Dietary fructose‐induced hepatocellular carcinoma development manifested in mice lacking apoptosis inhibitor of macrophage (AIM)

The consumption of fructose, including the use of high‐fructose corn syrup as a sweetener, has increased continuously in recent decades. Although the involvement of fructose in the development of metabolic diseases has been emphasized recently, whether fructose intake increases susceptibility to steatosis‐associated hepatocellular carcinoma (HCC) is unclear. Here, we investigated this issue using mice lacking a circulating protein, apoptosis inhibitor of macrophage (AIM, encoded by cd5l). AIM does not induce carcinogenesis of hepatocytes, but provokes necrotic death specifically in AIM‐bound cancer cells through complement cascade activation, thereby preventing HCC tumor development in wild‐type mice. When subjected to a high‐fructose diet (HFrD), AIM‐deficient (AIM–/–) mice showed liver steatosis and subsequent liver inflammation as well as fibrosis, but at much milder levels compared with mice fed a high‐fat diet. However, AIM–/– mice were markedly susceptible to HCC tumor development, whereas no wild‐type mice developed the disease. Systemic metabolic states, including obesity and insulin resistance, were similar in both types of mice after HFrD challenge, indicating no influence of AIM on HFrD‐induced metabolic changes. Our results suggest that dietary fructose increases the risk for liver carcinogenesis and that individuals with low blood AIM levels may be susceptible to HCC under chronic fructose intake. In this study, by using mice lacking apoptosis inhibitor of macrophage (AIM) protein, we found that dietary fructose highly increases the risk for liver carcinogenesis. Our results might alert people to the risk of dietary fructose, in particular, in terms of liver carcinogenesis.