Role of Gax Overexpression in Proliferation and Cell Cycle of Rat Pulmonary Arterial Smooth Muscle Cells Exposed to Hypoxia

Objective:Toexplore the effects of growth arrest-specific homeobox(Gax)transfection on overexpression of Gax gene and proliferation of rat pulmonary arterial smooth muscle cells(PASMCs) exposure to hypoxia.Methods:PASMCs were transfected with Gax gene by a replication-deficient adenovirus expressing the hemagglutinin-tagged Gax cDNA(Ad-Gax).Exposure to normal oxygentention (21% O2) or hypoxia(2.5% O2) for 2,6,12,24,48 h,expressions of Gax mRNA and proteins in PASMCs were detected by RT-PCR and immunocytochemistry.MTT analysis,3H-TdR incorporation and flow cytometry were used to measure the PASMCs proliferation.Results:The Gax overexpression in transfection group was confirmed by RT-PCR and immunocytochemistry.After exposure to nomoxia or hypoxia for 2,6,12,24,48 h,the OD values of PASMCs without Ad-Gax transfection were 0.38±0.02,0.44±0.11,0.48±0.05,0.59±0.07,0.67±0.03 and 0.75±0.18,respectively.Compared with that in PASMCs exposure to nomoxia,the OD values of PASMCs exposure to hypoxia displayed a marked increase after 12 h (P0.05).However,the OD values of PASMCs with Ad-Gax transfection were 0.17±0.04,0.15±0.02,0.24±0.11,0.33±0.13,0.31±0.03 and 0.37±0.09,respectively.Compared with that in non-transfection groups,the OD values of PASMCs exposure to hypoxia significantly decreased after 12 h (P0.05 and 0.01).Compared with that in PASMCs without Ad-Gax transfection,the ratio of G0/Gl increased ,but the ratio of S+G2/M decreased significantly in PASMCs transfected by Ad-Gax exposure to hypoxia (P0.01).Conclusion:Gax overexpression occurred in PASMCs which were transfected with Ad-Gax and Gax overexpression could inhibit the PASMCs proliferation induced by hypoxia.