Qiliqiangxin Attenuates Angiotensin Ⅱ-Induced Cardiac Hypertrophy Through Downregulation Of MiR-27b

Background:Pathological cardiomyocyte hypertrophy is one of the major factors leading to heart failure.Qiliqiangxin capsule is composed of 11 kinds of traditional Chinese medicine prescription,has obvious clinical efficacy in the treatment of heart failure.However,the mechanism of Qiliqiangxin on cardiomyocyte hypertrophy is not clear.Our previous studies have found that Qiliqiangxin improves myocardial function and retards heart failure progress through the PPAR-γ signal pathway in myocardial infarction mouse model,miR-27b has been reported to have the effect of regulation of myocardial hypertrophy through the PPAR-y signal pathway both in vivo and vitro.But its mechanism is still unclear.The aim of this study was to determine whether Qiliqiangxin could play a role in the treatment of angiotensin II-induced cardiomyocyte hypertrophy in vitro and to study the role of miR-27b in the therapeutic effect of Qiliqiangxin.Methods:The model of cardiomyocyte hypertrophy was established by separating the hearts of newborn rats,and then separating the primary cardiomyocytes from the heart.Then,we used angiotensin II(10 ＾ 6 mol/L,48 hours)to induce the model of cardiomyocyte hypertrophy.The expression of ANP,BNP and Myh7 in cardiomyocytes were detected by real-time PCR.The surface area of cardiomyocytes was compared through double-stained immunofluorescence of a-actin protein and Dapi-Detection of protein/DNA ratio to evaluate the level of protein synthesis.Followed by adding Qiliqiangxin(0.5 ug/ml,48 hours),we identify the role of Qiliqiangxin in treatment of cardiomyocyte hypertrophy by comparing the three indicators between treatment and control group.Finally,miR-27b mimics and inhibitors were added to cardiomyocyte,by comparing the changes between each group,we clarified the role of miR-27b in the therapeutic effect of Qiliqiangxin.For database management and statistical analysis,we used GraphPad software.Significance was a two-tailed a-level of 0.05 or less Means were compared using t test,Multi-group comparison using one-way analysis of variance,adjusting significance levels by Tukey method.Results:Our results suggests that the stimulation of angiotensin II could increase the expression of ANP,BNP and Myh7 genes in the cardiomyocyte,increased the cell surface area and protein synthesis.After stimulating cardiomyocytes with Qiliqiangxin,ANP,BNP,Myh7 expression decreased significantly,cell surface area and protein synthesis decreased.But Qiliqiangxin didn’t reduce the basic level of ANP,BNP,Myh7 expression,cell surface area and protein synthesis.We found that the expression of miR-27b increased in cardiomyocyte hypertrophy model,while Qiliqiangxin could significantly reduce the level of miR-27b.The addition of miR-27b mimics can increase the expression of reduced ANP,BNP and Myh7 genes,increase the surface area and the protein synthesis.After adding the inhibitor of miR-27b in the model didn’t further improve myocardial hypertrophy.Conclusion:At the cellular level,Qiliqiangxin relieves the hypertrophy of cardiomyocytes induced by angiotensin II and inhibits the expression of miR-27b.On the basis of this,increasing the expression of miR-27b leads to the recurrence of cardiac hypertrophy,while inhibition of miR-27b cannot further aggravate the process of cardiac hypertrophy.Therefore,miR-27b plays an important role in the process of QiliQiangxin’s inhibition of pathological cardiomyocyte hypertrophy.