Incorporation of cordycepin (3′-deoxyadenosine) into ribonucleic acid and deoxyribonucleic acid of human tumor cells

Abstract

Cordycepin (3′-deoxyadenosine), a nucleoside analog, is inhibitory to growing human tumor cells in culture. When these tumor cells were incubated with [ 3H]-cordycepin, the acid-soluble pool, the RNA and the DNA were radioactive. The RNA and DNA were hydrolyzed. The radioactive cordycepin was then isolated and crystallized to constant specific activities from the terminal and internal positions of the RNA. The cordycepin was also isolated and crystallized to constant specific activity from the DNA. In addition, the [ 3H]cordycepin, isolated after hydrolysis of the RNA (internal position) and the DNA, was further hydrolyzed to adenine and 3-deoxyribose. The 3-deoxyribose from the RNA (internal position) and the DNA was radioactive. No radioactivity was present in the 2-deoxyribose from the 2′-deoxyadenosine in the DNA. These results provide evidence that cordycepin is incorporated into the internal and terminal positions of RNA and the DNA and that 3-deoxyribose is not converted to 2-deoxyribose in H.Ep. No. 1 cells. The isolation of radioactive 3-deoxyribose from the cordycepin located in the internal position of the RNA indicates that a 2′,5′-phosphodiester bond is formed. The location (terminal or internal position) of the cordycepin in the DNA is not known.