Sequences homologous to the mouse mammary tumor virus env gene in human breast carcinoma correlate with overexpression of laminin receptor

We previously reported that a 660-bp sequence that is homologous to the env gene of the mouse mammary tumor virus (MMTV) but not to endogenous retrovi ruses or to other known genes was present in 38% of human breast cancers an d in some breast cancer cell lines studied (Y. Wang et al., Cancer Res., 55 : 5173-5179, 1995), Here, we have investigated whether the MMTV-like sequen ces were associated with the clinical, pathological, and molecular paramete rs that have been reported to define two subsets of human breast cancers, Archival breast carcinoma samples were analyzed for four clinical parameter s, obtained from patients' records, and for sis pathological characteristic s. Expression of cel erbB-2, p53, bcl-2, progesterone receptor, laminin rec eptor, and cathepsin D was detected by immunochemistry using monoclonal ant ibodies. PCRs were used to amplify 250 bp of the MMTV env gene-like sequenc e. The chi(2), log-rank, and generalized Wilcoxon tests were used to analyz e the data. The MMTV env gene-like sequence was detected in 37.7% of the samples. The p resence of this sequence was not significantly associated with any of the p athological clinical or biological parameters studied. It did correlate, ho wever, with expression of the laminin receptor, a marker for invasiveness a nd poor prognosis. This is the first phenotypic characterization of human b reast cancers containing retroviral sequences.