Evaluation of the frequency of ultra-short and ultra-long telomeres in chronically exposed women

Introduction. Telomere length is considered a potential biomarker for individual human radiosensitivity and radioresistance. Radiation exposure can both increase and decrease the average telomere length in cells, while the lengths of individual telomeres vary widely. The assessment of ultra-short and ultra-long telomere frequency may indicate alterations in the replicative potential of cells and radiation-induced genomic instability.

Objective. To investigate the relative telomere length using the Q-FISH method in exposed individuals and to identify the proportion of ultra-short and ultra-long chromosomal telomeric regions in this cohort.

Materials and methods. The study involved 43 volunteer donors (women) from different age groups (21–28; 60–67; and 71–83 years). At stage I, an investigation of the dose-dependence of relative telomere length was performed in the control group. The donors were divided into groups: younger (n = 4) — non-exposed women aged 21–28 years; middle-aged (n = 12) — women aged 60–67 years; older (n = 5) — women aged 71–83 years. At stage II, the reference for average telomere length was established using donors (n = 5) from the older age group. At stage III, considering the established reference values, telomere length was studied in exposed individuals (n = 22), including analysis based on age and bone marrow dose. Cytogenetic preparations were obtained according to a protocol that includes cell culturing to the metaphase stage, hypotonic treatment, fixation of metaphase plates, and chromosome slide preparation. Telomeres were fluorescently stained using probes (DAKO, Denmark) in accordance with the manufacturer’s protocol. Standard methods of descriptive and comparative statistics were used.

Results. In exposed individuals, the median telomere length was statistically significantly higher than that in the comparison group (10.3% vs. 5.8%, p = 0.0001). Concurrently, this group exhibited a reduced frequency of ultra-short telomeres (1.6% vs. 5%) and an increased frequency of ultra-long telomeres (19.5% vs. 5%, p < 0.0001). A case-control study confirmed this pattern for the individuals with medium and high bone marrow doses. A statistically significant decrease in median telomere length was observed in donors with a high bone marrow dose compared to those with medium doses (11.9% vs. 10.6%, p = 0.0001). An increase in the bone marrow dose led to an exponential decrease in the frequency of ultra-short telomeres (R² = 0.23, p = 0.0036).

Conclusions. A decrease in relative telomere length was observed in non-exposed individuals with an increase in age. In the group of young donors aged 20–28 years, the median telomere length was 31.0%, comprising 13.0% and 5.8% (p = 0.0001) in the 60–67 and 71–83 age groups, respectively. The reference range for ultra-short telomeres in the 71–83 year group was 0–0.7%, being 25.6% and above for ultra-long telomeres. In exposed individuals, the median telomere length was statistically significantly higher than in the comparison group (p = 0.0001). Exposed individuals exhibited a reduced frequency of ultra-short telomeres and an increased frequency of ultra-long telomeres with respect to the comparison group (p = 0.004). A non-linear regression dependence of the frequency of ultra-short telomeres on bone marrow dose manifested in an exponential decrease in frequency with an increase in dose was noted.

1. Akhmadullina YuR, Vozilova AV, Krivoshchapova YV. The effect of chronic exposure on the parameters of cytogenetic markers of senescence in the residents of the Techa riverside settlements. Extreme Medicine. 2024;26(2):56–66 (In Russ.). https://doi.org/10.47183/mes.2024.018

2. Baird DM, Rowson J, Wynford-Thomas D, Kipling D. Extensive allelic variation and ultrashort telomeres in senescent human cells. Nature Genetics. 2003;33(2):203–7. https://doi.org/10.1038/ng1084

3. Graakjaer J, Londono-Vallejo JA, Christensen K, Kølvraa S. The pattern of chromosome-specific variations in telomere length in humans shows signs of heritability and is maintained through life. Annals of the New York Academy of Sciences. 2006;1067:311–6. https://doi.org/10.1196/annals.1354.042

4. Berardinelli F, Nieri D, Sgura A, Tanzarella C, Antoccia A. Telomere loss, not average telomere length, confers radiosensitivity to TK6-irradiated cells. Mutation Research. 2012;740(1–2):13–20. https://doi.org/10.1016/j.mrfmmm.2012.11.004

5. Lustig A, Shterev I, Geyer S, Shi A, Hu Y, Morishita Y, et al. Long term effects of radiation exposure on telomere lengths of leukocytes and its associated biomarkers among atomicbomb survivors. Oncotarget. 2016;7(26):38988. https://doi.org/10.18632/oncotarget.8801

6. Reste J, Zvigule G, Zvagule T, Kurjane N, Eglite M, Gabruseva N, et al. Telomere length in Chernobyl accident recovery workers in the late period after the disaster. Journal of Radiation Research. 2014;55(6):1–12. https://doi.org/10.1093/jrr/rru060

7. Scherthan H, Sotnik N, Peper M, Schrock G, Azizova T, Abend M. Telomere Length in Aged Mayak PA Nuclear Workers Chronically Exposed to Internal Alpha and External Gamma Radiation. Radiation Research. 2016;185(6):658–67. https://doi.org/10.1667/RR14271.1

8. Slijepcevic P. Is there a link between telomere maintenance and radiosensitivity? Radiation Research. 2004;161(1):82–6. https://doi.org/10.1667/rr3093

9. Fiesco-Roa MÓ, García B, Leal-Anaya P, van ‘t Hek R, Wegman-Ostrosky T, Frías S, et al. Fanconi anemia and dyskeratosis congenita/telomere biology disorders: Two inherited bone marrow failure syndromes with genomic instability. Frontiers in Oncology. 2022;12:949435. https://doi.org/10.3389/fonc.2022.949435

10. Hemann MT, Strong MA, Hao LY, Greider CW. The shortest telomere, not average telomere length, is critical for cell viability and chromosome stability. Cell. 2001;107(1):67–77. https://doi.org/10.1016/s0092-8674(01)00504-9

11. Cagsin H, Uzan A, Tosun O, Rasmussen F, Serakinci N. Tissue-Specific Ultra-Short Telomeres in Chronic Obstructive Pulmonary Disease. International Journal of Chronic Obstructive Pulmonary Disease. 2020;15:2751–7. https://doi.org/10.2147/COPD.S267799

12. Akleev AV, ed. The consequences of radioactive contamination of the Techa River. Chelyabinsk: Kniga; 2016 (In Russ.).

13. Shishkina EA, Napier BA, Preston DL, Degteva MO. Dose estimates and their uncertainties for use in epidemiological studies of radiation-exposed populations in the Russian Southern Urals. PLoS One. 2023;18(8):e0288479. https://doi.org/10.1371/journal.pone.0288479

14. Krivoshchapova YV. Estimation of the impact of chronic radiation exposure on telomere loss in women’s T lymphocytes. Bulletin of RSMU. 2024;6:172–8 (In Russ.). https://doi.org/10.24075/brsmu.2024.055

15. Krivoshchapova YaV, Vozilova AV. The study of the telomere length of the chromosomes in T-lymphocytes of the exposed individuals. Radiation Safety Problems. 2022;3(107):71–96 (In Russ.). EDN: FPBYYE

16. Yasumoto S, Kunimura C, Kikuchi K, Tahara H, Ohji H, Yamamoto H, et al. Telomerase activity in normal human epithelial cells. Oncogene. 1996;13(2):433–9.

17. Drosopoulos WC, Deng Z, Twayana S, Kosiyatrakul ST, Vladimirova O, Lieberman PM, et al. TRF2 Mediates Replication Initiation within Human Telomeres to Prevent Telomere Dysfunction. Cell Reports. 2020;33(6):108379. https://doi.org/10.1016/j.celrep.2020.108379

18. Wang C, Zhao L, Lu S. Role of TERRA in the regulation of telomere length. International Journal of Biological Sciences. 2015;11(3):316–23. https://doi.org/10.7150/ijbs.10528

19. Mirjolet C, Boidot R, Saliques S, Ghiringhelli F, Maingon P, Créhange G. The role of telomeres in predicting individual radiosensitivity of patients with cancer in the era of personalized radiotherapy. Cancer Treatment Reviews. 2015;41(4):354–60. https://doi.org/10.1016/j.ctrv.2015.02.005

20. Stanley SE, Rao AD, Gable DL, McGrath-Morrow S, Armanios M. Radiation Sensitivity and Radiation Necrosis in the Short Telomere Syndromes. International Journal of Radiation Oncology, Biology, Physics. 2015;93(5):1115–7. https://doi.org/10.1016/j.ijrobp.2015.08.048