Gene-specific damage produced by cisplatin, ormaplatin and UV light in human cells as assayed by the polymerase chain reaction.

The level of DNA damage in the total genome of leukocytes from patients receiving cisplatin therapy has been previously correlated with therapeutic outcome. Based on the fact that unrepaired damage in transcribed genes has been well correlated with sensitivity to a number of DNA damaging agents, the correlations with therapeutic response might be improved if the level of DNA damage in specific genes was assessed. We previously established a polymerase chain reaction (PCR)-based assay to measure cisplatin lesions in specific genes. The major advantages of this assay include its potential to quantify DNA lesions produced by any DNA damaging agent, and to measure it in minute samples of cells. This assay has been further improved to realize this potential. Specifically, cells were damaged with cisplatin, a related analogue ormaplatin, and ultraviolet light, and PCR was performed on the DNA from 1000 cells after direct lysis with no purification. Human HL-60 cells were used to compare the efficacy of the various agents to damage the alpha-fetoprotein gene. This was then extrapolated to damage in the total genome and compared to the cytotoxicity for each agent. At a dose that killed 50% of the cells, ormaplatin, cisplatin and ultraviolet light produced 19,200, 48,000, and 1,080,000 lesions per cell, demonstrating that ormaplatin lesions were the most effective at killing cells. Mononuclear cells were obtained from freshly isolated blood from five individuals. These cells were damaged with the three agents, and PCR of the alpha-fetoprotein gene was performed. No significant difference between the individuals was observed in the level of DNA damage produced by any of the agents.(ABSTRACT TRUNCATED AT 250 WORDS)