Downregulated the expression of DNMT3B by suppressing PI3K/Akt signaling pathway and enhances the chemosensitivity of glioblastoma to temozolomide.

Abstract

Abstract Purpose Glioblastoma is the most common malignant brain tumors and has the poorest prognosis. And a poor prognosis is attributed to chemoresistance to temozolomide (TMZ), the first-line drug for treating glioblastoma. This study aimed to investigate how to enhance the chemosensitivity of glioblastoma to temozolomide. Methods Human glioblastoma cell line U251 was used to established temozolomide-resistant U251 (U251-TMZ) cell line by stepwise induction of temozolomide-resistant strains. Reverse Transcription-quantitative PCR(RT-PCR) was applied to detect chemoresistance-related gene expression. Following DNMT3B-siRNA lentiviral vectors transfection and suppressing PI3K/Akt signaling pathway, western Blotting (WB) and RT-PCR were applied to detect DNMT3B gene, p-Akt, t-Akt, p-PI3K, t-PI3K protein expression and cell apoptosis was detect flow cytometry analyses. Results Whole-transcriptome analysis revealed that the level of DNMT3B gene expression was significantly up-regulated in U251-TMZ cell line compared to U251 cell line. Moreover, we found that DNMT3B down-expression is correlated with increasing the chemosensitivity of glioblastoma cells to TMZ. Meanwhile, we also found that p-Akt and p-PI3K protein expression in U251-TMZ cells were significant elevated compared with U251 cells. Subsequently, the PI3K/Akt signaling pathway was suppressed using LY294002, leading to a notable inhibition of PI3K phosphorylation and a significant decrease in DNMT3B expression in U251-TMZ cells. Conclusion DNMT3B down-expression can inhibit the proliferation of glioblastoma cells and induce the glioblastoma cells apoptosis in vitro. Additionally, the PI3K/Akt signaling pathway plays an important role in the chemosensitivity of glioblastoma cells to temozolomide by regulating the DNMT3B expression.