Concurrent development of resistance to 6-azauridine and adenosine in a mouse cell line

A variant of the hypoxanthine-guanine phosphoribosyltransferase deficient, and adenine phosphoribosyltransferase deficient mouse resistant to 6-azauridine. These cells are not only resistant to 6-azauridine (5 X 10(-4) M), but also to adenosine (10(-3) M). Resistance persists indefinitely even in the absence of both compounds. The resistant cells are killed by 5-fluorouridine (10(-6) M), indicating that the part of the salvage pathway for pyrimidine ribonucleotide biosynthesis which is relevant to the action of 6-azauridine is intact. The heritable change producing concurrent resistance to 6-azauridine and adenosine probably involves the de novo pyrimidine biosynthetic pathway.