title: How stemlike are sphere cultures from long-term cancer cell lines? Lessons from mouse glioma models.
abstract: Cancer stem cells may mediate therapy resistance and recurrence in various types of cancer, including glioblastoma. Cancer stemlike cells can be isolated from long-term cancer cell lines, including glioma lines. Using sphere formation as a model for cancer cell stemness in vitro, we derived sphere cultures from SMA-497, SMA-540, SMA-560, and GL-261 glioma cells. Gene expression and proteomics profiling demonstrated that sphere cultures uniformly showed an elevated expression of stemness-associated genes, notably including CD44. Differences in neural lineage marker expression between nonsphere and sphere cultures were heterogeneous except for a uniform reduction of β-III-tubulin in sphere cultures. All sphere cultures showed slower growth. Self-renewal capacity was influenced by medium conditions but not nonsphere versus sphere culture phenotype. Sphere cultures were more resistant to irradiation, whereas both nonsphere and sphere cultures were highly resistant to temozolomide. Nonsphere cells formed more aggressive tumors in syngeneic mice than sphere cells in all models except SMA-560. There were no major differences in vascularization or infiltration by T cells or microglia/macrophages between nonsphere and sphere cell-derived tumors implanted in syngeneic hosts. Together, these data indicate that mouse glioma cell lines may be induced in vitro to form spheres that acquire features of stemness, but they do not exhibit a uniform biologic phenotype, thereby challenging the view that they represent a superior model system.
authors.affiliation: From the Laboratory of Molecular Neuro-Oncology, Departments of Neurology (MA, PR, MW) and Neurosurgery (MA, KF); University Hospital Zurich, and Neuroscience Center (MA, KF, PR, MW), University of Zurich, Zurich, Switzerland; Interdisciplinary Institute for Bioinformatics, University of Leipzig, Leipzig, Germany (EW, HB); Molecular Proteomics Laboratory, Center for Biological and Medical Research (BMFZ) (AS, KS); Department of Neuropathology and German Cancer Consortium (DKTK), partner site Essen/Düsseldorf (KK, GR); and Institute for Molecular Medicine (KS), Heinrich Heine University, Düsseldorf, Germany.
authors.forename: Mushfika
authors.initials: M
authors.lastname: Ahmad
authors.forename: Karl
authors.initials: K
authors.lastname: Frei
authors.forename: Edith
authors.initials: E
authors.lastname: Willscher
authors.forename: Anja
authors.initials: A
authors.lastname: Stefanski
authors.forename: Kerstin
authors.initials: K
authors.lastname: Kaulich
authors.forename: Patrick
authors.initials: P
authors.lastname: Roth
authors.forename: Kai
authors.initials: K
authors.lastname: Stühler
authors.forename: Guido
authors.initials: G
authors.lastname: Reifenberger
authors.forename: Hans
authors.initials: H
authors.lastname: Binder
authors.forename: Michael
authors.initials: M
authors.lastname: Weller
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005910:Glioma / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D014411:Neoplastic Stem Cells / Q000473:pathology*