Checkpoint kinase 1 (CHK1) is an integral component of the cell cycle as well as the DNA Damage Response (DDR) pathway. Previous work has demonstrated the effectiveness of inhibiting CHK1 with small-molecule inhibitors, but the role of CHK1 mediated DDR in medulloblastoma is unknown. CHK1, both at the mRNA and protein level, is highly expressed in medulloblastoma and elevated CHK1 expression in Group3 medulloblastoma is an adverse prognostic marker. CHK1 inhibition with the small-molecule drug AZD7762, results in decreased cell growth, increased DNA damage and cell apoptosis. Furthermore, AZD7762 acts in synergy with cisplatin in reducing cell proliferation in medulloblastoma. Similar phenotypic changes were observed with another CHK1 inhibitor, PF477736, as well as genetic knockdown using siRNA against CHK1. Treatments with small-molecule inhibitors of CHK1 profoundly modulated the expression of both upstream and downstream target proteins within the CHK1 signaling pathways. This suggests the presence of a feedback loop in activating CHK1. Overall, our results demonstrate that small-molecule inhibition of CHK1 in combination with, cisplatin, is more advantageous than either treatment alone, especially for Group 3 medulloblastoma, and therefore this combined therapeutic approach serves as an avenue for further investigation.

Leukemia/lymphoma-related factor (LRF), a zinc-finger transcription factor encoded by Zbtb7a, is a protooncogene that regulates differentiation in diverse cell lineages, and in the CNS, its function is relatively unexplored. This study is the first to examine the role of LRF in CNS pathology. We first examined LRF expression in a murine viral model of spinal cord demyelination with clinically relevant lesion characteristics. LRF was rarely expressed in oligodendrocyte progenitors (OP) yet, was detected in nuclei of the majority of oligodendrocytes in healthy adult CNS and during remyelination. Plp/CreER T :Zbtb7a fl/fl mice were then used with cuprizone demyelination to determine the effect of LRF knockdown on oligodendrocyte repopulation and remyelination. Cuprizone was given for 6 weeks to demyelinate the corpus callosum. Tamoxifen was administered at 4, 5, or 6 weeks after the start of cuprizone. Tamoxifen-induced knockdown of LRF impaired remyelination during 3 or 6-week recovery periods after cuprizone. LRF knockdown earlier within the oligodendrocyte lineage using NG2CreER T :Zbtb7a fl/fl mice reduced myelination after 6 weeks of cuprizone.LRF knockdown from either the Plp/CreER T line or the NG2CreER T line did not significantly change OP or oligodendrocyte populations. In vitro promoter assays demonstrated the potential for LRF to regulate transcription of myelin-related genes and the notch target Hes5, which has been implicated in control of myelin formation and repair. In summary, in the oligodendrocyte lineage, LRF is expressed mainly in oligodendrocytes but is not required for oligodendrocyte repopulation of demyelinated lesions. Furthermore, LRF can modulate the extent of remyelination, potentially by contributing to interactions regulating transcription. K E Y W O R D Sdemyelination, cuprizone, notch, differentiation, oligodendrocyte progenitor

DIPG (Diffuse Intrinsic Pontine Gliomas) is a brain stem tumor which affects children between the age of 6 and 9 years old. These tumors are very aggressive and inoperable due to their location, resulting in a 0% survival rate. While the importance of identifying new agents for DIPG therapeutics has long been appreciated, progress has been limited. Whole-genome sequencing has identified histone H3K27M mutations in DIPG tumors that result in deregulation of the epigenetic code. However, there is limited understanding of the functional roles epigenetic regulators play in controlling DIPG tumorigenesis. We hypothesized that other key epigenetic regulators provide DIPG cells with a survival advantage in the presence of a H3K27M mutation. To addressthis, we performed a shRNA-based functional genomic screen in H3K27M mutant DIPG cells by targeting 408 epigenetic genes. One of our top hits was BMI1, which is a part of the PRC1 complex. PRC1 regulates cell self-renewal and stem cell behavior in both normal and tumor cells. Stable knockdown of BMI1 in DIPG cells decreased cell proliferation, cell self-renewal capacity and decreased stem cell markers. BMI1 depletion enhances the effect of radiation in DIPG cells, as measured by cell colony formation. In addition, PTC-209, a small-molecule inhibitor of BMI, decreased the stem cell expression and growth in DIPG cells. These studies suggest that targeting BMI1 in DIPG tumors in patients before giving the standard-of-care bolus radiation could be a more effective treatment.

BACKGROUND: Battlefield pain occurs in combat casualties who experience multiple severe injuries. The nature of battlefield scenarios requires a distinct approach to battlefield pain research. A battlefield pain summit was thus convened to identify shortcomings in the current understanding of battlefield pain management, review the current state of battlefield pain research, and shape the direction of future research. METHODS:On January 10 to 11, 2022, a hybrid in-person and virtual meeting hosted by the US Army Institute of Surgical Research defined research priorities for the Combat Casualty Care Research Program's Battlefield Pain research portfolio. Summit participants identified the following key focus areas under the umbrella of battlefield pain research: battlefield injury patterns; use of ketamine and nonopioid analgesics; analgesic delivery systems; the impact of analgesia on performance, cognition, and survival; training methods; battlefield regional anesthesia; and research models. Preliminary statements presented during the summit were refined and rank ordered through a Delphi process. RESULTS:Consensus was achieved on 7 statements addressing ideal analgesic properties, delivery systems, operational performance concerns, and pain training. Ketamine was identified as safe and effective for battlefield use, and further research into nonopioid analgesics represented a high priority. CONCLUSION: The 7 consensus statements that emerged from this battlefield pain summit serve as a template to define the near-term research priorities for military-specific battlefield pain research.