DETECTION OF HYPERDIPLOIDY AND BREAKAGE AFFECTING THE 1CEN-1Q12 REGION OF CULTURED INTERPHASE HUMAN-LYMPHOCYTES TREATED WITH VARIOUS GENOTOXIC AGENTS

Chromosomal aberrations are associated with cancer, birth defects, and pregnancy loss. Previous studies using banding techniques have reveal ed that chromosomal alterations induced in human peripheral lymphocyte s by many genotoxic agents occur nonrandomly throughout the genome. On e of the regions prone to breakage is the centromeric heterochromatin of chromosome 1. We have developed a fluorescence in situ hybridizatio n (FISH) procedure using tandem DNA probes to distinguish hyperdiploid y From breakage occurring in this region. Interphase nuclei exhibiting breakage or exchanges affecting the 1cen-1q12 region can readily be d istinguished from nuclei hyperdiploid for this chromosome by identifyi ng the number and location of the hybridization signals. This hybridiz ation approach was tested using cultured human lymphocytes treated wit h a series of known aneuploidy-inducing agents (colchicine, diethylsti lbestrol, and vincristine sulfate), several potent clastogens (ionizin g radiation, mitomycin C, and etoposide), as well as sodium arsenite a nd hydroquinone, agents that have been reported to have relatively wea k aneuploidy-inducing and clastogenic activity. Significant increases in chromosomal alterations were seen with all agents tested and the re sults were generally consistent with those previously seen using stand ard cytogenetic techniques. Treatment with colchicine, diethylstilbest rol, and vincristine sulfate resulted in high frequencies of primarily hyperdiploid nuclei, and cells exposed to radiation, mitomycin C, and etoposide exhibited elevated frequencies of breakage affecting the 1c en-1q12 region. Sodium arsenite and hydroquinone induced relatively mi nor but significant increases in both hyperdiploidy and breakage. Thes e results indicate that this tandem labeling approach can be used to d istinguish aneuploidy-inducing agents from those causing breakage in i nterphase human cells and may be a valuable procedure for monitoring h uman populations exposed to genotoxic agents. (C) 1997 Wiley-Liss, Inc .