Insulin-like growth factor-binding protein 3 (IGFBP-3)

Insulin-like growth factor-binding protein 3 is the most abundant member of a family that binds insulin-like growth factors I and II with high affinity in circulation. Produced mainly by the liver under control of growth hormone, it regulates availability, transport, stability, and activity duration for these potent mitogenic peptides. Beyond simply sequestering or delivering IGFs to their receptors (primarily IGF1R), it also exerts intrinsic biological effects—including modulation of apoptosis/cell cycle progression—through both extracellular interactions with other proteins/growth factors and nuclear functions such as DNA repair regulation. Its serum concentration reflects integrated GH action over time rather than acute fluctuations. Clinically relevant roles include use as a biomarker for disorders involving GH/IGF dysregulation (e.g., short stature syndromes) or prognosis in some cancers; however, direct therapeutic targeting remains complex due to widespread physiological roles across tissues.

Other names

IGFBP-3IBP3Insulin-like growth factor binding protein III

Drugs that modulate the GH/IGF axis—such as recombinant human growth hormone—increase circulating levels of both IGF‑1 and IGFBP‑3 by stimulating their hepatic synthesis. Experimental approaches in cancer may involve blocking or mimicking the binding activity to alter tumor cell proliferation/apoptosis via both IGF-dependent and independent mechanisms.