P atients with the most malignant type of glioma, Grade IV glioblastoma, have a mean survival time of approximately 15 months and an estimated 5-year survival rate of less than 5%.11 High-grade gliomas (Grades III and IV) are the most common primary brain tumors in adults and the fourth leading cause of cancerrelated death. 40 Tumor hypoxia is thought to play an important role in glioblastoma tumor pathobiology by proabbreviatioNs CA-IX = carbonic anhydrase-IX; CED = convection-enhanced delivery; DAB = 3,3′-diaminobenzidine tetrahydrochloride; DCA = dichloroacetate; EHCO = 1-(aminoethyl)iminobis [N-(oleicylcysteinylhistinyl-1-aminoethyl)propionamide]; GFP = green fluorescent protein; GLUT-1 = glucose transporter 1; HIF-1a = hypoxia-inducible factor 1a; IHC = immunohistochemistry; MVD = microvascular density; PEG = polyethylene glycol; PI = proliferation index; RNAi = RNA interference; siRNA = small interfering RNA; VEGF = vascular endothelial growth factor. obJeCt High-grade gliomas are the most common form of adult brain cancer, and patients have a dismal survival rate despite aggressive therapeutic measures. Intratumoral hypoxia is thought to be a main contributor to tumorigenesis and angiogenesis of these tumors. Because hypoxia-inducible factor 1a (HIF-1a) is the major mediator of hypoxia-regulated cellular control, inhibition of this transcription factor may reduce glioblastoma growth. MetHoDs Using an orthotopic mouse model with U87-LucNeo cells, the authors used RNA interference to knock down HIF-1a in vivo. The small interfering RNA (siRNA) was packaged using a novel multifunctional surfactant, 1-(amino ethyl)iminobis[N-(oleicylcysteinylhistinyl-1-aminoethyl)propionamide] (EHCO), a nucleic acid carrier that facilitates cellular uptake and intracellular release of siRNA. Stereotactic injection was used to deliver siRNA locally through a guide-screw system, and delivery/uptake was verified by imaging of fluorescently labeled siRNA. Osmotic pumps were used for extended siRNA delivery to model a commonly used human intracranial drug-delivery technique, convectionenhanced delivery. resUlts Mice receiving daily siRNA injections targeting HIF-1a had a 79% lower tumor volume after 50 days of treatment than the controls. Levels of the HIF-1 transcriptional targets vascular endothelial growth factor (VEGF), glucose transporter 1 (GLUT-1), c-MET, and carbonic anhydrase-IX (CA-IX) and markers for cell growth (MIB-1 and microvascular density) were also significantly lower. Altering the carrier EHCO by adding polyethylene glycol significantly increased the efficacy of drug delivery and subsequent survival. CoNClUsioNs Treating glioblastoma with siRNA targeting HIF-1a in vivo can significantly reduce tumor growth and increase survival in an intracranial mouse model, a finding that has direct clinical implications.
Purpose Individuals with multiple osteochondromas (MO) demonstrate shortened long bones. Ext1 or Ext2 haploinsufficiency cannot recapitulate the phenotype in mice. Loss of heterozygosity for Ext1 may induce shortening by steal of longitudinal growth into osteochondromas or by a general derangement of physeal signaling. Methods We induced osteochondromagenesis at different time points during skeletal growth in a mouse genetic model, then analyzed femora and tibiae at 12 weeks using micro-CT and a point-distribution-based shape analysis. Bone lengths and volumes were compared. Metaphyseal volume deviations from normal, as a measure of phenotypic widening, were correlated with length deviations. Results Mice with osteochondromas had shorter femora and tibiae than controls, more consistently when osteochondromagenesis was induced earlier during skeletal growth. Volumetric metaphyseal widening did not correlate with longitudinal shortening, although some of the most severe shortening was in bone with abundant osteochondromas. Conclusions Loss of heterozygosity for Ext1 was sufficient to drive bone shortening in a mouse model of MO, but shortening did not correlate with osteochondroma volumetric growth. While a steal phenomenon seems apparent in individual cases, some other mechanism must also be capable of contributing to the short bone phenotype, independent of osteochondroma formation. Clones of chondrocytes lacking functional heparan sulfate must blunt physeal signaling generally, rather than stealing growth potential focally.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.