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Presence of mouse mammary tumour-like virus gene sequences may be associated with morphology of specific human breast cancer
  1. J S Lawson1,
  2. D D Tran2,
  3. E Carpenter3,
  4. C E Ford4,
  5. W D Rawlinson4,
  6. N J Whitaker5,
  7. W Delprado6
  1. 1School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia
  2. 2SydPath, St Vincent’s Hospital, Darlinghurst, New South Wales, Australia
  3. 3Department of Microbiology, The Mount Sinai School of Medicine, One Gustave Levy Place, New York, USA
  4. 4Virology Division, Department of Microbiology, South Eastern Sydney Area Laboratory Services, Prince of Wales Hospital, Sydney
  5. 5School of Bitechnology and Biomolecular Sciences, University of New South Wales
  6. 6Department of Anatomical Pathology, Douglass, Hanley, Moir–Pathology, Sydney
  1. Correspondence to:
 Professor Emeritus J S Lawson
 36 The Point Road, Woolwich, NSW 2110, Australia; james.lawson{at}unsw.edu.au

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

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Footnotes

  • Published Online First 12 May 2006

  • Funding: This investigation was partially supported by the US Department of Defense breast cancer research program and the Cooper Medical Research Foundation.

  • Competing interests: None.

  • 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.

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