Carcinogen- and radiation-transformed C3H 10T1/2 cells contain RNAs homologous to the long terminal repeat sequence of a murine leukemia virus.

Carcinogen- or radiation-transformed C3H 10T1/2 murine fibroblasts transcribe a set of poly(A)+RNAs that contain sequences homologous to the long terminal repeat (LTR) sequence of Moloney murine sarcoma virus. These LTR-containing RNAs consist of a series of discrete bands ranging in size from about 38 to 18 S. The higher molecular weight molecules (30-38 S) in this set of RNAs also contain sequences homologous to the gag, pol, and env genes of a murine leukemia virus. A 24S RNA contains sequences homologous to the env gene of murine leukemia virus. A 20S and an 18S RNA also share homology with the LTR probe but fail to hybridize to the gag, pol, or env probes or to a probe for the U3 region of the LTR sequence. Thus, the latter transcripts do not appear to arise from a known endogenous murine leukemia virus genome. Although this entire set of RNAs is absent from normal C3H 10T1/2 cells (or is present at an extremely low level), these RNAs are induced by BrdUrd or 5-azacytidine. The presence of these RNAs may provide highly sensitive molecular markers of transformation of murine cells.