Senescence Of Alveolar Epithelial Cells And Its Regulatio PTEN

Background:Idiopathic pulmonary fibrosis(IPF)is a disease which cannot be cure by any treatment so far and its pathogenesis is also unclear.Many researchers found out that accelerated senescence or premature aging exited in alveolar epithelial cells(AEC)during pathogenesis of IPF.So we may find new targets in senescence of AEC to improve the treatment of IPF.Purpose:Our research aimed to verify that loss of PTEN can trigger the senescence of AEC to mediate the pathogenesis of IPF,and whether the regulation of PTEN is through PI3K/AKT pathway or overloaded ROS in cells.Methods:Object of the study was A549 cells for its similar characteristics with typeⅡ AEC.(1)Aging model of AEC:Different concentration of bleomycin were added to induce the senescence of AEC for 5 days,then several markers of senescence such as protein p21,SA-β-gal and SASP were tested.(2)PTEN expression in the model:After the model established successfully,expression of PTEN was tested by western blot.(3)Role of PTEN in the model:Lentivirus vector was applied to transfect the AEC to up-regulate and knock out the expression of PTEN respectively,then bleomycin were added to stimulate cells.After 5 days,PTEN expression and aging markers were tested.(4)p21 and PTEN expression in human lung tissue of IPF:The lung samples were from lung transplantation of IPF patients and normal lung tissues were from lung cancer patients.Western blot was conducted to test the expression of p21 and PTEN.(5)The mechanism of PTEN mediated senescence:ROS production in aging cells was tested by Flow Cytometer and activiation of PI3K/AKT pathway also were tested by western blot.Results:(1)Aging markers were increased gradually along with the increasing of bleomycin.(2)Expression of PTEN was decreased gradually in the model.(3)Overexpression and silence of PTEN can relieve and induce aging of AEC respectively.(4)In lung samples of IPF patients,p21 was increased significantly and PTEN was decreased in several patients.(5)In the aging model,ROS production had no change but PI3K/AKT pathway were activated significantly.Conclusions:Bleomycin can stably induce senescence of AEC,and loss of PTEN can trigger the senescence of AEC so as to mediate the pathogenesis of IPF,the mechanism may involved in activation of PI3K/AKT pathway but had no relate to ROS production.