Observations on the RNA Metabolism of Leukaemic Cell Cultures

Abstract

MORE than half the RNA synthesized in mammalian cells is ribosomal and transfer RNA. This RNA is rich in guanine (G) and cytosine (C) and is polymerized by a DNA-dependent RNA polymerase^1,2. Conversely, the RNA synthesized in mammalian cells infected with cytocidal single-stranded RNA viruses, such as polio-viruses and EMC virus, is predominantly viral RNA. This RNA is rich in adenine (A) and uracil (U) and is polymerized by virus-induced, RNA-dependent RNA polymerase^3–7. Cells infected with such viruses also show repression of the synthesis of GC-rich cellular RNA^8,9. Little is known about the metabolism of RNA in mammalian cells infected with leukaemia viruses. The present study was undertaken to examine some gross characteristics of RNA synthesis in leukaemia cells from mice in which the leukaemias resulted from infection either with the Rauscher leukaemia virus or with a virus from radiation-induced myeloid leukaemia¹⁰. Recent investigations have shown that the nucleic acid of the Rauscher virus is single-stranded RNA with about 52 per cent total G + C and a low uridine content^11,12. The nature of the nucleic acid of the radiation-induced myeloid leukaemia virus is not known.