Invasive pattern of lac-Z-transfected human glioblastoma cells in nude mice brain

Primary, malignant brain tumors show an extensive infiltrative invasion into surrounding normal brain. At present, little information is available regarding the local invasive behavior of human brain tumors and until now no animal model suitable to mimic human gliomas has been reported. To identify the infiltrative behavior of an established glioblastoma cell line (SNB19), we achieved a stable transfection of the SNB19 cell line with beta-galactosidase (lac-Z) plasmid. The stable beta-galactosidase-expressing cells were then injected intracerebrally into nude mice in an attempt to follow its pattern of spread. The mice were sacrificed at 3, 4, and 6 weeks postinjection. We could detect tumor formation in all of the animals, and the tumor size increased gradually over the 6 week time period. Three weeks after injection, tumor cells showed characteristic infiltrative invasion along the corpus callosum. We also observed tumor-cell invasion into the anterior commissure in some animals, and each tumor cell could be identified by lac-Z expression as visualized by its blue color. Further invasion was identified at 4 and 6 weeks postinjection. Our results suggest that this model could be used to study the molecular mechanisms involved in the invasion of gliomas so that appropriate therapeutic intervention strategies could be designed.