Mouse mammary tumour virus related sequences are present in human DNA

MuMTV-related sequences have been identified in the DNA of human breast cancer cells using the Southern transfer technique and hybridisation with cloned MuMTV DNA under conditions in which partial ly mismatched sequences form stable hybrids. Hybridisation with cloned fragments of the MuMTV genome showed that the gag-pol region shares the most homology (estimated to be >80%) with the human MuMTV-reIated sequences, however, DNA fragments partially homologous to the MuMTV LTR, gag and env regions were also detected. Analysis of several human DNA samples suggests that the majority of the human MuMTV-related sequences are genetically transmitted but additional Eco Rl fragments were detected in the DNA of one out of three breast cancer cell lines, MCF7. These sequences are potential probes for the human MuMTV-related retroviral sequences and will allow their possible role in human breast cancer to be evaluated.