title: Analysis of differential gene expression in colorectal cancer and stroma using fluorescence-activated cell sorting purification.
abstract: Tumour stroma gene expression in biopsy specimens may obscure the expression of tumour parenchyma, hampering the predictive power of microarrays. We aimed to assess the utility of fluorescence-activated cell sorting (FACS) for generating cell populations for gene expression analysis and to compare the gene expression of FACS-purified tumour parenchyma to that of whole tumour biopsies. Single cell suspensions were generated from colorectal tumour biopsies and tumour parenchyma was separated using FACS. Fluorescence-activated cell sorting allowed reliable estimation and purification of cell populations, generating parenchymal purity above 90%. RNA from FACS-purified and corresponding whole tumour biopsies was hybridised to Affymetrix oligonucleotide microarrays. Whole tumour and parenchymal samples demonstrated differential gene expression, with 289 genes significantly overexpressed in the whole tumour, many of which were consistent with stromal gene expression (e.g., COL6A3, COL1A2, POSTN, TIMP2). Genes characteristic of colorectal carcinoma were overexpressed in the FACS-purified cells (e.g., HOX2D and RHOB). We found FACS to be a robust method for generating samples for gene expression analysis, allowing simultaneous assessment of parenchymal and stromal compartments. Gross stromal contamination may affect the interpretation of cancer gene expression microarray experiments, with implications for hypotheses generation and the stability of expression signatures used for predicting clinical outcomes.
authors.affiliation: Department of Academic Surgery, University College Cork, Cork, Ireland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Smith
authors.forename: A C
authors.initials: AC
authors.lastname: Culhane
authors.forename: M
authors.initials: M
authors.lastname: Donovan
authors.forename: J C
authors.initials: JC
authors.lastname: Coffey
authors.forename: B D
authors.initials: BD
authors.lastname: Barry
authors.forename: M A
authors.initials: MA
authors.lastname: Kelly
authors.forename: D G
authors.initials: DG
authors.lastname: Higgins
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
authors.forename: W O
authors.initials: WO
authors.lastname: Kirwan
authors.forename: T G
authors.initials: TG
authors.lastname: Cotter
authors.forename: H P
authors.initials: HP
authors.lastname: Redmond
mesh_terms: D001706:Biopsy; D015815:Cell Adhesion Molecules / Q000235:genetics; D002469:Cell Separation / Q000379:methods; D003094:Collagen / Q000235:genetics; D024042:Collagen Type I; D024142:Collagen Type VI / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D005434:Flow Cytometry; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D017154:Stromal Cells / Q000473:pathology*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics
chemical_list: D015815:Cell Adhesion Molecules; D024042:Collagen Type I; D024142:Collagen Type VI; C512835:POSTN protein, human; D012334:RNA, Neoplasm; D019716:Tissue Inhibitor of Metalloproteinase-2; D003094:Collagen