Tumor Growth-Inhibitory Effect of an Angiotensin-Converting Enzyme Inhibitor (captopril) in a Lung Cancer Xenograft Model Analyzed Using 18F-FDG-PET/CT.

IntroductionWe administered an angiotensin-converting enzyme inhibitor (captopril) to mice implanted with a human lung adenocarcinoma epithelial cell line (A549 cells) and investigated the tumor growth-inhibitory effect of captopril from the viewpoint of glucose metabolism using F-18-fluorodeoxyglucose (F-18-FDG)-PET/CT.MethodsSubcutaneous implantation of A549 cells (1.9x10(6) cells) was carried out in the lower right flank of mice. Fifteen days after the transplantation of A549 cells, mice (six in each group) were treated with captopril (3.0 mg/mouse) or saline (1000 mu l/mouse) for 5 days. We performed F-18-FDG-PET/CT imaging of the mice before and after the treatment and evaluated the degree of F-18-FDG accumulation in tumors. In both groups (the captopril-administrated and control groups), values for the metabolic tumor volume (MTV), maximum standardized uptake value, total lesion glycolysis, and tumor volume after treatment had a tendency to increase. However, tumor growth was suppressed in the captopril-administrated group compared with the control group.ResultsIn terms of the growth rate, the MTV and tumor volume were significantly different (P < 0.05). It was found that captopril exerted a potential tumor growth-inhibitory effect; this was because the captopril-administrated group showed low values of MTV, maximum standardized uptake value, total lesion glycolysis, and tumor volume in comparison with the control group.