Insulin-like Growth Factors (IGFs) are peptide hormones structurally similar to insulin, playing a key role in growth, development, and cellular regulation. There are two main types:
IGF-1 (Insulin-like Growth Factor 1)
Primarily produced in the liver in response to growth hormone (GH) stimulation.
Acts as the main mediator of the anabolic and growth-promoting effects of GH.
Essential for childhood growth and contributes to tissue repair, muscle maintenance, and metabolic regulation in adulthood.
Levels decline with age and are influenced by nutrition, exercise, and health status.
IGF-2 (Insulin-like Growth Factor 2)
More active during fetal development.
Functions largely independent of GH.
Its role in adults remains less clearly understood.
Biological Properties
Mitogenic: Stimulates cell proliferation.
Anti-apoptotic: Promotes cell survival.
Binds to IGF receptors, especially IGF-1R, activating pathways such as PI3K-AKT and MAPK.
Circulates bound to IGF-binding proteins (IGFBPs), especially IGFBP-3, which regulate its bioavailability.
Clinical Relevance
↑ IGF-1: Associated with acromegaly, neoplasms, and insulin resistance.
↓ IGF-1: Linked to growth disorders, frailty, osteoporosis, and aging.