Fig. 6: Oxygen competition and cellular cross-talk mediate enhanced growth and reduced radiation sensitivity in unirradiated mixed PC3 spheroids.
a Images showing spatial localisation of parental (green pseudo-colour) and radioresistant (RR, magenta pseudo-colour) cell populations, markers of nuclei (Hoechst, cyan pseudo-colour), hypoxia (EF5, red pseudo-colour) and proliferation (Ki67, red pseudo-colour), and H/E staining in homogeneous and mixed PC3 spheroids isolated on days 5 and 11. To indicate overlapping areas, the six spheroid sections shown in the row spatial localisation are also shown in the row nuclei/hypoxia, with different channels merged together as indicated by row title. Spheroid sections shown in row nuclei/proliferation are different. Scale bar, 100 μm. b Clonogenic survival of cell populations isolated from untreated spheroids dissociated at day 5 and day 11 (n = 2 experiments). *Padj = 0.04, 1-way ANOVA with Sidak correction. c Oxygen consumption rate (OCR) of parental (white circles) and RR (black circles) PC3 populations, normalised to cell density (n = 4 experiments). Bar indicates mean value. *Padj < 0.01, paired t test, two-tailed. d The spatial distribution of cell populations based on OCR in mixed PC3 spheroids, as predicted by the cellular automaton (CA) model. e Growth curves predicted solely by competition for space and oxygen in untreated homogeneous (parental, white circles; RR, black circles) and mixed (blue diamonds) spheroids. The CA model described in d was used to generate a growth curve (see Supplementary Methods section 2). f Cell count of parental and RR cells cultured separately or together in hypoxia (0.1% O2) or in normoxia using Transwell inserts, in which cells share medium but are separated by a membrane (n = 4 experiments for hypoxia; n = 5 experiments for normoxia). Bar indicates mean value. *Padj < 0.01, **Padj < 0.001, using overdispersed Poisson regression.
