Telomere length in Chernobyl accident recovery workers in the late period after the disaster

Abstract

The outcome of the Chernobyl nuclear power plant (CNPP) accident was that a huge number of people were exposed to ionizing radiation. Previous studies of CNPP clean-up workers from Latvia revealed a high occurrence of age-associated degenerative diseases and cancer in young adults, as well as a high mortality as a result of cardiovascular disorders at age 45–54 years. DNA tandem repeats that cap chromosome ends, known as telomeres, are sensitive to oxidative damage and exposure to ionizing radiation. Telomeres are important in aging processes and carcinogenesis. The aim of this study was to investigate the long-term effect of protracted ionizing radiation exposure on telomere length in CNPP clean-up workers. Relative telomere length (RTL) was measured in peripheral blood leukocytes of 595 CNPP clean-up workers and 236 gender- and age-matched controls using real-time quantitative polymerase chain reaction (q-PCR). Close attention was paid to participation year and tasks performed during the worker's stay in Chernobyl, health status, and RTL differences between subgroups. Telomere shortening was not found in CNPP clean-up workers; on the contrary, their RTL was slightly greater than in controls (P = 0.001). Longer telomeres were found in people who worked during 1986, in those undertaking ‘dirty’ tasks (digging and deactivation), and in people with cancer. Shorter telomeres appeared frequently in those with cataract, osteoporosis, atherosclerosis, or coronary heart disease. We conclude that the longer telomeres revealed in people more heavily exposed to ionizing radiation probably indicate activation of telomerase as a chromosome healing mechanism following damage, and reflect defects in telomerase regulation that could potentiate carcinogenesis.

Long term effects of radiation exposure on telomere lengths of leukocytes and its associated biomarkers among atomic-bomb survivors

“…Several factors such as age, health status, and physiological determinants have been associated with telomere length [16]. Finally, recent studies show that IR exposure causes telomere length shortening in vitro [18] and in vivo [19]. However, the long-term effect of IR on telomere length and its change with age remains to be determined.…”

Telomeres and Telomerase: Molecular Views and Perspectives

“…Since telomere maintenance is one of the key events in cancer, it causes activation of the hTERT gene by chromatin remodeling [74] [75]. Reste et al (2014) implicates in their study that in order to initiate the upregulation of telomerase gene, the combined contribution of several conditions viz., a specific mixture of regulating cytokines and a certain confirmation of telomeric ends is required simultaneously [41]. Upregulation of telomerase activity is partly independent of hTERT mRNA expression as in some studies the later was demonstrated to remain unaffected [76] [77].…”

“…The telomere is thought to be an internal clock which terminates a cell's life [41]. Telomerase compensates the loss of telomere end sequences during cell division by adding specific DNA repeats at the chromosomal 3' ends [42].…”

Telomere Length and Its Relation to Human Health

“…The Chernobyl nuclear power plant accident forced workers to clean up the region. Some studies revealed high occurrence of age-associated degenerative diseases, cardiovascular disorders, and cancer among them (reviewed by Reste et al [93]). However, when telomere length was analyzed, longer telomeres were found for the workers undertaking excavation and deactivation, and in workers with cancer.…”

“…However, when telomere length was analyzed, longer telomeres were found for the workers undertaking excavation and deactivation, and in workers with cancer. The authors suggest that the exposure to ionizing radiation led to longer telomeres through telomerase activation, which could potentiate carcinogenesis [93]. Even so, it is possible to highlight that most occupational exposures induce telomere shortening.…”