Study On The Role And Mechanism Of Annexin A2in Hepatopulmonary Syndrome Rat Serum-induced Proliferation Of Pulmonary Arterial Smooth Muscle Cells

Objective: Hepatopulmonary syndrome (HPS) is definedas an arterial oxygenation defect induced by microangiopathy whichassociates with hepatic diseases. Pulmonary vascular remodeling is akey pathophysiological component in microangiopathy, currently, toexplore the crucial target in the pathogenesis has become key point ofstudy. Annexin A2(ANXA2) is member of the annexin superfamily ofcalcium-dependent phospholipid-binding proteins, which involves inmany cellular regulatory processes, such as cell differentiation,proliferation, migration and apoptosis. In this study, we sought toexplore the role of ANXA2in HPS rat serum-induced proliferation ofpulmonary arterial smooth muscle cells （PASMCs） and clarify themolecular mechanism of HPS-associated pulmonary vascularremodeling and provide evidences for prevention and cure. Methods:PASMCs were primary cultured and identified, and then divided to twogroups: group C consisted of PASMCs that were cultured in normal ratserum, group HPS consisted of PASMCs that were incubated in HPS ratserum for various time periods:24,48,72h. The changes of PASMCsproliferation were determined by3H-TdR incorporated way and MTT assay. The levels of ANXA2mRNA and protein expression weredetected by RT-PCR and western blot respectively. Silenced ANXA2expression by RNA interference (RNAi) and further observed the effectof HPS rat serum-induced PASMCs proliferation and examined thealtered phosphorylation level of ERK1/2and NF-κB by western blot.Results: The value of3H-TdR and MTT of PASMCs that incubated inserum for24,48,72h in group HPS were greater than group C at eachtime-point, and the differences were statistically significant (P<0.05).Accompanying the prolongation of incubated time, the increased valueof3H-TdR and MTT were higher than group C. The mRNA and proteinexpression of ANXA2could be detected in both groups, compared togroup C, ANXA2mRNA and protein expression were higher in groupHPS, and the longer PASMCs were incubated in HPS rat serum, thegreater were increasd in expression（P<0.05）. After downregulating theexpression of ANXA2by siRNA and incubating in HPS rat serum, thevalue of3H-TdR and MTT of PASMCs were greatly reduced comparedwith control groups. Compared with group C, the phosphorylation levelof ERK1/2and NF-κB were higher in cultures treated with HPS ratserum, after ANXA2downregulation, HPS rat serum-inducedphosphorylation of ERK1/2and NF-κB were lower than control groups.Conclusion: HPS rat serum induced PASMCs proliferation; the alteredactivation of pro-proliferative signaling such as ERK1/2and NF-κB, in association with HPS rat serum were mediated by ANXA2, suggestingan important mechanism of PASMCs proliferation.