Journal
CLINICAL CANCER RESEARCH
Volume 23, Issue 20, Pages 6138-6150Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/1078-0432.CCR-17-1232
Keywords
-
Categories
Funding
- NIH Breast SPORE [P50 CA098131]
- Vanderbilt-Ingram Cancer Center [P30 CA68485]
- SusanG. Komen for the Cure Foundation [SAC100013]
- Breast Cancer Research Foundation
- Susan G. Komen Career Catalyst Research award [CCR 299052]
- Conquer Cancer Foundation ASCO [8364]
- Susan G. Komen Postdoctoral Fellowship [PDF15329319]
- NIH [K08 CA148912]
- [NIH/NCI4R00 CA181491]
Ask authors/readers for more resources
Purpose: FGFR1 amplification occurs in approximately 15% of estrogen receptor-positive (ER+) human breast cancers. Weinvestigated mechanisms by which FGFR1 amplification confers antiestrogen resistance to ER+ breast cancer. Experimental Design: ER+ tumors from patients treated with letrozole before surgery were subjected to Ki67 IHC, FGFR1 FISH, and RNA sequencing (RNA-seq). ER+/FGFR1-amplified breast cancer cells, and patient-derived xenografts (PDX) were treated with FGFR1 siRNA or the FGFR tyrosine kinase inhibitor lucitanib. Endpoints were cell/xenograft growth, FGFR1/ER alpha association by coimmunoprecipitation and proximity ligation, ER genomic activity by ChIP sequencing, and gene expression by RT-PCR. Results: ER+/FGFR1-amplified tumors in patients treated with letrozole maintained cell proliferation (Ki67). Estrogen deprivation increased total and nuclear FGFR1 and FGF ligands expression in ER+/FGFR1-amplified primary tumors and breast cancer cells. In estrogen-free conditions, FGFR1 associated with ER alpha in tumor cell nuclei and regulated the transcription of ER-dependent genes. This association was inhibited by a kinase-dead FGFR1 mutant and by treatment with lucitanib. ChIP-seq analysis of estrogen-deprived ER+/FGFR1-amplified cells showed binding of FGFR1 and ERa to DNA. Treatment with fulvestrant and/or lucitanib reduced FGFR1 and ER alpha binding to DNA. RNA-seq data from FGFR1-amplified patients' tumors treated with letrozole showed enrichment of estrogen response and E2F target genes. Finally, growth of ER+/FGFR1-amplified cells and PDXs was more potently inhibited by fulvestrant and lucitanib combined than each drug alone. Conclusions: These data suggest the ER alpha pathway remains active in estrogen-deprived ER+/FGFR1-amplified breast cancers. Therefore, these tumors are endocrine resistant and should be candidates for treatment with combinations of ER and FGFR antagonists. (C) 2017 AACR.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available