Objective: To study the genotoxicity and antitumor activity of a Chinese medicinal herb, Tripterygium Hypoglaucum (Level) Hutch (THH). Methods: The genotoxicity and antitumor activity of TH-H were investigated in human promyelocytic leukemia cells on the mutation of hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene by using single cell clone culture, two-way screening counting, multiplex PCR amplification and gel electrophoresis. Results: The results showed that different mutant spectra existed between the spontaneous mutation and induced mutation by THH. Only 7. 7% (1/13) of spontaneous mutants showed deletion mutations, whereas the induced mutants included 46.6% (27/58) deletions. Mapping of all intragenic deletion breakpoints showed a random distribution in all 9 exons, but toward the 3'-end of the HPRT gene. Deletion of exon 1 only appeared when whole gene was deleted. Deletions of exon 7/8 and 9 often showed linkage deletions (71.4%). Conclusion: THH can induce the mutation, mainly deletions, of HPRT gene in human promyelocytic leukemia cells.
