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- Faedo, Margaret, et al.
(author)
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Mouse mammary tumor-like virus is associated with p53 nuclear accumulation and progesterone receptor positivity but not estrogen positivity in human female breast cancer
- 2004
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In: Clinical Cancer Research. - 1078-0432. ; 10:13, s. 4417-4419
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Journal article (peer-reviewed)abstract
- PURPOSE: The purpose is to compare the presence of proteins with known associations with breast cancer-progesterone receptor (PgR), estrogen receptor, and p53, with the prevalence of mouse mammary tumor virus (MMTV)-like DNA sequences in human female breast cancers. EXPERIMENTAL DESIGN: A cohort of 128 Australian female breast cancers were screened for MMTV-like DNA sequences using PCR. The presence of PgR, estrogen receptor, and nuclear accumulation of p53 protein was assessed in the same samples using immunohistochemical staining. RESULTS: Nuclear accumulation of p53 was significantly more prevalent (P = 0.05) in archival human breast cancers containing MMTV-like DNA sequences. The presence of progesterone receptor was significantly higher in MMTV-positive than MMTV-negative breast cancers (P = 0.01). No correlation between estrogen receptor and MMTV-like DNA sequences was found. CONCLUSIONS: MMTV causes breast cancer in mice, and hormones up-regulate expression of virus in mice mammary tissue. It is unknown if this is the case in human breast cancers shown to contain DNA of MMTV-like viruses. The positive association between MMTV-like DNA sequences and PgR indicates hormones and MMTV may play a role in human breast cancer. Mutations of the tumor suppressor gene p53 are common in human breast cancer and are associated with higher grades of cancer. The association of MMTV-like DNA sequences with higher grades of cancer, and the positive association between p53 and MMTV-like DNA sequences clearly warrant additional investigation.
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| 2. |
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| 3. |
- Ford, Caroline, et al.
(author)
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Mouse mammary tumor virus-like RNA transcripts and DNA are found in affected cells of human breast cancer
- 2004
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In: Clinical Cancer Research. - 1078-0432. ; 10:21, s. 7284-7284
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Journal article (peer-reviewed)abstract
- Identifiable risk factors for the development of breast cancer include age, diet, family history, and lifetime estrogen exposure. An infectious agent (mouse mammary tumor virus; MMTV) is known to cause murine breast tumors and may be involved in the pathogenesis of human disease. Multiple studies have detected MMTV-like sequences in 30 to 60% of breast cancer samples and up to 1.8% of samples from normal breast. Using in situ PCR of MMTV-like sequences of formalin-fixed, paraffin-embedded breast tissue, viral sequences have been located in cancerous epithelial cells in breast acini of male and female breast tumors, but not in adjacent nonmalignant cells. MMTV-like sequences were also located in the epithelial cells of male gynecomastia samples. Using reverse transcriptase in situ PCR, RNA transcripts from the env gene were also detected within cancerous epithelial cells of 78% of DNA-positive tumors, 80% of gynecomastia samples, and 0% of normal tissues screened. This suggests the virus may be replicating in these cells. The epidemiologic and histopathological data are consistent with the association of an MMTV-like virus with breast cancers in men and women. The association with gynecomastia, a benign, possibly premalignant condition suggests hormonal influences, rather than cancer per se, may be the dominant factor in determining viral presence and replication.
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| 4. |
- Ford, Caroline, et al.
(author)
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Progression from normal breast pathology to breast cancer is associated with increasing prevalence of mouse mammary tumor virus-like sequences in men and women
- 2004
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In: Cancer Research. - 1538-7445. ; 64:14, s. 4755-4759
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Journal article (peer-reviewed)abstract
- Mouse mammary tumor virus (MMTV)-like sequences have been found in up to 40% of breast cancer samples but in <2% of normal breast tissue samples from Australian women studied by our group. Screening of a larger and more diverse cohort of female breast cancer samples has now shown a correlation of MMTV-like sequences with the severity (grade) of breast cancer. Thirty-two percent (43 of 136) of female breast cancer samples were positive for MMTV-like sequences when screened using PCR. A significant gradient of MMTV positivity was observed with increasing severity of cancer from 23% of infiltrating ductal carcinoma (IDC) grade I tumors to 34% of IDC grade II tumors (P = 0.00034) and 38% of IDC grade III tumors (P = 0.00002). We also report for the first time the detection of MMTV-like sequences in 62% (8 of 13) of male breast cancer samples and 19% (10 of 52) of male gynecomastia samples screened. MMTV-like sequences were demonstrated in various premalignant breast lesions of females, including fibroadenoma (20%) and fibrocystic disease (28%) samples, at a significantly higher prevalence than that seen in normal breast tissue (1.8%; P = 0.00001). Study of a longitudinal cohort of female breast cancer patients indicated that MMTV was co-incident with tumor but was not present when tumor was absent on histology. These results support the association of MMTV-like sequences with development of breast tumors in men and women and suggest association of MMTV with increasing severity of cancer.
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