The platelet derived growth factor receptor alpha (PDGFRA) belongs to a family of receptor tyrosine kinases (RTKs) that include PDGFRA and PDGFRB. The binding of ligands, such as platelet derived growth factor (PDGF), induces a conformational change that facilitates receptor homo- or heterodimer formation, thereby resulting in activation of PDGFRA tyrosine kinase activity. Activated PDGFRA then phosphorylates its substrates, resulting in activation of multiple downstream pathways within the cell, including the PI3K-AKT-mTOR pathway, which is involved in cell survival, and the RAS-RAF-MEK-ERK pathway, which is involved in cell proliferation (Figure 1).
Mutant PDGFRA has been implicated in the pathogenesis of a number of cancers. For example, mutations are found in gastrointestinal stromal tumors (GIST; Corless et al. 2005; Heinrich et al. 2003), and fusions are found in hypereosinophilic syndrome (Cools et al. 2003). In dermatofibrosarcoma protuberans, PDGFRA is activated by a PDGFB fusion protein; as a result, imatinib, as a PDGFRA inhibitor, has shown activity and is approved for clinical use (Labropoulos and Razis 2007; Simon et al. 1997).
Figure 1. Schematic of PDGFRA signaling pathways. The binding of the ligand, platelet-derived growth factor (PDGF), to the PDGFRA receptor tyrosine kinase results in activation of the MAPK signaling pathway (RAS-RAF-MEK-ERK) and the PI3K pathway (PI3K-AKT-mTOR). The letter "K" within the schema denotes the tyrosine kinase domain.