title: Erk activation as a possible mechanism of transformation of subependymal nodule into subependymal giant cell astrocytoma.
abstract: BACKGROUND
  Subependymal nodule (SEN) and subependymal giant cell astrocytoma (SEGA) are brain lesions frequently found in tuberous sclerosis (TS). As about 10-15% of SENs enlarge and transform into SEGAs, we examined here the possible mechanism of the phenomenon.
  
  
  METHODS
  Using Western blot we studied 1 SEN and 3 SEGA samples; SEN and 1 SEGA came from the same TS patient. We evaluated e.g. the activation of the phosphorylated forms of proteins belonging to Akt, Erk and mTOR pathways.
  
  
  RESULTS
  Differences in Erk pathway activation between SEN and SEGA were found. There was no upregulation of p-Erk, p-Mek or p-RSK1 in the SEN specimen, whilst we found these proteins to be significantly uptriggered in SEGA samples. Also, for the first time, we found p-Akt, p-GSK3 and p-PDK1 upregulated in both SEN and SEGA from the same TS patient.
  
  
  CONCLUSIONS
  Our current study shows for the first time the possible mechanism of SEN/SEGA transformation, where Erk pathway hyperactivation seems to be significant. We hypothesize that SEN/SEGA transformation may depend on Erk potentiation.
authors.forename: M
authors.initials: M
authors.lastname: Siedlecka
authors.forename: S
authors.initials: S
authors.lastname: Szlufik
authors.forename: W
authors.initials: W
authors.lastname: Grajkowska
authors.forename: M
authors.initials: M
authors.lastname: Roszkowski
authors.affiliation: Jarosław Jóźwiak, Department of Histology and Embryology, Center for Biostructure Research, Medical University of Warsaw, ul. Chalubinskiego 5, 02-004 Warsaw, Poland, fax: +48 22 629 52 82, e-mail: jaroslaw.jozwiak@gmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Jóźwiak
mesh_terms: D001254:Astrocytoma / Q000201:enzymology* / Q000473:pathology*; D001932:Brain Neoplasms / Q000201:enzymology* / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology*; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D014402:Tuberous Sclerosis / Q000201:enzymology / Q000473:pathology