Transcriptional Characterization of Glioma Neural Stem Cells Diva ...

3.3 Glioma Culture Systems Introduction
well delineated with little tumour cell infiltration, a characteristic pheno-
typically identical to the human tumour xenografts generated from the
standard glioma cell lines, demonstrating that only tumours derived from
NBE cells phenocopy the critically important histopathological features
of the original human glioblastoma tumours.
· Transcriptional activity. The gene expression profiles of NBE cells,
serum cells, their derived xenograft tumours, and the original glioblas-
toma tumours, show that the transcriptional landscape of NBE cells
and their derivative xenograft tumours is more closely related to that
of NS cells, and parental tumours, while the transcriptional landscape
of serum cells and their derivative xenografts is more closely related to
that of glioma cell lines and their derivative tumours. These data demon-
strate that NBE cells are remarkably similar to normal NS cells and their
derivative tumours properly maintain many biological characteristics of
the parental glioblastomas and other primary glioblastomas, whereas tra-
ditionally grown, serum-cultured cancer cell lines do not.
· Genomic changes. These were evaluated by performing SNP analy-
sis and spectral karyotyping (SKY) on NBE and serum-cultured glioma
cells. Deletion of the CDKN2A:ARF locus on chromosome 9, loss of
chromosome 10q, trisomy of chromosome 7, and local amplification of
the EGFR locus are common genomic features in primary glioblastomas
and they were found in all surgical samples. The serial genomic DNA
profiles of NBE and serum cultured cells at various passage numbers were
analysed by SNP analysis and showed that even after one year of main-
tenance (more than 70 passages) in NBE culture condition, NBE cells
largely maintained their parental tumour genotype, while serum cells
underwent significant genomic rearrangements as early as two months
of culture (less than 10 passages). Intriguingly, LOH in chromosomes 4
and 17 found in most of the late passage serum cells coincided with the
onset of increased proliferation, tumourigenicity and aneuploidy typical
of these cells, and carried the hCDC4 and p53 genes, respectively. The
fact that the remaining copy of hCDC4 was found to be down-regulated
hinted at the possibility that this E3 ubiquitin ligase involved in the
regulation of the aurora kinase STK15, up-regulated in these cells and
known to cause aneuploidy through inactivation [313,416], was partially
responsible for the increased proliferation, tumourigenicity, and aneu-
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