title: Differential gene expression profiling of functionally and developmentally distinct human prostate epithelial populations.
abstract: BACKGROUND
  Human fetal prostate buds appear in the 10th gestational week as solid cords, which branch and form lumens in response to androgen 1. Previous in vivo analysis of prostate epithelia isolated from benign prostatectomy specimens indicated that Epcam⁺ CD44⁻ CD49f(Hi) basal cells possess efficient tubule initiation capability relative to other subpopulations 2. Stromal interactions and branching morphogenesis displayed by adult tubule-initiating cells (TIC) are reminiscent of fetal prostate development. In the current study, we evaluated in vivo tubule initiation by human fetal prostate cells and determined expression profiles of fetal and adult epithelial subpopulations in an effort to identify pathways used by TIC.
  
  
  METHODS
  Immunostaining and FACS analysis based on Epcam, CD44, and CD49f expression demonstrated the majority (99.9%) of fetal prostate epithelial cells (FC) were Epcam⁺ CD44⁻ with variable levels of CD49f expression. Fetal populations isolated via cell sorting were implanted into immunocompromised mice. Total RNA isolation from Epcam⁺ CD44⁻ CD49f(Hi) FC, adult Epcam⁺ CD44⁻ CD49f(Hi) TIC, Epcam⁺ CD44⁺ CD49f(Hi) basal cells (BC), and Epcam⁺ CD44⁻ CD49f(Lo) luminal cells (LC) was performed, followed by microarray analysis of 19 samples using the Affymetrix Gene Chip Human U133 Plus 2.0 Array. Data was analyzed using Partek Genomics Suite Version 6.4. Genes selected showed >2-fold difference in expression and P < 5.00E-2. Results were validated with RT-PCR.
  
  
  RESULTS
  Grafts retrieved from Epcam⁺ CD44⁻ fetal cell implants displayed tubule formation with differentiation into basal and luminal compartments, while only stromal outgrowths were recovered from Epcam- fetal cell implants. Hierarchical clustering revealed four distinct groups determined by antigenic profile (TIC, BC, LC) and developmental stage (FC). TIC and BC displayed basal gene expression profiles, while LC expressed secretory genes. FC had a unique profile with the most similarities to adult TIC. Functional, network, and canonical pathway identification using Ingenuity Pathway Analysis Version 7.6 compiled genes with the highest differential expression (TIC relative to BC or LC). Many of these genes were found to be significantly associated with prostate tumorigenesis.
  
  
  CONCLUSIONS
  Our results demonstrate clustering gene expression profiles of FC and adult TIC. Pathways associated with TIC are known to be deregulated in cancer, suggesting a cell-of-origin role for TIC versus re-emergence of pathways common to these cells in tumorigenesis.
authors: Department of Urology, David Geffen School of Medicine at UCLA, Los Angeles, California; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California.
authors: Haibo
authors: H
authors: Liu
authors: Radu M
authors: RM
authors: Cadaneanu
authors: Kevin
authors: K
authors: Lai
authors: Baohui
authors: B
authors: Zhang
authors: Lihong
authors: L
authors: Huo
authors: Dong Sun
authors: DS
authors: An
authors: Xinmin
authors: X
authors: Li
authors: Michael S
authors: MS
authors: Lewis
authors: Isla P
authors: IP
authors: Garraway
mesh_terms: D000328:Adult; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D000071858:Epithelial Cell Adhesion Molecule; D004847:Epithelial Cells / Q000502:physiology*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism; D039503:Integrin alpha6 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009024:Morphogenesis / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D011467:Prostate / Q000196:embryology / Q000502:physiology*; D012334:RNA, Neoplasm / Q000737:chemistry / Q000235:genetics
chemical_list: D000951:Antigens, Neoplasm; C497483:CD44 protein, human; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D018960:Hyaluronan Receptors; D039503:Integrin alpha6; D012334:RNA, Neoplasm
keywords: basal cell; fetal prostate; human prostate epithelial microarray; prostate stem cell; prostate tissue regeneration; prostate tubule initiation