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McMullen ER, Skala SL, Gonzalez ME, Djomehri S, Chandrashekar DS, Varambally S, Kleer CG. Subcellular localization of EZH2 phosphorylated at T367 stratifies metaplastic breast carcinoma subtypes. Breast Cancer 2020; 28:496-505. [PMID: 33247371 DOI: 10.1007/s12282-020-01189-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 11/08/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Metaplastic carcinoma is an aggressive, triple-negative breast cancer (TNBC) with differentiation towards squamous, spindle, or mesenchymal cell types. The molecular underpinnings of the histological subtypes are unclear. Our lab discovered a cytoplasmic function of EZH2, a transcriptional repressor, whereby pEZH2 T367 binds to cytoplasmic proteins in TNBC cells and enhances invasion and metastasis. Here, we investigated the expression and subcellular localization of pEZH2 T367 protein in metaplastic carcinomas. METHODS Thirty-five metaplastic carcinomas (17 squamous, 10 mesenchymal, and 8 spindle) were evaluated and immunostained with anti-pEZH2 T367. We analyzed staining intensity (score 1-4), subcellular localization (nuclear/cytoplasmic), and localization within the tumor (center/invasive edge). Protein expression of pEZH2 T367-binding partners was measured from a quantitative multiplex proteomics analysis performed in our lab. RESULTS Cytoplasmic pEZH2 T367 was significantly upregulated in squamous (14 of 17, 82%) compared to mesenchymal (4 of 10, 40%) and spindle (2 of 6, 33%) subtypes (p = 0.011). Twenty-five of 34 (73%) tumors with available tumor-normal interface showed accentuated cytoplasmic pEZH2 T367 at the infiltrative edge. Cytoplasmic pEZH2 T367 was upregulated in 9 of 10 (90%) tumors with lymph node metastasis (p = 0.05). Bioinformatics analyses identified an EZH2 protein network in metaplastic carcinomas (p value: < 1.0e-16). Using quantitative proteomics, we found significantly increased expression of cytoplasmic EZH2-binding partners in squamous compared to spindle and mesenchymal subtypes. CONCLUSIONS pEZH2 T367 expression and subcellular localization may be useful to distinguish metaplastic carcinoma subtypes. pEZH2 T367 may play a role in the histological diversity and behavior of these tumors.
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Affiliation(s)
- Emily R McMullen
- Department of Pathology, University of Michigan Medical School, 4217 Rogel Cancer Center, 1500 E. Medical Center Dr, Ann Arbor, MI, 48109, USA
| | - Stephanie L Skala
- Department of Pathology, University of Michigan Medical School, 4217 Rogel Cancer Center, 1500 E. Medical Center Dr, Ann Arbor, MI, 48109, USA
| | - Maria E Gonzalez
- Department of Pathology, University of Michigan Medical School, 4217 Rogel Cancer Center, 1500 E. Medical Center Dr, Ann Arbor, MI, 48109, USA.,Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Sabra Djomehri
- Department of Pathology, University of Michigan Medical School, 4217 Rogel Cancer Center, 1500 E. Medical Center Dr, Ann Arbor, MI, 48109, USA.,Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.,Molecular and Cellular Pathology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Darshan Shimoga Chandrashekar
- O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, 35233, AL, USA.,Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, 35233, AL, USA
| | - Sooryanarayana Varambally
- O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, 35233, AL, USA.,Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, 35233, AL, USA.,The Informatics Institute, University of Alabama at Birmingham, Birmingham, 35233, AL, USA
| | - Celina G Kleer
- Department of Pathology, University of Michigan Medical School, 4217 Rogel Cancer Center, 1500 E. Medical Center Dr, Ann Arbor, MI, 48109, USA. .,Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA. .,Molecular and Cellular Pathology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA.
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