| Objections To study the related individual acquired factors,which would result in the different antihypertension efficacy of metoprolol inβ1-adrenergic receptor(β1-AR)gene - directed therapy.In addition,to investigate the role of DNA methylation in the control of expression ofβ1-AR gene,this may be the epigenetic molecular mechanism of different antihypertension efficacy of metoprolol.Our goal was to enrich and increase the basic and clinical study data.Methods Chain reaction-restriction fragment length polymorphism (PCR-RFLP)and polymerase chain reaction(PCR)methods were applied to detect CYP2D6 andβ1-AR gene polymorphisms.According toβ1-AR Gly389Arg genotypes,107 patients of essential hypertension with *10*10 of CYP2D6*10 genotypes were divided into two genotype groups——Arg/Arg group and Gly/Arg+Gly/Gly group.Both the two groups were administrated with metoprolol 100mg/day,twice per day. The related data,such as,sex,age,body height,body weight,blood glucose,blood lipid and history of smoking,was collected before administration.Indexes,as blood pressure,heart rate and adverse effect, were observed during the 8-week follow-up visit.In the present study as before,63 patients of essential hypertension with *10*10 of CYP2D6*10 genotypes and Arg/Arg ofβ1-AR Gly389Arg genotypes were chosen,the related data and antihypertension efficacy of metoprolol were both collected.Single factor analysis and multiple regression analysis were used to analyze the relationships between the acquired factors,such as age,baseline blood pressure,body mass index(BMI),hyperlipidemia and smoking,and different antihypertension efficacy of metoprolol.Furthermore,H9c2 rat miocardial cells were routinely cultured and randomly divided into two groups:5-aza-2'-deoxycytidine(5-aza-dC) groups in which cells were treated by different concentration of 5-aza-dC -0.5μmol / L,2.0μmol / L,5.0μmool / L and 10.0μmol / L and control group in which cells were treated by DMSO.ALL the cells were treated for 72 hours.AO/EB staining was applied to observe the cell morphology and apoptosis.Genomic DNA was isolated for bisulfite genomic sequencing and methylation-sensitive PCR(MSP)analysis to explore the methylation status ofβ1-AR gene promoter.Total RNA was extracted for fluorescence-quantitative RT-PCR analysis to determine the expression ofβ1-AR gene mRNA.Results 1.The results of different antihypertension efficacy of metoprolol inβ1-AR gene - directed therapy:According toβ1-AR Gly389Arg genotypes,107 patients with 10*10 of CYP2D6*10 genotypes were divided into two genotype groups - Arg/Arg(n=63)and Gly/Arg+Gly/Gly(n=44).The effective rate of metoprolol of the two groups was 65.5%and 40.9%,separately,which showed significantly statistical difference(P<0.05).For further study,23 patients with Arg/Arg ofβ1-AR Gly389Arg genotypes were not sensitive to metoprolol,and the ineffective rate was up to 35.5%.2.The results of the related acquired factors of different antihypertension efficacy of metoprolol inβ1-AR gene - directed therapy: single factor analysis indicated that baseline systolic blood pressure(SBP) and BMI significantly influenced the antihypertention efficacy of metoprolol(P<0.05).While,age,baseline diastolic blood pressure(DBP), hyperlipidemia and smoking showed no significant relationship with effective rate of metoprolol(P>0.05).Furthermore,multiple regression analysis also claimed that baseline SBP showed the significant effect to antihypertension efficacy of metoprolol.3.The results of epigenetic molecular mechanism of different antihypertension efficacy of metoprolol inβ1-AR gene - directed therapy:β1-AR gene promoter of H9c2 miocardial cells was methylated.The methylation status ofβ1-AR gene promoter of H9c2 cells treated by 5.0μmol/L 5-aza-dC was significantly down-regulated.While,the expression ofβ1-AR gene mRNA was up-regulated,which showed the significantly statistical difference(P<0.05).Conclusions 1.β1-AR Gly389Arg genotypes influenced the antihypertension efficacy of metoprolol.Patients with Arg/Arg had the better efficacy.However,the significantly different individual responses to metoprolol among them still existed.Baseline SBP and BMI were the causes for the different antihypertension efficacy of metoprolol inβ1-AR gene - directed therapy.Higher baseline SBP and normal BMI predicted the better drug efficacy.2.β1-AR gene promoter had many methylated positions.The down-regulated methylation of the promoter would result in the up-regulated expression ofβ1-AR gene mRNA.So,it was possible that DNA methylation regulated the expression ofβ1-AR gene mRNA,this would be the epigenetic molecular mechanism of different antihypertension efficacy of metoprolol inβ1-AR gene - directed therapy. |
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