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Prevalence and characteristics of the MMTV-like associated breast carcinomas in Tunisia
M Hachana1, M Trimeche, S Ziadi
1Department of Pathology, Farhat Hached Hospital, Sousse 4000, Tunisia.
Abstract:
The involvement of a retrovirus homologous to the mouse mammary tumor virus (MMTV) in the pathogenesis of human breast cancer (BC) has long been assumed, but has never been proven. Previous studies have reported the detection of MMTV-like env sequences in variable proportions that did not exceed 40% of BC cases in several countries. However, these viral sequences have been found in higher proportion (74%) in Tunisian diagnosed with BC during the seventies. This study is an attempt to evaluate the current prevalence of MMTV-like env gene in BC in Tunisian women. We used semi-nested PCR that amplify a 190-bp MMTV-like env sequence, followed by direct sequencing to screen a series of 122 cases of BC randomly selected. The findings were correlated to clinicopathological data and immunohistochemical expression status of progesterone and oestrogen receptors, HER2, and P53. Specific MMTV-like env sequences were found in 17 (13.9%) cases of breast carcinomas, whereas the same sequences were not detected in matched normal breast tissues. The presence of the viral sequences correlates inversely with progesterone receptor expression (6.8% versus 20.3%; P=0.03) and HER2 overexpression (3.1% versus 17.7%; P=0.04). This present study confirms the presence of MMTV-like env sequences in BC in Tunisian women but describes an important decrease in the prevalence of the viral sequences compared with previous studies. This reduction may be due to some changes in the virological characteristics or exposure to the virus.
Insights
Mouse mammary tumor virus (MMTV)-like sequences were found in 13.9% of Tunisian breast cancer (BC) cases, a decrease from previous decades. These viral sequences inversely correlated with progesterone receptor and HER2 expression in BC patients.
Area of Science:
- Oncology
- Virology
- Molecular Biology
Background:
- The potential role of mouse mammary tumor virus (MMTV)-like retroviruses in human breast cancer (BC) pathogenesis remains an area of investigation.
- Previous studies reported MMTV-like env sequences in up to 40% of BC cases globally, with a higher prevalence (74%) noted in Tunisian women during the 1970s.
Purpose of the Study:
- To assess the current prevalence of MMTV-like env gene in breast cancer (BC) among Tunisian women.
- To correlate the presence of MMTV-like env sequences with clinicopathological data and specific biomarker expression.
Main Methods:
- Semi-nested PCR was employed to amplify a 190-bp MMTV-like env sequence from 122 randomly selected BC cases.
- Direct sequencing was used to confirm the presence of viral sequences.
- Immunohistochemistry was performed to evaluate progesterone receptor, oestrogen receptor, HER2, and P53 expression.
Main Results:
- MMTV-like env sequences were detected in 17 (13.9%) of the breast carcinoma cases, but not in matched normal breast tissues.
- The prevalence of MMTV-like env sequences in this cohort is significantly lower than previously reported for Tunisian women in the 1970s.
- A significant inverse correlation was observed between the presence of MMTV-like env sequences and progesterone receptor expression (P=0.03) and HER2 overexpression (P=0.04).
Conclusions:
- This study confirms the continued presence of MMTV-like env sequences in breast cancer (BC) in Tunisian women.
- A notable decrease in prevalence compared to earlier studies suggests potential changes in viral characteristics or exposure patterns.
- The inverse correlation with progesterone receptor and HER2 suggests a potential role for MMTV-like viruses in specific BC subtypes.
