Project description:This is a genome-wide approach to identifying genes persistently induced in the mouse mammary gland by acute whole body low dose ionizing radiation (10cGy), 1 and 4 weeks after exposure. Gene expression that is modified under these parameters were compared between Tgfb1 wild type and heterozygote littermates in order to determine which genes induced or repressed by radiation were mediated via Tgfb1 status. Differential gene expression was analyzed in Tgfb1 heterozygote and wild type littermate 4th mammary glands, after whole body exposure to an acute dose of 10cGy ionizing radiation. Estrus cycle was normalized in all mice two days prior to irradiation by injection with an estrogen and progesterone mixture. It is widely believed that the carcinogenic action of ionizing radiation is due to targeted DNA damage and resulting mutations, but there is also substantial evidence that non-targeted radiation effects alter epithelial phenotype and the stromal microenvironment. Activation of transforming growth factor beta 1 (TGFbeta) is a non-targeted radiation effect that mediates cell fate decisions following DNA damage and regulates microenvironment composition; it could either suppress or promote cancer. Gene expression profiling shown herein demonstrates that low dose radiation (10 cGy) elicits persistent changes in Tgfb1 wild type and heterozygote murine mammary gland that are highly modulated by TGFbeta. We asked if such non-targeted radiation effects contribute to carcinogenesis by using a novel radiation chimera model. Unirradiated Trp53 null mammary epithelium was transplanted to the mammary stroma of mice previously exposed to a single low (10 -100 cGy) radiation dose. By 300 days, 100% of transplants in irradiated hosts at either 10 or 100 cGy had developed Trp53 null breast carcinomas compared to 54% in unirradiated hosts. Tumor growth rate was also increased by high, but not low, dose host irradiation. In contrast, irradiation of Tgfb1 heterozygote mice prior to transplantation failed to decrease tumor latency, or increase growth rate at any dose. Host irradiation significantly reduced the latency of invasive ductal carcinoma compared to spindle cell carcinoma, as well as those tumors negative for smooth muscle actin in wild type but not Tgfb1 heterozygote mice. However, irradiation of either host genotype significantly increased the frequency of estrogen receptor negative tumors. These data demonstrate two concepts critical to understanding radiation risks. First, non-targeted radiation effects can significantly promote the frequency and alter the features of epithelial cancer. Second, radiation-induced TGFbeta activity is a key mechanism of tumor promotion. Keywords: Differential gene expression after low dose irradiation Two genotypes: TGBbeta1 heterozygote and wildtype mouse mammary glands. Two time points post-10cGy-irradiation per genotype (1 week, 4 weeks); control time point was 1 week post-sham-irradiation. Two or three replicates per time point.
Project description:Using a novel flood source construct, we performed a direct comparison of genome-wide gene expression regulations resulting from exposure of primary human prostate fibroblast cultures to acute (10cGy and 200cGy) and longer-term chronic (1.0-2.45cGy cumulative over 24hr) exposures. Samples were collected at 24 hours after an acute 10cGy or 200cGy exposure (48cGy per minute) versus immediately after an accumulated 24 hour chronic 1.0 to 2.45cGy low dose-rate exposure (7 to 17M-BM-5Gy per minute). Control 0cGy samples were collected at the same time. A total of 4 independent experimental replicates were used for each sample resulting in (2 individuals M-CM-^W 4 experimental conditions M-CM-^W 4 experimental replicates) 32 microarrays.
Project description:Skin is usually exposed during human exposures to ionizing radiation, however there are few experiments that evaluate the radiation responsiveness of the cells of the epidermis (keratinocytes) and those of the dermis (fibroblasts) in the same studies. We evaluated the transcriptional responses of quiesent primary keratinocytes and fibroblasts from the same individual and compared them with quiescent keratinocytes and fibroblasts that were immortalized by human telomerase (hTert). The primary transcriptional responses to 10-500 cGy ionizing radiation were p53-mediated responses; however, we did identify distinct responses between the keratinocytes and the fibroblasts. Keywords: keratinocytes and fibroblasts - dose response to ionizing radiation
Project description:Radiation biodosimetry can play a critical role in the response to a large-scale radiologic emergency, and gene expression profiles have shown promise for providing biodosimetric information. This study was designed to test if gene expression could be used to distinguish between doses received from acute exposures and more protracted exposures, such as those that would result from fallout. Mice were exposed to whole body X-rays at low dose rate (LDR, 3.09 mGy/min) for 6, 12, or 24 hours (1.1, 2.2, or 4.4 Gy), or to equivalent doses delivered at high dose rate (HDR, 1.03 Gy/min). Global gene expression was measured in their blood 24 h after the start of exposure, and genes with the potential to classify samples by radiation dose and dose rate were identified. Data consist of 48 samples, representing 6 independent samples each from 3 doses delivered as either acute or low dose rate x-rays, plus 12 controls representing both acute and low dose rate sham treatments.
Project description:<p>Long-term low-dose ionizing radiation (LLIR) widely exists in human life and has been confirmed to have potential pathogenic effects on cancer and cardiovascular diseases. However, it is technically and ethically unfeasible to explore LLIR-induced phenotypic changes in the human cohort, leading to slow progress in revealing the pathogenesis of LLIR. In this work, we recruited 32 radiation workers and 18 healthy non-radiation workers from the same city with the same eating habits for radiation damage evaluation and metabolomics profiling. It was found that clear metabolic phenotypic differences existed between LLIR and non-LLIR exposed participants. Moreover, LLIR exposed workers can be further divided into 2 types of metabolic phenotypes, corresponding to high and low damage types, respectively. 3-hydroxypropanoate and glycolaldehyde were identified as sensitive indicators to radiation damage, which specific response to the chromosomal aberration of workers and may be potential monitoring markers for LLIR protection. Taurine metabolism-related pathways were identified as the main differential metabolic pathway under LLIR inducing, which had been confirmed to have a response to acute or chronic radiation exposure. We expect our study can be helpful to LLIR damage monitoring and symptomatic intervention in the future.</p>
Project description:Transcription profiling of IMR90 fibroblasts after ionizing radiation. Cells were harvested 30 minutes (acute response) or 5 days (cell cycle arrested) after being irradiated with 5Gy of ionizing radiation.
Project description:Background: The effects of dose-rate and its implications on radiation biodosimetry methods are not well studied in the context of large-scale radiological scenarios. There are significant health risks to individuals exposed to an acute dose in such an event, but the most realistic scenario would be a combination of exposure to both high and low dose-rates, from both external and internal radioactivity. It is important therefore, to understand the biological response to prolonged exposure; and further, discover biomarkers that can be used to estimate the extent of damage from low-dose rate exposure and propose appropriate clinical treatment. Methods: We irradiated human whole blood ex vivo to three doses, 0.56 Gy, 2.25 Gy and 4.45 Gy, using two dose rates: 1.1Gy/min and 3.1mGy/min. After 24 hours, we isolated RNA from blood cells and hybridized these to Agilent Whole Human genome microarrays. We validated the microarray results using qRT-PCR. Results: Microarray results showed that there were 454 significantly differentially expressed genes after prolonged exposure to all doses. After acute exposure, 598 genes were differentially expressed to all doses combined. Gene ontology terms enriched in both sets of genes were related to immune processes and B cell mediated immunity. Genes responding to acute exposure was also enriched in functions related to natural killer cell activation and cell-to-cell signaling. As expected, p53 pathway was found to be significantly enriched at all doses and by both dose-rates of radiation. Prediction algorithms were able to distinguish between low dose-rate and acute exposures, on the basis of a group of genes. These maybe candidates for preliminary testing as markers for differences in gene expression based on dose-rate. Radiation induced gene expression was measured in ex vivo irradiated human blood, at the 24hr time point after irradiation. Doses (0.56 Gy, 2.2 Gy and 4.45 Gy) were delivered by two dose rates, acute dose rate of 1Gy/min and low dose rate of 3.1 mGy/min.