Growth kinetics rather than stress accelerate telomere shortening in cultures of human diploid fibroblasts in oxidative stress-induced premature senescence

WI-38 human diploid fibroblasts underwent accelerated telomere shortening (490 bp/stress) and growth arrest after exposure to four subcytotoxic 100 muM tert-butylhydroperoxide (t-BHP) stresses, with a stress at every two population doublings; (PD). After subcytotoxic 160 muM H2O2 stress or five repeated 30 muM t-BHP stresses along the same PD, respectively a 322 +/- 55 and 380 +/- 129 bp telomere shortening was observed only during the first PD after stress. The percentage of cells resuming proliferation after stress suggests this telomere shortening is due to the number of cell divisions accomplished to reach confluence during the first PD after stress. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.