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Various AGC repeat numbers in the coding region of the human transcription factor gene E2F-4
Abstract:
The E2F family of transcription factors regulates the expression of genes required for DNA synthesis and cell cycle control. The AGC triplet repeat in the coding region of the E2F-4 gene, a member of the family, has been reported to be mutated in colorectal cancers with a microsatellite instability (MSI) phenotype. We found a wider range variation of the repeat number in DNAs from tumors, the corresponding normal mucosa, and healthy individuals. A total of 5 repeat variants, ranging from 8 to 17 AGC repeats, was detected in 6 (9.7%) of the 62 healthy individuals and 8 (8.9%) of the 90 normal DNAs of the patients. The wild-type 13 repeat was present in all of these individuals. The variation of the AGC repeat number may be a polymorphism. Further, loss of heterozygosity (LOH) at the E2F-4 locus in the tumor tissues of 2 (25%) of the 8 informative cases was detected. The variation may be a useful marker for detection of LOH in primary tumors.
Insights
The E2F-4 gene
Area of Science:
- Molecular Biology
- Cancer Genetics
Background:
- E2F transcription factors are crucial for DNA synthesis and cell cycle regulation.
- Mutations in the E2F-4 gene's AGC triplet repeat are linked to colorectal cancers with microsatellite instability (MSI).
Purpose of the Study:
- To investigate the variation in the AGC triplet repeat number within the E2F-4 gene.
- To determine if this variation represents a polymorphism and its potential role in loss of heterozygosity (LOH).
Main Methods:
- Analysis of AGC triplet repeat numbers in E2F-4 gene from tumor, normal mucosa, and healthy individual DNA samples.
- Detection of loss of heterozygosity (LOH) at the E2F-4 locus in tumor tissues.
Main Results:
- A wider range of AGC repeat variants (5 variants, 8-17 repeats) was observed in healthy individuals and patient normal DNA.
- The wild-type 13-repeat was consistently found.
- Loss of heterozygosity (LOH) at the E2F-4 locus was detected in 25% of informative tumor cases.
Conclusions:
- The observed variation in E2F-4 AGC repeat number likely represents a common polymorphism.
- This E2F-4 repeat variation may serve as a useful marker for detecting LOH in primary tumors.