Kinetic analysis of apoptosis induction in human cell lines by UVA and 8-MOP.
Whereas previous studies have indicated that DNA damage as a result of 8-methoxypsoralen (8-MOP) and UVA treatment leads to cell death, this study establishes the minimum concentrations of 8-MOP and UVA necessary to induce apoptosis in human T-lymphocytic and monocytic cell lines. In order to asses apoptosis, we used fluorescent microscopy to examine changes in light scattering as well as internucleosomal DNA fragmentation. Generation of a dose response curve showed that the minimum combination of UVA and 8-MOP that was necessary to induce greater than background levels of apoptosis within 24 h of treatment was 0.5 J/cm2 UVA and 12.5 ng/mL of 8-MOP. A striking observation was that UVA alone at doses > or = 1.0 J/cm2, but not 8-MOP alone (0-300 ng/mL), induced significant apoptosis in the Sup-T1 cells induced by UVA alone was not as great as that of 8-MOP and UVA in combination, a highly significant correlation between the product of the concentration of 8-MOP (ng/mL) times the dose of UVA (J/cm2) and the percentage of apoptotic cells was observed. This correlation provides an important tool for studying the relationship of UVA-induced DNA damage to apoptosis induction. moreover, it will provide a means by which early events in the apoptotic pathway can be dissected.
Vowels
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BR
Department of Dermatology, School of Medicine, University of Pennsylvania, Philidelphia 19104-6142, USA. vowelsb@mail.med.upenn.edu
Yoo
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EK
Gasparro
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FP
D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D002460:Cell Line; D004273:DNA, Neoplasm / Q000187:drug effects / Q000302:isolation & purification / Q000528:radiation effects; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D008730:Methoxsalen / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D010778:Photochemotherapy; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
D004273:DNA, Neoplasm; D008730:Methoxsalen