Absence of mouse mammary tumor virus proviral amplification in chemically induced lymphomas of RF/J mice

Abstract

are susceptible to the induction of thymic lymphomas by the carcinogens 3-methylcholanthrene and N-methyl-N-nitrosourea. Given the association of mouse mammary tumor virus (MMTV) with certain thymomas, we examined genomic DNA from chemically induced lymphomas of RF/J mice for new MMTV proviruses. Of 13 tissue culture lines derived from 3-methylcholanthrene-induced tumors, 5 had acquired new proviruses. MMTV amplification coincided with the appearance of viral mRNAs and proteins. However, no primary tumors or animal-passaged tumors contained new proviruses. These observations indicate that MMTV does not have a role in the tumor induction process, although it may become activated and amplified in tissue culture lines derived from tumors.

Altered mouse mammary tumor virus transcript synthesis in T-cell lymphoma cells

“…There is also strong circumstantial evidence for the involvement of MTV-2, the virulent mammary tumor-inducing provirus of GR mice, in the induction of T-cell lymphomas in male mice of that strain (21)(22)(23). For carcinogen-induced lymphomas of RF/J mice, however (16), the amplification of MMTV proviral copies has been reported to be a tissue culture phenomenon. ACKNOWLEDGMENTS I am grateful to Harry Beyer for expert technical assistance and for the contributions made by Gary Zimmer.…”