Glioblastoma stielartigen Zelllinien entweder mit Instandhaltung oder Verlust der High-Level-EGFR Amplifikation erzeugt über eine Modulation der Ligandenkonzentration.

Purpose: Despite the high incidence of epidermal growth factor receptor (EGFR) gene amplification and

rearrangement in glioblastomas, no suitable cell line exists that preserves these alterations in vitro and is

tumorigenic in immunocompromised mice. On the basis of previous observations that glioblastoma cells

cultured with serum lose the EGFR amplification rapidly and that EGF can inhibit the growth of EGFRamplified

tumor cells, we hypothesized that serum-free and EGF-free culture conditions could promote

maintenance of the EGFR amplification.

Experimental Design: Cells from EGFR-amplified glioblastomas were taken into culture using neural

stem cell conditions with modifications, including varying oxygen concentrations and omission of routine

EGF supplementation.

Results: High-level EGFR amplification was rapidly lost in 5 glioblastoma cultures supplemented with

EGF, whereas it was preserved in cultures from the same tumors established without EGF. Cultures from 2

glioblastomas developed into pairs of cell lines, with either stable maintenance or irreversible loss of highlevel

EGFR amplification in the majority of cells. One EGFR-amplified cell line preserved expression of the

receptor variant EGFRvIII. Cell lines with high-level EGFR amplification/EGFRvIII expression formed highly

aggressive tumors in nude mice, whereas nonamplified cell lines were either nontumorigenic or grew

significantly more slowly. In contrast, nonamplified cell lines proliferated faster in vitro. All cell lines

responded to erlotinib, with inhibition of receptor activation and proliferation but partly different effects on

downstream signaling and migration.

Conclusions: Isogenic glioblastoma cell lines maintaining stable differences in EGFR/EGFRvIII status

can be derived by varying exposure to EGF ligand and reflect the intratumoral genetic heterogeneity.

Purpose: Despite the high incidence of epidermal growth factor receptor (EGFR) gene amplification and rearrangement in glioblastomas, no suitable cell line exists that preserves these alterations in vitro and is tumorigenic in immunocompromised mice. On the basis of previous observations that glioblastoma cells cultured with serum lose the EGFR amplification rapidly and that EGF can inhibit the growth of EGFRamplified tumor cells, we hypothesized that serum-free and EGF-free culture conditions could promote maintenance of the EGFR amplification. 

Experimental Design: Cells from EGFR-amplified glioblastomas were taken into culture using neural stem cell conditions with modifications, including varying oxygen concentrations and omission of routine EGF supplementation. Results: High-level EGFR amplification was rapidly lost in 5 glioblastoma cultures supplemented with EGF, whereas it was preserved in cultures from the same tumors established without EGF. Cultures from 2 glioblastomas developed into pairs of cell lines, with either stable maintenance or irreversible loss of highlevel EGFR amplification in the majority of cells. One EGFR-amplified cell line preserved expression of the receptor variant EGFRvIII. Cell lines with high-level EGFR amplification/EGFRvIII expression formed highly aggressive tumors in nude mice, whereas nonamplified cell lines were either nontumorigenic or grew significantly more slowly. In contrast, nonamplified cell lines proliferated faster in vitro. All cell lines responded to erlotinib, with inhibition of receptor activation and proliferation but partly different effects on downstream signaling and migration. 

Conclusions: Isogenic glioblastoma cell lines maintaining stable differences in EGFR/EGFRvIII status can be derived by varying exposure to EGF ligand and reflect the intratumoral genetic heterogeneity.