Involvement of cell cycle control in bleomycin-induced mutagen sensitivity.
Bleomycin-induced chromosomal instability, generally referred to as mutagen sensitivity, is associated with an increased risk for the development of environmentally related cancer including head and neck squamous cell carcinoma and lung cancer. On average, the cultured lymphocytes of patients with these types of cancer show an increased number of chromatid breaks per cell after bleomycin exposure in the late S or G2 phase of the cell cycle as compared to lymphocytes from control persons. The aim of the present study was to investigate whether cell cycle regulation is involved in mutagen sensitivity. We determined cell cycle arrest after bleomycin-induced DNA damage in 21 lymphoblastoid cell lines that varied in mutagen sensitivity score. An ataxia telangiectasia (AT) cell line was included for comparison. Using a cut-off point of 0.70 breaks per cell, eight cell lines were classified as insensitive and 13 cell lines showed the hypersensitive phenotype. Compared to insensitive cell lines, bleomycin-treated hypersensitive cells remained at a relatively high level of DNA synthesis, as measured by thymidine incorporation, and showed a decreased accumulation of cells in G2 and M phase, as measured by flow cytometry. AT cells showed an extremely high mutagen sensitivity score, a high level of DNA synthesis, and a strong G2 block. In conclusion, mutagen sensitivity is associated with "damage-resistant growth," which is indicative of impaired cell cycle arrest. By which specific pathway(s) this checkpoint defect is explained has yet to be elucidated; however, it is probably distinct from the checkpoint defect in AT cells. Environ. Mol. Mutagen. 40:79-84, 2002.
Cloos
Jacqueline
J
Section Tumor Biology, Department of Otolaryngology/Head and Neck Surgery, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
Temmink
Olaf
O
Ceelen
Manon
M
Snel
Mireille H J
MH
Leemans
Charles R
CR
Braakhuis
Boudewijn J M
BJ
D001761:Bleomycin / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D002842:Chromatids / Q000187:drug effects; D002869:Chromosome Aberrations; D004249:DNA Damage; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000473:pathology*; D008938:Mitosis / Q000187:drug effects; D009153:Mutagens / Q000633:toxicity*; D012016:Reference Values; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D009153:Mutagens; D001761:Bleomycin; D013936:Thymidine