Neuroblastoma Cell Death Induced by eEF1A2 Knockdown Is Possibly Mediated by the Inhibition of Akt and mTOR Phosphorylation

Background The protein kinase B/mammalian target of the rapamycin (Akt/mTOR) pathway is one of the most potent prosurvival signaling cascades that is constitutively active in neuroblastoma. The eukaryotic translation elongation factor-1, alpha-2 (eEF1A2) protein has been found to activate the Akt/mTOR pathway. However, there is a lack of data on the role of eEF1A2 in neuroblastoma. The present study investigated the effect of eEF1A2 silencing on the viability of neuroblastoma cells and its possible signaling. Materials and Methods: Human SH-SY5Y neuroblastoma cells were transfected with small interfering RNA (siRNA) against eEF1A2. After 48 h of transfection, cell viability was assessed using an MTT assay. The mRNA expression of p53, Bax, Bcl-2, caspase-3 and members of the phosphoinositide 3-kinases (PI3K)/Akt/mTOR pathway was determined using quantitative real-time RT-PCR (qRT-PCR). The protein expression of Akt and mTOR was measured using Western blot analysis. Results: eEF1A2 knockdown significantly decreased the viability of neuroblastoma cells. No significant changes were observed on the expression of p53, Bax/Bcl-2 ratio, and caspase-3 mRNAs; however, the upregulated trends were noted for the p53 and Bax/Bcl-2 ratio. eEF1A2 knockdown significantly inhibited the phosphorylation of both Akt and mTOR. Almost all of the class I (PIK3CA, PIK3CB, and PIK3CD) and all of the class II PI3K genes were slightly increased in tumor cells with eEF1A2 knockdown. In addition, a slightly decreased expression of the Akt2, mTORC1, and mTORC2 was observed. Conclusion: eEF1A2 knockdown induced neuroblastoma cell death, in part through the inhibition of Akt and mTOR, suggesting a potential role of eEF1A2 as a molecular target for neuroblastoma therapy.