FGFR2 Abnormalities Underlie a Spectrum of Bone, Skin, and Cancer Pathologies

Fibroblast growth factor receptor (FGFR) 2 is regulated on the basis of the balance of FGFs, heparan-sulfate proteoglycans, FGFR2 isoforms, endogenous inhibitors, and microRNAs. FGFR2 signals cross-talk with hedgehog, bone morphogenetic protein, and other regulatory networks. Some cases of congenital skeletal disorders with an FGFR2 mutation show skin phenotypes, including acne, cutis gyrata, and acanthosis nigricans. Gain-of-function mutations or variations of human FGFR2 occur in estrogen receptor-positive breast cancer, diffuse-type gastric cancer, and endometrial uterine cancer. Oral administration of AZD2171 or Ki23057 inhibits in vivo proliferation of cancer cells with aberrant FGFR2 activation in rodent therapeutic models. However, loss-of-function mutations of FGFR2 are reported in human melanoma. Conditional Fgfr2b knockout in the rodent epidermis leads to increased macrophage infiltration to the dermis and adipose tissue, epidermal thickening accompanied by basal-layer dysplasia and parakeratosis, and the promotion of chemically induced squamous-cell carcinoma. Dysregulation of FGFR2 results in a spectrum of bone and skin pathologies and several types of cancer.