Time-lapse phenotyping of invasive glioma cells ex vivo reveals subtype-specific movement patterns guided by tumor core signaling

Abstract

The biology of glioblastoma invasion and its mechanisms are poorly understood. We demonstrate using time-lapse microscopy that grafting of glioblastoma (GBM) tumorspheres into rodent brain slices results in experimental ex vivo tumors with invasive properties that recapitulate the invasion observed after orthotopic transplantation into the rodent brain. The migratory movements and mitotic patterns were clearly modified by signals extrinsic to the invading cells. The cells migrated away from the tumorspheres, and removal of the spheres reduced the directed invasive movement. The cell cultures contained different populations of invasive cells that had distinct morphology and invasive behavior patterns. Grafts of the most invasive GBM culture contained 91±8% cells with an invasive phenotype, characterized by small soma with a distinct leading process. Conversely, the majority of cells in less invasive GBM grafts were phenotypically heterogeneous: only 6.3±4.1% of the cells had the invasive phenotype. Grafts of highly and moderately invasive cultures had different proportions of cells that advanced into the brain slice parenchyma during the observation period: 89.2±2.2% and 23.1±6.8%, respectively. In grafts with moderately invasive properties, most of the cells (76.8±6.8%) invading the surrounding brain tissue returned to the tumor bulk or stopped centrifugal migration. Our data suggest that the invasion of individual GBM tumors can be conditioned by the prevalence of a cell fraction with particular invasive morphology and by signaling between the tumor core and invasive cells. These findings can be important for the development of new therapeutic strategies that target the invasive GBM cells.

Zeb1 potentiates genome‐wide gene transcription with Lef1 to promote glioblastoma cell invasion

“…To further assess a role for Prex1 in glioma cell invasion, we seeded tumorspheres of Prex1‐ or Zeb1‐silenced and control non‐silenced NCH421k cells onto organotypic slice cultures of adult mouse brains as an ex vivo tumor model (Fayzullin et al , ). In our experimental setup, tumor spheres exhibited either an invasive phenotype with substantial numbers of cells migrating out‐ or completely dispersing into the parenchyma, or a non‐invasive phenotype with tumorspheres retaining a round and compact appearance and none to few cells migrating out.…”

Phenotypic and Expressional Heterogeneity in the Invasive Glioma Cells

“…Seven primary cell cultures were established from brain tumor biopsies, all from IDH wild-type, treatment-naïve GBMs, of which one was classified as a giant cell GBM. Two of these cultures have previously been described (T0965, T1008) [12] , [21] , [22] . The tumorigenicity of all cultures was confirmed upon xenografting to SCID mice.…”

“…These cells can be propagated as tumorspheres under serum-free, growth factor-enriched media and establish phenocopies of the parent tumor in serial xenotransplantation [7] , [9] , [10] . Importantly, these induced tumors are highly invasive, harboring cells that migrate widely throughout the brain [9] , [11] , [12] , [13] .…”

Recapitulating in vivo-like plasticity of glioma cell invasion along blood vessels and in astrocyte-rich stroma

“…Consequently, live brain slice assays are considered as “gold standard” recapitulating the complexity of brain tissue; however, they support mainly perivascular but not parenchymatous routes of glioma cell invasion (Alfi et al 2002 ; Miao et al 2015 ; Fayzullin et al 2016 ). To this end, we hypothesize that the complexity of glioma invasion requires the combined application of a set of complementary in vitro models to enable an adaptive range of glioma invasion types, including collective perivascular invasion and network-like interstitial invasion patterns (Osswald et al 2015 , 2016 ).…”