Figure 1. Targeting coactivators for therapy.
Left panel: Coactivator (e.g., SRC-3/AIB1) regulates the coordinate expression of multiple downstream genes (ER-responsive; E2F1-responsive; Her-2 responsive; NF-κB responsive; and protein kinase [P13K/AKT] responsive). These TF-responsive genes are all required for proliferation and metastasis of cancer cells. Targeting the individual pathways by using SERMS/aromatase inhibitors (for ER) or Herceptin (for Her-2/neu) only inhibits one or two pathways (for combinations). Cancer growth is then slowed, but the other pathways are upregulated to compensate, thereby producing eventual resistance to the therapy.
Right panel: If the coactivator is targeted and its function inhibited, simultaneous suppression of all pathways occurs. This scenario blocks alternate pathway compensatory upregulation, decreasing the onset of eventual drug resistance.