title: Differences in stemness properties associated with the heterogeneity of luminal-type breast cancer.
abstract: BACKGROUND
  Luminal-type breast cancers are the most abundant subtype. Endocrine therapies targeting estrogen receptor (ER) or estradiol (E2) synthesis have achieved marked improvement in disease-free and overall survival of ER-positive cancers. However, approximately one-third of these cancers are poorly responsive to endocrine therapies, suggesting nonuniform tumor cell characteristics of this subtype. Recently, the tumorigenesis theory which states that CSCs are capable of self-renewal, tumorigenicity, and therapeutic resistance, became widely accepted. We investigated the relationship between the heterogeneity of luminal-type breast cancer and stemness properties.
  
  
  METHODS
  CSC surface markers and expression of stemness-related genes, including Octamer-binding transcription factor 4 (OCT4), Nanog homeobox (NANOG), and Kruppel-like factor 4 (KLF4), were analyzed in clinical samples. ER activities were analyzed using the adenovirus vector carrying the ERE-green fluorescent protein (GFP). We separated the luminal-type breast cancers into 2 groups according to stemness-related gene expression patterns in mammospheres.
  
  
  RESULTS
  The group that predominantly expressed NANOG mRNA showed a high percentage of the cells that were positive for CD44 and negative for CD24 and Hoechst (possessing high-stemness properties), younger patient age, higher p53 expression, and tended to show higher histological grade and higher topoisomerase IIα expression. The ERE-GFP assay revealed that the luminal-type breast cancer mammospheres were heterogeneous. Mammospheres from several specimens lacked ER activity and responsiveness to E2 but some retained ER activities.
  
  
  CONCLUSIONS
  ERE activity differences might be associated with endocrine therapy effectiveness. Mammosphere stemness properties could be a useful and novel criterion for subclassification of luminal-type breast cancers.
authors.affiliation: Department of Blood and Cell Treatment, Tohoku University Hospital, Sendai, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Ito
authors.affiliation: Department of Molecular and Functional Dynamics, Graduate School of Medicine, Tohoku University, Sendai, Japan.
authors.forename: Nozomi
authors.initials: N
authors.lastname: Sato
authors.affiliation: Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Molecular and Functional Dynamics, Graduate School of Medicine, Tohoku University, Sendai, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Tazawa
authors.affiliation: Department of Pathology, Kawasaki Medical School, Kurashiki, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Moriya
authors.affiliation: Department of Surgery, Tohoku Kosai Hospital, Sendai, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hirakawa
authors.affiliation: Department of Molecular and Functional Dynamics, Graduate School of Medicine, Tohoku University, Sendai, Japan; Center for Regulatory Epigenome and Diseases, Graduate School of Medicine, Tohoku University, Sendai, Japan. Electronic address: shin@med.tohoku.ac.jp.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Hayashi
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000473:pathology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D000090062:Kruppel-Like Factor 4; D014411:Neoplastic Stem Cells / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4
keywords: Cancer stem cells; Estrogen response element activity; Mammosphere; Primary breast cancer; Stemness-related genes