Loss-of-function RNAi screens in breast cancer cells identify AURKB, PLK1, PIK3R1, MAPK12, PRKD2, and PTK6 as sensitizing targets of rapamycin activity

Cancer Lett. 2014 Nov 28;354(2):336-47. doi: 10.1016/j.canlet.2014.08.043. Epub 2014 Sep 1.

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.

Keywords: Breast cancer; HDAC inhibition; RNAi screen; Rapamycin.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Aurora Kinase B / antagonists & inhibitors
  • Benzamides / administration & dosage
  • Benzamides / pharmacology
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / enzymology
  • Breast Neoplasms / genetics*
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Line, Tumor
  • Class Ia Phosphatidylinositol 3-Kinase
  • Drug Screening Assays, Antitumor / methods*
  • Drug Synergism
  • Female
  • Humans
  • MCF-7 Cells
  • Mice
  • Mice, SCID
  • Mitogen-Activated Protein Kinase 12 / antagonists & inhibitors
  • Neoplasm Proteins / antagonists & inhibitors
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Kinase Inhibitors / administration & dosage
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Proto-Oncogene Proteins / antagonists & inhibitors
  • Pyridines / administration & dosage
  • Pyridines / pharmacology
  • RNA Interference
  • Random Allocation
  • Sirolimus / administration & dosage
  • Sirolimus / pharmacology*
  • Xenograft Model Antitumor Assays

Substances

  • Benzamides
  • Cell Cycle Proteins
  • Neoplasm Proteins
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • Pyridines
  • entinostat
  • Protein Kinases
  • Mitogen-Activated Protein Kinase 12
  • PIK3R1 protein, human
  • protein kinase D2
  • Class Ia Phosphatidylinositol 3-Kinase
  • Protein-Tyrosine Kinases
  • PTK6 protein, human
  • AURKB protein, human
  • Aurora Kinase B
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • Sirolimus