Combination Therapy with AKT3 and PI3KCA siRNA Enhances the Antitumor Effect of Temozolomide and Carmustine in T98G Glioblastoma Multiforme Cells.

Abstract

Glioblastoma multiforme (GBM) is the most malignant and invasive human brain tumor, and it is characterized by a poor prognosis and short survival time. Current treatment strategies for GBM, using surgery, chemotherapy and/or radiotherapy, are ineffective. The PI3K/AKT/PTEN signaling pathway is frequently deregulated in this cancer, and it is connected with regulation of the cell cycle, apoptosis, and autophagy. The current study was undertaken to examine the effect of small interfering RNA (siRNA) targeting the AKT3 and PIK3CA genes on the susceptibility of T98G cells to temozolomide (TMZ) and carmustine (BCNU). T98G cells were transfected with AKT3 or PI3KCA siRNA. Transfection efficiency was assessed using flow cytometry and fluorescence microscopy. The influence of AKT3 and PI3KCA siRNA in combination with TMZ and BCNU on T98G cell viability, proliferation, apoptosis, and autophagy was evaluated as well. Alterations in messenger RNA (mRNA) expression of apoptosis-related and autophagy-related genes were analyzed using quantitative reverse transcription polymerase chain reaction (QRT-PCR). Transfection of T98G cells with AKT3 or PI3KCA siRNA and exposure to TMZ and BCNU led to a significant reduction in cell viability, accumulation of subG1-phase cells, and reduction of cells in the Sand G2/M phases, as well as induction of apoptosis or necrosis, and regulation of autophagy. The siRNA-induced AKT3 and PI3KCA mRNA knockdown in combination with TMZ and BCNU inhibited proliferation and induced apoptosis and autophagy in T98G cells. Thus, knockdown of these genes in combination with TMZ and BCNU may offer a novel therapeutic strategy to more effectively control the growth of human GBM cells, but further studies are necessary to confirm a positive phenomenon for the treatment of GBM.