Expression of mature micro-RNA involved in the functioning of P53-dependent system of maintaining the genome stability of the individuals exposed to radiation at clinically relevant doses

Purpose: to explore the content of mature micro-RNA involved in the functioning of p53-dependent system of maintaining the genome stability in the blood of patients in distant time after irradiation at clinically relevant doses and to compare these micro-RNA with the development of malignant tumors in the period of late consequences of radiation injury. Materials and methods. We used the blood samples of patients with acute radiation syndrome (ARS), acute radiation syndrome with the development of local radiation injury (ARS+LRI) and local radiation injury (LRI) obtained through 1-51 year after radiation injury. The mature mir34a, mir21, mir145, mir16, mir125b, Iet7a which contained in the common fractions of RNA were reverse transcribed by using specific "stem-loop" — primers. The relative amount of micro-RNA in blood of patients by real-time PCR. Statistical analysis of the results was carried out using the non-parametric Mann —Whitney test. Data are presented as median and quartiles, normalized to median of control group accepted for 1. Results. We found a significant reduction of content of mir34a, mir21 in the blood of patients with a diagnosis ARS and the increase of content of mir145 in patients with LRI. Analysis of the individual values of micro-RNA expression in the blood of patients whose cancer was detected, except for patients with a bazalioma, showed consistency of changes with risk of carcinogenesis. Conclusion. For the first time was investigated the functional activity of p53-dependent system of maintaining the genome stability by measuring of micro-RNA in the blood of patients after many years post radiation injury. We found a significant reduction of content of mir34a, mir21 in blood of patients with ARS, and increased mir145 in patients with LRI. Our results suggest that further research with groups of patients, and analysis the dynamics of micro-RNA content would allow for use the micro-RNA as indicators of risk of late consequences after ARS and LRI.