Up-regulated PTEN Expression Increases The Chemosensitivitv In K562/ADM Cells

Objective To investigate the mechanism of reversal of chemoresistance to ADM on K562/ADM cells by up-regulating PTEN expression. Methods K562/ADM cells were transient transfected with PTEN or empty vector. The level of PTEN in K562/ADM cells was assayed by Western blot and RT-PCR. Cell viability on K562/ADM was determined by MTT assay. Cell apoptosis was assayed by flow cytometry. Activity of caspase-3was assayed with a Caspase Colorimetric Assay Kit. The proteins of LC3-I/II, Beclinl, p-Akt, p-P70S6K were assayed by Western blot. The autophagic vacuoles were detected by MDC stain and Electron microscopy. Results①The mRNA and protein levels of PTEN in K562/ADM cells transfected with pGFP-PTEN were increased significantly compared with the controls(untreated and tranfected with empty vector), P<0.05.②nhanced expression of PTEN by gene transfection resulted in a reversal of resistance to ADM. Compared with the empty vector group, cell viability of K562/ADM cells tranfected with PTEN mRNA was decreased from (94.07±2.61)%to (53.83±4.23)%,and cell apoptotic rate increased from (11.89±1.69)%to (43.69±2.30)%, P <0.05. The cell viability and cell apoptotic rate between the untreated and empty vector group [(95.26±3.42)%vs(94.07±2.61)%,(7.64±3.62)%vs(11.89±1.69)%] have no difference, P>0.05. Meanwhile, pretreated with caspase-3inhibitor (Z-DEVE-FMK) didn’t completely inhibit the cytotoxicity of ADM to K562/ADM cells.③After treatment of ADM for12or24hours, the activities of casepase-3in PTEN-transfected K562/ADM cells increased compared with those tranfected with empty vector [(2.27±0.13) vs (1.19±0.14),(3.15±0.08) vs (1.48±0.06)], P<0.05.(4) Compared with empty vector group,the protein levels of LC3-II and Beclinl in K562/ADM cells transfected with PTEN were increased by83%and18%respectively, and the protein levels of p-Akt and p-p70S6K were declined by96%and87%respectively.⑤The upregulation of PTEN in K562/ADM cells improved the number of autophagic vacuoles. Conclusions The upregulation of PTEN expression increased the chemosensitivity of K562/ADM,which may be related with the inhibition of PI3K/AKT/mTOR pathway and the induction of apoptosis and autophagy induced by PTEN transfection.