Transforming Growth Factor β: Tumor Suppressor or Promoter? Are Host Immune Cells the Answer?

Therapies targeting transforming growth factor beta (TGF beta) signaling using neutralizing antibodies and small molecular inhibitors are in multiple clinical trails. However, TGF beta is known to work as both a tumor suppressor and a tumor promoter, and current knowledge does not provide sufficient information on what factors mediate this switch in function and when this switch occurs. Recent advances in multiple disciplines suggest that immune cells from the tumor host may provide the answer. [Cancer Res 2008;68(22):9107-11]