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Age and Space Irradiation Modulate Tumor Progression: Implications for Carcinogenesis Risk

ABSTRACT: Age plays a major role in tumor incidence and is an important consideration when modeling the carcinogenesis process or estimating cancer risks. Epidemiological data show that from adolescence through middle age, cancer incidence increases with age. This effect is commonly attributed to a lifetime accumulation of cellular, particularly DNA, damage. However, during middle-age, the incidence begins to decelerate and, for many tumor sites, it actually decreases at sufficiently advanced ages. We investigated if the observed deceleration and potential decrease in incidence could be attributed to a decreased capacity of older hosts to support tumor progression, and whether HZE (high atomic number (Z), high energy (E)) radiation differentially modulates tumor progression in young versus middle-age hosts, issues relevant to estimating carcinogenesis risk for astronauts. Lewis lung carcinoma (LLC) cells were injected into syngeneic mice (143 and 551 days old), which were then subject to whole-body 56Fe irradiation (1GeV/amu). Three findings emerged: 1) among unirradiated animals, substantial inhibition of tumor progression and significantly decreased tumor growth rates were seen for middle-aged mice compared to young mice; 2) whole-body 56Fe irradiation (1GeV/amu) inhibited tumor progression in both young and in middle-aged mice (with greater suppression seen in case of young animals), with little effect on tumor growth rates; and 3) 56Fe irradiation (1GeV/amu) suppressed tumor progression in young mice, to a degree not significantly different than transiting from young to middle-aged. Thus, 56Fe irradiation (1GeV/amu) acted similar to aging with respect to tumor progression. We further investigated the molecular underpinnings driving the radiation modulation of tumor dynamics in young and middle-aged mice. Through global gene expression analysis, the key players, FASN, AKT1, and the CXCL12/CXCR4 complex, were determined to be contributory. In sum, these findings demonstrate a reduced capacity of middle-aged hosts to support the progression phase of carcinogenesis and identify molecular factors contributory to HZE radiation modulation of tumor progression as a function of age.

ORGANISM(S): Mus musculus

PROVIDER: GSE45606 | GEO | 2013/06/13

SECONDARY ACCESSION(S): PRJNA195389

REPOSITORIES: GEO

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Project description:Age plays a major role in tumor incidence and is an important consideration when modeling the carcinogenesis process or estimating cancer risks. Epidemiological data show that from adolescence through middle age, cancer incidence increases with age. This effect is commonly attributed to a lifetime accumulation of cellular, particularly DNA, damage. However, during middle-age, the incidence begins to decelerate and, for many tumor sites, it actually decreases at sufficiently advanced ages. We investigated if the observed deceleration and potential decrease in incidence could be attributed to a decreased capacity of older hosts to support tumor progression, and whether HZE (high atomic number (Z), high energy (E)) radiation differentially modulates tumor progression in young versus middle-age hosts, issues relevant to estimating carcinogenesis risk for astronauts. Lewis lung carcinoma (LLC) cells were injected into syngeneic mice (143 and 551 days old), which were then subject to whole-body 56Fe irradiation (1GeV/amu). Three findings emerged: 1) among unirradiated animals, substantial inhibition of tumor progression and significantly decreased tumor growth rates were seen for middle-aged mice compared to young mice; 2) whole-body 56Fe irradiation (1GeV/amu) inhibited tumor progression in both young and in middle-aged mice (with greater suppression seen in case of young animals), with little effect on tumor growth rates; and 3) 56Fe irradiation (1GeV/amu) suppressed tumor progression in young mice, to a degree not significantly different than transiting from young to middle-aged. Thus, 56Fe irradiation (1GeV/amu) acted similar to aging with respect to tumor progression. We further investigated the molecular underpinnings driving the radiation modulation of tumor dynamics in young and middle-aged mice. Through global gene expression analysis, the key players, FASN, AKT1, and the CXCL12/CXCR4 complex, were determined to be contributory. In sum, these findings demonstrate a reduced capacity of middle-aged hosts to support the progression phase of carcinogenesis and identify molecular factors contributory to HZE radiation modulation of tumor progression as a function of age. For genome-wide expression profiling of tumor tissue, Mouse WG-6 BeadArray chips (Illumina, San Diego, CA) were used. Total RNA was amplified with the Ambion Illumina TotalPrep Amplification Kit (Ambion, Austin, TX) and labeled from all replicate biological samples for each condition. The number of tumor sample replicates used from each condition is as follows: 10 samples from young unirradiated mice, 8 samples from young irradiated mice, 7 samples from middle-aged unirradiated mice, 5 samples from middle-aged irradiated mice. Total RNA was isolated and purified using Trizol (Invitrogen) or RNeasy (Qiagen), quantified and qualified using Agilent Bioanalyzer (Agilent) and samples were deemed suitable for amplification and hybridization if they had O.D. 260/280 = 1.7 - 2.1, 28s/18s = 2:1, RIN (RNA integrity number) >7. Total RNA of 500ng per sample was amplified using Ambion TotalPrep (Ambion), and 1.5Âµg of the product was loaded onto the chips. Following hybridization at 55C, the chips were washed and then scanned using the Illumina iScan (Illumina), and the data were analyzed using GenomeStudio (Illumina). Data were first analyzed for gene expression and then culled for present genes (genes that meet the criteria of detection p-value < 0.05). Expression above background was included in an expressed genes working data set for further analyses. Rank variant normalization was applied to the data before extensive analysis. Differential gene expression analysis was used to compare to the reference group, young unirradiated mice, and genes were then evaluated and validated.

Project description:Given that aging is the major determinant of cancer incidence, and that cancer incidence is dictated in large part by processes modulating progression of existing subclinical cancers, we demonstrate that aging may be an organizing axis for identifying cancer progression-modulating processes. This would permit the broad understanding of the aging process to directly inform the question of what changes in aggregate host signaling favor cancer progression. Exploring this idea, a syngeneic murine Lewis lung cancer model in adolescent (68 days), young adult (143 days), middle-aged (551 days), and old (736 days) C57BL/6 mice was used to identify the signaling and functional processes varying significantly with host age. As anticipated, many of these specific endpoints proved to be major determinants of cancer progression. Older hosts demonstrated decreased angiogenesis, decreased metabolism and dysregulated apoptosis, all identified as hallmarks of cancer progression. Transforming growth factor 1, downregulated in older hosts, was also identified as a central player in these systemic processes. It is concluded that the strong host-age dependence here observed for tumor advancement facilitates the identification of an overarching tumor control dynamic exerted by the host. Revealed is insight into a mechanistic basis for the role of aging on modulation of tumor progression that may be therapeutically exploitable. For genome-wide expression profiling of tumor tissue, Mouse WG-6 BeadArray chips (Illumina, San Diego, CA) were used. Total RNA was amplified with the Ambion Illumina TotalPrep Amplification Kit (Ambion, Austin, TX) and labeled from all replicate biological samples for each condition. For tumor replicates, 20 tumor samples from adolescent, 10 from young adult, 10 from middle-aged, and 20 from old mice, were used. All replicate samples were run individually. Total RNA was isolated and purified using TRIzol (Invitrogen) and quantified using an Agilent Bioanalyzer. Samples were deemed suitable for amplification and hybridization if they had 28s/18s = 2:1, RIN >7. Total RNA of 500ng per sample was amplified using AmbionTotalPrep, and 1.5ug of the product was loaded onto the chips. Following hybridization at 55C, the chips were washed and then scanned using the Illumina iScan System. The data was checked with GenomeStudio (Illumina) for quality control. Data were corrected through normalization of the housekeeping genes, quantile normalized, then imported into MultiExperiment Viewer, MeV for analysis. Statistically significant genes were determined by applying a one-way ANOVA with an adjusted Bonferroni correction and false discovery rate (FDR) < 0.05 that resulted in a list of significant genes.

Project description:Proton irradiation is touted for its improved tumor targeting due to the physical advantages of ion beams for radiotherapy. Recent studies from our laboratory have shown that, in addition to targeting advantages, proton irradiation can inhibit angiogenic and immune factors and thereby modulate tumor progression. High-energy protons also constitute a principal component of the galactic cosmic rays to which astronauts are exposed. Increased understanding of the biological effects of proton exposure would thus contribute to both improved cancer therapy and carcinogenesis risk assessment for space travel. In addition, age plays a major role in tumor incidence and is a critical consideration for estimating cancer risk. We investigated the effects of host age and proton exposure on tumor progression. Tumor lag time and growth dynamics were tracked following injection of murine Lewis lung carcinoma (LLC) cells into young (68 day) versus old (736 day) mice with or without coincident irradiation. Tumor progression was suppressed in old compared to young mice. Differences in progression were further modulated by proton irradiation (1GeV), with increased inhibition evident in old mice. Through global transcriptome analysis, TGFÎ²1 and TGFÎ²2 were determined to be key players that contributed to the tumor dynamics observed. These findings point to older hosts providing decreased systemic tumor support, which can be further inhibited by proton irradiation. For genome-wide expression profiling of tumor tissue, Mouse WG-6 BeadArray chips (Illumina, San Diego, CA) were used. Total RNA was amplified with the Ambion Illumina TotalPrep Amplification Kit (Ambion, Austin, TX) and labeled from all replicate biological samples for each condition. For tumor replicates, thirty tumor samples from adolescent and thirty tumor samples from old mice, for a total of 60 tumor samples, were used. All replicate samples were run individually. For each age group, ten tumor samples had received proton irradiation while twenty tumor samples were from unirradiated mice (as described above). Total RNA was isolated and purified using TRIzol (Invitrogen) and quantified using an Agilent Bioanalyzer. Samples were deemed suitable for amplification and hybridization if they had 28s/18s = 2:1, RIN >7. Total RNA of 500ng per sample was amplified using AmbionTotalPrep, and 1.5ug of the product was loaded onto the chips. Following hybridization at 55C, the chips were washed and then scanned using the Illumina iScan System. The data was checked with GenomeStudio (Illumina) for quality control. In GenomeStudio, data was background subtracted and rank invariant normalization was applied. Data was imported into MultiExperiment Viewer, MeV, for statistical analysis. The statistically significant genes were determined using MeV by applying a one-way ANOVA analysis with standard Bonferroni correction with a FDR <0.05 that resulted in a list of significant genes. Average gene expression signals <10 were filtered out due to signal being

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Age and Space Irradiation Modulate Tumor Progression: Implications for Carcinogenesis Risk

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