title: Genomics screen in transformed stem cells reveals RNASEH2A, PPAP2C, and ADARB1 as putative anticancer drug targets.
abstract: Since the sequencing of the human genome, recent efforts in cancer drug target discovery have focused more on the identification of novel functions of known genes and the development of more appropriate tumor models. In the present study, we investigated in vitro transformed human adult mesenchymal stem cells (MSC) to identify novel candidate cancer drug targets by analyzing the transcriptional profile of known enzymes compared with non-transformed MSC. The identified enzymes were compared with published cancer gene expression data sets. Surprisingly, the majority of up-regulated enzymes are already known cancer drug targets or act within known druggable pathways. Only three enzymes (RNASEH2A, ADARB1, and PPAP2C) are potentially novel targets that are up-regulated in transformed MSC and expressed in numerous carcinomas and sarcomas. We confirmed the overexpression of RNASEH2A, PPAP2C, and ADARB1 in transformed MSC, transformed fibroblasts, and cancer cell lines MCF7, SK-LMS1, MG63, and U2OS. In functional assays, we show that small interfering RNA knockdown of RNASEH2A inhibits anchorage-independent growth but does not alter in vitro proliferation of cancer cell lines, normal MSC, or normal fibroblasts. Knockdown of PPAP2C impaired anchorage-dependent in vitro growth of cancer cell lines and impaired the in vitro growth of primary MSC but not differentiated human fibroblasts. We show that the knockdown of PPAP2C decreases cell proliferation by delaying entry into S phase of the cell cycle and is transcriptionally regulated by p53. These in vitro data validate PPAP2C and RNASEH2A as putative cancer targets and endorse this in silico approach for identifying novel candidates.
authors.affiliation: Cancer Research UK Viral Oncology Group, University College London Cancer Institute, Paul O'Gorman Building, 74 Huntley Street, London, United Kingdom WC1E 6BT. j.flanagan@ucl.ac.uk
authors.forename: James M
authors.initials: JM
authors.lastname: Flanagan
authors.forename: Juan M
authors.initials: JM
authors.lastname: Funes
authors.forename: Stephen
authors.initials: S
authors.lastname: Henderson
authors.forename: Laurence
authors.initials: L
authors.lastname: Wild
authors.forename: Nessa
authors.initials: N
authors.lastname: Carey
authors.forename: Chris
authors.initials: C
authors.lastname: Boshoff
mesh_terms: D000243:Adenosine Deaminase / Q000235:genetics* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D015894:Genome, Human / Q000235:genetics; D023281:Genomics; D006801:Humans; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins; D016914:Ribonuclease H / Q000235:genetics* / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D016601:RNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; C091139:ribonuclease HII; D016914:Ribonuclease H; D010711:Phosphatidate Phosphatase; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase