Related Experiment Videos
Expression of E2F-1 and E2F-4 is reduced in primary and metastatic breast carcinomas
G H Ho1, J E Calvano, M Bisogna
1Department of Surgery, Singapore General Hospital, Singapore.
Abstract:
The E2F family of transcription factors can induce both cell proliferation and apoptosis. Whether they function as oncogenes or tumor suppressors appears to be tissue specific. Their role in breast carcinogenesis remains unclear. We found a decreased expression of E2F-1 and E2F-4 in 70% (7/10) of primary breast carcinomas and in all (10/10) metastatic nodal tissues when compared with the corresponding normal breast tissue. No tumor-specific mutation was detected, but polymorphisms were identified in E2F-1 exon 5 and in the polyserine tract of E2F-4. The presence of polymorphisms did not correlate with E2F expression. Among the 12 human breast cancer cell lines, one contained a missense mutation in E2F-1 exon 2. Five (42%) cell lines overexpressed E2F-1, while three (25%) expressed low levels of the protein. Our results suggest that not only are the E2Fs likely to function as tumor suppressors in breast cancer, but also that their down-regulation may be important in the development of metastases.
Insights
E2F transcription factors, crucial for cell growth and death, appear to act as tumor suppressors in breast cancer. Their reduced expression is linked to tumor development and the spread of cancer to lymph nodes.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- The E2F family of transcription factors regulates cell proliferation and apoptosis.
- Their function as oncogenes or tumor suppressors is tissue-specific, and their role in breast cancer is not fully understood.
Purpose of the Study:
- To investigate the expression and potential role of E2F-1 and E2F-4 in breast carcinogenesis and metastasis.
Main Methods:
- Compared E2F-1 and E2F-4 expression in primary breast carcinomas, metastatic tissues, and normal breast tissue.
- Analyzed E2F-1 and E2F-4 for mutations and polymorphisms in tumor samples and cell lines.
- Assessed E2F-1 protein levels in human breast cancer cell lines.
Main Results:
- Decreased expression of E2F-1 and E2F-4 was observed in 70% of primary breast carcinomas and 100% of metastatic nodal tissues.
- No tumor-specific mutations were found, but polymorphisms in E2F-1 and E2F-4 were identified, though not correlated with expression levels.
- In breast cancer cell lines, one had an E2F-1 missense mutation, 42% overexpressed E2F-1, and 25% had low E2F-1 levels.
Conclusions:
- E2F transcription factors likely function as tumor suppressors in breast cancer.
- Down-regulation of E2Fs may play a significant role in the development of breast cancer metastasis.