Aphidicolin and bleomycin induced chromosome damage as biomarker of mutagen sensitivity: a twin study

The induction of chromosome damage in cultured human lymphocytes by in vitro treatments with aphidicolin (APC) and bleomycin (BLM) has been proposed as test of sensitivity to mutagens. To assess their validity, we have investigated whether the individual expression of induced chromosome damage has a genetic rather than an environmental basis. Metaphase analysis for chromosomal aberrations (CA) and micronucleus (MN) assay in cytokinesis-blocked cells have been performed in peripheral blood lymphocytes from 19 healthy male twins (9 monozygotic and 10 dizygotic pairs), aged 70-78 years, after APC, BLM and APC+BLM treatments. Concordance between twins revealed a high genetic component in the sensitivity towards clastogenic action of APC both as percentages of CA and MN. The micronucleus assay demonstrated a genetic basis also in the expression of chromosome damage induced by BLM and APC+BLM treatments. Since twins were elderly people, to investigate the possible role of age, CA and MN frequencies were compared with those found in lymphocytes from 11 young male donors. Basal and APC-induced chromosome damage were clearly increased in the former. Following BLM and APC+BLM treatments, age significantly increased mitotic delay, as shown by the mitotic indexes (MI) and by the ratios between binucleated and mononucleated (B/M) cells.