Radiation Oncology/Radiobiology/Growth Factors



Growth Factors


ErbBEdit

  • Family of 4 receptor tyrosine kinases
    • ErbB-1 (EGFR)
    • ErbB-2 (her2)
    • ErbB-3
    • ErbB-4
  • Transmembrane proteins, existing as monomers at surface
  • When a ligand binds, dimerisation arm becomes untethered, and the proteins dimerize
  • Tyrosine kinase activity


EGFREdit


Review: PMID 15142631, Herbst R, IJROBP 2004

EGFR PathwaysEdit

  • EGFR -> Ras -> Raf -> MEK -> MAPK -> myc -> transcription
  • EGFR -> Ras -> Raf -> MEK -> MAPK -> RSK -> S6 -> transcription
  • EGFR -> PI3K -> AKT -> mTOR


PTENEdit

  • PTEN gene encodes a phosphatase, which uses PIP-3, which is also produced by PI3K above. Loss of PTEN therefore increases PIP-3 levels, leading to inappropriate AKT activity, and subsequent protection of cancer cells from apoptosis
  • PTEN is a tumor suppressor
  • PTEN loss confers resistance to EGFR inhibitors
  • Please see PTEN Hamartoma Tumor Syndrome