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SR protein expression and CD44 splicing pattern in human breast tumours.
1Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Man., Canada.
Breast Cancer Research and Treatment
|June 5, 2003
Summary
SR proteins influence mRNA splicing in breast cancer. Higher SR55 protein levels correlate with altered CD44 variants, but other factors are also key in regulating alternative splicing.
Area of Science:
- Molecular Biology
- Cancer Research
- Gene Expression
Background:
- Alternative splicing of messenger RNAs (mRNAs) contributes to altered gene expression during breast tumor progression.
- SR proteins are recognized as critical regulators of RNA splicing and the inclusion of alternative exons.
Purpose of the Study:
- To investigate SR protein expression in human breast cell lines and invasive breast tumors.
- To examine the relationship between SR protein expression and alternatively spliced isoforms of the CD44 gene.
Main Methods:
- Western blot analysis was used to assess SR protein expression in breast cell lines and 101 invasive breast tumors.
- Reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis were employed to determine CD44 variant patterns.
Main Results:
- Multiple SR proteins (SR75, SR55, SR40, SR30) were detected in most samples, with expression levels independent of tumor grade, size, or nodal status.
- Elevated SR55 protein expression was linked to a modified pattern of CD44 variants, specifically those including exon v7 (p = 0.047).
- Transient transfection with SR55 did not directly alter CD44 v7 variant expression in MCF7 and HBL100 cells.
Conclusions:
- SR proteins are important for mRNA splicing but do not solely regulate the alternative splicing of CD44 variants.
- Additional regulatory factors are involved in controlling the expression of alternatively spliced CD44 isoforms in breast cancer.