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Cancer risks from ionising radiation exposure

According to current regulations for ionizing radiation, effective doses of workers should be below 100 milliSievert (mSv); for planned actions, effective doses of the population should be below 1 mSv. The knowledge of cancer risks in this low dose range is limited.
Cancer risks from ionising radiation exposure
The EU-funded EPIRADBIO project will combine epidemiology with radiobiology to quantitatively assess cancer risks arising from such exposures to optimise radiation protection measures.

Telomere length measurements, array-based comparative genomic hybridisation (aCGH), and 2D and 3D modelling using normal human breast and lung epithelial cells will be carried out. In addition, cancer tissue and blood samples from major epidemiological cohorts such as the French–Swedish–Italian Thyroid Cancer Cohort and Mayak Worker Cohort will be analysed.

EPIRADBIO researchers have to date assessed genomic instability using flow cytometry, and cytogenetic and fluorescent microscopy analysis. Data validation was done using the Southern blot technique.

DNA, RNA and miRNA were extracted from normal and cancerous breast and lung tissue samples. State-of-the-art next-generation sequencing is currently ongoing for expression profiling of aCGH and miRNA. Three miRNA signatures with reduced expression in radiation-exposed thyroid cancer tissue samples were identified. However, no significant links were found between radiation-induced thyroid cancer and miRNA regulation. Researchers have focused on finding links between methylated DNA changes and radiation exposure. A model has been proposed for integrated miRNA and mRNA gene expression analysis.

Dose-response curves were obtained on exposing stem cells and cell lines to different radiation dose ranges. Researchers investigated the molecular mechanisms involved in radiation-induced cancer formation with epithelial mesenchymal transition (EMT) and long non-coding telomeric repeat-containing RNA (TERRA) molecules as measures. EMT is characterised by cell transition to mesenchymal phenotype after loss of polarity in the epithelial cells. In addition, DNA damage induction, intra-cellular communication, clonogenic survival and cell cycle progression were assessed. The effects of TGFβ treatment and alpha particle irradiation on EMT were studied using markers, 2D difference gel electrophoresis and protein expression profiles.

Data collection and database updating is ongoing to estimate radiation risks for breast, lung, digestive tract and thyroid cancers after dosimetry and Monte Carlo calculations. Efforts will be made to develop suitable carcinogenesis models using data from the GENRISK-T project, likelihood ratio test and lifetime risk calculations with empirical models.

Successful project outcomes will allow cancer risk estimates for low-dose exposures taking into account individual factors, which can be applied, e.g., in personalized optimisations of applications of ionizing radiation in medicine.

Related information

Record Number: 91975 / Last updated on: 2014-07-04
Domain: Biology, Medicine