Mouse mammary tumor virus and mammary tumorigenesis in wild mice

Abstract

The current knowledge of the distribution of the mouse mammary tumor virus (MMTV) proviral genomes and the mechanism of mammary tumorigenesis by MMTV in mice, with the main emphasis on Asian feral mice, is reviewed. The relevant earlier discoveries on the mode of MMTV transmission are summarized to provide an outline of the biology of MMTV. Finally, the viral etiology of human breast cancer will be discussed.

Mouse Mammary Tumor Virus-like RNA Transcripts and DNA Are Found in Affected Cells of Human Breast Cancer

“…7), whereas others have suggested that these sequences are not, in fact, a separate virus, but rather MMTV acting as a zoonotic virus (34). An exogenous source of MMTV is supported by the geographical differences in breast cancer and MMTV sequence positivity rates in different countries around the world (16,17,34,35).…”

Of mice, cats, and men: Is human breast cancer a Zoonosis?

“…Numerous transgenic mouse models have been developed (Li et al, 2000;Stewart et al, 1984), many of them utilizing MMTV-LTR for targeting transgene expression to the mammary epithelium and allowing stimulation by lactogenic hormones. In reproductively separated feral mouse species (Callahan et al, 1982Escot et al, 1986;Gallahan et al, 1986;Imai, 1996;Imai et al, 1994,;Morris et al, 1977;Schlom et al, 1978) and Asian mouse populations Michalides and Schlom, 1975;Teramoto et al, 1980), tumor formation occurs in low percentages. In certain Asian mouse populations of Mus musculus, BC occurs with less than 1% of incidence, and with relatively long latency, after 18 months of age.…”

The Envelope Glycoprotein of Human Endogenous Retrovirus Type W Uses a Divergent Family of Amino Acid Transporters/Cell Surface Receptors

“…Examples of advantageous endogenous retroviral sequences are the Fv-1, Fv-4, and Rmcf genes of mice, which confer resistance to infections by exogenous retroviruses (21,52). However, other endogenous retroviruses can participate in infectious processes that cause disease (13), for example, in leukemogenesis of AKR mice (18), in breast cancers caused by mouse mammary tumor viruses (24), and in immunodeficiencies caused by FELIX in domestic cats (3). In general, inherited proviruses within a single family occur in a spectrum of forms, with some being fully endogenized or repressed and others being expressed in certain conditions or genetic backgrounds and potentially contributing to retrotransposition processes or to diseases.…”