ORIGINAL ARTICLE

Presence of mouse mammary tumour-like virus gene sequences may be associated with morphology of specific human breast cancer

J S Lawson¹, D D Tran², E Carpenter³, C E Ford⁴, W D Rawlinson⁴, N J Whitaker⁵ and W Delprado⁶

¹ School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia
² SydPath, St Vincent’s Hospital, Darlinghurst, New South Wales, Australia
³ Department of Microbiology, The Mount Sinai School of Medicine, One Gustave Levy Place, New York, USA
⁴ Virology Division, Department of Microbiology, South Eastern Sydney Area Laboratory Services, Prince of Wales Hospital, Sydney
⁵ School of Bitechnology and Biomolecular Sciences, University of New South Wales
⁶ Department of Anatomical Pathology, Douglass, Hanley, Moir–Pathology, Sydney

Correspondence to:
Correspondence to:
Professor Emeritus J S Lawson
36 The Point Road, Woolwich, NSW 2110, Australia; james.lawson{at}unsw.edu.au

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.

Abbreviations: DCIS, ductal carcinoma in situ; HPV, human papilloma virus; IDC, invasive ductal carcinoma; MMTV, mouse mammary tumour virus

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This article has been cited by other articles:

• Glenn, W. K, Lawson, J. S, Whitaker, N. J (2007). Mouse mammary tumour-like virus gene sequences and specific breast cancer morphology. J. Clin. Pathol. 60: 1071-1071 [Full Text]