Central nervous system cancers Brem, Steven S; Bierman, Philip J; Black, Peter ...
Journal of the National Comprehensive Cancer Network
6, Številka:
5
Journal Article
Mechanisms of action of rapamycin in gliomas1 Heimberger, Amy B.; Wang, Enze; McGary, Eric C. ...
Neuro-oncology (Charlottesville, Va.),
01/2005, Letnik:
7, Številka:
1
Journal Article
Recenzirano
Rapamycin has previously been shown to be efficacious against intracerebral glioma xenografts and to act in a cytostatic manner against gliomas. However, very little is known about the mechanism of ...action of rapamycin. The purpose of our study was to further investigate the in vitro and in vivo mechanisms of action of rapamycin, to elucidate molecular end points that may be applicable for investigation in a clinical trial, and to examine potential mechanisms of treatment failure. In the phosphatase and tensin homolog deleted from chromosome 10 (PTEN)-null glioma cell lines U-87 and D-54, but not the oligodendroglioma cell line HOG (PTEN null), doses of rapamycin at the IC
50
resulted in accumulation of cells in G
1
, with a corresponding decrease in the fraction of cells traversing the S phase as early as 24 h after dosing. All glioma cell lines tested had markedly diminished production of vascular endothelial growth factor (VEGF) when cultured with rapamycin, even at doses below the IC
50
. After 48 h of exposure to rapamycin, the glioma cell lines (but not HOG cells) showed downregulation of the membrane type–1 matrix metalloproteinase (MMP) invasion molecule. In U-87 cells, MMP-2 was downregulated, and in D-54 cells, both MMP-2 and MMP-9 were downregulated after treatment with rapamycin. Treatment of established subcutaneous U-87 xenografts in vivo resulted in marked tumor regression (
P
< 0.05). Immunohistochemical studies of subcutaneous U-87 tumors demonstrated diminished production of VEGF in mice treated with rapamycin. Gelatin zymography showed marked reduction of MMP-2 in the mice with subcutaneous U-87 xenografts that were treated with rapamycin as compared with controls treated with phosphate-buffered saline. In contrast, treatment of established intracerebral U-87 xenografts did not result in increased median survival despite inhibition of the Akt pathway within the tumors. Also, in contrast with our findings for subcutaneous tumors, immunohistochemistry and quantitative Western blot analysis results for intracerebral U-87 xenografts indicated that there is not significant VEGF production, which suggests possible deferential regulation of the hypoxia-inducible factor 1α in the intracerebral compartment. These findings demonstrate that the complex operational mechanisms of rapamycin against gliomas include cytostasis, anti-VEGF, and anti-invasion activity, but these are dependent on the in vivo location of the tumor and have implications for the design of a clinical trial.
Abstract
Sporadic glioma occurs in companion dogs at frequencies comparable to humans, despite differences in environmental exposures and age at time of diagnosis. Despite advances in molecular and ...phenotypic characterization of adult gliomas, accurate prognostication and curative treatment modalities are often limited by lack of animal translational models that can faithfully recapitulate underlying oncogenic processes and treatment response to newer therapies. Studying canine glioma at molecular level has several merits: First, it has a distinct advantage over genetically modified animal models to study natural course of glioma in dogs. Second, breed-specific elevated cancer risk, e.g., short-nosed breeds have higher risk for gliomas and smaller effective population size compared to humans potentially allow better characterization driver elements in the evolving canine glioma. Finally, dogs with the natural mammalian immune system have spontaneous occurrence of glioma, making it an ideal model for preclinical immunotherapy testing. Based on these merits, we performed whole genome, exome, transcriptome and methylation (reduced bisulfite) sequencing on 178 canine tumor and germline samples. As in humans, we show frequently occurring mutations and copy number alterations in canine gliomas in p53 pathway, cell cycle pathway (CDK4, CDKN2A), and receptor tyrosine kinases (EGFR, PDGFRA). We identified R132 mutations in the IDH1 gene reflecting a remarkable and species-agnostic but cancer-specific driving effect. Frequent whole chromosome gains were observed of syntenic region of chromosome 13, harboring human glioma oncogenes PDGFRA and MYC, but human glioma specific changes such as 1p/19q co-deletion and whole chromosome 10 loss/whole chromosome 7 gain were absent. We calculate mutational processes and highlight ones related to DNA damage repair and transcriptional strand bias in driving glioma in both species. Based on recent study, we also estimate relative timing of mutations in driver genes and copy number gains in canine glioma and compare those to human glioma in mapping life history of glioma, i.e., are canine glioma more similar to adult or pediatric human glioma cohort? In addition, transcriptional profiling delineated tumor-associated cell fractions from 22 immune cell types. The monocyte gene signature scored highest among canine glioma transcriptomes, in contrast to macrophages/microglia in human disease. Our results suggest similarities between the canine and human glioma microenvironment and we are validating those using canine immunohistochemistry. In bringing together a large canine glioma genomic and transcriptomic sequencing dataset and comparing to human glioma, our study provides unique new insights into glioma etiology and the chronology of glioma-causing somatic alterations.
Citation Format: Samirkumar B. Amin, Juan Emmanuel Martinez-Ledesma, Beth Boudreau, Hoon Kim, Kevin C. Johnson, Peter V. Dickinson, Rebecca Packer, Amanda R. Taylor, John H. Rossmeisl, Amy Heimberger, Jonathan Levine, Roel Verhaak. Genomic profiling of canine glioma: Comparative analyses with respect to drivers of human glioma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1176.
In order to examine the mechanisms by which clonal deletion of autoreactive T cells occurs, a peptide antigen was used to induce deletion of antigen-reactive thymocytes in vivo. Mice transgenic for a ...T cell receptor (TCR) that reacts to this peptide contain thymocytes that progress from the immature to the mature phenotype. Intraperitoneal administration of the peptide antigen to transgenic mice results in a rapid deletion of the immature CD4$^+$CD8$^+$ TCR$^{lo}$ thymocytes. Apoptosis of cortical thymocytes can be seen within 20 hours of treatment. These results provide direct evidence for the in vivo role of apoptosis in the development of antigen-induced tolerance.
To address the mechanisms controlling T helper (Th) phenotypedevelopment, we used DO10, a transgenic mouse line that expresses the αβ T-cell receptor from an ovalbumin-reactive T hybridoma, as a ...source of naive T cells that can be stimulated in vitro with ovalbumin peptide presented by defined antigen-presenting cells (APCs). We have examined the role of cytokines and APCs in the regulation of Thphenotype development. Interleukin 4 (IL-4) directs development toward the Th2phenotype, stimulating IL-4 and silencing IL-2 and interferon γ production in developing T cells. Splenic APCs direct development toward the Th1phenotype when endogenous IL-10 is neutralized with anti-IL-10 antibody. The splenic APCs mediating these effects are probably macrophages or dendritic cells and not B cells, since IL-10 is incapable of affecting Thphenotype development when the B-cell hybridoma TA3 is used as the APC. These results suggest that early regulation of IL-4 and IL-10 in a developing immune response and the identity of the initiating APCs are critical in determining the Thphenotype of the developing T cells.
In order to examine the mechanisms by which clonal deletion of autoreactive T cells occurs, a peptide antigen was used to induce deletion of antigen-reactive thymocytes in vivo. Mice transgenic for a ...T cell receptor (TCR) that reacts to this peptide contain thymocytes that progress from the immature to the mature phenotype. Intraperitoneal administration of the peptide antigen to transgenic mice results in a rapid deletion of the immature CD4+ CD8+ TCRlo thymocytes. Apoptosis of cortical thymocytes can be seen within 20 hours of treatment. These results provide direct evidence for the in vivo role of apoptosis in the development of antigen-induced tolerance.
PDF
