Fig. 1: AHR functions as a suppressor of lung cancer metastasis in vivo and correlates with progression of early-stage lung cancer in resected patients.

a Schematic overview of the experimental layout of an shRNA-library screen to uncover metastases-associated genes in an orthotopic mouse model of lung cancer (Luc = Luciferase, GFP = green fluorescent protein). b Bioluminescence imaging (BLI) of SCID CB.17 mice transplanted with GFP-Luc+ H1975 expressing the shRNA library (lower panel) or parental GFP-Luc+ H1975 cells (upper panel). c Differential representation of individual shRNAs with highest enrichment in metastatic tumors. Data were normalized to shRNA representation in the initial cell population. On the left side, dots representing genes that are targeted by these shRNAs are displayed as a fraction of read counts for individual genes relating to all read counts resulting from barcode sequencing of the samples from two different metastases obtained in two mice (met1, met2; ‘freq.’ = frequency). On the right side, these data are presented as fold change (FC) between metastatic and primary tumors from the same two mice (referred to as ‘met1’, ‘met2’, and ‘prim1’, ‘prim2’, respectively). In both graphs, genes close to the diagonal are expected to be consistently enriched in metastatic tumors. Therefore, aryl hydrocarbon receptor (AHR, red circle) was selected for further characterization. d Kaplan–Meier plots displaying progression-free survival (PFS) in patients with stage I lung adenocarcinomas with high or low AHR expression (20820_at)⁴⁵. AHR expression was dichotomized at the median expression level. e Immunoblotting of AHR expression in GFP-Luc+ H1975 shAHR-K2 and GFP-Luc+ H1975 shScr. f Representative BLI images of SCID CB.17 mice transplanted with either GFP-Luc+ H1975 shAHR-K2 or GFP-Luc+ H1975 shScr. g Metastasis-free survival of SCID CB.17 mice bearing GFP-Luc+ H1975 expressing shAHR (K2) or shScr. P-value, determined by log-rank test.