title: Expansive growth of two glioblastoma stem-like cell lines is mediated by bFGF and not by EGF.
abstract: BACKGROUND
  Patient-derived glioblastoma (GBM) stem-like cells (GSCs) represent a valuable model for basic and therapeutic research. GSCs are usually propagated in serum-free Neural Basal medium supplemented with bFGF and EGF. Yet, the exact influence of these growth factors on GSCs is still unclear. Recently it was suggested that GBM stem-like cells with amplified EGFR should be cultured in stem cell medium without EGF, as the presence of EGF induced rapid loss of EGFR amplification. However, patient biopsies are usually taken into culture before their genomic profiles are defined. Thus, an important question remains whether GBM cells without EGFR amplification also can be cultured in stem cell medium without EGF.
  
  
  METHODS
  [corrected] To address this question, we used two heterogeneous glioblastoma GSC lines (NCH421k and NCH644) that lack EGFR amplification.
  
  
  RESULTS
  Although both cell lines showed very low EGFR expression under standard growth conditions, bFGF stimulation induced higher expression of EGFR in NCH644. In both cell lines, expression of the stem cell markers nestin and CD133 was higher upon stimulation with bFGF compared to EGF. Importantly, bFGF stimulated the growth of both cell lines, whereas EGF had no effect. We verified that the growth stimulation by bFGF was either mediated by proliferation (NCH421k) or resistance to apoptosis (NCH644).
  
  
  CONCLUSIONS
  We demonstrate that GSC cultures without EGFR amplification can be maintained and expanded with bFGF, while the addition of EGF has no significant effect and therefore can be omitted.
authors.affiliation: Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia.
authors.forename: Neza
authors.initials: N
authors.lastname: Podergajs
authors.forename: Narve
authors.initials: N
authors.lastname: Brekka
authors.forename: Bernhard
authors.initials: B
authors.lastname: Radlwimmer
authors.forename: Christel
authors.initials: C
authors.lastname: Herold-Mende
authors.forename: Krishna M
authors.initials: KM
authors.lastname: Talasila
authors.forename: Katja
authors.initials: K
authors.lastname: Tiemann
authors.forename: Uros
authors.initials: U
authors.lastname: Rajcevic
authors.forename: Tamara T
authors.initials: TT
authors.lastname: Lah
authors.forename: Rolf
authors.initials: R
authors.lastname: Bjerkvig
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Miletic
keywords: EGF; EGFR; bFGF; glioblastoma; stem cell cultures