Insulin-like growth factor 1 receptor and insulin receptor hybrid receptors (IGF-1R/IR hybrids)

The Insulin-like growth factor 1 receptor (IGF-1R) and its hybrid forms with the Insulin Receptor (IR) are essential mediators of the somatotropic axis, regulating cell growth, development, and metabolic homeostasis (UniProt P08069). IGF-1R is a tetrameric receptor tyrosine kinase that activates the PI3K/Akt and MAPK signaling pathways upon binding IGF-1 or IGF-2 (Belfiore et al., 2009, PMID: 19395345). Hybrid receptors (IGF-1R/IR) form when hemireceptors of IGF-1R and IR dimerize, creating a receptor that typically exhibits high affinity for IGFs but low affinity for insulin, thereby expanding the signaling repertoire of the IGF system (Slaaby et al., 2006, PMID: 16434445). These receptors are frequently overexpressed in various cancers, including breast, prostate, and lung carcinomas, where they drive tumor cell proliferation and survival while contributing to therapeutic resistance (Belfiore et al., 2009, PMID: 19395345). Pharmacological targeting includes monoclonal antibodies like teprotumumab, which is approved for thyroid eye disease, and small molecule inhibitors like linsitinib, though clinical utility in oncology has been limited by metabolic side effects such as hyperglycemia due to cross-reactivity with the insulin receptor (Smith et al., 2017, PMID: 28467880; Pollak, 2012, PMID: 22351405).

Other names

IGF-1RIGF1RInsulin receptor/IGF-1 receptor hybridsIR/IGF-1R hybridsHybrid IGF-1RCD221

Monoclonal antibodies target the extracellular domain to inhibit ligand binding and promote receptor degradation, while small molecule inhibitors target the intracellular tyrosine kinase domain to block ATP binding and subsequent phosphorylation events.