Fig. 1: Glioblastoma cells without mtDNA form tumours with delay.

Parental (par) and ρ⁰ GL261 cells were assessed for the level of mtDNA by qPCR (A), for the level of mtDNA-coded mtCO1 protein by WB (B), and for routine mitochondrial respiration using the Oxygraph (C). Dependency of ρ⁰ cells for exogenous uridine was confirmed by cultivation of parental and ρ⁰ cells in media with ( + uri) or without (-uri) added uridine (D). 5 × 10⁴ parental or ρ⁰ cells were implanted into the right hemisphere (coordinates: bregma 2,2) of syngeneic C57Bl/6 mice as indicated (E). Mice grafted with parental and ρ⁰ cells (n ≥ 9) were assessed for survival (F). Tumours formed from parental cells (par T) and from ρ⁰ cells (ρ⁰ T), and contralateral brain tissue were excised at the endpoint of the experiment (after detection of 15% animal weight loss and behavioural changes) and their CI- and CII-dependent respiration (CI R, CII R, respectively) was assessed by the Oxygraph (G), protein expression of subunits of respiratory complexes (CI, CII, CIII and CV) was assessed by WB (H), and gene expression of mtDNA-encoded genes by qRT-PCR (I).