Fig. 1: Identification of functional mediators of brain metastasis.

a Schematic of experimental design to generate temporal transcriptome of breast cancer brain metastases. b Representative images of brain mets at 7 or 40 dpi, as indicated. Tissues were H&E stained and cytokeratin 8 (K8) stained to show tumor tissue. Scale bar 200 µm. c Heatmap showing expression of 125 genes differentially expressed between 7 and 40 dpi. Fisher’s combined test, Bonferroni-corrected p-value < 0.05. d Schematic of selection of Drosophila homologs, the genotype and phenotype of the Drosophila screening line, and the functional screening model used. e Data are presented as strictly standardized mean difference (SSMD) calculated with respect to the negative control (yw, no RNAi construct) shown in green, and the positive control (PTEN^RNAi) shown in purple for a minimum of 15 larvae per cross. Hits are characterized as moderate or strong positives as indicated. Representative images for both controls, and a strong positive hit are shown. f For each RNAi line that yielded a strong, moderate or weak negative phenotype, the number of RNAi lines for that gene is plotted against the average integrated intensity SSMD. Datapoints are colored by average integrated intensity SSMD, with orange indicating a negative average SSMD, and gray indicating a positive average SSMD. g qRT-PCR for 20 genes with lowest average integrated intensity SSMD scores in MDA-231 primary mammary fat pad tumors (Primary Tumor, white), and brain metastases (Brain Met, orange to gray). Brain metastasis samples are colored to correspond to the gene’s average integrated intensity SSMD, as in F. n = 7 animals/group. Boxes, first to third interquartile range, line, mean, whiskers, minimum and maximum values. Pairwise comparisons made as indicated using Student’s t test. *p < 0.05, **p < 0.01.