Identification of a novel set of genes reflecting different in vivo invasive patterns of human GBM cells.
BACKGROUND
Most patients affected by Glioblastoma multiforme (GBM, grade IV glioma) experience a recurrence of the disease because of the spreading of tumor cells beyond surgical boundaries. Unveiling mechanisms causing this process is a logic goal to impair the killing capacity of GBM cells by molecular targeting.We noticed that our long-term GBM cultures, established from different patients, may display two categories/types of growth behavior in an orthotopic xenograft model: expansion of the tumor mass and formation of tumor branches/nodules (nodular like, NL-type) or highly diffuse single tumor cell infiltration (HD-type).


METHODS
We determined by DNA microarrays the gene expression profiles of three NL-type and three HD-type long-term GBM cultures. Subsequently, individual genes with different expression levels between the two groups were identified using Significance Analysis of Microarrays (SAM). Real time RT-PCR, immunofluorescence and immunoblot analyses, were performed for a selected subgroup of regulated gene products to confirm the results obtained by the expression analysis.


RESULTS
Here, we report the identification of a set of 34 differentially expressed genes in the two types of GBM cultures. Twenty-three of these genes encode for proteins localized to the plasma membrane and 9 of these for proteins are involved in the process of cell adhesion.


CONCLUSIONS
This study suggests the participation in the diffuse infiltrative/invasive process of GBM cells within the CNS of a novel set of genes coding for membrane-associated proteins, which should be thus susceptible to an inhibition strategy by specific targeting.Massimiliano Monticone and Antonio Daga contributed equally to this work.
IRCCS Azienda Ospedaliera Universitaria San Martino - IST - Istituto Nazionale per la Ricerca sul Cancro, Largo R, Benzi, 10, 16132 Genoa, Italy. massimiliano.monticone@istge.it
Massimiliano
M
Monticone
Antonio
A
Daga
Simona
S
Candiani
Francesco
F
Romeo
Valentina
V
Mirisola
Silvia
S
Viaggi
Ilaria
I
Melloni
Simona
S
Pedemonte
Gianluigi
G
Zona
Walter
W
Giaretti
Ulrich
U
Pfeffer
Patrizio
P
Castagnola
D000368:Aged; D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D002869:Chromosome Aberrations; D016000:Cluster Analysis; D005260:Female; D020869:Gene Expression Profiling; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D015151:Immunoblotting; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured