Presence of mouse mammary tumour-like virus gene sequences may be associated with morphology of specific human breast cancer
- 1School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia
- 2SydPath, St Vincent’s Hospital, Darlinghurst, New South Wales, Australia
- 3Department of Microbiology, The Mount Sinai School of Medicine, One Gustave Levy Place, New York, USA
- 4Virology Division, Department of Microbiology, South Eastern Sydney Area Laboratory Services, Prince of Wales Hospital, Sydney
- 5School of Bitechnology and Biomolecular Sciences, University of New South Wales
- 6Department of Anatomical Pathology, Douglass, Hanley, Moir–Pathology, Sydney
- Correspondence to: Professor Emeritus J S Lawson 36 The Point Road, Woolwich, NSW 2110, Australia; james.lawson{at}unsw.edu.au
- Accepted 7 February 2006
- Published Online First 12 May 2006
Abstract
Background: Mouse mammary tumour virus (MMTV) has a proven role in breast carcinogenesis in wild mice and genetically susceptible in-bred mice. MMTV-like env gene sequences, which indicate the presence of a replication-competent MMTV-like virus, have been identified in some human breast cancers, but rarely in normal breast tissues. However, no evidence for a causal role of an MMTV-like virus in human breast cancer has emerged, although there are precedents for associations between specific histological characteristics of human cancers and the presence of oncogenic viruses.
Aim: To investigate the possibility of an association between breast cancer and MMTV-like viruses.
Methods: Histological characteristics of invasive ductal human breast cancer specimens were compared with archival MMTV-associated mammary tumours from C3H experimental mice. The presence of MMTV-like env DNA sequences in the human breast cancer specimens was determined by polymerase chain reaction and confirmed by Southern hybridisation.
Results: MMTV-like env gene sequences were identified in 22 of 59 (37.3%) human breast cancer specimens. Seventeen of 43 (39.5%) invasive ductal carcinoma breast cancer specimens and 4 of 16 (25%) ductal carcinoma in situ specimens had some histological characteristics, which were similar to MMTV-associated mouse mammary tumours. However, these similarities were not associated with the presence or absence of MMTV-like gene sequences in the human breast tumour specimens. A significant (p = 0.05) correlation was found between the grade of the human breast cancer and similarity to the mouse mammary tumours. The lower the grade, the greater the similarity.
Conclusion: Some human breast cancer specimens, in which MMTV-like env DNA sequences have been identified, were shown to have histological characteristics (morphology) similar to MMTV-associated mouse mammary tumours. These observations are compatible with, but not conclusive of, an association between the presence of MMTV-like env DNA sequences and some human breast cancers.
- DCIS, ductal carcinoma in situ
- HPV, human papilloma virus
- IDC, invasive ductal carcinoma
- MMTV, mouse mammary tumour virus
Footnotes
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Published Online First 12 May 2006
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Funding: This investigation was partially supported by the US Department of Defense breast cancer research program and the Cooper Medical Research Foundation.
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Competing interests: None.
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Ethical approval: The Australian Institutional Ethics Authorities approved this investigation.
The images were prepared by the Illustrations and Imaging services at the University of New South Wales, Sydney.
