title: HER2 expression identifies dynamic functional states within circulating breast cancer cells.
abstract: Circulating tumour cells in women with advanced oestrogen-receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer acquire a HER2-positive subpopulation after multiple courses of therapy. In contrast to HER2-amplified primary breast cancer, which is highly sensitive to HER2-targeted therapy, the clinical significance of acquired HER2 heterogeneity during the evolution of metastatic breast cancer is unknown. Here we analyse circulating tumour cells from 19 women with ER+/HER2-primary tumours, 84% of whom had acquired circulating tumour cells expressing HER2. Cultured circulating tumour cells maintain discrete HER2+and HER2-subpopulations: HER2+circulating tumour cells are more proliferative but not addicted to HER2, consistent with activation of multiple signalling pathways; HER2-circulating tumour cells show activation of Notch and DNA damage pathways, exhibiting resistance to cytotoxic chemotherapy, but sensitivity to Notch inhibition. HER2+and HER2-circulating tumour cells interconvert spontaneously, with cells of one phenotype producing daughters of the opposite within four cell doublings. Although HER2+and HER2-circulating tumour cells have comparable tumour initiating potential, differential proliferation favours the HER2+state, while oxidative stress or cytotoxic chemotherapy enhances transition to the HER2-phenotype. Simultaneous treatment with paclitaxel and Notch inhibitors achieves sustained suppression of tumorigenesis in orthotopic circulating tumour cell-derived tumour models. Together, these results point to distinct yet interconverting phenotypes within patient-derived circulating tumour cells, contributing to progression of breast cancer and acquisition of drug resistance.
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Nicole Vincent
authors.initials: NV
authors.lastname: Jordan
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Bardia
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Ben S
authors.initials: BS
authors.lastname: Wittner
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Cyril
authors.initials: C
authors.lastname: Benes
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Surgery, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Matteo
authors.initials: M
authors.lastname: Ligorio
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Yu
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Tilak K
authors.initials: TK
authors.lastname: Sundaresan
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Licausi
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Rushil
authors.initials: R
authors.lastname: Desai
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: O'Keefe
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Richard Y
authors.initials: RY
authors.lastname: Ebright
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Myriam
authors.initials: M
authors.lastname: Boukhali
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Srinjoy
authors.initials: S
authors.lastname: Sil
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Pathology, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Maristela L
authors.initials: ML
authors.lastname: Onozato
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Pathology, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Iafrate
authors.affiliation: Center for Bioengineering in Medicine and Shriners Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Kapur
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Pathology, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Sgroi
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Ting
authors.affiliation: Department of Surgery, Harvard Medical School, Boston, Massachusetts 02114, USA.|Center for Bioengineering in Medicine and Shriners Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Toner
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Ramaswamy
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Haas
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Surgery, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Shyamala
authors.initials: S
authors.lastname: Maheswaran
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.|Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Haber
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D009360:Neoplastic Cells, Circulating / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D010641:Phenotype; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000172:deficiency / Q000378:metabolism*; D051881:Receptor, Notch1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D051881:Receptor, Notch1; C497761:NOTCH1 protein, human; C508053:ERBB2 protein, human