Platelet-Derived Growth Factor Receptor

Definition

• PDGFR is a receptor tyrosine kinase involved in cell growth, differentiation, and angiogenesis.
• It is mainly expressed on mesenchymal cells (fibroblasts, smooth muscle cells, pericytes).

Structure and Types

• Two main types:
  • PDGFR-α (alpha)
  • PDGFR-β (beta)
• These can form homodimers (αα or ββ) or heterodimers (αβ) upon ligand binding.
• Each receptor has:
  • An extracellular ligand-binding domain
  • A transmembrane domain
  • An intracellular tyrosine kinase domain

Activation by PDGF Ligands

• Activated by platelet-derived growth factor (PDGF) ligands (PDGF-AA, BB, AB, etc.)
• Ligand binding → receptor dimerization → autophosphorylation
• Triggers intracellular signaling (e.g., PI3K/AKT, RAS/MAPK pathways)
• Leads to:
  • Cell proliferation
  • Migration
  • Survival
  • Angiogenesis (especially via recruitment of pericytes and vascular remodeling)
• Relevance in Cancer Biology
  • Overexpression or mutation of PDGFR can drive:
  • Tumor angiogenesis
  • Stromal proliferation (tumor-supporting environment)
  • Autocrine loops that sustain tumor growth
• Seen in:
  • Gastrointestinal stromal tumors (GIST) (especially PDGFRA mutations)
  • Gliomas
  • Leukemias
  • Some sarcomas
• Targeted Therapies
  • Sunitinib, imatinib, regorafenib, and pazopanib can inhibit PDGFR activity.
• These drugs are used in tumors where PDGFR is mutated or overactive (e.g., GIST).
• Blocking PDGFR can reduce:
  • Tumor blood vessel support
  • Stromal-tumor interactions
  • Direct tumor proliferation (in PDGFR-driven cancers)