fumarates and Glioblastoma

Early detection of tumor cell death in glioblastoma following treatment with chemoradiation has the potential to distinguish between true disease progression and pseudoprogression. Tumor cell death can be detected noninvasively in vivo by imaging the production of [2,3-2H2]malate from [2,3-2H2]fumarate using 2H magnetic resonance (MR) spectroscopic imaging. We show here that 2H MR spectroscopy and spectroscopic imaging measurements of [2,3-2H2]fumarate metabolism can detect tumor cell death in orthotopically implanted glioblastoma models within 48 hours following the completion of chemoradiation. Following the injection of [2,3-2H2]fumarate into tumor-bearing mice, production of [2,3-2H2]malate was measured in a human cell line-derived model and in radiosensitive and radioresistant patient-derived models of glioblastoma that were treated with temozolomide followed by targeted fractionated irradiation. The increase in the [2,3-2H2]malate/[2,3-2H2]fumarate signal ratio posttreatment, which correlated with histologic assessment of cell death, was a more sensitive indicator of treatment response than diffusion-weighted and contrast agent-enhanced 1H MRI measurements, which have been used clinically to detect responses of glioblastoma to chemoradiation. Overall, early detection of glioblastoma cell death using 2H MRI of malate production from fumarate could help improve the clinical evaluation of response to chemoradiation.. 2H magnetic resonance imaging of labeled fumarate metabolism can detect early evidence of tumor cell death following chemoradiation, meeting a clinical need to reliably detect treatment response in glioblastoma.

Topics: Animals; Brain Neoplasms; Contrast Media; Fumarates; Glioblastoma; Humans; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Malates; Mice; Temozolomide

Cancer-specific TERT promoter mutations have been linked to the reactivation of epigenetically silenced TERT gene by creating de novo binding motifs for E-Twenty-Six transcription factors, especially GABPA. How these mutations switch on TERT from epigenetically repressed states to expressed states have not been defined. Here, we revealed that EGFR activation induces ERK1/2-dependent phosphorylation of argininosuccinate lyase (ASL) at Ser417 (S417), leading to interactions between ASL and GABPA at the mutant regions of TERT promoters. The ASL-generated fumarate inhibits KDM5C, leading to enhanced trimethylation of histone H3 Lys4 (H3K4me3), which in turn promotes the recruitment of c-Myc to TERT promoters for TERT expression. Expression of ASL S417A, which abrogates its binding with GABPA, results in reduced TERT expression, inhibited telomerase activity, shortened telomere length, and impaired brain tumor growth in mice. This study reveals an unrecognized mechanistic insight into epigenetically activation of mutant TERT promoters where GABPA-interacted ASL plays an instrumental role.

Topics: Animals; Argininosuccinate Lyase; Cell Line, Tumor; ErbB Receptors; Fumarates; Gene Expression Regulation, Neoplastic; Glioblastoma; Histones; Mice; Mutation; Promoter Regions, Genetic; Telomerase; Telomere; Telomere Shortening; Transcription Factors

The present studies examined the biology of the multiple sclerosis drug dimethyl-fumarate (DMF) or its in vivo breakdown product and active metabolite mono-methyl-fumarate (MMF), alone or in combination with proteasome inhibitors, in primary human glioblastoma (GBM) cells. MMF enhanced velcade and carfilzomib toxicity in multiple primary GBM isolates. Similar data were obtained in breast and colon cancer cells. MMF reduced the invasiveness of GBM cells, and enhanced the toxicity of ionizing radiation and temozolomide. MMF killed freshly isolated activated microglia which was associated with reduced IL-6, TGFβ and TNFα production. The combination of MMF and the multiple sclerosis drug Gilenya further reduced both GBM and activated microglia viability and cytokine production. Over-expression of c-FLIP-s or BCL(-)XL protected GBM cells from MMF and velcade toxicity. MMF and velcade increased plasma membrane localization of CD95, and knock down of CD95 or FADD blocked the drug interaction. The drug combination inactivated AKT, ERK1/2 and mTOR. Molecular inhibition of AKT/ERK/mTOR signaling enhanced drug combination toxicity whereas molecular activation of these pathways suppressed killing. MMF and velcade increased the levels of autophagosomes and autolysosomes and knock down of ATG5 or Beclin1 protected cells. Inhibition of the eIF2α/ATF4 arm or the IRE1α/XBP1 arm of the ER stress response enhanced drug combination lethality. This was associated with greater production of reactive oxygen species and quenching of ROS suppressed cell killing.

Topics: Antineoplastic Agents; Biomarkers; Cell Line, Tumor; Cell Survival; Dimethyl Fumarate; Drug Synergism; Fumarates; Glioblastoma; Humans; Microglia; Proteasome Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction

We compared the cytotoxicity of the bioreductive antitumor agents mitomycin C (MMC) and streptonigrin (SN) with or without the DT-diaphorase (DTD) inducer dimethyl fumarate (DMF) in four human glioblastoma cell lines with the conventional chemotherapeutic agent, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). We also examined four other types of cancer cells to compare with glioblastoma cells. Cytotoxicity was measured with the sulforhodamine B (SRB) assay and was represented by 50% inhibition concentration (IC50). Enzymatic activities of DTD, cytochrome b5 reductase and glutathione-S-transferase (GST) in cells were measured spectrophotometrically. IC50 for BCNU was in a range of 28-300 microM in the glioblastoma cell lines. Glioblastoma cells were more sensitive to MMC or SN than to BCNU. Pretreatment with DMF significantly increased cytotoxicity of MMC and SN in glioblastoma cell lines and the NCI-H1299 lung cancer cell line, but had no effect on BCNU cytotoxicity. DMF significantly increased DTD and cytochrome b5 reductase activity, and decreased GST in three of four glioblastoma cell lines. Addition of the DTD inhibitor, dicumarol, significantly inhibited cytotoxicity of MMC and SN, and reversed the increased cytotoxicity seen when DMF was combined with either MMC or SN in all glioblastoma cell lines. Combining inducers of DTD and cytochrome b5 reductase with bioreductive agents may be a potential therapeutic strategy for glioblastoma.

Topics: Antineoplastic Agents; Carmustine; Cell Death; Cell Line, Tumor; Cytochrome-B(5) Reductase; Dicumarol; Dimethyl Fumarate; Drug Synergism; Enzyme Induction; Fumarates; Glioblastoma; Glutathione Transferase; Humans; Mitomycin; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Streptonigrin