ABSTRACT
ATRX, a chromatin remodeler protein, is recurrently mutated in H3F3A-mutant pediatric glioblastoma (GBM) and isocitrate dehydrogenase (IDH)-mutant grade 2/3 adult glioma. Previous work has shown that ATRX-deficient GBM cells show enhanced sensitivity to irradiation, but the etiology remains unclear. We find that ATRX binds the regulatory elements of cell-cycle phase transition genes in GBM cells, and there is a marked reduction in Checkpoint Kinase 1 (CHEK1) expression with ATRX loss, leading to the early release of G2/M entry after irradiation. ATRX-deficient cells exhibit enhanced activation of master cell-cycle regulator ATM with irradiation. Addition of the ATM inhibitor AZD0156 doubles median survival in mice intracranially implanted with ATRX-deficient GBM cells, which is not seen in ATRX-wild-type controls. This study demonstrates that ATRX-deficient high-grade gliomas (HGGs) display Chk1-mediated dysregulation of cell-cycle phase transitions, which opens a window for therapies targeting this phenotype.
Subject(s)
Checkpoint Kinase 1/metabolism , Glioma/metabolism , X-linked Nuclear Protein/metabolism , Animals , Brain Neoplasms/metabolism , Cell Cycle/genetics , Cell Cycle Checkpoints/genetics , Cell Line, Tumor , Checkpoint Kinase 1/physiology , Female , Histones/metabolism , Humans , Isocitrate Dehydrogenase/genetics , Male , Mice , Mice, Inbred C57BL , Mutation , Neoplasm Recurrence, Local/metabolism , Primary Cell Culture , X-linked Nuclear Protein/geneticsABSTRACT
The modalities of vascular access for the extracorporeal artificial placenta (AP) have undergone many iterations over the past decade. We hypothesized that single lumen cannulation (SLC) of the jugular vein using tidal flow extracorporeal life (ECLS) support is a feasible alternative to venovenous (VV) umbilical-jugular cannulation and double lumen cannulation (DLC) and can maintain fetal circulation, stable hemodynamics, and adequate gas exchange for 24 hours. After in vitro evaluation of the tidal flow system, six preterm lambs at estimated gestational age 118-124 days (term 145 days) were delivered and underwent VV-ECLS. Three were supported using DLC and three with SLC utilizing tidal flow AP support. Hemodynamics, circuit flow, and gas exchange were monitored. Target fetal parameters were as follows: mean arterial pressure 40-60 mmHg, heart rate 140-240 beats per minute (bpm), SatO2% 60-80%, PaO2 25-50 mmHg, PaCO2 30-55 mmHg, oxygen delivery >5 ml O2/dl/kg/min, and circuit flow 100 ± 25 ml/kg/min. All animals survived 24 hours and maintained fetal circulation with stable hemodynamics and adequate gas exchange. Parameters of the tidal flow group were comparable with those of DLC. Single lumen jugular cannulation using tidal flow is a promising vascular access strategy for AP support. Successful miniaturization holds great potential for clinical translation to support extremely premature infants.