The Mechanism Of 17β-estradiol/miRNA-21 Signaling Pathway To Inhibite Pulmonary Vascular Remodeling Of Hypoxica-induced Pulmonary Hypertension

Objective:To observe and analysis the expression changes of miRNA-21（mi R-21）in rat pulmonary artery intervened by 17β-estradiol（E₂）and lay the foundation to explore the effect of E₂ on PASMCs proliferation.Methods:1 Animal expreriment:thirty-two healthy female Sprague-Dawdley rats were divided randomly into four groups after Castrated surgery:normoxia group,normoxia+E₂ group,hypoxia group,hypoxia+E₂ group.normoxia+E₂group and hypoxia+E₂ group received subcutaneous injection of E₂ 20ug/kg.d,and the other groups received subcutaneous injection of physiological saline with the same volume.The hypoxic groups were placed in the hypoxic chamber 24 hours everyday,and normoxic groups were kept in the room air.The rats were fed continuously for 8 weeks to establish hypoxia-induced pulmonary hypertention model.The pulmonary artery remodeling,mean pulmonary artery pressure（mPAP）,right ventricule hypertrophy index（RVHI）were observed.The mRNA level of proliferation cell nuclear antibody（PCNA）,mi R-21 in pulmoary artery were measured by real-time PCR and PCNA protein level by Western blot.2 In vitro:human pulmonary artery smooth muscle cells（hPASMCs）were divided into 3 groups:normoxia group,hypoxia group,hypoxia+E₂ group.It is determined by MTT experiment for cell proliferation.Real-time PCR to test mi R-21 and mRNA level of PCNA.Western blot to test the level of PCNA protein.Results:1 E₂ reduced the lung small artery remodeling,mPAP and Degree of right ventricular hypertrophy induced by hypoxia.Compared with normoxiagroup,The mPAP,RVHI of hypoxia group rats increased obviously（P<0.01）;normoxia+E₂ group did not change obviously（P>0.05）,the level of hypoxia+E₂group is between normoxia and hypoxia（P<0.01）.2 Hypoxia could upregulate miR-21 expression and the upregulation could be inhibited by E₂.Compared with normoxia group,the expression levels of PCNA mRNA,protein and miR-21 rose markly in hypoxia group（P<0.01）;normoxia+E₂ group had no significant difference（P>0.05）;the change in hypoxia+E₂ group is lower than hypoxia group but with the same trend（P<0.01）.3 Hypoxia promoted proliferation of hPASMCs and the proliferation could be inhibite by E₂.Compared with normoxia group,the proliferation of hPASMCs were obviously promoted by hypoxia（P<0.01）,the proliferation induced by hypoxia were obviously inhibited by E₂（P<0.01）.4 Hypoxia raised the expression of miR-21 and PCNA in hPASMCs and E₂ can reduce the increasing degree of miR-21.Compared with normoxia group,the expression levels of PCNA mRNA and protein,miR-21 rose markly（P<0.01）.Compared with hypoxia group,after intervention of E₂,the expression levels of PCNA mRNA and protein,miR-21 decreased markly（P<0.01）.Conclusions:E₂ could effectly decrease mPAP,degree of right heart hypertrophy,Pulmonary vascular remodeling of rat models,the protective effect may be associated with downregulating the expression of miR-21 and PCNA to inhibite the proliferation of hPASMCs.