Project description:Temozolomide (TMZ) resistance may contribute to the treatment failure in patients with glioblastoma (GBM). Hence, understanding the underlying mechanisms and developing effective strategies against TMZ resistance are highly desired in the clinic. long non-coding RNAs (lncRNAs) have emerged as new regulatory molecules with diverse functions in biological processes and been deregulated in many pathologies, involved in the therapeutic resistance. It is urgent to elucidate the underlying lncRNA-based mechanisms of TMZ resistance in GBM patients.
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:TMZ resistance is one of the main reasons why treatment of glioblastoma (GBM) fails. In order to investigate the underlying mechanism associated with TMZ resistance, we conducted a cytoplasmic proteome research of U87 cells treated with TMZ for 1 week. A total of 162 DEPs including 66 up-regulated proteins and 96 down-regulated proteins were identified.
Project description:In order to identify factors involved in TMZ-resistance, we engineered different TMZ-resistant glioblastoma cell lines. Wildtype cells were treated twice a week in duplicate with a clinically relevant concentration of TMZ (33 µM) for multiple weeks, until two individual resistant subclones were generated. Gene expression profiling was performed to identify differentially expressed genes in the resistant cells compared to their wildtype cells. three wildtype glioblastoma cell lines (U87, LNZ308, Hs683) and their resistant subclones, two of each wildtype, were analyzed The experiments were performed technically as dual channel but processed/normalized as single channel (i.e. two sample records per one raw data file). The raw data file for each sample is indicated in the sample description field but linked as Series supplementary file.
Project description:Glioblastoma (GBM) is the most common and aggressive malignant brain tumor with poor prognosis. Temozolomide (TMZ) is the standard chemotherapy for glioblastoma treatment, but TMZ resistance significantly compromises its efficacy. In the present study, we generated a TMZ-resistant cell line and identified that mitochondrial dysfunction was a novel factor contrib-uting to TMZ resistance though multi-omics analyses and energy metabolism analysis. Further-more, we found that rotenone treatment induced TMZ resistance to a certain level in glioblastoma cells. Notably, we further demonstrated that elevated Ca2+ levels and JNK–STAT3 pathway activa-tion contributed to TMZ resistance and that inhibiting JNK or STAT3 increases susceptibility to TMZ. Taken together, our results indicate that co-administering TMZ with a JNK or STAT3 inhibi-tor holds promise as a potentially effective treatment for glioblastoma.
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: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:Temozolomide (TMZ) has been used for the treatment of glioblastoma (GBM) since last decade, but its treatment benefits are limited by acquired resistance, a process that remains incompletely understood. Here we report that a novel enhancer, located between the promoters of Ki67 and O6-methylguanine-DNA-methyltransferase (MGMT) genes, is activated in TMZ-resistant patient-derived xenograft (PDX) lines as well as in recurrent tumor samples. Activation of the enhancer correlates with increased MGMT expression, a major known mechanism for TMZ resistance. We show that forced activation of the enhancer in cell lines with low MGMT expression results in elevated MGMT expression. Deletion of this enhancer in cell lines with high MGMT expression leads to reduced levels of MGMT and Ki67, increased TMZ sensitivity and impaired proliferation. Together, these studies uncover a novel mechanism that regulates MGMT expression, confers TMZ resistance and potentially regulates tumor proliferation.
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:In order to identify factors involved in TMZ-resistance, we engineered different TMZ-resistant glioblastoma cell lines. Wildtype cells were treated twice a week in duplicate with a clinically relevant concentration of TMZ (33 µM) for multiple weeks, until two individual resistant subclones were generated. Gene expression profiling was performed to identify differentially expressed genes in the resistant cells compared to their wildtype cells.