The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Mitchell S. Turker - One of the best experts on this subject based on the ideXlab platform.
-
Simulated space radiation-induced mutants in the mouse Kidney display widespread genomic change
PloS one, 2017Co-Authors: Mitchell S. Turker, Gwen Hryciw, Dmytro Grygoryev, Michael R. Lasarev, Anna Ohlrich, Cristian Dan, Bradley Eckelmann, Furaha A. Rwatambuga, Sorrel Johnson, Jian-hua MaoAbstract:Exposure to a small number of high-energy heavy charged particles (HZE ions), as found in the deep space environment, could significantly affect astronaut health following prolonged periods of space travel if these ions induce mutations and related cancers. In this study, we used an in vivo mutagenesis assay to define the mutagenic effects of accelerated 56Fe ions (1 GeV/amu, 151 keV/μm) in the mouse Kidney Epithelium exposed to doses ranging from 0.25 to 2.0 Gy. These doses represent fluences ranging from 1 to 8 particle traversals per cell nucleus. The Aprt locus, located on chromosome 8, was used to select induced and spontaneous mutants. To fully define the mutagenic effects, we used multiple endpoints including mutant frequencies, mutation spectrum for chromosome 8, translocations involving chromosome 8, and mutations affecting non-selected chromosomes. The results demonstrate mutagenic effects that often affect multiple chromosomes for all Fe ion doses tested. For comparison with the most abundant sparsely ionizing particle found in space, we also examined the mutagenic effects of high-energy protons (1 GeV, 0.24 keV/μm) at 0.5 and 1.0 Gy. Similar doses of protons were not as mutagenic as Fe ions for many assays, though genomic effects were detected in Aprt mutants at these doses. Considered as a whole, the data demonstrate that Fe ions are highly mutagenic at the low doses and fluences of relevance to human spaceflight, and that cells with considerable genomic mutations are readily induced by these exposures and persist in the Kidney Epithelium. The level of genomic change produced by low fluence exposure to heavy ions is reminiscent of the extensive rearrangements seen in tumor genomes suggesting a potential initiation step in radiation carcinogenesis.
-
Accelerated 48Ti Ions Induce Autosomal Mutations in Mouse Kidney Epithelium at Low Dose and Fluence
Radiation research, 2015Co-Authors: Gwen Hryciw, Dmytro Grygoryev, Michael R. Lasarev, Anna Ohlrich, Cristian Dan, Ravi Madhira, Bradley Eckelmann, Stacey Gauny, Amy Kronenberg, Mitchell S. TurkerAbstract:Exposure to high-energy charged particles (HZE ions) at low fluence could significantly affect astronaut health after prolonged missions in deep space by inducing mutations and related cancers. We tested the hypothesis that the mutagenic effects of HZE ions could be detected at low fluence in a mouse model that detects autosomal mutations in vivo. Aprt heterozygous mice were exposed to 0.2, 0.4 and 1.4 Gy of densely ionizing 48Ti ions (1 GeV/amu, LET = 107 keV/μm). We observed a dose-dependent increase in the Aprt mutant fraction in Kidney Epithelium at the two lowest doses (an average of 1 or 2 particles/cell nucleus) that plateaued at the highest dose (7 particles/cell nucleus). Mutant cells were expanded to determine mutation spectra and translocations affecting chromosome 8, which encodes Aprt. A PCR-based analysis for loss of heterozygosity (LOH) events on chromosome 8 demonstrated a significant shift in the mutational spectrum from Ti ion exposure, even at low fluence, by revealing “radiation signat...
-
Comparative analysis of cell killing and autosomal mutation in mouse Kidney Epithelium exposed to 1 GeV protons in vitro or in vivo.
Radiation research, 2013Co-Authors: Amy Kronenberg, Dmytro Grygoryev, Michael R. Lasarev, Cristian Dan, Stacey Gauny, Ely Kwoh, Gianfranco Grossi, Mitchell S. TurkerAbstract:Human exposure to high-energy protons occurs in space flight scenarios or, where necessary, during radiotherapy for cancer or benign conditions. However, few studies have assessed the mutagenic effectiveness of high-energy protons, which may contribute to cancer risk. Mutations cause cancer and most cancer-associated mutations occur at autosomal loci. This study addresses the cytotoxic and mutagenic effects of 1 GeV protons in mouse Kidney Epithelium. Mutant fractions were measured for an endogenous autosomal locus (Aprt) that detects all types of mutagenic events. Results for Kidneys irradiated in vivo are compared with the results for Kidney cells from the same strain exposed in vitro. The results demonstrate dose-dependent cell killing in vitro and for cells explanted 3–4 months postirradiation in vivo. Incubation in vivo for longer periods (8–9 months) further attenuates proton-induced cell killing. Protons are mutagenic to cells in vitro and for in vivo irradiated Kidneys. The dose-response for Aprt ...
-
Marked aneuploidy and loss of multiple chromosomes are common in autosomal mutants isolated from normal mouse Kidney Epithelium.
Genes chromosomes & cancer, 2011Co-Authors: Cristian Dan, Dmytro Grygoryev, Michael R. Lasarev, Amy Kronenberg, Kelly Sandfort, Marissa Connolly, Brittany Cross, Mitchell S. TurkerAbstract:Marked aneuploidy and loss of multiple chromosomes are hallmarks of cancer, but whether these events are only present in malignant cells is not known. In prior work, we showed that approximately half of spontaneous autosomal mutants isolated directly from normal Kidney Epithelium arose from loss of a marker chromosome 8 containing the wild type Aprt gene. Chromosome loss was detected by loss of heterozygosity (LOH) for all chromosome 8 polymorphic loci examined (Turker et al, Aging Cell, 6:73-86, 2007). To determine whether loss of chromosome 8 reflected a larger mitotic event, LOH was examined for polymorphic loci on 11 non-selected chromosomes in Aprt mutants that lost the selected chromosome 8 homologue. LOH events were detected for one or more non-selected chromosomes in 38% of these mutants. The additional LOH events also reflected apparent chromosome loss based on the molecular analysis. Metaphase spreads from mutants that lost chromosome 8 were markedly aneuploid and chromosome painting revealed reduced levels for any chromosome shown to be lost with the LOH analysis. In contrast, LOH on non-selected chromosomes was infrequent in Aprt mutants exhibiting intragenic events or mitotic recombination for chromosome 8, and marked aneuploidy was absent. These observations suggest that the mechanism leading to chromosome loss in somatic mammalian cells is often not a simple non-disjunction event and instead could result from a single catastrophic event. They also suggest that cells with characteristics of malignancy are present in normal appearing tissue.
-
comparative analysis of cell killing and autosomal mutation in mouse Kidney Epithelium exposed to 1 gev nucleon iron ions in vitro or in situ
Radiation Research, 2009Co-Authors: Amy Kronenberg, Michael R. Lasarev, Cristian Dan, Stacey Gauny, Ely Kwoh, Lanelle Connolly, Mitchell S. TurkerAbstract:Abstract Astronauts receive exposures to high-energy heavy ions from galactic cosmic radiation. Although high-energy heavy ions are mutagenic and carcinogenic, their mutagenic potency in epithelial cells, where most human cancers develop, is poorly understood. Mutations are a critical component of human cancer, and mutations involving autosomal loci predominate. This study addresses the cytotoxic and mutagenic effects of 1 GeV/nucleon iron ions in mouse Kidney Epithelium. Mutant fractions were measured for an endogenous autosomal locus (Aprt) that detects all types of mutagenic events contributing to human cancer. Results for Kidneys irradiated in situ are compared with results for Kidney cells from the same strain exposed in vitro. The results demonstrate dose-dependent cell killing in vitro and for cells explanted 3–4 months postirradiation in situ, but in situ exposures were less likely to result in cell death than in vitro exposures. Prolonged incubation in situ (8–9 months) further attenuated cell ki...
Barbara Seliger - One of the best experts on this subject based on the ideXlab platform.
-
Candidate biomarkers in renal cell carcinoma.
Journal of Clinical Oncology, 2011Co-Authors: Barbara Seliger, Rudolf Lichtenfels, Derek Atkins, Christian V. Recktenwald, Sven P. Dressler, Stefan StevanovicAbstract:405 Background: Renal cell carcinoma (RCC) represents a heterogeneous disease with widely varying prognosis. Therefore, the screening for biomarkers, which allow the diagnosis as well as the assessment of the individual risk of disease progression and mortality are a prerequisite for the selection of patients for different modes of therapies and the implementation of individually tailored surveillance protocols. Methods: Various proteome-based technologies such as 2DE-based proteomics, PROTEOMEX or ligandomics in combination with mass spectrometry have been applied. Bioinformatic data mining led to the categorization and priorization of the respective target lists. Selected candidate targets were further independently verified by qRT-PCR, Western blot and/or immunohistochemistry. Results: A large series of differentially expressed/immunoreactive proteins have been identified in clear cell RCC when compared to normal Kidney Epithelium. With the different approaches distinct sets of potential candidate targ...
-
Epigenetic control of the ubiquitin carboxyl terminal hydrolase 1 in renal cell carcinoma
Journal of translational medicine, 2009Co-Authors: Barbara Seliger, Rudolf Lichtenfels, Diana Handke, Elisabeth Schabel, Juergen Bukur, Reinhard DammannAbstract:Background: The ubiquitin carboxyl-terminal hydrolase 1 (UCHL1) gene involved in the regulation of cellular ubiquitin levels plays an important role in different cellular processes including cell growth and differentiation. Aberrant expression of UCHL1 has been found in a number of human solid tumors including renal cell carcinoma (RCC). In RCC, UCHL1 overexpression is associated with tumor progression and an altered von Hippel Lindau gene expression. Methods: To determine the underlying mechanisms for the heterogeneous UCHL1 expression pattern in RCC the UCHL1 promoter DNA methylation status was determined in 17 RCC cell lines as well as in 32 RCC lesions and corresponding tumor adjacent Kidney Epithelium using combined bisulfite restriction analysis as well as bisulfite DNA sequencing. Results: UCHL1 expression was found in all 32 tumor adjacent Kidney Epithelium samples. However, the lack of or reduced UCHL1 mRNA and/or protein expression was detected in 13/32 RCC biopsies and 7/17 RCC cell lines and due to either a total or partial methylation of the UCHL1 promoter DNA. Upon 2'-deoxy-5-azacytidine treatment an induction of UCHL1 mRNA and protein expression was found in 9/17 RCC cell lines, which was linked to the demethylation degree of the UCHL1 promoter DNA. Conclusion: Promoter hypermethylation represents a mechanism for the silencing of the UCHL1 gene expression in RCC and supports the concept of an epigenetic control for the expression of UCHL1 during disease progression.
-
Structure, expression and function of HLA-G in renal cell carcinoma.
Seminars in cancer biology, 2007Co-Authors: Barbara Seliger, Gerald SchlafAbstract:Tumors have developed different strategies to escape from immune cell recognition which include the downregulation or loss of the classical HLA class I antigens as well as aberrant expression of non-classical HLA antigens like HLA-G. Abnormalities in MHC class surface expression have also been described in renal cell carcinoma (RCC) and represent mechanisms to avoid elimination by immune effector cells. We here review the structure/polymorphism, mRNA and protein expression profile of HLA-G in RCC and corresponding normal Kidney Epithelium, its mode of regulation and its functional consequences on immune responses. A heterogeneous constitutive HLA-G mRNA and/or protein expression was found in both RCC lesions and RCC cell lines, whereas normal Kidney Epithelium totally lack HLA-G mRNA and protein expression. In comparison to other tumor entities, the frequency of HLA-G expression is relatively high in RCC. Since HLA-G expression is lost during cultivation of RCC cells, the tumor microenvironment and/or endothelium appear to be involved in the regulation of HLA-G expression in this disease. HLA-G expression could be transcriptionally upregulated in RCC by interferons, IL-10 and gangliosides. Silencing of HLA-G expression in RCC is often associated with methylation of the HLA-G promoter which could be reverted by the treatment with demethylating agents. Functional studies using natural killer cells, lymphokine activated killer cells as well as antigen-specific CD8+ cytotoxic T lymphocytes demonstrated that HLA-G expression prevents lysis of RCC cells by these different immune effector cells. In contrast, HLA-G-negative normal Kidney cells as well as HLA-G-negative RCC cells were not recognized by NK and T cells. Thus, HLA-G represents one important immune escape mechanism of human RCC which has an impact on the design of T and NK cell-based immunotherapies in this disease.
-
Ubiquitin COOH-terminal hydrolase 1: a biomarker of renal cell carcinoma associated with enhanced tumor cell proliferation and migration.
Clinical cancer research : an official journal of the American Association for Cancer Research, 2007Co-Authors: Barbara Seliger, Derek Atkins, Angelika Ackermann, Walburgis Brenner, Alla Fedorushchenko, Samir M. Hanash, Rudolf LichtenfelsAbstract:Purpose: Renal cell carcinoma (RCC) accounts for 2% to 3% of all malignancies. It represents one of the most radiation- and chemotherapy-resistant tumors and surgical resections are only effective in organ-defined disease. However, RCC is an immunogenic tumor with response rates to immunotherapies between 10% and 20% of the treated patients. Due to the currently inefficient therapies and the low 5-year survival rates of RCC patients, novel diagnostic, prognostic, and therapeutic markers are urgently needed for this disease. Experimental Design: Proteome-based approaches were used to identify ( a ) differentially expressed proteins in RCC compared with normal Kidney Epithelium and ( b ) proteins that are able to induce an antibody response in RCC patients. Based on these experiments, a promising candidate was subsequently validated by reverse transcription-PCR, Western blot analyses, and immunohistochemistry. In addition, functional assays were done in generated transfectants. Results: The ubiquitin COOH-terminal hydrolase L1 (UCHL1) was found to be differentially expressed in both RCC lesions and RCC cell lines and immunoreactive using patients9 sera. UCHL1 expression was often down-regulated in primary RCC when compared with normal Kidney Epithelium but dependent on the RCC subtype, the von Hippel-Lindau phenotype, and the tumor grading. Moreover, the frequency and the level of UCHL1 expression were higher in metastases when compared with primary RCC lesions. Gain-of-function transfectants exhibited a significant higher proliferation and migration rate than UCHL1-negative RCC cells. Conclusions: UCHL1 expression seems to be associated with the metastatic phenotype of RCC and therefore might serve as potential biomarker for the diagnosis and prognosis of RCC patients.
-
Down-regulation of HLA class I antigen processing molecules: an immune escape mechanism of renal cell carcinoma?
Journal of Urology, 2004Co-Authors: Derek Atkins, Stefan Störkel, Soldano Ferrone, Gerd E. Schmahl, Barbara SeligerAbstract:ABSTRACTPurpose: Proper HLA class I antigen processing and presentation is a prerequisite for the recognition of tumor cells by cytotoxic T lymphocytes. To date there exist only limited information on the expression of components of the HLA class I associated antigen processing machinery (APM) in surgically removed benign renal cell adenoma, and primary and metastatic renal cell carcinoma (RCC).Materials and Methods: A total of 133 primary RCCs of different subtypes, 10 renal cell adenoma biopsies, 32 matched metastases of different localization and autologous normal Kidney Epithelium were immunohistochemically analyzed for the expression of HLA class I antigens, low molecular weight protein (LMP)2 and LMP7, the transporter associated with antigen processing subunit (TAP1) and β2-microglobulin (β2-m).Results: Normal Kidney tissue showed strong cytoplasmic staining intensity for LMP2, LMP7 and TAP1, whereas β2-m and HLA class I heavy chains were detected on the cell surface. A low frequency of HLA class I ...
Thomas M. Coffman - One of the best experts on this subject based on the ideXlab platform.
-
Abstract P646: Vascular AT1 Angiotensin Receptors Regulate Sodium Transporter Abundance in Kidney Epithelium
Hypertension, 2015Co-Authors: Matthew A. Sparks, Donna L. Ralph, Daian Chen, Hooman A. Azad, Susan B. Gurley, Alicia A. Mcdonough, Thomas M. CoffmanAbstract:Vasoconstriction is a signature physiological action of angiotensin II (AngII) acting via AT1 receptors (AT1R). In order to define the contribution of AT1R in vascular smooth muscle cells (VSMCs) to BP control, we generated mice with cell-specific deletion of AT1AR from VSMCs (SMKOs) using Cre-loxp technology. Baseline BP was reduced by ~7 mmHg and responses to AngII-induced hypertension were significantly blunted by in SMKO mice compared to controls (16 vs. 30 mm Hg change in BP from baseline after 4 wks AngII, P
-
abstract p646 vascular at1 angiotensin receptors regulate sodium transporter abundance in Kidney Epithelium
Hypertension, 2015Co-Authors: Matthew A. Sparks, Donna L. Ralph, Daian Chen, Hooman A. Azad, Susan B. Gurley, Alicia A. Mcdonough, Thomas M. CoffmanAbstract:Vasoconstriction is a signature physiological action of angiotensin II (AngII) acting via AT1 receptors (AT1R). In order to define the contribution of AT1R in vascular smooth muscle cells (VSMCs) to BP control, we generated mice with cell-specific deletion of AT1AR from VSMCs (SMKOs) using Cre-loxp technology. Baseline BP was reduced by ~7 mmHg and responses to AngII-induced hypertension were significantly blunted by in SMKO mice compared to controls (16 vs. 30 mm Hg change in BP from baseline after 4 wks AngII, P<0.02). Baseline renal blood flow (RBF) was higher, and renal vasoconstriction after Ang II was impaired in SMKOs. Moreover, SMKO mice displayed Na+ sensitivity and exaggerated natriuresis during chronic AngII infusion. To investigate the mechanism of the lower baseline BP and the enhanced natriuresis during AngII infusion (1000ng/kg/min for 5 days), we measured a panel of key Na+ transporters in the Kidney by immunoblot. Baseline measurements in SMKO vs. controls detected reductions in NKCC2 in both cortex (0.8±0.03 vs. 1±0.03; P=0.0002) and medulla (0.6±0.02 vs. 1±0.05; P<0.0001); medullary NHE3 was similarly reduced (0.6±0.07 vs. 1±0.07; P=0.002). In controls, AngII infusion was associated with reduced levels of cortical and medullary NHE3 and medullary NKCC, consistent with the pressure-natriuresis response, whereas cortical NKCC, NCC and ENaC were all significantly activated. By contrast, in SMKOs, there was no AngII infusion dependent depression in cortical or medullary NHE3, nor medullary NKCC. However, the extent of increase in activated (cleaved) αENaC was significantly less than controls (cortex: 1.46±0.16 vs. 2.58±0.17, P=0.002; medulla: 1.49±0.09 vs. 2.22±0.31, P=0.01). Yet, 24 hr urinary aldosterone excretion was not different between the groups (18.6±2.7 vs. 15.8±4.5 ng/24hrs). Our studies indicate that the lower baseline BP in SMKO mice is associated with reduced Na+ transporter abundance along the loop of Henle, and that attenuated hypertension and improved natriuresis during AngII infusion are associated with diminished ENaC activation. In conclusion, we suggest that vascular-epithelial cross-talk modulates renal Na+ handling and thereby contributes to control of BP at baseline and during hypertension.
Matthew A. Sparks - One of the best experts on this subject based on the ideXlab platform.
-
Competing Actions of Type 1 Angiotensin II Receptors Expressed on T Lymphocytes and Kidney Epithelium during Cisplatin-Induced AKI
Journal of the American Society of Nephrology : JASN, 2016Co-Authors: Jiandong Zhang, Matthew A. Sparks, Nathan P. Rudemiller, Mehul B. Patel, Qingqing Wei, Norah S. Karlovich, Alexander D. Jeffs, Jamie R. Privratsky, Marcela HerreraAbstract:Inappropriate activation of the renin-angiotensin system (RAS) contributes to many CKDs. However, the role of the RAS in modulating AKI requires elucidation, particularly because stimulating type 1 angiotensin II (AT1) receptors in the Kidney or circulating inflammatory cells can have opposing effects on the generation of inflammatory mediators that underpin the pathogenesis of AKI. For example, TNF-α is a fundamental driver of cisplatin nephrotoxicity, and generation of TNF-α is suppressed or enhanced by AT1 receptor signaling in T lymphocytes or the distal nephron, respectively. In this study, cell tracking experiments with CD4-Cre mT/mG reporter mice revealed robust infiltration of T lymphocytes into the Kidney after cisplatin injection. Notably, knockout of AT1 receptors on T lymphocytes exacerbated the severity of cisplatin-induced AKI and enhanced the cisplatin-induced increase in TNF-α levels locally within the Kidney and in the systemic circulation. In contrast, knockout of AT1 receptors on Kidney epithelial cells ameliorated the severity of AKI and suppressed local and systemic TNF-α production induced by cisplatin. Finally, disrupting TNF-α production specifically within the renal tubular Epithelium attenuated the AKI and the increase in circulating TNF-α levels induced by cisplatin. These results illustrate discrepant tissue-specific effects of RAS stimulation on cisplatin nephrotoxicity and raise the concern that inflammatory mediators produced by renal parenchymal cells may influence the function of remote organs by altering systemic cytokine levels. Our findings suggest selective inhibition of AT1 receptors within the nephron as a promising intervention for protecting patients from cisplatin-induced nephrotoxicity.
-
Abstract P646: Vascular AT1 Angiotensin Receptors Regulate Sodium Transporter Abundance in Kidney Epithelium
Hypertension, 2015Co-Authors: Matthew A. Sparks, Donna L. Ralph, Daian Chen, Hooman A. Azad, Susan B. Gurley, Alicia A. Mcdonough, Thomas M. CoffmanAbstract:Vasoconstriction is a signature physiological action of angiotensin II (AngII) acting via AT1 receptors (AT1R). In order to define the contribution of AT1R in vascular smooth muscle cells (VSMCs) to BP control, we generated mice with cell-specific deletion of AT1AR from VSMCs (SMKOs) using Cre-loxp technology. Baseline BP was reduced by ~7 mmHg and responses to AngII-induced hypertension were significantly blunted by in SMKO mice compared to controls (16 vs. 30 mm Hg change in BP from baseline after 4 wks AngII, P
-
abstract p646 vascular at1 angiotensin receptors regulate sodium transporter abundance in Kidney Epithelium
Hypertension, 2015Co-Authors: Matthew A. Sparks, Donna L. Ralph, Daian Chen, Hooman A. Azad, Susan B. Gurley, Alicia A. Mcdonough, Thomas M. CoffmanAbstract:Vasoconstriction is a signature physiological action of angiotensin II (AngII) acting via AT1 receptors (AT1R). In order to define the contribution of AT1R in vascular smooth muscle cells (VSMCs) to BP control, we generated mice with cell-specific deletion of AT1AR from VSMCs (SMKOs) using Cre-loxp technology. Baseline BP was reduced by ~7 mmHg and responses to AngII-induced hypertension were significantly blunted by in SMKO mice compared to controls (16 vs. 30 mm Hg change in BP from baseline after 4 wks AngII, P<0.02). Baseline renal blood flow (RBF) was higher, and renal vasoconstriction after Ang II was impaired in SMKOs. Moreover, SMKO mice displayed Na+ sensitivity and exaggerated natriuresis during chronic AngII infusion. To investigate the mechanism of the lower baseline BP and the enhanced natriuresis during AngII infusion (1000ng/kg/min for 5 days), we measured a panel of key Na+ transporters in the Kidney by immunoblot. Baseline measurements in SMKO vs. controls detected reductions in NKCC2 in both cortex (0.8±0.03 vs. 1±0.03; P=0.0002) and medulla (0.6±0.02 vs. 1±0.05; P<0.0001); medullary NHE3 was similarly reduced (0.6±0.07 vs. 1±0.07; P=0.002). In controls, AngII infusion was associated with reduced levels of cortical and medullary NHE3 and medullary NKCC, consistent with the pressure-natriuresis response, whereas cortical NKCC, NCC and ENaC were all significantly activated. By contrast, in SMKOs, there was no AngII infusion dependent depression in cortical or medullary NHE3, nor medullary NKCC. However, the extent of increase in activated (cleaved) αENaC was significantly less than controls (cortex: 1.46±0.16 vs. 2.58±0.17, P=0.002; medulla: 1.49±0.09 vs. 2.22±0.31, P=0.01). Yet, 24 hr urinary aldosterone excretion was not different between the groups (18.6±2.7 vs. 15.8±4.5 ng/24hrs). Our studies indicate that the lower baseline BP in SMKO mice is associated with reduced Na+ transporter abundance along the loop of Henle, and that attenuated hypertension and improved natriuresis during AngII infusion are associated with diminished ENaC activation. In conclusion, we suggest that vascular-epithelial cross-talk modulates renal Na+ handling and thereby contributes to control of BP at baseline and during hypertension.
Amy Kronenberg - One of the best experts on this subject based on the ideXlab platform.
-
Accelerated 48Ti Ions Induce Autosomal Mutations in Mouse Kidney Epithelium at Low Dose and Fluence
Radiation research, 2015Co-Authors: Gwen Hryciw, Dmytro Grygoryev, Michael R. Lasarev, Anna Ohlrich, Cristian Dan, Ravi Madhira, Bradley Eckelmann, Stacey Gauny, Amy Kronenberg, Mitchell S. TurkerAbstract:Exposure to high-energy charged particles (HZE ions) at low fluence could significantly affect astronaut health after prolonged missions in deep space by inducing mutations and related cancers. We tested the hypothesis that the mutagenic effects of HZE ions could be detected at low fluence in a mouse model that detects autosomal mutations in vivo. Aprt heterozygous mice were exposed to 0.2, 0.4 and 1.4 Gy of densely ionizing 48Ti ions (1 GeV/amu, LET = 107 keV/μm). We observed a dose-dependent increase in the Aprt mutant fraction in Kidney Epithelium at the two lowest doses (an average of 1 or 2 particles/cell nucleus) that plateaued at the highest dose (7 particles/cell nucleus). Mutant cells were expanded to determine mutation spectra and translocations affecting chromosome 8, which encodes Aprt. A PCR-based analysis for loss of heterozygosity (LOH) events on chromosome 8 demonstrated a significant shift in the mutational spectrum from Ti ion exposure, even at low fluence, by revealing “radiation signat...
-
Comparative analysis of cell killing and autosomal mutation in mouse Kidney Epithelium exposed to 1 GeV protons in vitro or in vivo.
Radiation research, 2013Co-Authors: Amy Kronenberg, Dmytro Grygoryev, Michael R. Lasarev, Cristian Dan, Stacey Gauny, Ely Kwoh, Gianfranco Grossi, Mitchell S. TurkerAbstract:Human exposure to high-energy protons occurs in space flight scenarios or, where necessary, during radiotherapy for cancer or benign conditions. However, few studies have assessed the mutagenic effectiveness of high-energy protons, which may contribute to cancer risk. Mutations cause cancer and most cancer-associated mutations occur at autosomal loci. This study addresses the cytotoxic and mutagenic effects of 1 GeV protons in mouse Kidney Epithelium. Mutant fractions were measured for an endogenous autosomal locus (Aprt) that detects all types of mutagenic events. Results for Kidneys irradiated in vivo are compared with the results for Kidney cells from the same strain exposed in vitro. The results demonstrate dose-dependent cell killing in vitro and for cells explanted 3–4 months postirradiation in vivo. Incubation in vivo for longer periods (8–9 months) further attenuates proton-induced cell killing. Protons are mutagenic to cells in vitro and for in vivo irradiated Kidneys. The dose-response for Aprt ...
-
Marked aneuploidy and loss of multiple chromosomes are common in autosomal mutants isolated from normal mouse Kidney Epithelium.
Genes chromosomes & cancer, 2011Co-Authors: Cristian Dan, Dmytro Grygoryev, Michael R. Lasarev, Amy Kronenberg, Kelly Sandfort, Marissa Connolly, Brittany Cross, Mitchell S. TurkerAbstract:Marked aneuploidy and loss of multiple chromosomes are hallmarks of cancer, but whether these events are only present in malignant cells is not known. In prior work, we showed that approximately half of spontaneous autosomal mutants isolated directly from normal Kidney Epithelium arose from loss of a marker chromosome 8 containing the wild type Aprt gene. Chromosome loss was detected by loss of heterozygosity (LOH) for all chromosome 8 polymorphic loci examined (Turker et al, Aging Cell, 6:73-86, 2007). To determine whether loss of chromosome 8 reflected a larger mitotic event, LOH was examined for polymorphic loci on 11 non-selected chromosomes in Aprt mutants that lost the selected chromosome 8 homologue. LOH events were detected for one or more non-selected chromosomes in 38% of these mutants. The additional LOH events also reflected apparent chromosome loss based on the molecular analysis. Metaphase spreads from mutants that lost chromosome 8 were markedly aneuploid and chromosome painting revealed reduced levels for any chromosome shown to be lost with the LOH analysis. In contrast, LOH on non-selected chromosomes was infrequent in Aprt mutants exhibiting intragenic events or mitotic recombination for chromosome 8, and marked aneuploidy was absent. These observations suggest that the mechanism leading to chromosome loss in somatic mammalian cells is often not a simple non-disjunction event and instead could result from a single catastrophic event. They also suggest that cells with characteristics of malignancy are present in normal appearing tissue.
-
comparative analysis of cell killing and autosomal mutation in mouse Kidney Epithelium exposed to 1 gev nucleon iron ions in vitro or in situ
Radiation Research, 2009Co-Authors: Amy Kronenberg, Michael R. Lasarev, Cristian Dan, Stacey Gauny, Ely Kwoh, Lanelle Connolly, Mitchell S. TurkerAbstract:Abstract Astronauts receive exposures to high-energy heavy ions from galactic cosmic radiation. Although high-energy heavy ions are mutagenic and carcinogenic, their mutagenic potency in epithelial cells, where most human cancers develop, is poorly understood. Mutations are a critical component of human cancer, and mutations involving autosomal loci predominate. This study addresses the cytotoxic and mutagenic effects of 1 GeV/nucleon iron ions in mouse Kidney Epithelium. Mutant fractions were measured for an endogenous autosomal locus (Aprt) that detects all types of mutagenic events contributing to human cancer. Results for Kidneys irradiated in situ are compared with results for Kidney cells from the same strain exposed in vitro. The results demonstrate dose-dependent cell killing in vitro and for cells explanted 3–4 months postirradiation in situ, but in situ exposures were less likely to result in cell death than in vitro exposures. Prolonged incubation in situ (8–9 months) further attenuated cell ki...
-
Comparative Analysis of Cell Killing and Autosomal Mutation in Mouse Kidney Epithelium Exposed to 1 GeV/nucleon Iron Ions In Vitro or In Situ
Radiation research, 2009Co-Authors: Amy Kronenberg, Michael R. Lasarev, Cristian Dan, Stacey Gauny, Ely Kwoh, Lanelle Connolly, Mitchell S. TurkerAbstract:Abstract Astronauts receive exposures to high-energy heavy ions from galactic cosmic radiation. Although high-energy heavy ions are mutagenic and carcinogenic, their mutagenic potency in epithelial cells, where most human cancers develop, is poorly understood. Mutations are a critical component of human cancer, and mutations involving autosomal loci predominate. This study addresses the cytotoxic and mutagenic effects of 1 GeV/nucleon iron ions in mouse Kidney Epithelium. Mutant fractions were measured for an endogenous autosomal locus (Aprt) that detects all types of mutagenic events contributing to human cancer. Results for Kidneys irradiated in situ are compared with results for Kidney cells from the same strain exposed in vitro. The results demonstrate dose-dependent cell killing in vitro and for cells explanted 3–4 months postirradiation in situ, but in situ exposures were less likely to result in cell death than in vitro exposures. Prolonged incubation in situ (8–9 months) further attenuated cell ki...
