Dietary and Genetic Cholesterol Loading Rather Than Steatosis Promotes Liver Tumorigenesis and NASH-Driven HCC

Abstract

The association of nonalcoholic steatohepatitis (NASH) with obesity and type 2 diabetes is a major determinant factor for the continued rise of NASH-driven HCC. Unfortunately, the mechanisms underlying the progression from NASH to HCC are not well-understood. Steatosis is characterized by the accumulation of different lipid species, and cholesterol has emerged as an important player in NASH development, which has been shown to promote NASH-driven HCC. However, recent findings indicated a tumor suppressor role of cholesterol in liver carcinogenesis and HCC development. Thus, we examined the contribution of hepatic steatosis with or without cholesterol accumulation induced by dietary or genetic approaches in liver tumorigenesis and whether the role of cholesterol in NASH-driven HCC is species-dependent. While diethylnitrosamine (DEN) treatment to rats or mice fed a choline-deficient diet decreased the hepatic steatosis, feeding an atherogenic diet enriched in cholesterol potentiated the liver tumor markers. Similar effects were observed in DEN-treated transgenic SREBP-2 mice but not wild-type (WT) mice fed a regular chow diet. Remarkably, long-term feeding of a high-fat high-cholesterol diet (HFHC) but not a high-fat diet (HFD) to WT mice caused severe NASH with spontaneous progression to HCC. A similar outcome was observed in MUP-uPA transgenic mice fed a HFHC diet, which resulted in increased liver tumors and expression of the genes involved in the immune checkpoints. Ezetimibe treatment ameliorated chronic liver disease and, more importantly, tumor multiplicity in HFHC-fed MUP-uPA mice or DEN-treated WT mice. Thus, these results revealed a differential role of steatosis and cholesterol in NASH-driven HCC and indicated that the tumor-promoter role of cholesterol is species-independent and associated with impaired immunosurveillance.

Inflammation and Cancer: From the Development of Personalized Indicators to Novel Therapeutic Strategies

“…These effects were not associated with increased bleeding (Sitia et al, 2012). The antitumor effect of Aspirin and Clopidogrel was also confirmed in a recent study, where this combination prevented nonalcoholic steatohepatitis and subsequent HCC development in different dietary and genetic mouse models (Ribas et al, 2021). This study also found that another P2Y12 inhibitor, Ticagrelor, had a similar effect.…”

GST-Perfringolysin O production for the localization and quantification of membrane cholesterol in human and mouse brain and liver

“…The accumulation of cholesterol in NPC disease is not limited to the brain but also occurs in visceral organs, including the liver, underlying the liver failure present in some patients with NPC disease ( Patterson et al., 2012 ). Similarly, increased cholesterol in the liver has emerged as a key player in non-alcoholic steatohepatitis (NASH) ( Conde de la Rosa et al., 2021 ; Ribas et al., 2021 ), an advanced stage of non-alcoholic fatty liver disease (NAFLD). Moreover, NASH can progress to hepatocellular carcinoma (HCC) ( Park et al., 2010 ; El-Serag and Kanwal, 2014 ; Forner et al., 2018 ), one of the most important causes of cancer-related deaths.…”

Ezetimibe and Cancer: Is There a Connection?

“…On the contrary, more and more evidence supports that ezetimibe plays an active role in combating cancer. For example, several in vitro and in vivo studies ( Table 1 ) show that ezetimibe can inhibit multiple cancers, such as prostate cancer ( Solomon et al, 2009 ), breast cancer ( Pelton et al, 2014 ), pancreatic cancer ( Nicolle et al, 2017 ), urinary bladder cancer ( Yang et al, 2021 ), colorectal cancer ( He et al, 2015 ), hepatocellular carcinoma ( Ribas et al, 2021 ), melanoma ( Wang et al, 2022 ) and renal cell carcinoma ( Wang et al, 2022 ) through various mechanisms, including anti-angiogenesis, apoptosis, anti-proliferation, anti-inflammation, stem cell inhibition, and immune enhancement. Existing evidence shows that ezetimibe should be considered as a safe and effective cholesterol-lowering agent, and may become an academic bomb-shell for cancer treatment and prevention.…”

“…Recent reports suggest that cholesterol rather than hepatic steatosis promotes the development of NASH to HCC. Ezetimibe prevents HFHC diet-induced liver fibrosis, tumorigenesis, and NASH-driven HCC by inhibiting the intestinal absorption of dietary cholesterol and liver cholesterol content in diethylnitrosamine (DEN)-treated wild-type (WT) mice and transgenic MUP-uPA mice ( Ribas et al, 2021 ). More specifically, the mechanism is that ezetimibe reduces the expression of involved genes in fibrogenesis (Col1a1, Acta2, and Spp1) and immune checkpoints (cd274, also known as Pd-1L, Ctla4, and entpd2), as well as the mRNA expression of HCC-related markers (Ly6d, Afp, Gpc3, Birc5, and Cd44) ( Ribas et al, 2021 ).…”

“…Ezetimibe prevents HFHC diet-induced liver fibrosis, tumorigenesis, and NASH-driven HCC by inhibiting the intestinal absorption of dietary cholesterol and liver cholesterol content in diethylnitrosamine (DEN)-treated wild-type (WT) mice and transgenic MUP-uPA mice ( Ribas et al, 2021 ). More specifically, the mechanism is that ezetimibe reduces the expression of involved genes in fibrogenesis (Col1a1, Acta2, and Spp1) and immune checkpoints (cd274, also known as Pd-1L, Ctla4, and entpd2), as well as the mRNA expression of HCC-related markers (Ly6d, Afp, Gpc3, Birc5, and Cd44) ( Ribas et al, 2021 ). Zhang et al report that ezetimibe drives serum cholesterol-lowering, promotes antitumor immunity and extenuates prostate tumor growth and metastasis by suppressing protein kinase B (Akt) phosphorylation and mammalian target of rapamycin complex 2 (mTORC2) signaling in lymphocytes, and by enhancing CD8 + lymphocytes memory function and tumor infiltration ( Wang et al, 2022 ).…”