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Published on: August 13, 2016
Subcellular localization of the spindle proteins Aurora A, Mad2, and BUBR1 assessed by immunohistochemistry
Espen Burum-Auensen1, Paula M De Angelis, Aasa R Schjølberg
1The Pathology Clinic, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Oslo, Norway. Espen.Burum-auensen@medisin.uio.no
Abstract:
The spindle checkpoint, the primary mechanism to ensure that two daughter cells receive the same amount of DNA, is compromised in many malignant tumors and has been implicated as a contributor to aneuploidy and carcinogenesis. The extent of expression and subcellular localization of the spindle proteins Aurora A, Mad2, and BUBR1 varies considerably in different immunohistochemical (IHC) reports from archival tumor tissues. Given the conflicting reports in the literature about the localization of these proteins, we examined the subcellular localization of Aurora kinase A, Mad2, and BUBR1 in normal and cancerous human tissues by IHC. In normal tissues, Aurora A was mainly localized to the nucleus when monoclonal or purified polyclonal antibodies were used, and Mad2 was localized to the nucleus, whereas BUBR1 was localized to the cytoplasm. In malignant tissues, Aurora A showed additional staining in the cytoplasm in the majority of tumors analyzed. Furthermore, BUBR1 was also localized to both the nucleus and cytoplasm in a significant fraction of tumors. Subcellular localization of Mad2 was similar in normal and malignant tissues. Thus, the validity of some earlier IHC studies of Aurora A, Mad2, and BUBR1 should be reconsidered, indicating that high-quality antibodies and a high-alkaline antigen-retrieval technique are required to achieve optimal results. We conclude that the subcellular localizations of these spindle proteins are different, although they have overlapping biological functions, and that Aurora A and BUBR1 undergo a shift in the subcellular localization during malignant transformation.
Insights
The spindle checkpoint ensures correct DNA distribution. This study reveals Aurora A and BUBR1 spindle proteins shift subcellular localization during cancer development, impacting aneuploidy and carcinogenesis.
Area of Science:
- Cell Biology
- Cancer Research
- Molecular Biology
Background:
- The spindle checkpoint is crucial for genomic stability, preventing aneuploidy and carcinogenesis.
- Expression and localization of spindle proteins like Aurora A, Mad2, and BUBR1 are inconsistently reported in cancer tissues.
- Conflicting immunohistochemical (IHC) data necessitates re-evaluation of spindle protein localization.
Purpose of the Study:
- To investigate and clarify the subcellular localization of Aurora kinase A, Mad2, and BUBR1 in normal and cancerous human tissues using IHC.
- To address discrepancies in existing literature regarding the localization patterns of these key spindle proteins.
Main Methods:
- Immunohistochemistry (IHC) was employed to examine the subcellular localization of Aurora A, Mad2, and BUBR1.
- Analysis was conducted on both normal and cancerous human tissue samples.
- High-quality antibodies and a high-alkaline antigen-retrieval technique were utilized for optimal IHC results.
Main Results:
- In normal tissues, Aurora A localized to the nucleus, Mad2 to the nucleus, and BUBR1 to the cytoplasm.
- Malignant tissues showed additional cytoplasmic staining for Aurora A in most tumors.
- BUBR1 exhibited both nuclear and cytoplasmic localization in a significant portion of tumors, while Mad2 localization remained consistent.
- Aurora A and BUBR1 demonstrated a shift in subcellular localization during malignant transformation.
Conclusions:
- The subcellular localization patterns of Aurora A, Mad2, and BUBR1 differ, despite their overlapping functions in the spindle checkpoint.
- Aurora A and BUBR1 undergo a notable shift in subcellular localization from normal to malignant tissues.
- The findings underscore the importance of high-quality antibodies and optimized antigen retrieval for accurate IHC analysis of spindle proteins.
