СHARACTERISTICS OF CYCLIN D1-MEDIATED REGULATION OF CELL CYCLE OF PERIPHERAL BLOOD LIMPHOCYTES OF CHORNOBYL CLEAN-UP WORKERS AND PERSONS WITH MALIGNANT NEOPLASMS OF THE ORAL CAVITY, OROPHARYNX AND LARYNGOPHARYNX. / KhARAKTERYSTYKA TsYKLIN D1-OPOSEREDKOVANOÏ REGULIaTsIÏ KLITYNNOGO TsYKLU LIMFOTsYTIV PERYFERYChNOÏ KROVI UChASNYKIV LIKVIDATsIÏ NASLIDKIV AVARIÏ NA ChAES TA OSIB, KhVORYKh NA ZLOIaKISNI NOVOUTVORENNIa POROZhNYNY ROTA, ROTOVOÏ TA GORTANNOÏ ChASTYN GLOTKY.

OBJECTIVE: to explore proliferative potential of peripheral blood lymphocytes of Chornobyl clean-up workers and persons with malignant neoplasms of the oral cavity, oropharynx and laryngopharynx by level of expression of cyclin D1 and quantitative parameters of cell cycle. MATERIALS AND METHODS: A total of 294 men aged (58.47 ± 7.32) were surveyed, 215 of them were Chornobyl clean"up workers (1986-1987), exposed at the dose range 10.43-3623.31 mSv; 49 persons of the control group and 30persons with malignant neoplasms of the oral cavity, oropharynx and laryngopharynx at III, IVА and IVВ stages ofthe disease. The analysis of parameters of cell cycle and proliferative activity of peripheral blood (PB) lymphocyteswas performed using the flow cytometry. The evaluation of distribution of cells by G0/G1, S, G2/M cell cycle phaseswas done in vivo and in in vitro. Proliferative potential was analyzed by level of expression of cytoplasmic protein ofcyclin D1. RESULTS: Proliferative potential of PB lymphocytes of Chornobyl clean"up workers and persons with malignant neo"plasms of the oral cavity, oropharynx and laryngopharynx was assessed. An increase in the level of spontaneousсyclin D1 expression and disturbance of сyclin D1-dependent regulation of cell cycle of PB lymphocytes after mito"gen activation were determined in the Chornobyl clean-up workers. An increase in pool of cells in the S" and G2/M"phases of cell cycle was detected, which characterizes high proliferative potential of PB lymphocytes. These changesare most pronounced in the subgroup of persons with a radiation dose of D > 500 mSv, and in persons with oncolo"gical pathology. CONCLUSIONS: A positive linear dependence has been established between the radiation dose and the number of cellsin the S"phase of cell cycle in the subgroup of Chornobyl clean"up workers with a radiation dose of D > 500 mSv. The detected changes of cyclin D1-dependent regulation of cell cycle and proliferative status of lymphocytes depend on the radiation dose, can be a manifestation of genome instability and be a cause for risks of oncogenesis, in a remote period after radiation exposure.

Overexpression of TP53, TP53I3 and BIRC5, alterations of gene regulation of apoptosis and aging of human immune cells in a remote period after radiation exposure.

OBJECTIVE: To identify a contributive role of changes in gene regulation of apoptosis and telomere length at tran scriptional and translational levels to the formation of radiation induced effects in immune system. PATIENTS AND METHODS: Study groups included 310 Chornobyl (Chornobyl) cleanup workers (dose of external expo sure (360.82 ± 32.3) mSv; age 58.9 ± 0.6 (M ± SD) years) and control (n = 77; age (52.9 ± 0.64) (M ± SD) years). Expression of CD95, phosphatidylserine receptors, bcl2 and p53 proteins was studied by flow cytometry; the relative expression (RQ) of BAX, BIRC5, FASLG, MADD, MAPK14, TP53, TP53I3, TERT, TERF1, TERF2 genes was performed using 7900 HT Fast RT PCR System and TagMan technology. Relative telomere length (RTL) was quantified by flow FISH assay. RESULTS: Dose dependent deregulation of apoptosis was shown at transcriptional level (TP53, TP53 I3, BAX, BIRC5, FASL genes) and translational level (bcl 2 and p53 proteins) with blocking entry to apoptosis, dose dependent activation of anti apoptotic proteins and TP53 mediated expression of genes inhibitors of apoptosis. After exposure below 100 mSv a decrease in TERT gene RQ was associated with shortened telomeres, after exposure to doses over 500 mSv the TERT RQ and RTL increase were associated with imbalance in TERF1 and TERF2 genes expression. CONCLUSION: Our study demonstrates a presence of subsequent changes in gene expression, regulatory proteins pres entation, telomere length and distribution of cells by the stages of apoptosis in a late period after radiation expo sure from low dose range to doses over 500 mSv. Results of the study contribute to the basic concepts on the late biological effects in immune system.