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Updated: May 11, 2026
Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material
Published on: August 1, 2018
Tuberin and p27 expression in breast cancer patients with or without BRCA germline mutations
Anne Catharina Dressler1, Gernot Hudelist, Anneliese Fink-Retter
1Clinical Division of Gynaecology and Gynaecological Oncology, Department of Obstretrics and Gynecology, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
Background:
Tuberin, the protein product of tuberous sclerosis gene 2 (TSC2), is the functional component of the TSC1/TSC2 complex and regulates cell cycle through activation of the cyclin-dependent kinase inhibitor p27. The transcriptional regulation of p27 is, however, also linked to a functional BRCA protein, since in BRCA1 mutant breast cancer cells, which lack the ability to repair DNA damages by homologous recombination, p27 is down-regulated. We have therefore investigated the expression of both tuberin and p27 in normal breast tissue, and in malignant epithelium from women with and without a BRCA mutation.
Materials And Methods:
immunohistochemistry was used to compare p27 and tuberin protein expression in 26 BRCA1 and 2 mutation carriers, in 53 matched breast cancer patients without a family history, and in 74 benign breast tissues in a case-control study.
Results:
Tuberin and p27 protein expression were significantly more common in benign when compared to malignant breast tissue (p = 0.01 and p = 0.03), but no difference was observed when sporadic and BRCA-mutated breast cancer specimen were compared. Tuberin and p27 were positively correlated with each other (p = 0.0017, r = 0.2527). Furthermore, p27 expression was positively correlated with ER and PR, and negatively correlated with tumor size. The expression of tuberin and p27 in breast cancer was not correlated with clinical outcome.
Conclusion:
Our results suggest that tuberin and p27 are aberrantly expressed in malignant tissue, but their expression does not appear to be dependent on the BRCA mutation state of a breast cancer patient.
Insights
Tuberin and p27 proteins are less common in malignant breast tissue compared to benign tissue. Their expression in breast cancer is not linked to BRCA mutation status or clinical outcome.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Tuberin (TSC2) and p27 regulate cell cycle.
- p27 expression is linked to BRCA protein function.
- BRCA1 mutant cells show reduced p27 levels.
Purpose of the Study:
- Investigate tuberin and p27 expression in normal and malignant breast tissue.
- Compare expression in BRCA mutation carriers versus non-carriers.
Main Methods:
- Immunohistochemistry used to assess protein expression.
- Study included BRCA mutation carriers, sporadic breast cancer patients, and benign breast tissues.
Main Results:
- Tuberin and p27 were more frequent in benign than malignant breast tissue.
- No difference in expression between sporadic and BRCA-mutated breast cancers.
- Tuberin and p27 expression correlated positively with each other and with ER/PR, negatively with tumor size.
Conclusions:
- Tuberin and p27 are aberrantly expressed in malignant breast tissue.
- Expression is not dependent on BRCA mutation status.
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