The AKT2
kinase (protein kinase Bβ) is overexpressed in high-grade
gliomas. Upregulation of the AKT2 gene has been previously observed in
glioblastoma patients suffering from
chemotherapy failure and
tumor progress. In this study, we aimed to evaluate the effect of AKT2 on viability and chemoresistance in the human
glioblastoma cell line U251. The U251 cell line was stably transfected with
short hairpin RNA (
shRNA) targeting AKT2. U251 cells underexpressing AKT2 were then examined for viability with
temozolomide (TMZ) treatment, and tested for cell apoptosis both in vitro and in
tumor-implanted mice. Next, expressions of several chemoresistance-related molecules were measured by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blot analysis. The results showed that the 50% inhibitory concentration (IC50) of AKT2
shRNA-transfected cells was significantly lower compared with Lenti-GFP-transfected and nontransfected controls and that the
tumor growth of the AKT2-shRNA and TMZ combined-treated mice was obviously suppressed in either mass or volume. Concomitantly, the apoptosis of TMZ-treated
tumor cells was significantly enhanced after knockdown of AKT2, as measured by flow cytometry and in situ
terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis. Furthermore, AKT2-inhibition in TMZ-treated
glioblastoma U251 cells upregulated apoptotic effector
caspase-3, whereas it downregulated antiapoptotic
protein Bcl-2,
DNA repairing
protein MGMT, and
drug efflux pump
protein MRP1. Our study identified AKT2 as an important gene in presenting chemoresistance in
glioblastoma, and a potential target to potentiate the clinical effect of
chemotherapy in
glioma treatment.