title: Selection of brain metastasis-initiating breast cancer cells determined by growth on hard agar.
abstract: An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44(+) and CD133(+) and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice.
authors.affiliation: Department of Cancer Biology-Cancer Metastasis Research Center, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Lixia
authors.initials: L
authors.lastname: Guo
authors.forename: Dominic
authors.initials: D
authors.lastname: Fan
authors.forename: Fahao
authors.initials: F
authors.lastname: Zhang
authors.forename: Janet E
authors.initials: JE
authors.lastname: Price
authors.forename: Ju-Seog
authors.initials: JS
authors.lastname: Lee
authors.forename: Dario
authors.initials: D
authors.lastname: Marchetti
authors.forename: Isaiah J
authors.initials: IJ
authors.lastname: Fidler
authors.forename: Robert R
authors.initials: RR
authors.lastname: Langley
mesh_terms: D000362:Agar; D000818:Animals; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000556:secondary; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis / Q000235:genetics / Q000473:pathology*; D014411:Neoplastic Stem Cells; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000473:pathology*
chemical_list: D000362:Agar