Effect of bromodeoxyuridine on the proliferation and growth of ethyl methanesulfonate-exposed P3 cells: Relationship to the induction of sister-chromatid exchanges

Abstract

Although sister-chromatid exchange (SCE) analysis is recognized as an indicator of exposure to DNA-damaging agents, the results of these analyses have been confounded by the use of bromodeoxyuridine (BrdUrd) to differentially label the sister chromatids. Not only does BrdUrd itself induce SCE, it also modulates the frequency of SCE induced by certain DNA-damaging agents. In order to examine this effect of BrdUrd on SCE frequency, an indirect method which lends itself to measurements both with and without BrdUrd was employed. Human teratocarcinoma-derived (P3) cells were exposed to ethyl methanesulfonate (EMS) and cultured with increasing concentrations of BrdUrd for lengths of time corresponding to one, two, and three generations of cell growth. At each time point, the distribution of nuclei among the phases of the cell-cycle and cell growth were evaluated for each concentration and chemical. A statistical model was employed which tested both for the main effects of chemicals and culture times and for interactions between these factors. Both EMS and BrdUrd significantly affected the percentages of nuclei within the cell-cycle. Exposure to EMS resulted in decreases in the percentages of nuclei in G0 + G1 and increases in the G2 + M compartment. Exposure to BrdUrd affected the size of the G0 + G1 compartment as well as the percentage of S-phase nuclei. Cell growth was reduced as a consequence of increasing EMS concentration and as a function of BrdUrd concentration; the effects of these chemicals were more readily apparent at the later time points. Most importantly, for both the cell-cycle kinetics data and the cell growth data, no evidence of an interaction between the effects of EMS and the effects of BrdUrd was detected statistically. These results may be interpreted to mean that while both EMS and BrdUrd affect the induction of SCE, under the conditions of this experiment, the effects are additive rather than interactive.

BrdU Birth Dating Can Produce Errors in Cell Fate Specification in Chick Brain Development

“…In chicken embryos, BrdU injection can result in developmental delay, growth retardation, increased mortality, and the appearance of ventral body wall defects (Lee et al 1974;Bannigan et al 1981; Gould et al 1999). Incorporation of BrdU, a halopyrimidine, into DNA can produce base pairing of the bromouracil with guanine instead of adenine, so it is perhaps not surprising that frank genetic problems, including mutations and breaks in double-stranded DNA, can be caused by BrdU (Hsu and Somers 1961;Roy-Burman 1970;Bannigan and Langman 1979;Saffhill and Ockey 1985;Morris 1991;Morris et al 1992;Duque and Rakic 2011).…”

Methods for Inferring Cell Cycle Parameters Using Thymidine Analogues

“…In vivo studies, on the other hand, have shown that a single administration of BrdU at doses ranging from 100 to 300 mg/kg is able to alter the proliferative behavior of neuroblasts and leads to the activation of apoptotic cellular events in the rat cerebellar neuroepithelium [ 21 ]. In line with this, it has been shown that BrdU is an antitumoral agent because a single exposure to this thymidine analogue produces a severe impairment of cell cycle (accumulation in the G1 phase) as well as a lengthening of the time that the cells remain in S-phase [ 31 , 32 ]. Moreover, it is essential to accept that the detection of BrdU, IdU, CldU, and EdU, in tissue sections, should not be a demonstration that this cell was in the S-phase of the cell cycle during marker administration.…”