title: Loss-of-function RNAi screens in breast cancer cells identify AURKB, PLK1, PIK3R1, MAPK12, PRKD2, and PTK6 as sensitizing targets of rapamycin activity.
abstract: The use of molecularly targeted drugs as single agents has shown limited utility in many tumor types, largely due to the complex and redundant nature of oncogenic signaling networks. Targeting of the PI3K/AKT/mTOR pathway through inhibition of mTOR in combination with aromatase inhibitors has seen success in particular sub-types of breast cancer and there is a need to identify additional synergistic combinations to maximize the clinical potential of mTOR inhibitors. We have used loss-of-function RNAi screens of the mTOR inhibitor rapamycin to identify sensitizers of mTOR inhibition. RNAi screens conducted in combination with rapamycin in multiple breast cancer cell lines identified six genes, AURKB, PLK1, PIK3R1, MAPK12, PRKD2, and PTK6 that when silenced, each enhanced the sensitivity of multiple breast cancer lines to rapamycin. Using selective pharmacological agents we confirmed that inhibition of AURKB or PLK1 synergizes with rapamycin. Compound-associated gene expression data suggested histone deacetylation (HDAC) inhibition as a strategy for reducing the expression of several of the rapamycin-sensitizing genes, and we tested and validated this using the HDAC inhibitor entinostat in vitro and in vivo. Our findings indicate new approaches for enhancing the efficacy of rapamycin including the use of combining its application with HDAC inhibition.
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Ou
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Konrad
authors.initials: K
authors.lastname: Huppi
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Sirisha
authors.initials: S
authors.lastname: Chakka
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Kristen
authors.initials: K
authors.lastname: Gehlhaus
authors.affiliation: Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Dubois
authors.affiliation: Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Patel
authors.affiliation: Office of Science and Technology Partnerships, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Jinqiu
authors.initials: J
authors.lastname: Chen
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Mackiewicz
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Jones
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Pitt
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Martin
authors.affiliation: Office of Science and Technology Partnerships, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Goldsmith
authors.affiliation: Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: John K
authors.initials: JK
authors.lastname: Simmons
authors.affiliation: Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Beverly A
authors.initials: BA
authors.lastname: Mock
authors.affiliation: Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: ncaplen@mail.nih.gov.
authors.forename: Natasha J
authors.initials: NJ
authors.lastname: Caplen
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D064107:Aurora Kinase B / Q000037:antagonists & inhibitors; D001549:Benzamides / Q000008:administration & dosage / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors; D045744:Cell Line, Tumor; D058543:Class Ia Phosphatidylinositol 3-Kinase; D004354:Drug Screening Assays, Antitumor / Q000379:methods*; D004357:Drug Synergism; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D016513:Mice, SCID; D048291:Mitogen-Activated Protein Kinase 12 / Q000037:antagonists & inhibitors; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000091283:Protein Kinase D2; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology; D034622:RNA Interference; D011897:Random Allocation; D020123:Sirolimus / Q000008:administration & dosage / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D000097869:Polo-Like Kinase 1
chemical_list: D064107:Aurora Kinase B; D001549:Benzamides; D018797:Cell Cycle Proteins; D058543:Class Ia Phosphatidylinositol 3-Kinase; D048291:Mitogen-Activated Protein Kinase 12; D009363:Neoplasm Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000091283:Protein Kinase D2; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D011725:Pyridines; D020123:Sirolimus; D000097869:Polo-Like Kinase 1; C118739:entinostat; C588001:PIK3R1 protein, human; C088375:PTK6 protein, human; C576921:AURKB protein, human
keywords: Breast cancer; HDAC inhibition; RNAi screen; Rapamycin