title: Global profiling of prolactin-modulated transcripts in breast cancer in vivo.
abstract: BACKGROUND
  Prolactin (PRL) is essential for normal mammary gland development. PRL promotes mammary tumor formation in rodents and elevated serum prolactin is associated with increased risk of estrogen-receptor positive breast cancer in women. On the other hand, PRL may also exert pro-differentiation effects and act to suppress invasive features of established breast cancer. Previously published limited global transcript profiling analyses of prolactin-regulated gene expression in human breast cancer cells have exclusively been performed in vitro. The present study aimed to shed new light on how PRL modulates estrogen receptor (ER)-positive breast cancer through global transcript profiling of a human breast cancer xenograft model in vivo.
  
  
  METHODS
  The prolactin-responsive human T47D breast cancer cell line was xenotransplanted into nude mice and global transcript profiling was carried out following treatment with or without human PRL for 48 h. A subset of PRL-modulated transcripts was further validated using qRT-PCR and immunohistochemistry.
  
  
  RESULTS
  The in vivo analyses identified 130 PRL-modulated transcripts, 75 upregulated and 55 downregulated, based on fold change >1.6 and P-value <0.05. From this initial panel of transcripts, a subset of 18 transcripts with established breast cancer-relevance were selected and validated by qRT-PCR. Some but not all of the transcripts were also PRL-modulated in vitro. The selected PRL-modulated transcripts were tested for dependence on Stat5, Jak1 or Jak2 activation, and for co-regulation by 17β-estradiol (E2). The protein encoded by one of the PRL-regulated transcripts, PTHrP, was examined in a panel of 92 human breast cancers and found by in situ quantitative immunofluorescence analysis to be highly positively correlated with nuclear localized and tyrosine phosphorylated Stat5. Gene Ontology analysis revealed that PRL-upregulated genes were enriched in pathways involved in differentiation. Finally, a gene signature based on PRL-upregulated genes was associated with prolonged relapse-free and metastasis-free survival in breast cancer patients.
  
  
  CONCLUSIONS
  This global analysis identified and validated a panel of PRL-modulated transcripts in an ER-positive human breast cancer xenotransplant model, which may have value as markers of relapse-free and metastasis-free survival. Gene products identified in the present study may facilitate ongoing deciphering of the pleiotropic effects of PRL on human breast cancer.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
authors.forename: Thai H
authors.initials: TH
authors.lastname: Tran
authors.forename: Amy R
authors.initials: AR
authors.lastname: Peck
authors.forename: Chengbao
authors.initials: C
authors.lastname: Liu
authors.forename: Adam
authors.initials: A
authors.lastname: Ertel
authors.forename: Justin
authors.initials: J
authors.lastname: Lin
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Neilson
authors.forename: Hallgeir
authors.initials: H
authors.lastname: Rui
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D063990:Gene Ontology; D006801:Humans; D053613:Janus Kinase 1 / Q000378:metabolism; D053614:Janus Kinase 2 / Q000378:metabolism; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D020411:Oligonucleotide Array Sequence Analysis; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011388:Prolactin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D014408:Biomarkers, Tumor; D044162:Parathyroid Hormone-Related Protein; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D019000:Phosphotyrosine; D004958:Estradiol; D011388:Prolactin; C507904:JAK1 protein, human; C507924:JAK2 protein, human; D053613:Janus Kinase 1; D053614:Janus Kinase 2