Project description:Age plays a crucial role in the interplay between tumor and host; with further perturbations induced by irradiation. Proton irradiation on tumors induces biological modulations including inhibition of angiogenic and immune factors critical to “hallmark” processes impacting tumor development, in addition to physical targeting advantages. These advantages have provided promising results for proton therapy in cancer. Additionally, protons have implications for carcinogenesis risk of space travel (due to the high proportion of high energy protons in space radiation). Through a systems biology approach, we investigated how host tissue (i.e. splenic tissue) of tumor-bearing mice is altered with age, with or without whole-body proton exposure. Transcriptome analysis was performed on splenic tissue from adolescent (68 day) versus old (736 day) C57BL/6 male mice injected with Lewis lung carcinoma cells with or without three fractionations of 0.5Gy (1GeV) proton irradiation. Global transcriptome analysis indicated that proton irradiation of adolescent hosts caused significant signaling changes within splenic tissues that support carcinogenesis within the mice, as compared to old subjects. Increases in cell cycling and immunosuppression in irradiated adolescent hosts with CDK2, MCM7, CD74, and RUVBL2 as the key players were involved in the regulatory changes in host environment response (i.e. spleen). These results suggest a significant biological component to proton irradiation, operative through host age, that would indicate a modulation of host’s ability to support carcinogenesis in adolescence and the bestowal of resistance to immunosuppression, carcinogenesis, and genetic perturbation by old 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. For spleen replicates, 9 spleen samples from adolescent with 0Gy , 10 from adolescent with 0.5Gyx3 protons, 9 from old from old with 0Gy, and 10 from old mice with 0.5Gyx3 protons, 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 COMBAT correction, quantile normalized, collapsed to genes from probes, 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) < 0.001 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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Mus musculus

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