Knockdown of AKT2 expression by RNA interference inhibits proliferation, enhances apoptosis, and increases chemosensitivity to the anticancer drug VM-26 in U87 glioma cells

Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, No. 415 FengYang Road, Shanghai 200003, People's Republic of China.
Brain research (Impact Factor: 2.84). 07/2012; 1469:1-9. DOI: 10.1016/j.brainres.2012.06.043
Source: PubMed


The AKT2 kinase (protein kinas Bβ) is frequently overexpressed in malignant gliomas. In this study, the human glioblastoma cell line U87 was stably transfected with a lentivirus vector expressing a short hairpin RNA (shRNA) targeting AKT2. Knockdown of AKT2 by the shRNA inhibited U87 cell proliferation and increased the rate of apoptosis. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot analysis revealed that cells stably underexpressing AKT2 showed lower expression of the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and enhanced expression of the apoptosis effector caspase-3 compared to U87 cells stably transfected with a control vector. Furthermore, expression levels of AKT2 were correlated with the IC50 of the antitumor drug VM-26 (teniposide); the VM-26 IC50 was reduced from 6.46±0.42μg/ml in control glioma cells to 1.15±0.22μg/ml in U87 cells underexpressing AKT2. Combined AKT2 knockdown and VM-26 treatment inhibited cell proliferation in vitro more effectively than either treatment alone. Knockdown of AKT2 expression was associated with decreased expression of the multidrug resistance-associated protein 1 (MRP1) without affecting MRP1 mRNA expression. However, the mRNA and protein levels of MDR1 (p-glycoprotein) were unaffected by AKT2 knockdown. These results indicate that inhibition of AKT2 expression may be an effective means for overcoming AKT2-associated chemoresistance in human malignant glioma cells and may represent a potential gene-targeting approach to treat glioma.

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