title: Single-cell analysis reveals a stem-cell program in human metastatic breast cancer cells.
abstract: Despite major advances in understanding the molecular and genetic basis of cancer, metastasis remains the cause of >90% of cancer-related mortality. Understanding metastasis initiation and progression is critical to developing new therapeutic strategies to treat and prevent metastatic disease. Prevailing theories hypothesize that metastases are seeded by rare tumour cells with unique properties, which may function like stem cells in their ability to initiate and propagate metastatic tumours. However, the identity of metastasis-initiating cells in human breast cancer remains elusive, and whether metastases are hierarchically organized is unknown. Here we show at the single-cell level that early stage metastatic cells possess a distinct stem-like gene expression signature. To identify and isolate metastatic cells from patient-derived xenograft models of human breast cancer, we developed a highly sensitive fluorescence-activated cell sorting (FACS)-based assay, which allowed us to enumerate metastatic cells in mouse peripheral tissues. We compared gene signatures in metastatic cells from tissues with low versus high metastatic burden. Metastatic cells from low-burden tissues were distinct owing to their increased expression of stem cell, epithelial-to-mesenchymal transition, pro-survival, and dormancy-associated genes. By contrast, metastatic cells from high-burden tissues were similar to primary tumour cells, which were more heterogeneous and expressed higher levels of luminal differentiation genes. Transplantation of stem-like metastatic cells from low-burden tissues showed that they have considerable tumour-initiating capacity, and can differentiate to produce luminal-like cancer cells. Progression to high metastatic burden was associated with increased proliferation and MYC expression, which could be attenuated by treatment with cyclin-dependent kinase (CDK) inhibitors. These findings support a hierarchical model for metastasis, in which metastases are initiated by stem-like cells that proliferate and differentiate to produce advanced metastatic disease.
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.
authors.forename: Devon A
authors.initials: DA
authors.lastname: Lawson
authors.affiliation: Department of Medicine, University of California, San Francisco, California 94143, USA.
authors.forename: Nirav R
authors.initials: NR
authors.lastname: Bhakta
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.|Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Kessenbrock
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.
authors.forename: Karin D
authors.initials: KD
authors.lastname: Prummel
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Takai
authors.affiliation: Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: Zhou
authors.affiliation: Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA.
authors.forename: Henok
authors.initials: H
authors.lastname: Eyob
authors.affiliation: Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Balakrishnan
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.|Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Chih-Yang
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Yaswen
authors.affiliation: Department of Medicine, University of California, San Francisco, California 94143, USA.|Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Goga
authors.affiliation: Department of Anatomy, University of California, San Francisco, California 94143, USA.
authors.forename: Zena
authors.initials: Z
authors.lastname: Werb
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000473:pathology; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004195:Disease Models, Animal; D018450:Disease Progression; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D016259:Genes, myc / Q000235:genetics; D006801:Humans; D008648:Mesoderm / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009362:Neoplasm Metastasis / Q000188:drug therapy / Q000473:pathology*; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D059010:Single-Cell Analysis; D023041:Xenograft Model Antitumor Assays
chemical_list: D018844:Cyclin-Dependent Kinases