CHANGES OF CYCLIN D1-DEPENDENT REGULATION OF CELL CYCLE IN PERIPHERAL BLOOD LYMPHOCYTES OF CHORNOBYL CLEAN-UP WORKERS AT A REMOTE PERIOD AFTER RADIATION EXPOSURE. / PORUShENNIa TsYKLIN D1-ZALEZhNOÏ REGULIaTsIÏ KLITYNNOGO TsYKLU LIMFOTsYTIV PERYFERYChNOÏ KROVI UChASNYKIV LIKVIDATsIÏ NASLIDKIV AVARIÏ NA ChAES U VIDDALENOMU PERIODI PISLIa OPROMINENNIa.

OBJECTIVE: To study proliferative potential of peripheral blood lymphocytes of Chornobyl clean-up workers by levelof expression of cyclin D1 and quantitative parameters of cell cycle at a remote period after radiation exposure. MATERIALS AND METHODS: The research subject was the peripheral blood lymphocytes (PB) of Chornobyl clean-upworkers 30-33 years after radiation exposure. A total of 207 men were surveyed, 164 of them were clean-up workers exposed in the dose range 10.43-3623.31 mSv and 43 persons of the control group. Analysis of proliferationpotential (cell cycle initiation) and cyclin D1 expression in PB lymphocytes were performed in vitro by a micro methodof whole blood leukocytes culture with phytohemagglutinine-P (PHA). Sample preparation was performed by a standard immunofluorescent assay for intracellular proteins using the FITC labelled Mouse Anti-Human Cyclin D1Antibody Set. Cell distribution by cell cycle phases studied by propidium iodide DNA staining and analysis onFACSCalibur laser flow cytometer in histogram mode with separation of G0/G1-, S- and G2/M-regions and Sub-G0/G1-region (apoptotic cells). RESULTS AND CONCLUSIONS: An increase in the level of spontaneous сyclin D1 expression and disturbance of сyclinD1-dependent regulation of cell cycle of PB lymphocytes after mitogen activation were determined in a remote period after radiation exposure. An increase in the level of cyclin D1 expression was accompanied by increase in pool ofcells in the S- and G2/M-phases of cell cycle which characterizes the high proliferative potential of PB lymphocytes.Mitogen-induced delay of cell cycle of lymphocytes in G1/S check point and reduction of S-phase was revealed.These changes are a manifestation of genomic instability caused by the effect of radiation and depend on the radiation dose. The results confirm the hypothesis about the significance of levels of cyclin D1 expression, as a criterion for manifestations of genome instability and risks of oncogenesis in a remote period after irradiation.

Expression of Cyclin d1 protein and CCND1 та PNKP genes in peripheral blood mononuclear cells in clean up worker of Chornobyl accident with different state of immune system. / EKSPRESIIa BILKA CYCLIN D1 TA GENIV CCND1 I PNKP U MONONUKLEARAKh PERYFERYChNOI KROVI UChASNYKIV LIKVIDATsII NASLIDKIV AVARII NA ChAES Z RIZNYM STANOM IMUNITETU.

OBJECTIVE: to investigate the Cyclin D1+ cells levels changes, associated CCND1 and PNKP genes in peripheral blood mononuclear cells in clean up workers of Chornobyl accident with different state of immune system in depends on the dose irradiation. MATERIAL AND METHODS: Relative level of Cyclin D1+cells in peripheral blood mononuclears of 39 clean up workers, men, irradiated in dose range (0,01-2,00) Gy have been analyzed. Immunological status of examinee' subjects was determined by CD3/19, CD4/8, CD3/HLA DR, СD3/16/56 testing using flow cytometry method and Ig A,M,G testing by immunoenzymatic assay in blood. CCND1 та PNKP gene expression, which associated with Cyclin D1 metabolism, was conducted using PCR real time method. The obtained results were compared in relation to data from 18 healthy men, who had no contact with ionizing radiation over then nature background. RESULTS: Аnalyzed data of the nuclear controller of cell cycle - Cyclin D1 protein expression changes and related CCND1 та PNKP genes in peripheral blood mononuclear cells in clean up workers Chornobyl accident with different status of immune system in remote period after exposure is represented. It is shown, that in examinees' subjects exposed in dose > 0,1 Gy percentage of Суclin D1+ cells is elevated against normal range and correlates with dose of radiation (rs = 0,417, p = 0,048). Normal range deflation of relative amount of Cyclin D1+cells connects with changes in cellular and humoral immunity. Decline of relative amount of Cyclin D1+ cells below the control level following CD3+ lymphocytes decrease and CD3 16+56+ elevation in clean up workers exposed in dose < 0,35 Gy. Increase of relative amount of Cyclin D1+ cells above the control range associates with CD3+ fall together with tendency of CD3+16+56+ lymphocytes fall that attends the IgG elevation in examinees' subjects with dose > 0,35 Gy. Percentage of Cyclin D1+ cells correlates with CD3 16+56+ (rs = 0,872, p = 0,049), CD8+ and IgG (rs = 0,683, p = 0,042; rs = 0,809, p = 0,014), CD4+ (rs = 0,602, p = 0,029), CD19+ and IgM (rs = 0,604, p = 0,017; rs = 0,538, p = 0,038) under condition of increased level CD4+, CD19+, Іreg. and IgG accordantly. Reviled decrease the CCND1 and PNKP gene expression in clean up workers exposed in dose > 0,1 Gy following appearance of correlation between (relative quantification) RQ PNKP and irradiation dose (rs = 0,638, p = 0,035) and also with RQ PNKP and percentage of Cyclin D1+ cells (rs = 0,792, p = 0,034).Concusions. Reveled changes in expression of Cyclin D1+ cells and regulation of related genes may point on possi ble radiation associated firm molecular disturbances occurred during elimination of consequences of Chornobyl accident, that could be a potential basis for cell and humoral communicative links breach in immune system result ing in elevation of stochastic effects like oncopathology in clean up workers of Chornobyl accident in remote peri od after exposure.

Gene expression, telomere and cognitive deficit analysis as a function of Chornobyl radiation dose and age: from in utero to adulthood. / PORUShENNIa GENNOI EKSPRESII, TELOMER TA KOGNITYVNYY DEFITsYT IaK FUNKTsIIa DOZY U OPROMINENYKh IN UTERO TA V DOROSLOMU VITsI VNASLIDOK AVARII NA ChAES.

UNLABELLED: Objective - to estimate the possible effects of low dose ionizing radiation on human cognitive function in adult hood and in utero. MATERIALS AND METHODS: Cognitive tests, telomere length and expression of genes regulating telomere function were studied in Chornobyl cleanup workers who were exposed to doses under 500 mSv (n = 326) and subjects exposed in utero during the first days after the accident Prypiat town (n = 104). The neurocognitive assessment covered mem ory, attention, language, executive and visiospatial functions. In young adults after prenatal exposure a relation ship was analyzed between a cognitive function and radiation dose to foetus, brain and thyroid gland. Internal con trols were used for both groups - the group of Chornobyl cleanup workers exposed in doses less than 20 mSv and an age matched comparison group from radioactively contaminated areas for subjects exposed in utero. RESULTS: Cognitive functions in cleanup workers exposed to ionizing radiation at adulthood are characterized by symptoms of a mild cognitive impairment according to the MMSE (mean group score 25,58 ± 2,95) and a significant ly higher level of mental disorders according to the BPRS in a dose related manner. Cleanup workers exposed to doses over 500 mSv demonstrate a significant cognitive deficit in comparison with those exposed below 500 mSv and espe cially non exposed patients. Subjects exposed in utero during the check at age of 25-27 years exhibit an excess of the disorders of autonomic nervous system (ICD 10: G90). Neurological microsymptoms as well as neurotic, stress relat ed and somatoform disorders (F40-F48) dominate. Relationship were revealed between the TERT, TERF1, TERF2 genes expression, relative telomere length (RTL),cognitive deficit and cerebrovascular pathology, radiation dose and age. Telomere length in cleanup workers is sreduced after 50 years (6.1 %). The most significant reduction in telomere length is shown after 70 years (11.7 %). Negative correlation was found between telomere length and degree of cog nitive deficit (MMSE scale) and between age and degree of cognitive deficit. The RTL is significantly decreased in groups of persons with cognitive deficit compared to a comparison group. Telomere length at the late period after low dose radiation exposure is downregulated by the high TERF2 gene expression combined with low expression of TERT gene. After exposure to doses over 250-500 mSv a cognitive deficit and dementia were associated with a substantial increase in TERT gene expression, overexpression of TERF1 and decrease in expression of TERF2 gene. A relationship was revealed between the TERF2 gene expression and CD95+ cell fraction susceptible to apoptosis. CONCLUSIONS: This study shows that cognitive deficit in humans at a late period after radiation exposure is influ enced by dose, age at exposure and gene regulation of telomere function.

TERF1 and TERF2 downregulate telomere length in cognitive deficit at the late period after low-dose exposure. / Negatyvna reguljacija dovzhyny telomer genamy TERF1 ta TERF2 pry kognityvnomu deficyti u viddalenomu periodi pislja oprominennja u malyh dozah.

Purpose - to explore the role of radiation dose on gene regulation of telomere length and its influence on the patho-genesis of cerebrovascular neurocognitive deficit at the remote period of low-dose irradiation as a result of the Chornobyl accident. Materials and methods. We performed a study of TERF1, TERF2 and TERT genes expression (GE) by RT-PCR, and relative telomere length (RTL) by flow-FISH in 258 clean-up workers of Chornobyl accident divided by radiation dose groups (range 22-2800 mSv) and 78 controls with vascular cognitive deficit. Detailed psychometric interviews were performed to obtain quantitative data on the stage of cognitive deficit. Results. Statistically significant telomere shortening was demonstrated in groups of clean-up workers with radiation doses in 100-250 mSv and 250-500 mSv range (subsequently M ± SD: 15.85 ± 0.27; p< 0.02; 15.89 ± 0,33; p< 0.02; control: 17.21 ± 0,23). A decrease in RTL was in parallel to radiation dose increase and overexpression of negative telomere length regulators: TERF2 genes and, to a lesser extent TERF1; the opposite tendency was demonstrated for TERT GE. In exposed over 500 mSv a significant TERT overexpression was combined with decreased TERF1 and TERF2 GE, and absence of significant RTL changes in comparison with clean-up workers exposed to lower doses indicating a certain independency between gene expression and telomere length changes and possible threshold effects at this dose range. Analysis of the group of exposed in comparison with non-exposed demonstrated a significant decrease (p = 0.03) both of the mean MMSE and RTL parameters suggesting influence of previous exposure. Conclusion. This study shows parallel changes in decline of cognitive function and telomere length and differences in TERF2, TERT and TERF1 gene regulation at the late period after low dose and over 500 mSv exposure.

Role of VEGF-A gene in the formation of late effects after the Chornobyl accident.

OBJECTIVE: To characterize the VEGF-A gene expression and its main effects on immune cells in the Chornobyl NPP accident clean-up workers. MATERIALS AND METHODS: VEGF-A gene expression and its main effects on immune cells were studied in 55 persons by a real-time PCR analysis and immunophenotyping of immune competent cells. RESULTS: Disorders of regulation of neoangiogenesis were found in remote period upon radiation exposure. Elevated levels of VEGF-A gene expression correlated with TP53 gene expression in the ChNPP accident clean-up workers. Correlation was established between the percentage of the immunoregulatory T-cell subpopulations and VEGF-A expressing in the group of exposed persons and there was demonstrated a suppression of specific immune response of CD4⁻8⁺ T cells. Correlation between the percentage of CD4⁺25⁺ cells and radiation dose in a group of Chornobyl clean-up workers is not related to VEGF-A expression, so this type of immune response can be regarded as a manifestation of long-term effects after exposure. CONCLUSIONS: Some parameters were identified characterizing the state and abnormalities of the "immunity-angio-genesis" system. Those parameters could be promising in prediction of neoplastic process in remote period upon radiation exposure.