Biology subjects

Brunt, B.

Publications and source records attributed to Brunt, B..

3 recordsLinked to original sources

bioRxiv2024

Targeting Diffuse Midline Glioma with a novel anti-CD99 Antibody

Diffuse midline gliomas (DMGs) are devastating brain tumors that occur primarily in children. The salient feature of these tumors is the presence of a H3K27M mutation (K27M), associated with the worst prognosis. We identified the cell surface antigen CD99 as notably expressed in DMGs, particularly in K27M+DMGs. We found that the increased expression of CD99 in K27M+DMGs was a result of the onco-histone K27M mutation. In K27M+DMG cells, CD99 inactivation impaired tumor growth by inducing cell differentiation, indicating an oncogenic role of CD99 enabled by blocking differentiation. We then developed a novel therapeutic anti-CD99 chimeric antibody, 10D1, with a membrane-proximal binding epitope, and evaluated its antitumor efficacy in preclinical models of K27M+DMG. 10D1 suppressed DMG growth in vitro and in vivo by inducing apoptosis. When combined with radiation treatment, 10D1 exhibited improved antitumor efficiency and xenograft survival, providing a strong justification for its clinical development as a therapy for DMGs. Statement of SignificanceThis study emphasizes that CD99 overexpression occurs due to the H3K27M mutation in Diffuse Midline Gliomas (DMGs). This heightened expression suppresses apoptosis, inhibits differentiation, and induces radio-resistance in DMGs. This research justifies using a novel CD99 antibody alone or combined with radiation therapy in human pediatric clinical trials.

cancer biology↗

bioRxiv2024

Transcriptional Regulation of Protein Synthesis by Mediator Kinase in MYC-driven Medulloblastoma

MYC-driven medulloblastoma (MB) is a highly aggressive cancer type with poor prognosis and limited treatment options. Through CRISPR-Cas9 screening across MB cell lines, we identified the Mediator-associated kinase CDK8 as the top dependence for MYC-driven MB. Loss of CDK8 markedly reduces MYC expression and impedes MB growth. Mechanistically, we demonstrate that CDK8 depletion suppresses ribosome biogenesis and mRNA translation. CDK8 regulates occupancy of phospho-Polymerase II at specific chromatin loci facilitating an epigenetic alteration that promotes transcriptional regulation of ribosome biogenesis. Additionally, CDK8-mediated phosphorylation of 4EBP1 plays a crucial role in initiating eIF4E-dependent translation. Targeting CDK8 effectively suppresses cancer stem and progenitor cells, characterized by increased ribosome biogenesis activity. We also report the synergistic inhibition of CDK8 and mTOR in vivo and in vitro. Overall, our findings establish a connection between transcription and translation regulation, suggesting a promising therapeutic approach targets multiple points in the protein synthesis network for MYC-driven MB.

cancer biology↗

bioRxiv2023

MRI-Guided Focused Ultrasound Blood-Brain Barrier Opening Increases Drug Delivery and Efficacy in a Diffuse Midline Glioma Mouse Model

Diffuse intrinsic pontine glioma (DIPG) is the most common and deadliest pediatric brainstem tumor and is difficult to treat with chemotherapy in part due to the blood-brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) have been shown to cause BBB disruption (BBBD), allowing larger chemotherapeutics to enter the parenchyma. Panobinostat is an example of a promising in vitro agent in DIPG with poor clinical efficacy due to low BBB penetrance. In this study, we hypothesized that using FUS to disrupt the BBB allows higher concentrations of panobinostat to accumulate in the tumor, providing a therapeutic effect. Mice were orthotopically injected with a patient-derived DMG cell line, BT-245. MRI was used to guide FUS/MB (1.5 MHz, 0.615 MPa PNP, 1 Hz PRF, 10 ms PL, 3 min treatment time) / (25 {micro}L/kg, IV) targeting to the tumor location. In animals receiving panobinostat (10 mg/kg, IP) in combination with FUS/MB, a 3-fold increase in tumor panobinostat concentration was observed, with only insignificant increase of the drug in the forebrain. In mice receiving three weekly treatments, the combination of panobinostat and FUS/MB led to a 71% reduction of tumor volumes by MRI (p = 0.01). Furthermore, FUS/MB improved the mean survival from 21 to 31 days (p < 0.0001). Our study demonstrates that FUS-mediated BBBD can increase the delivery of panobinostat to an orthotopic DMG tumor, providing a strong therapeutic effect and increased survival. One Sentence SummaryFUS and microbubbles can increase the delivery of panobinostat to a patient-derived xenograft (PDX) orthotopic DMG tumor, providing a strong therapeutic effect and increased survival.

bioengineering↗