title: A genome-wide siRNA screen for regulators of tumor suppressor p53 activity in human non-small cell lung cancer cells identifies components of the RNA splicing machinery as targets for anticancer treatment.
abstract: Reinstating wild-type tumor suppressor p53 activity could be a valuable option for the treatment of cancer. To contribute to development of new treatment options for non-small cell lung cancer (NSCLC), we performed genome-wide siRNA screens for determinants of p53 activity in NSCLC cells. We identified many genes not previously known to be involved in regulating p53 activity. Silencing p53 pathway inhibitor genes was associated with loss of cell viability. The largest functional gene cluster influencing p53 activity was mRNA splicing. Prominent p53 activation was observed upon silencing of specific spliceosome components, rather than by general inhibition of the spliceosome. Ten genes were validated as inhibitors of p53 activity in multiple NSCLC cell lines: genes encoding the Ras pathway activator SOS1, the zinc finger protein TSHZ3, the mitochondrial membrane protein COX16, and the spliceosome components SNRPD3, SF3A3, SF3B1, SF3B6, XAB2, CWC22, and HNRNPL. Silencing these genes generally increased p53 levels, with distinct effects on CDKN1A expression, induction of cell cycle arrest and cell death. Silencing spliceosome components was associated with alternative splicing of MDM4 mRNA, which could contribute to activation of p53. In addition, silencing splice factors was particularly effective in killing NSCLC cells, albeit in a p53-independent manner. Interestingly, silencing SNRPD3 and SF3A3 exerted much stronger cytotoxicity to NSCLC cells than to lung fibroblasts, suggesting that these genes could represent useful therapeutic targets.
authors.affiliation: Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Siebring-van Olst
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Maxime
authors.initials: M
authors.lastname: Blijlevens
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Renee X
authors.initials: RX
authors.lastname: de Menezes
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Ida H
authors.initials: IH
authors.lastname: van der Meulen-Muileman
authors.affiliation: Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands.|Department of Thoracic Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Egbert F
authors.initials: EF
authors.lastname: Smit
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Victor W
authors.initials: VW
authors.lastname: van Beusechem
mesh_terms: D000072283:A549 Cells; D017398:Alternative Splicing / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics*; D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins; D002470:Cell Survival; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects; D020868:Gene Silencing; D055106:Genome-Wide Association Study; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000502:physiology*; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53
keywords: 
  NSCLC
  ; RNA splice factor; RNAi screen; p53 pathway inhibitor; spliceosome