We have measured the forward mutation rate at the hypoxanthine phosphoribosyltransferase (HPRT) gene of the human promyelocytic leukemia cell line HL-60 and have determined the molecular spectrum of spontaneous HPRT mutations in 45 independent 6-thioguanine-resistant HL-60 sublines. Four fluctuation tests using a total of 132 replicate HL-60 cultures revealed a mean forward mutation rate of HL-...

Ascites cell tumors were found to cleave thioguanine riboside relatively rapidly. In tumor cell lines lacking the ribonucleotide pyrophosphorylase necessary for formation of thioguanine ribonucleotide, thioguanine riboside was converted to nucleotide to a small extent. This nucleotide formation was enhanced, after a short time lag, by 9-methyl thioguanine. The nucleoside, adenine arabinoside, w...

onists, azaserine (O-diazoacetyl-L-serine) and DON (6diazo-5-oxo-L-norleucine), in combination with either 6mercaptopurine or 6-thioguanine, synergistically inhibit the growth of a spectrum of transplanted neoplasms of rodents ; these results have been summarized in a recent review (20). In man, although the glutarnine analogs have not proved useful, the purinethiols have achieved some importan...

Cultured Chinese hamster cells were labeled with 6-3H-thymidine or 5-methyl-3H-thymidine and allowed to accumulate damage from 3H decays for various periods of time while frozen. The frequencies of cells resistant to 6-thioguanine or ouabain and the amount of DNA damage (i.e., number of single-strand breaks) were determined and compared with the mutation frequencies resulting from X and ultravi...

We have measured the forward mutation rate at the hypoxanthine Phosphoribosyltransferase (HPRT) gene of the human promyelocytic leukemia cell line III,-6(1 and have determined the molecular spectrum of spontaneous HPRT mutations in 45 independent 6-thioguanine-resistant HL-60 sublines. Four fluctuation tests using a total of 132 replicate 111,-60 cultures revealed a mean forward mutation rate o...