Abstract

Gallbladder stones (cholecystolithiasis) are the main risk factor for gallbladder cancer, a lethal biliary malignancy with poor survival rates worldwide. Gallbladder stones are thought to damage the gallbladder epithelium and trigger chronic inflammation, promoting an environment where, through processes not fully understood, preneoplastic lesions arise and can eventually lead to invasive carcinoma. Here, we developed a novel gallbladder preneoplasia mouse model by the administration of two lithogenic diets (low- and high-cholesterol) in wild type C57BL/6 mice over a period of 9 months. Additionally, we evaluated two potential chemopreventive strategies through the use of the anti-inflammatory drug aspirin and the cholesterol-absorption inhibitor ezetimibe. Both lithogenic diets induced early gallbladder stones formation, together with extensive inflammatory changes and widespread induction of metaplasia, an epithelial adaptation to tissue injury. Dysplastic lesions were presented only in mice fed with high-cholesterol diet (62.5%) in late stages (9th month) and no invasive carcinoma was observed at any stage. The cholesterol-absorption inhibitor ezetimibe inhibited gallbladder stone formation and completely prevented the onset of metaplasia and dysplasia in both lithogenic diets, while antiinflammatory aspirin partially reduced metaplasia development only in low-cholesterol diet. This model recapitulates several of the structural and inflammatory findings observed in human cholecystolithiasic gallbladders, enabling its use for the study of gallbladder carcinogenesis. In addition, our results suggest that the use of cholesterol-absorption inhibitors and antiinflammatory drugs can be evaluated as chemopreventive strategies to reduce the burden of gallbladder cancer among high-risk populations.