Potential Glioblastoma cell survival mechanisms in Temozolomide-induced resistance

摘要

WHO defines the Glioblastoma multiforme (GBM) as a grade IV glioma which is the most common and hostile malignant primary brain tumor in human population Previous studies showed that the GBM median survival is less than 15 months The 5 year survival rate is less than 4% Temozolomide (TMZ) is one of the most widely used drugs to treat GBM Recently it has been showed that TMZ treatment can induce apoptosis autophagy cell senescence and cell cycle arrest depend on MGMT expression level However the TMZ-induced resistance formation mechanism remains unclear This study intends to establish two TMZ-induced resistance cell lines and test the role of apoptosis cell senescence autophagy and cell cycle arrest in their survival and death The 1306-MG (human GBM) CNS-1 (rat GBM) and human astrocyte cell lines were used for establish TMZ-induced resistance (TIR) model All of these cell lines were checked for MGMT expression level by immunoblotting Trypan Blue Exclusion Assay (TBEA) method and cell counting were used to assess cell viability Furthermore TUNEL was used to observe apoptosis LC3 staining was used to observe autophagy SA-βGal was used to observe cell senescence and zymography was used to observe MMP-9 activity and cell flow-cytometry was used to determine cell cycle change The MGMT expression levels of TIR GBM were not changed through generation of resistance The cell viability increased through establishment of TIR accumulation under same concentrations of TMZ treatment; TIR significantly reduced the numbers of senescence cells in 1306-MG and CNS-1 TIR cell; the autophagy level and MMP-9 activity of TIR-GBM were elevated in 1306-MG and CNS-1 cells with generation of TIR cell; TIR cells showed significantly decreased SubG1 phase of cell cycle through generation of TIR cell while both 1306-MG and CNS-1 showed decreased cell cycle distribution of S and G2/M phases We had established 1306-MG and CNS-1 TMZ-induced resistance model We also found that TIR formation accompanied with decreased apoptosis diminished cellular senescence arising autophagy cell cycle arrest at G0/G1 phase and increased MMP-9 activity We conclude apoptosis autophagy cellular senescence and cell cycle arrest all participate in the development of TMZ-induced resistance

獎項日期	2015 2月 11
原文	English
監督員	Chun-I Sze (Supervisor)