Human leukemic cells: Properties of an RNA synthesized in the presence of actinomycin D

RNA biosynthesis in the presence of high concentrations of actinomycin D has been studied, utilizing human cells derived from normal healthy donors, patients with infectious mononucleosis and acute lymphatic leukemia. Actinomycin D-resistant RNA synthesis ranged from 18–38, with a higher percentage in human leukemic (CCRF-CEM; CCRF-HSB) cells, as compared with normal (CCRF-EFB; CCRF-TOH) human lymphocytic cells. The RNA synthesized in the presence of actinomycin D was resistant to ribonuclease (A and T 1); and greater resistance was observed in human leukemic cells as compared to the other lymphocytic cells studied herein. Sucrose density gradient analyses and exclusion column chromatography indicated that this particular ribonuclease-resistant RNA synthesized in the presence of actinomycin D exhibited the sedimentation characteristics of low molecular weight RNA (4S). Polyacrylamide gel electrophoresis analyses indicated that this particular RNA is similar to 4 S RNA, which is synthesized in the absence of actinomycin D. Biochemical and biophysical studies indicate that this particular RNA behaves like double-stranded RNA, and its properties are similar to viral RNA. The nature and apparent presence of this double-stranded viral-like RNA in human leukemic lymphocytes, and its possible implication in ‘neoplastic transformation’ are considered.