FOXC1 identifies basal-like breast cancer in a hereditary breast cancer cohort
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Jeff Johnson1, Michael Choi1, Farnaz Dadmanesh2, Bingchen Han1, Ying Qu1, Yi Yu-Rice1, Xiao Zhang3, Sanjay Bagaria5, Clive Taylor6, Armando E. Giuliano1,4, Farin Amersi1,4, Xiaojiang Cui1,4
1Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
2Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
3Biostatistics and Bioinformatics Research Center, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
4Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
5Department of Surgery, Mayo Clinic, Jacksonville, FL 32224, USA
6Department of Pathology and Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
Farin Amersi, email: firstname.lastname@example.org
Xiaojiang Cui, email: email@example.com
Keywords: basal-like breast cancer, immunohistochemistry, BRCA, FOXC1, PARP inhibitor
Received: June 04, 2016 Accepted: September 21, 2016 Published: September 30, 2016
Breast cancers arising in the setting of the hereditary breast cancer genes BRCA1 and BRCA2 are most commonly classified as basal-like breast cancer (BLBC) or luminal breast cancer, respectively. BLBC is an aggressive subtype of breast cancer associated with liver and lung metastases and poorer prognosis than other subtypes and for which chemotherapy is the only systemic therapy. Multiple immunohistochemical markers are used to identify the basal-like subtype, including the absence of estrogen receptor alpha, progesterone receptor, and human epidermal growth factor receptor 2. Forkhead box C1 (FOXC1) has been identified as a specific marker expressed in BLBC in general breast cancer cohorts. We examined an institutional cohort of breast cancer patients with germline BRCA1 (n=46) and BRCA2 (n=35) mutations and found that FOXC1 expression on immunohistochemical staining is associated with BRCA1 vs BRCA2 mutations [30/46 vs. 6/35]. In BRCA1 mutant tumors, FOXC1 was expressed in 28/31 BLBC tumors and 2/13 non-BLBC tumors, In BRCA2 mutant tumors, FOXC1 was expressed in 5/5 BLBC tumors and 1/30 non-BLBC tumors. In cell culture models of BRCA1-mutant breast cancer, FOXC1 is associated with increased proliferation and may serve as a marker for sensitivity to PARP-inhibitor therapy with olaparib.
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