A chemical-genetic screen reveals a mechanism of resistance to PI3K inhibitors in cancer

Nat Chem Biol. 2011 Sep 25;7(11):787-93. doi: 10.1038/nchembio.695.


Linking the molecular aberrations of cancer to drug responses could guide treatment choice and identify new therapeutic applications. However, there has been no systematic approach for analyzing gene-drug interactions in human cells. Here we establish a multiplexed assay to study the cellular fitness of a panel of engineered isogenic cancer cells in response to a collection of drugs, enabling the systematic analysis of thousands of gene-drug interactions. Applying this approach to breast cancer revealed various synthetic-lethal interactions and drug-resistance mechanisms, some of which were known, thereby validating the method. NOTCH pathway activation, which occurs frequently in breast cancer, unexpectedly conferred resistance to phosphoinositide 3-kinase (PI3K) inhibitors, which are currently undergoing clinical trials in breast cancer patients. NOTCH1 and downstream induction of c-MYC over-rode the dependency of cells on the PI3K-mTOR pathway for proliferation. These data reveal a new mechanism of resistance to PI3K inhibitors with direct clinical implications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / genetics*
  • Cell Line, Tumor
  • Cell Proliferation
  • Drug Resistance, Neoplasm / genetics*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Mutation
  • Phosphoinositide-3 Kinase Inhibitors*
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism


  • Antineoplastic Agents
  • MYC protein, human
  • Phosphoinositide-3 Kinase Inhibitors
  • Proto-Oncogene Proteins c-myc
  • MTOR protein, human
  • TOR Serine-Threonine Kinases