Characterization of cells recovered from the xenotransplanted NG97 human-derived glioma cell line subcultured in a long-term in vitro.
BACKGROUND
In order to elucidate tumoral progression and drug resistance, cultured cell lines are valuable tools applied on tumor related assays provided they are well established and characterized. Our laboratory settled the NG97 cell line derived from a human astrocytoma grade III, which started to develop and express important phenotypical characteristics of an astrocytoma grade IV after injection in the flank of nude mice. Astrocytomas are extremely aggressive malignancies of the Central Nervous System (CNS) and account for 46% of all primary malignant brain tumors. Progression to worse prognosis occurs in 85% of the cases possibly due to changes in cell tumor microenvironment and through biological pathways that are still unclear.


METHODS
This work focused on characterizing the NG97 cell line specifically after being recovered from the xenotransplant, who maintained their undifferentiated characteristics along the following 60th passages in vitro. These cells were subcultivated to evaluate the possible contribution of these undifferentiated characteristics to the malignant progression phenotype. These characteristics were the expression of molecules involved in the processes of migration, dedifferentiation and chromosomal instability.


RESULTS
Results showed that NG97(ht) had an decrease in doubling time through sub cultivation, which was characterized by a converse modulation between the expression of glial fibrillary acidic protein (GFAP) and vimentin. In addition, beta1 integrins were present in intermediate levels while alpha5 integrins had a high expression profile as well as fibronectin and laminin. Cytogenetic analysis of NG97(ht) revealed several chromosomal abnormalities, 89% of the cells showed to be hyperdiploid and the modal number was assigned to be 63. Several acrocentric chromosomes were visualized and at least 30 figures were attributed to be murine. These findings suggest a possible fusion between the original NG97 cells with stromal murine cells in the xenotransplant.


CONCLUSIONS
In this study the NG97(ht) cells were characterized to embryonic recovery patterns of intermediate filaments, adhesion molecules expression, chromosomal imbalances and murine chromosomes. In the latter case, these presumably chromosomes were originated as fusions between murine stroma cells and NG97 cell lineage in the xenotransplant. Our results emphasize important queries about astrocytomas tumor progression.
Department of Microbiology and Immunology, Institute of Biology, UNICAMP - Campinas, São Paulo, Brazil. camilalongomachado@gmail.com
Camila M L
CM
Machado
Rafael Y
RY
Ikemori
Tatiana Q
TQ
Zorzeto
Ana C M A
AC
Nogueira
Suse D S
SD
Barbosa
Wilson
W
Savino
André A
AA
Schenka
José
J
Vassallo
Juliana K
JK
Heinrich
Fátima
F
Boetcher-Luiz
Liana
L
Verinaud
D000818:Animals; D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations; D005434:Flow Cytometry; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014183:Transplantation, Heterologous; D014746:Vimentin / Q000096:biosynthesis
D005904:Glial Fibrillary Acidic Protein; D019012:Integrin beta1; D014746:Vimentin