDS patients(14.3%)(P<0.05);At the same time, the mRNA expression level of SOCS-1gene in study group was significantly lower than the control group(P<0.05).The RASSF1A and SOCS-1gene methylation level of the MDS patient after Decitabine treatment is lower than that of newly diagnosed patients.Conclusion:A significant correlation existed between RASSF1A&SOCS-1gene hypermethylation and the loss of expression of RASSF1A&SOCS-1mRNA in MDS. The hypermethylation of the RASSF1A&SOCS-1gene promoter region is closely related to the pathogenesis of MDS. Detection methylation status of RASSF1A and SOCS-1genes’ promoter region is expected to become new indicator to judge the progression of MDS, guide the clinical diagnosis, treatment and prognosis of outcome of MDS. Decitabine can reduce the methylation levels in the RASSF1A and SOCS-1gene, and it also provide a new theoretical basis for using decitabine as the treatment of MDS.