Noninvasive evaluation of (18)F-FDG/(18)F-FMISO-based Micro PET in monitoring hepatic metastasis of colorectal cancer

This study aimed to explore the application of two radiotracers ((18)F-fluorodeoxyglucose (FDG) and (18)F-fluoromisonidazole (FMISO)) in monitoring hepatic metastases of human colorectal cancer (CRC). Mouse models of CRC hepatic metastases were established by implantation of the human CRC cell lines LoVo and HT29 by intrasplenic injection. Wound healing and Transwell assays were performed to examine cell migration and invasion abilities. Radiotracer-based cellular uptake in vitro and micro-positron emission tomography imaging of liver metastases in vivo were performed. The incidence of liver metastases in LoVo-xenografted mice was significantly higher than that in HT29-xenografted ones. The SUVmax/mean values of (18)F-FMISO, but not (18)F-FDG, in LoVo xenografts were significantly greater than in HT29 xenografts. In vitro, LoVo cells exhibited stronger metastatic potential and higher radiotracer uptake than HT29 cells. Mechanistically, the expression of HIF-1α and GLUT-1 in LoVo cells and LoVo tumor tissues was remarkably higher than in HT29 cells and tissues. Linear regression analysis demonstrated correlations between cellular (18)F-FDG/(18)F-FMISO uptake and HIF-1α/GLUT-1 expression in vitro, as well as between (18)F-FMISO SUVmax and GLUT-1 expression in vivo. (18)F-FMISO uptake may serve as a potential biomarker for the detection of liver metastases in CRC, whereas its clinical use warrants validation.