Fig. 2: Cancer cells transfer mitochondria to fibroblasts in vitro and in vivo.
a, qPCR for the human mtDNA encoding tRNA-Leu(UUR) relative to mouse nuclear DNA encoding beta2-microglobulin (B2m) using DNA from MitoTracker-positive and MitoTracker-negative mouse fibroblasts sorted from n = 3 cocultures. Total mtDNA content was calculated on the basis of Ct values. b, RT–qPCR for human and mouse FN1 and Fn1 relative to RPL27 or Rps29, respectively, using RNA from MitoTracker-high and MitoTracker-low mouse fibroblasts sorted from n = 3 cocultures. c, Transfer efficiency in human–human and human–mouse cocultures (n = 3 cocultures per group). d, Comparison of SNPs within the 16S rRNA gene region of A431 cell mitochondria with those of control and recipient mouse fibroblasts. SNPs from A431 cells in recipient fibroblasts are indicated with rectangles (n > 300,000 cells pooled from three independent cocultures). e, Experimental setup and fluorescence images of HPF Su9–RFP and A431 Su9–GFP cocultures. This image was created with BioRender.com. Bottom, (1) colocalization of A431 and HPF mitochondria (orange), (2) HPF periphery with own mitochondrial network (red) and (3) nonrecipient HPFs (red). f, Section of a xenograft tumor formed by Su9–RFP A431 cells, showing Su9–RFP fluorescence in mitochondria of keratin 14 (K14)-negative cells and cultured fibroblasts from these tumors showing Su9–RFP fluorescence (red) and vimentin expression. g, qPCR for the mtDNA-encoded human tRNA-Leu gene relative to the mouse B2m gene using total DNA from cultured mouse fibroblasts isolated from noninjected ear skin (NS) or A431 xenograft tumors (n = 3 normal skin samples and n = 3 tumor samples from different mice). h, Representative immunofluorescence staining of A431 xenograft tumors for COLI (green) and human mitochondria (red). Costaining (yellow) of stromal cells adjacent to tumors was confirmed by colocalization analysis (site indicated with an asterisk). The white arrow indicates the line along which the intensity values of the different fluorescence signals were measured, starting from the initial position at the base of the arrow and ending at the arrowhead. Separate channels of zoomed-in regions are displayed (n = 3 sections from different tumors). Graphs show the mean ± s.e.m. An unpaired two-sided Student’s t-test (a,c,g) or two-sided one-way ANOVA with Bonferroni post hoc multiple comparison test (b) was used to determine statistical significance. One control value was set to 1. Scale bars, 25 μm (e,f,h).
