title: ESR1 mutations affect anti-proliferative responses to tamoxifen through enhanced cross-talk with IGF signaling.
abstract: The purpose of this study was to address the role of ESR1 hormone-binding mutations in breast cancer. Soft agar anchorage-independent growth assay, Western blot, ERE reporter transactivation assay, proximity ligation assay (PLA), coimmunoprecipitation assay, silencing assay, digital droplet PCR (ddPCR), Kaplan-Meier analysis, and statistical analysis. It is now generally accepted that estrogen receptor (ESR1) mutations occur frequently in metastatic breast cancers; however, we do not yet know how to best treat these patients. We have modeled the three most frequent hormone-binding ESR1 (HBD-ESR1) mutations (Y537N, Y537S, and D538G) using stable lentiviral transduction in human breast cancer cell lines. Effects on growth were examined in response to hormonal and targeted agents, and mutation-specific changes were studied using microarray and Western blot analysis. We determined that the HBD-ESR1 mutations alter anti-proliferative effects to tamoxifen (Tam), due to cell-intrinsic changes in activation of the insulin-like growth factor receptor (IGF1R) signaling pathway and levels of PIK3R1/PIK3R3. The selective estrogen receptor degrader, fulvestrant, significantly reduced the anchorage-independent growth of ESR1 mutant-expressing cells, while combination treatments with the mTOR inhibitor everolimus, or an inhibitor blocking IGF1R, and the insulin receptor significantly enhanced anti-proliferative responses. Using digital drop (dd) PCR, we identified mutations at high frequencies ranging from 12 % for Y537N, 5 % for Y537S, and 2 % for D538G in archived primary breast tumors from women treated with adjuvant mono-tamoxifen therapy. The HBD-ESR1 mutations were not associated with recurrence-free or overall survival in response in this patient cohort and suggest that knowledge of other cell-intrinsic factors in combination with ESR1 mutation status will be needed determine anti-proliferative responses to Tam.
authors.affiliation: Department of Pharmacy, Health, and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Gelsomino
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Guowei
authors.initials: G
authors.lastname: Gu
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Yassine
authors.initials: Y
authors.lastname: Rechoum
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Amanda R
authors.initials: AR
authors.lastname: Beyer
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Sasha M
authors.initials: SM
authors.lastname: Pejerrey
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Tsimelzon
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Huffman
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ludlow
authors.affiliation: Department of Pharmacy, Health, and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Andò
authors.affiliation: Lester & Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA. sfuqua@bcm.edu.|Dan L Duncan Cancer Center, Houston, TX, USA. sfuqua@bcm.edu.
authors.forename: Suzanne A W
authors.initials: SAW
authors.lastname: Fuqua
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D008957:Models, Genetic; D009154:Mutation; D017526:Receptor, IGF Type 1; D011960:Receptors, Estrogen / Q000378:metabolism; D017451:Receptors, Somatomedin / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013629:Tamoxifen / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; C000597236:IGF1R protein, human; D011960:Receptors, Estrogen; D017451:Receptors, Somatomedin; D013629:Tamoxifen; D017526:Receptor, IGF Type 1
keywords: Estrogen Receptor; Everolimus; Fulvestrant; IGF-1; Mutations