Fig. 3. Increased progenitor-like ability of EGFR mutant cells following PM exposure.

a, PC analysis plot of RNA-seq data from epithelia samples taken from recombined Rosa26^{LSL-tdTomato/+} mice (T) and ET mice exposed to 50 μg PM or PBS. b, Heatmap of progenitor AT2 cell state (AT2), macrophage recruitment and epithelial alarmin (Alarm) gene expression in all mouse tumour samples. The colour scale in the heatmap represents high (red) to low (blue) transcript per million (TPM) expression z-scores. Asterisks indicate significantly different (FDR < 0.05) gene expression between ET and ET + PM (Methods). c, Schematic of the epithelial organoid assay. Lungs were taken from mice exposed to PM or PBS, followed by isolation and culture of epithelial (positive for epithelial cellular adhesion molecule (EpCAM⁺)) cells. d, Left, representative fluorescent images of tdTomato⁺ organoids at day 14 from ET mice exposed to PBS (control) or PM in vivo. Right, OFE within unrecombined (tdTomato⁻) or recombined (tdTomato⁺) EpCAM⁺ lung cells from ET mice exposed to PBS or PM. Two mice were pooled for each biological replicate for sufficient tdTomato⁺ cells. Data represent mean from tdTomato^-, n = 8 (16 mice); tdTomato⁺EGFR^L858R, n = 9 (18 mice). One-way ANOVA. e, Schematic of macrophage isolation from mice exposed to PM or PBS and co-cultured with naive (non-PM exposed) EGFR^L858R AT2 cells. f, Left, representative fluorescent images of tdTomato⁺EGFR^L858R AT2-cell-derived organoids from ET mice, co-cultured with IMs exposed to PM or PBS. Right, quantification of OFE of EGFR^L858R AT2 cells alone and compared with AT2 cells from the same mouse co-cultured with alveolar macrophages (AMs) exposed to PBS or PM (n = 5 mice, data are average of 2 technical replicates per mouse). Paired-t test. g, Left, representative haematoxylin and eosin images of PM-exposed mice treated with IgG control antibody or anti-IL-1β throughout exposure duration. Right, quantification of tumours (n = 8 mice per group). Mann–Whitney test. Scale bar, 500 μm (d,f). The illustrations in c and e were created using BioRender (https://biorender.com)