PTEN induces anoikis through its phosphatase activity in human bladder transitional carcinoma cells BIU-87

Objective:To investigate the effects and mechanisms of tumor suppressor gene PTEN on the induction of anoikis of human bladder transitional carcinoma cells BIU-87.Methods:BIU-87 cells were transfected with GFP plasmids containing wild-type PTEN or phosphatase inactivating mutant PTEN(C124A-PTEN)in vitro.The PTEN expression and the phosphorylation levels of focal adhesion kinase(FAK)and protein kinase B(PKB/Akt)were detected by Western blotting.Flow cytometry assay and laser scanning confocal microscopy were used to analyze apoptosis in adherent and non-adherent cells.Results: Compared with the control group,PTEN expression in the cells transfected with wild-type PTEN increased to 210%–260%, while the phosphorylation level of FAK and Akt decreased 59%(P<0.01)and 89%(P<0.01),respectively.And the anoikis percentage increased from 8.32±0.57%to 37.62±2.12%.In the cells transfected with C124A-PTEN,neither the phos- phorylation of FAK and Akt nor the anoikis percentage had obviously changed,although the PTEN expression enhanced remarkably in comparison with the control.Conclusion:Through its phosphatase activity,tumor suppressor gene PTEN can suppress the phosphorylation of FAK and Akt,and induce anoikis in human bladder transitional carcinoma cells BIU-87.