The role of fibroblast growth factor 8 in cartilage development and disease.

Fibroblast growth factor 8 (FGF-8), also known as androgen-induced growth factor (AIGF), is presumed to be a potent mitogenic cytokine that plays important roles in early embryonic development, brain formation and limb development. In the bone environment, FGF-8 produced or received by chondrocyte precursor cells binds to fibroblast growth factor receptor (FGFR), causing different levels of activation of downstream signalling pathways, such as phospholipase C gamma (PLCγ)/Ca 2+ , RAS/mitogen-activated protein kinase-extracellular regulated protein kinases (RAS/MAPK-MEK-ERK), and Wnt-β-catenin-Axin2 signalling, and ultimately controlling chondrocyte proliferation, differentiation, cell survival and migration. However, the molecular mechanism of FGF-8 in normal or pathological cartilage remains unclear, and thus, FGF-8 represents a novel exploratory target for studies of chondrocyte development and cartilage disease progression. In this review, studies assessing the relationship between FGF-8 and chondrocytes that have been published in the past 5 years are systematically summarized to determine the probable mechanism and physiological effect of FGF-8 on chondrocytes. Based on the existing research results, a therapeutic regimen targeting FGF-8 is proposed to explore the possibility of treating chondrocyte-related diseases.