Selenite induction of DNA strand breaks and apoptosis in mouse leukemic L1210 cells.
The effects of selenite on DNA integrity, cell viability, and long-term proliferative potential of mouse leukemic L1210 cells were examined in this study. Selenite treatment resulted in concentration-dependent increases in DNA single-strand breaks and double-strand breaks, as detected by a modified filter elution assay. A time-course experiment showed that DNA single-strand breaks preceded DNA double-strand breaks. Agarose gel electrophoresis of DNA extracted from selenite-treated cells displayed a nucleosomal fragmentation pattern that is characteristic of apoptotic cell death. The involvement of a Ca2+,Mg(2+)-dependent endonuclease responsible for DNA double-strand fragmentation was implied by the observation that two inhibitors of endonuclease activity, i.e. aurintricarboxylic acid and zinc, blocked selenite-induced DNA double-strand breaks. These inhibitors also prevented selenite-induced cell death as defined by loss of ability to exclude trypan blue dye. Selenite treatment severely impaired the colony-forming ability of cells capable of trypan blue exclusion. The induction of DNA strand breaks and commitment to apoptosis may explain the selenite-mediated growth inhibition and loss of long-term proliferative potential.
Lu
J
J
Division of Laboratory Research, AMC Cancer Research Center, Denver, CO 80214.
Kaeck
M
M
Jiang
C
C
Wilson
A C
AC
Thompson
H J
HJ
D000818:Animals; D017209:Apoptosis; D001312:Aurintricarboxylic Acid / Q000494:pharmacology; D002470:Cell Survival; D003114:Colony-Forming Units Assay; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000187:drug effects / Q000648:ultrastructure; D004720:Endonucleases / Q000037:antagonists & inhibitors; D007939:Leukemia L1210; D051379:Mice; D012643:Selenium / Q000032:analysis; D018038:Sodium Selenite / Q000494:pharmacology*; D013431:Sulfates / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D017967:Zinc Compounds / Q000494:pharmacology; D019287:Zinc Sulfate
D004277:DNA, Single-Stranded; D013431:Sulfates; D017967:Zinc Compounds; D001312:Aurintricarboxylic Acid; D019287:Zinc Sulfate; D004720:Endonucleases; D012643:Selenium; D018038:Sodium Selenite