Autoradiographic studies of in vitro incorporation of uridine and thymidine by human tumor tissue.

Summary The incorporation of tritiated thymidine and uridine by slices of human tumors was studied in short-term tissue cultures. The nucleoside incorporation and the effects of drugs on this uptake were evaluated autoradiographically. Both the control uptakes and the effects exerted by the drugs varied greatly among individual tumors. It was possible to correlate the in vitro data with patient response to chemotherapy in nineteen patients. No responses to chemotherapy were found in those patients whose tumors when incubated in vitro showed either ( a ) poor nucleoside incorporation, ( b ) poor inhibition of uridine incorporation produced by the drugs, or ( c ) stimulation of thymidine incorporation even though the drugs inhibited the uridine uptake. The group of patients receiving benefit from chemotherapy were those whose tumors when incubated in vitro ( a ) had good uridine and thymidine incorporation in the control incubations, ( b ) had marked inhibition of uridine incorporation produced by the drugs, and ( c ) had no stimulation of thymidine incorporation in the presence of the drug.