Project description:Comparison of parental GSC (GSC-parental) with treatment resistant GSC clones survived 500uM TMZ treatment (GSC-500uM TMZ) We used microarrays to identify defense profiles of GSC-500uM TMZ
Project description:Acquired resistance of temozolomide (TMZ) is one of the major obstacle of glioblastoma clinical treatment and the mechanism of TMZ resistance is still not very clear. In the presented research we show that deletion of rs16906252-associated MGMT enhancer in MGMT negative glioma cells induced increase sensitivity to temozolomide and combination of RNA-seq and Capture HiC identified several long-range target genes of rs16906252-associated MGMT enhancer. In addition, HiC data shows alterations of chromatin structures in glioma cells survived from high-dosage TMZ treatment and changes of TADs influence rs16906252-associated MGMT enhancer’s long-range regulations of target genes. Our study suggests rs16906252-associated MGMT enhancer regulates glioma cells’ TMZ sensitivity by long-range regulations of several target genes, which is a novel mechanism of regulation of TMZ sensitivity in glioma cells.
Project description:Comparison of treatment sensitive GSC clones (TSGC) with treatment resistant GSC clones (TRGC). We used microarrays to identify molecular signatures of TRGC (upregulated genes). We used radiation treatment (RT) or RT plus TMZ to select treatment resistant GSC clones (TRGC)
Project description:Glioblastoma (GBM) is among the most aggressive cancers. Despite aggressive radiotherapy and treatment with the alkylating agent temozolomide (TMZ), patients ultimately succumb to the disease. Although much interest has focused on highly tumorigenic GBM stem cells (GSCs), adaption of a concept from microbial research proposes that a minor population of dormant âpersisterâ cells in cancer evade current therapies. To separate dormant and treatment-resistant tumor cells in human GBM tumorspheres, we have refined density gradient protocols previously used for separation of neurosphere-forming neural stem cells (NSCs). We find that a minor cell population in human GBM tumorsphere cultures and patient-derived tumor biopsies display increased cell density. These high-density GBM cells (HDGCs) display dormancy, variable expression of proposed GSC markers, and 10-100 fold higher levels of reprogramming gene expression compared to low-density GBM cells (LDGCs). Transcriptional profiling data confirmed the slow-cycling state of HDGCs. As a result, HDGCs show decreased tumorsphere formation capacity in vitro and reduced tumorigenicity in vivo. Using tumorspheres and xenografts, we demonstrated that HDGCs show increased treatment-resistance to ionizing radiation (IR) and temozolomide treatment compared to LDGCs. Similar to the NSC lineage, our data suggest that dormant HDGCs become increasingly sensitive to anti-proliferative therapies as they become activated and further differentiate. In conclusion, density gradients represents a marker-independent approach to separate dormant and treatment-resistant tumor cells in human GBMs and other solid cancers. 12 samples, no replicates, derived from 5 individual patients
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:Glioblastoma therapy relies on the alkylating drug temozolomide (TMZ) administered to irradiated patients post-neurosurgery, which increases overall survival but cannot prevent fatal disease relapse. Using clinical samples and glioblastoma models, we here identify TMZ-driven enrichment of ALDH1A1+ tumor subclones acquiring AKT-dependent drug resistance en route to relapse. We demonstrate that this recurrent phenotype switch is predictable and can be countered by a sequential rather than simultaneous combinatorial treatment approach.
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 (GBM) is the deadliest brain cancer, driven in part by GBM stem cells (GSCs) that contribute to therapeutic resistance and tumor recurrence. Effective targeting and elimination of GSCs hold promise for preventing GBM recurrence and achieving potential cures. In this study, we explored the role of the epigenetic regulator SUV39H1 in GSC maintenance and GBM progression. We observed that SUV39H1 is upregulated in GBM samples compared to normal brain tissues. Single-cell RNA-seq data indicated that SUV39H1 is preferentially expressed in GSCs relative to non-stem GBM cells, possibly due to super-enhancer-mediated transcriptional activation. Knockdown of SUV39H1 in patient-derived GSCs impaired their proliferation and stemness. RNA-seq analysis revealed that SUV39H1 regulates G2/M cell cycle progression, stem cell maintenance, and cell death pathways in GSCs. Integrated ATAC-seq (assay for transposase-accessible chromatin followed by sequencing) and RNA-seq analyses demonstrated that targeting SUV39H1 altered chromatin accessibility in key genes associated with these pathways. Treatment with chaetocin, a SUV39H1 inhibitor, mimicked the effects of SUV39H1 knockdown in GSCs and sensitized them to the GBM chemotherapy drug temozolomide (TMZ). In vivo studies using an intracranial patient-derived xenograft model showed that targeting SUV39H1 inhibited GSC-driven tumor formation in mice. Our findings identify SUV39H1 as a critical regulator of GSC maintenance and suggest that targeting SUV39H1 could disrupt GSCs and enhance the efficacy of existing chemotherapy, offering a promising strategy for improving GBM treatment outcomes.
Project description:Glioblastoma (GBM) is the deadliest brain cancer, driven in part by GBM stem cells (GSCs) that contribute to therapeutic resistance and tumor recurrence. Effective targeting and elimination of GSCs hold promise for preventing GBM recurrence and achieving potential cures. In this study, we explored the role of the epigenetic regulator SUV39H1 in GSC maintenance and GBM progression. We observed that SUV39H1 is upregulated in GBM samples compared to normal brain tissues. Single-cell RNA-seq data indicated that SUV39H1 is preferentially expressed in GSCs relative to non-stem GBM cells, possibly due to super-enhancer-mediated transcriptional activation. Knockdown of SUV39H1 in patient-derived GSCs impaired their proliferation and stemness. RNA-seq analysis revealed that SUV39H1 regulates G2/M cell cycle progression, stem cell maintenance, and cell death pathways in GSCs. Integrated ATAC-seq (assay for transposase-accessible chromatin followed by sequencing) and RNA-seq analyses demonstrated that targeting SUV39H1 altered chromatin accessibility in key genes associated with these pathways. Treatment with chaetocin, a SUV39H1 inhibitor, mimicked the effects of SUV39H1 knockdown in GSCs and sensitized them to the GBM chemotherapy drug temozolomide (TMZ). In vivo studies using an intracranial patient-derived xenograft model showed that targeting SUV39H1 inhibited GSC-driven tumor formation in mice. Our findings identify SUV39H1 as a critical regulator of GSC maintenance and suggest that targeting SUV39H1 could disrupt GSCs and enhance the efficacy of existing chemotherapy, offering a promising strategy for improving GBM treatment outcomes.