Fig. 1.

Lrig1-Cre/+;Apcfl/+ mice develop multiple distal colonic tumors that can be monitored by colonoscopy and noninvasive PET imaging. A: schematic depiction of experimental design. Adult mice were injected with 2 mg of tamoxifen daily for 3 days, monitored by colonoscopy starting at day 50, and euthanized ∼100–120 days after tamoxifen induction. B: the largest tumors were observed in the distal colon, although the highest number of tumors was observed in the jejunum (Jej). Tumors did not develop in the proximal colon. Duo, duodenum; Ile, ileum; Col, colon. C: representative whole-mount images of duodenal and colonic tumors in mice >100 days postinduction. Measurement indicates tumor diameter. D and E: colonoscopic images from an Lrig1-Cre/+;Apcfl/+ mouse at 30 and 100 days postinduction. Luminal lesion is indicated by arrow in E. F and G: [¹⁸F]fluoro-d-glucose (FDG)- and translocator protein (TSPO)-PET imaging of wild-type (WT) and Lrig1-Cre/+;Apcfl/+ mice 95 days after induction. White brackets indicate uptake of the respective probe in the colon. In F, yellow asterisks indicate background uptake of FDG in the brain and kidney in wild-type and Lrig1-Cre/+;Apcfl/+ mice. In G, red and green reflect background uptake of TSPO ligand in the liver and lung in wild-type and Lrig1-Cre/+;Apcfl/+ mice. H: whole mount of a tumor-laden colon with increased TSPO ligand uptake. Black bracket indicates tumor burden in distal colon.