Silencing the PIK3CA Gene Enhances the Sensitivity of Childhood Leukemia Cells to Chemotherapy Drugs by Suppressing the Phosphorylation of Akt

ABSTRACT

PURPOSE: This study aimed to investigate the effects of PIK3CA on the sensitivity of acute B lymphocytic leukemia cells (Nalm-6 cells) to chemotherapy drugs. MATERIALS AND METHODS: Children's normal B lymphocytes and Nalm-6 cells were cultured. Nalm-6 cells were transfected with PIK3CA siRNA (siPIK3CA group) or its negative control (PIK3CA-Control group). Normal Nalm-6 cells were named Mock group. Nalm-6 cells transfected by PIK3CA siRNA were treated with Akt inhibitor (siPIK3CA+Akti-1/2 group). mRNA and protein expression was detected by qRT-PCR and Western blot. Proliferation and sensitivity to chemotherapeutic drugs was detected by MTT assay. Cell cycle and apoptosis was explored by low cytometry. Transwell assay was performed to test invasion. RESULTS: PIK3CA mRNA (p=0.008) and protein (p=0.006) expression was higher in Nalm-6 cells than that in normal B lymphocytes. Compared with the Mock group and PIK3CA-Control group, Nalm-6 cells of the siPIK3CA group had lower OD495 values (all p < 0.05) and invasion cell numbers (p=0.03 and p=0.025), as well as a higher proportion of G0/G1 phase cells (p=0.020 and p=0.022), percentage of apoptosis (p=0.016 and p=0.022), and inhibition rate (all p < 0.05). pAkt expression in the siPIK3CA group (p=0.026 and p=0.031) and siPIK3CA+Akti-1/2 group (p=0.019 and p=0.023) was lower than that in the Mock group. CONCLUSION: PIK3CA silencing inhibited Nalm-6 cell proliferation and invasion, and promoted their apoptosis and sensitivity to chemotherapeutic drugs, potentially through regulation of the PI3K/AKT signaling pathway.