Transmissible and Nontransmissible Complex Chromosome Aberrations Characterized by Three-Color and mFISH Define a Biomarker of Exposure to High-LET α Particles

Abstract

Insertions have been proposed as potential stable biomarkers of chronic high-LET radiation exposure. To examine this in vitro, we irradiated human peripheral blood lymphocytes in G(0) with either 50 cGy (238)Pu alpha particles (LET 121.4 keV/microm) or 3 Gy 250 kV X rays and stimulated their long-term culture up to approximately 22 population doublings postirradiation. Mitotic cells were harvested at regular intervals throughout this culture period and were assayed for chromosome aberrations using the techniques of three-color and 24-color mFISH. We observed the stable persistence of transmissible-type complex rearrangements, all involving at least one insertion. This supports the hypothesis that insertions are relevant indicators of exposure to high-LET radiation. However, one practical caveat of insertions being effective biomarkers is that their frequency is low due to the complexity and cell lethality of the majority of alpha-particle-induced complexes. Therefore, we propose a "profile of damage" that relies on the presence of insertions, a low frequency of stable simple reciprocal translocations (2B), and, significantly, the complexity of the damage initially induced. We suggest that the complexity of first- and second-division alpha-particle-induced nontransmissible complex aberrations reflects the structure of the alpha-particle track and as a consequence adds radiation-quality specificity to the biomarker, increasing the signal:noise ratio of the characteristic 2B:insertion ratio.

Identification of markers of occupational combined radiation exposure using a molecular cytogenetic mFISH technique

“…К стабильным сложным хромосомным перестрой-кам также относили инсерции, т.к. их можно считать результатом интерстициальной делеции и последующей встройки в другую хромосому или хромосомный участок [3]. Частота стабильных сложных хромосомных аберраций у лиц с содержанием 239 Pu в организме более 1,48 кБк (0,860,17 на 100 клеток) была статистически значимо выше по сравнению с частотой сложных хромосомных аберраций у работников с содержанием 239 Pu в организме менее 1,48 кБк (0,150,04 на 100 клеток).…”

“…Показано, что дицентрики и транслокации являются биологическим маркером внешнего облучения [1]. В то же время исследования о влиянии внутреннего альфа-излучения на геном человека немно-гочисленны и противоречивы, причём большинство из них являются экспериментальными ис-следованиями in vitro [2][3][4][5][6][7][8]. В доступной литературе практически отсутствуют данные о вкладе внутреннего и внешнего облучения в формирование радиационно-индуцированных хромосом-ных аберраций при пролонгированном сочетанном облучении.…”

Cellular radiosensitivity: How much better do we understand it?

“…Although the analysis of -H2AX formation has the potential to be useful, the cytogenetic assays has proven efficacy and strengths. A further hallmark of radiation exposure is the formation of balanced translocations (Anderson et al 2003). Although such aberrations are low in number, they are long lived.…”

BiodosEPR-2006 consensus committee report on biodosimetric methods to evaluate radiation doses at long times after exposure

“…Much effort has been expended to optimize protocols for employing chromosome painting as a retrospective biodosimeter and defining its limits of applicability . Full karyotyping or banding by FISH are still too expensive and time consuming for routine application although these techniques markedly improve the detection of chromosomal insertions and inversions, which can additionally provide a "fingerprint" for exposure to high LET radiation (Anderson et al, 2003;Hande et al, 2003).…”