title: Comparison of growth factor signalling pathway utilisation in cultured normal melanocytes and melanoma cell lines.
abstract: BACKGROUND
  The phosphatidylinositol-3-kinase (PI3K-PKB), mitogen activated protein kinase (MEK-ERK) and the mammalian target of rapamycin (mTOR- p70S6K), are thought to regulate many aspects of tumour cell proliferation and survival. We have examined the utilisation of these three signalling pathways in a number of cell lines derived from patients with metastatic malignant melanoma of known PIK3CA, PTEN, NRAS and BRAF mutational status.
  
  
  METHODS
  Western blotting was used to compare the phosphorylation status of components of the PI3K-PKB, MEK-ERK and mTOR-p70S6K signalling pathways, as indices of pathway utilisation.
  
  
  RESULTS
  Normal melanocytes could not be distinguished from melanoma cells on the basis of pathway utilisation when grown in the presence of serum, but could be distinguished upon serum starvation, where signalling protein phosphorylation was generally abrogated. Surprisingly, the differential utilisation of individual pathways was not consistently associated with the presence of an oncogenic or tumour suppressor mutation of genes in these pathways.
  
  
  CONCLUSIONS
  Utilisation of the PI3K-PKB, MEK-ERK and mTOR-p70S6K signalling pathways in melanoma, as determined by phosphorylation of signalling components, varies widely across a series of cell lines, and does not directly reflect mutation of genes coding these components. The main difference between cultured normal melanocytes and melanoma cells is not the pathway utilisation itself, but rather in the serum dependence of pathway utilisation.
authors.affiliation: Auckland Cancer Society Research Centre, The University of Auckland, Auckland, New Zealand. jieun.kim@auckland.ac.nz
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Clare
authors.initials: C
authors.lastname: Stones
authors.forename: Wayne R
authors.initials: WR
authors.lastname: Joseph
authors.forename: Euphemia
authors.initials: E
authors.lastname: Leung
authors.forename: Graeme J
authors.initials: GJ
authors.lastname: Finlay
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Shelling
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Phillips
authors.forename: Peter R
authors.initials: PR
authors.lastname: Shepherd
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Baguley
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D058534:Class I Phosphatidylinositol 3-Kinases; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D008544:Melanocytes / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D010766:Phosphorylation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D051059:PTEN Phosphohydrolase; D058539:Phosphatidylinositol 3-Kinase; D019869:Phosphatidylinositol 3-Kinases; D048493:Proto-Oncogene Proteins B-raf; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C484760:PIK3CA protein, human; C482119:BRAF protein, human; C494929:PTEN protein, human