Project description:Glioblastoma (GBM), a primary malignant brain tumor, has a poor prognosis, even with standard treatments such as radiotherapy and chemotherapy. In this study, we explored the anticancer effects of the synergistic combination of perphenazine (PER), a dopamine receptor D2/3 (DRD2/3) antagonist, and temozolomide (TMZ), a standard treatment for GBM, in patient-derived human GBM tumorspheres (TSs).
Project description:The gene expression of an orthotopic mouse model developed from human glioblastoma neurospheres was compared between temozolomide treated and untreated mice.
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:Patients diagnosed with glioblastoma (GBM) with sustained synthesis of the DNA repair enzyme, O6-methyl guanine DNA methytransferase (MGMT), are rendered resistant to Temozolomide (TMZ) chemotherapy. Here, we hypothesized that pretreatment with the proteasome inhibitor Bortezomib (BTZ, Velcade) might sensitize these GBM to TMZ by depleting MGMT.
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:The gene expression profiles were identified in glioblastoma cells treated with FAK inhibitor Y15, temozolomide alone or with combination of Y15 and Temozolomide DBTRG and U87 were treated with FAK inhibitor Y15 at 10 microM for 24 h; U87 cells were treated with Temozolomide 100 microM for 24 h and Y15+temozolomide at the same dose as each agent alone
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: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 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 (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.