Molecular analysis of Tripterygium hypoglaucum (level) Hutch-induced mutations at the HPRT locus in human promyelocytic leukemia cells by multiplex polymerase chain reaction

The genotoxicity and cytotoxicity of a Chinese medicinal herb, Tripterygium hypoglaucum (level) Hutch (THH), was investigated in human promyelocytic leukemia (HL-60) cells using the hypoxanthine-guanine phosphoribosyltransferase mutation assay. THH showed clear cytotoxicity and mutagenicity in HL-60 cells at concentrations between 6.7 and 20.0 mg/ml. When the mutants were characterized by techniques based on multiplex PCR, 46.6% of induced mutants were found to have deletions, whereas only 7.7% of spontaneous mutants showed deletions. The rest were not characterized, but were assumed to be mainly point mutations. Mapping of all intragenic deletion breakpoints showed a random distribution of breakpoints in nine exons. Deletion of exon 1 appeared as the only whole gene deletion, while deletions of exon 7/8 and 9 often occurred concomitantly (71.4%). It is concluded that THH is mutagenic in HL-60 cells, predominantly inducing deletions. Since this herb is widely used as a traditional medicine, its genotoxicity should be assessed in vivo in treated humans.