Sdudies On RIZ1Gene Expression And Its Promoter Methylation Status In Myelodysplastic Syndrome (MDS)

Objective1.To analyze the differences of RIZ1gene expression in various subtypes and risk groups of the patients with myelodysplastic syndrome (MDS) and explore the correlation between RIZ1gene expression and the clinical features.2. To analyze the differences of RIZ1gene promoter mythylation status in various subtypes and risk groups of the patients with myelodysplastic syndrome (MDS) and explore the correlation between RIZ1gene promter mythlation state and the clinical characteristics.3.To explore the correlation between RIZ1gene expression and its promoter mythylation status as well as their relationship with the development of myelodysplastic syndrome(MDS).Methods1.46patients with myelodysplastic syndrome (MDS) were collected for the study,of which33cases were male,13cases were female,the ages were16-83years.there were10cases in health control.According to the World Health Organization(WHO) criteria, there were17cases of refractory anemia/ring sideroblasts refractory anemia/refractory cytopenia with multilineage dysplasia (RA/RARS/RCMD);9cases of refractory anemia with excess blast-I(RAEB-I),14cases of refractory anemia with excess blast-Ⅱ(RAEB-Ⅱ) and6cases of AML deprived from MDS (MDS/AML). In accordance with the international prognosis system (IPSS), there were low-risk group (0)9cases, inter-risk-1group,(0.5-1.0)19cases, inter-risk-2group (1.5-2.0)10cases and high-risk group (>2.5)8cases.2The expression of RIZ1mRNA was detected by real time fluorescence quantitative PCR in various subtypes and risk groups of the patients with myelodysplastic syndrome (MDS) and normal health control.3. The mythylation state of RIZ1gene promter was detected by methylation specific PCR (MSP) in various subtypes and risk groups of the patients with myelodysplastic syndrome (MDS) and normal health control.4.The R-banding was used for chromosome karyotypes of patients with myelodysplastic syndrome (MDS). Results1. The median number of relative quantity level of RIZ1mRNA expression in the bone marrow cells of myelodysplastic syndrome patients and healthy controls were0.5571(0.3335,0.8147) and1.0034(0.9201、1.4517) respectively.In myelodysplastic syndrome patients samples, the expression of RIZ1mRNA was declined relative to normal people samples (P<0.001). The gene expression was declined in78%(36/46) of myelodysplastic syndrome (MDS) patients. According to the World Health Organization(WHO) criteria,compared to control group,the expression of RIZ1mRNA was decreased significantly in (RA/RARS/RCMD)0.7453(0.5170,1.1446),(RAEB-I)0.6025(0.2693,07565)、(RAEB-Ⅱ)0.3664(0.2535,0.7697), MDS/AML0.3516(0.2788,0.5764) subtype groups (P=0.013,0.001,<0.001,<0.001respectively).there were statical differences between RA/RARS/RCMD0.7453(0.5170,1.1446) and RAEB-Ⅱ0.3664(0.2535,0.7697), MDS/AML0.3516(0.2788,0.5764)subtype groups (P=0.011,0.036). In accordance with the international prognostic scoring system (IPSS), There were low-risk group, inter-risk-1group, inter-risk-2group and high-risk group.The expression of the RIZ1gene was0.7795(0.6358,1.0371), and0.5600(0.3645,0.9314), and0.4990(0.2603,0.7697),0.3255(0.2293、0.4170),respectively.Among the four groups, the statical differences between the low-risk group、inter-risk-1group、inter-risk-2group、high-risk group and control health group were exsited (P=0.04,0.001,<0.001,<0.001respectively) and there was also statical difference between low-risk group and high risk group(P=0.011). No relationship had been detected between the expression of the RIZ1gene and the clinical features including age, gender and white blood count, the hemoglobin, platelet count and karyotypes.2. The methylation specific PCR was performaned on30patients with myelodysplastic syndrome (MDS) and10cases in control group, the RIZ1gene methylation rate was37%(11/30), there was no any RIZ1gene methylation in control group.According to the World Health Organization(WHO) criteria, all MDS patients were divided into RA/RARS/RCMD11cases, RAEB-I8cases, RAEB-Ⅱ7cases and MDS/AML4cases. RIZ1methylation positive rates of the four groups were:18.1%,37.5%,42.9%,75.0%. In accordance with the international prognostic scoring system (IPSS),there were low-risk group6cases, inter-risk-1group12cases, inter-risk-2group7cases and high-risk group5cases. RIZl methylation positive rates of the four groups were:16.7%,25.0%,57.1%,60.0%.RIZ1promoter methylation state differences in different subtypes and different risk classification were not seen statistically significant (P=0.226、0.237). there was no correlation between RIZ1gene promoter methylation and clinical parameters including the age, gender,white blood count, the hemoglobin, platelet count and karyotypes.3. Among the30cases of myelodysplastic syndrome patients samples,22cases showed delined RIZ1gene expression level.Of22cases, the promoter mythlation rate of RIZ1gene was50%(11/22).the expression level of11myelodysplastic syndrome samples with the RIZ1gene promter mythlation was0.3347(0.2062,0.3553) while the expression of the19cases with unmytlationed promoter was0.7664(0.5599,1.1489) and the difference of the two groups was statistically significant (P<0.001)Conclusion1The lower expression of RIZ1mRNA is relatively common in the patients with myelodysplastic syndrome.and the expression levels of RIZ1mRNA is different in different subtypes and different risk classification. It suggests the gene may participate in the pathogenesis of MDS and be important in the progression of the disease.2. The RIZ1gene promoter methylation phenomenon exists in the patients with myelodysplastic syndrome and the methylation rate are in different subtypes and different risk classification. It suggests the gene promoter methylation may be involved in the pathogenesis of MDS.3There is negative correlation between the RIZ1gene promoter methylation and RIZ1mRNA expression in the patients with myelodysplastic syndrome.The RIZ1promoter mythlation can make its expression level downregulate but it is not the only mechanism.