Project description:Glioblastoma multiforme(GBM) is the most common and lethal malignant primary brain tumor. Temozolomide (TMZ) is a promising chemo-therapeutic agent to treat GBM. However, resistance to TMZ develops quickly with a high frequency. The mechanisms underlying GBM cells’ resistance to TMZ are not fully understood. Non-coding RNAs are aberrantly expressed in many cancers and are highly involved in their pathogenesis including drug-resistence. In order to systematically study the role of miRNAs in GBM cells' resistence to TMZ , we built gene expression profiles of TMZ-resistant cell line and TMZ-sensitive cell line using miRNA gene expression microarrays.
Project description:Glioblastoma multiforme (GBM) is the most common and lethal malignant primary brain tumor. Temozolomide (TMZ) is a promising chemo-therapeutic agent to treat GBM. However, resistance to TMZ develops quickly with a high frequency. The mechanisms underlying GBM cells’ resistance to TMZ are not fully understood. Long non-coding RNAs (lncRNAs) are aberrantly expressed in many cancers and are highly involved in their pathogenesis including drug-resistence. In order to systematically study the role of lncRNAs in GBM cells' resistence to TMZ , we built gene expression profiles of TMZ-resistant cell line and TMZ-sensitive cell line using lncRNA and mRNA gene expression microarrays.
Project description:cell culture:The human glioma cell line U87MG was obtained from the Cell Resource Center, Peking Union Medical College (Beijing, China), and U251MG was acquired from the American Type Culture Collection (Manassas, VA). Temozolomide (TMZ) resistant U87MG cells (U87TR) and TMZ resistant U251MG cells (U251TR) of glioblastoma (GBM) sub-cell lines, were established through repetitive exposure to increasing TMZ concentrations in vitro in our laboratory. Cells were cultured in DMEM culture medium supplemented with 10% FBS with a standard humidified incubator under 5% CO2 at 37°C.
Project description:Glioblastoma (GBM) carries a dismal prognosis largely due to acquired resistance to the standard treatment, which incorporates the chemotherapy temozolomide (TMZ). Inhibiting the proteasomal pathway is an emerging strategy, where combination treatments are under clinical investigation. We hypothesized that pre-treatment of GBM with bortezomib (BTZ) might sensitize glioblastoma to TMZ by abolishing autophagy survival signals to augment DNA damage and apoptosis. P3 patient-derived GBM cells as well as the tumor cell lines U87, HF66, A172 and T98G were investigated for clonogenic survival after single or combined treatment with TMZ and BTZ in vitro. Change in autophagic flux was examined after experimental treatments in conjunction with inhibitors of autophagy or downregulation of autophagy-related genes -5 and -7 (ATG5 and ATG7, respectively). Autophagic flux was increased in TMZ-resistant P3 and T98G cells as indicated by diminished levels of the autophagy markers LC3A/B-II and increased STX17, higher protein degradation and no formation of p62 bodies nor induction of apoptosis. In contrast, BTZ treatment attenuated ULK1 mRNA, total and phosphorylated protein, and accumulated LC3A/B-II, p62 and autophagosomes analogously to Baf1 and chloroquine autophagy inhibitors. These autophagosomes did not fuse with lysosomes, indicated by attenuated STX17 expression and reduced degradation of long-lived proteins, which culminated in enhanced caspase-3/8 dependent apoptosis. BTZ synergistically enhanced TMZ efficacy, attenuated tumor cell proliferation, triggered ATM/Chk2 DNA damage signalling to further augment caspase-3/8 mediated apoptosis in the TMZ resistant P3 and T98G GBM cells. Genetic or chemical inhibition of autophagy (with CRISPR-CAs9 ATG5, ATG7 shRNA, MRT68921 or VPS34-IN1) abrogated BTZ efficacy and rescued BTZ+ TMZ treated GBM cells from death. We conclude that Bortezomib ameliorates temozolomide resistance through ATG5/7-dependent abrogated autophagic flux and may be amenable in combination treatment regimens for TMZ refractory GBM patients.
Project description:Single cell derived clones were extracted from four glioblastoma tumors using fluorescence activated cell sorting with CD15 and CD133 markers. Unsorted bulk tumors were also derived. Gene expression analysis of clones of tumor GBM-482 involved comparison between TMZ resistant (n=5) and sensitive (n=2) clones.
Project description:Expression profiling of 559T(proneural subtype of glioblastoma), 592T(mesenchymal subtype of glioblastoma) and normal human astrocyte (NHA) Glioblastoma multiforme (GBM) is the most aggressive type of brain tumor with poor survival rate and temozolomide (TMZ) has been used as the standard chemotherapy for GBM treatment. However, a large number of patients either respond poorly to TMZ and/or develop resistance after long-term use, urging the need for the development of potent drugs with novel mechanisms of action. Here, using high-throughput compound screening (HTS), we found azathioprine, an immunosuppressive medication, to be a promising therapeutic agent for TMZ-resistant GBM treatment. Through integrative genome-wide analysis and global proteomic analysis, we identified the elevated lipid metabolism due to hyperactive EGFR/AKT/SREBP-1 signaling pathway being inhibited by azathioprine. In addition, azathioprine causes ER stress-induced apoptosis. Orthotopic xenograft models injected with patient-derived GBM cells exhibits reduced tumor volumes and increased apoptosis by azathioprine. These overall data indicate that azathioprine could be a powerful therapeutic option for TMZ-resistant GBM patients.