Abstract
Glioma cells grow in two phenotypic forms, as adherent monolayers and as free floating “neurospheres/tumorspheres”, using specific media supplements. Whether each phenotype is irreversible remains unknown. Herein we show that both states are reversible using patient derived glioblastoma cell cultures (i.e., HF2303, IN859, MGG8, IN2045). Both phenotypic states differ in proliferation rate, invasion, migration, chemotaxis and chemosensitivity. We used microarrays to characterize gene expression across the patient derived glioblastoma cell cultures, to find specific inhibitors of the sphere population. Traditional chemotherapeutics (i.e., doxorubicin or paclitaxel) inhibit rapidly dividing adherent cells; it has been more challenging to inhibit the growth of the sphere phenotype. PRKG1, known to induce apoptosis when activated, is increased in all patient derived glioblastoma spheres. Stimulation of PRKG1 activity preferentially reduced cell viability in the sphere phenotype. Computational network and gene ontology analysis identified novel potential target genes linked to the PRKG1 expression node.
Highlights
Lack of a precise experimental definition of glioma stem cells has led to variance in the way these cells are cultured in vitro, characterized in in vitro assays, and to confusing nomenclature
Cells grown adherently demonstrated a higher proliferation rate than the same cells grown under sphere conditions for all four patient derived glioblastoma cell cultures tested (Figure 1)
CD133 was expressed by cells of both the sphere and adherent phenotype (Figure S1), which made it unsuitable to use as a differential marker for glioma stem cells
Summary
Lack of a precise experimental definition of glioma stem cells has led to variance in the way these cells are cultured in vitro, characterized in in vitro assays, and to confusing nomenclature. In 2003, Singh et al, [3] published the first identification and purification of human brain tumor stem cells They defined human brain tumor stem cells as being capable of forming neurospheres in serum-free medium, expressing markers of differentiation when grown adherently on L-poly-ornithine coated coverslips in fetal bovine serum supplemented medium, and being CD133+ [3]. Subsequent to this report, the definition was expanded to include tumor growth when transplanted into rodent models [4,5]. This experimental definition was challenged when CD133- cells were shown to form tumor spheres in-vitro and tumors in-vivo [6,7,8]. As CD133 was expressed by cells of both the sphere and adherent phenotype, it could not be used as a differential marker
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
