MED12 controls the response to multiple cancer drugs through regulation of TGF-β receptor signaling

Cell. 2012 Nov 21;151(5):937-50. doi: 10.1016/j.cell.2012.10.035.


Inhibitors of the ALK and EGF receptor tyrosine kinases provoke dramatic but short-lived responses in lung cancers harboring EML4-ALK translocations or activating mutations of EGFR, respectively. We used a large-scale RNAi screen to identify MED12, a component of the transcriptional MEDIATOR complex that is mutated in cancers, as a determinant of response to ALK and EGFR inhibitors. MED12 is in part cytoplasmic where it negatively regulates TGF-βR2 through physical interaction. MED12 suppression therefore results in activation of TGF-βR signaling, which is both necessary and sufficient for drug resistance. TGF-β signaling causes MEK/ERK activation, and consequently MED12 suppression also confers resistance to MEK and BRAF inhibitors in other cancers. MED12 loss induces an EMT-like phenotype, which is associated with chemotherapy resistance in colon cancer patients and to gefitinib in lung cancer. Inhibition of TGF-βR signaling restores drug responsiveness in MED12(KD) cells, suggesting a strategy to treat drug-resistant tumors that have lost MED12.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / therapeutic use*
  • Carcinoma, Non-Small-Cell Lung / drug therapy
  • Drug Resistance, Neoplasm*
  • Epithelial-Mesenchymal Transition
  • Humans
  • Lung Neoplasms / drug therapy
  • MAP Kinase Signaling System
  • Mediator Complex / genetics
  • Mediator Complex / metabolism*
  • Neoplasms / drug therapy*
  • Receptors, Transforming Growth Factor beta / metabolism*
  • Signal Transduction*


  • Antineoplastic Agents
  • MED12 protein, human
  • Mediator Complex
  • Receptors, Transforming Growth Factor beta