Whether and how garlic-derived -allylmercaptocysteine (SAMC) inhibits hepatocellular carcinoma (HCC) is largely unknown. In the current study, the role of low-density lipoprotein receptor (LDLR)-related protein 6 (LRP6) in HCC progression and the anti-HCC mechanism of SAMC was examined in clinical sample, cell model and xenograft/orthotopic mouse models. We demonstrated that SAMC inhibited cell proliferation and tumorigenesis, while induced apoptosis of human HCC cells without influencing normal hepatocytes. SAMC directly interacted with Wnt-pathway co-receptor LRP6 on the cell membrane. LRP6 was frequently over-expressed in the tumor tissue of human HCC patients (66.7% of 48 patients) and its over-expression only correlated with the over-expression of -catenin, but not with age, gender, tumor size, stage and metastasis. Deficiency or over-expression of LRP6 in hepatoma cells could partly mimic or counteract the anti-tumor properties of SAMC, respectively. administration of SAMC significantly suppressed the growth of Huh-7 xenograft/orthotopic HCC tumor without causing undesirable side effects. In addition, stable down-regulation of LRP6 in Huh-7 facilitated the anti-HCC effects of SAMC. In conclusion, LRP6 can be a potential therapeutic target of HCC. SAMC is a promising specific anti-tumor agent for treating HCC subtypes with Wnt activation at the hepatoma cell surface.

Chronic alcohol consumption causes liver steatosis, cell death, and inflammation. Melatonin (MLT) is reported to alleviate alcoholic liver disease (ALD)-induced injury. However, its direct regulating targets in hepatocytes are not fully understood. In the current study, a cell-based screening model and a chronic ethanol-fed mice ALD model were used to test the protective mechanisms of MLT. MLT ameliorated ethanol-induced hepatocyte injury in both cell and animal models (optimal doses of 10 μmol/L and 5 mg/kg, respectively), including lowered liver steatosis, cell death, and inflammation. RNA-seq analysis and loss-of-function studies in AML-12 cells revealed that telomerase reverse transcriptase (TERT) was a key downstream effector of MLT. Biophysical assay found that epidermal growth factor receptor (EGFR) on the hepatocyte surface was a direct binding and regulating target of MLT. Liver specific knock-down of Tert or Egfr in the ALD mice model impaired MLT-mediated liver protection, partly through the regulation of nuclear brahma-related gene-1 (BRG1). Long-term administration (90 days) of MLT in healthy mice did not cause evident adverse effect. In conclusion, MLT is an efficacious and safe agent for ALD alleviation. Its direct regulating target in hepatocytes is EGFR and downstream BRG1-TERT axis. MLT might be used as a complimentary agent for alcoholics.

The mechanisms underlying autophagic defects in nonalcoholic steatohepatitis (NASH) remain largely unknown. We aimed to elucidate the roles of hepatic cyclooxygenase 1 (COX1) in autophagy and the pathogenesis of diet-induced steatohepatitis in mice. Human nonalcoholic fatty liver disease (NAFLD) liver samples were used to examine the protein expression of COX1 and the level of autophagy. Cox1^Δhepa mice and their wildtype littermates were generated and fed with 3 different NASH models. We found that hepatic COX1 expression was increased in patients with NASH and diet-induced NASH mice models accompanied by impaired autophagy. COX1 was required for basal autophagy in hepatocytes and liver specific COX1 deletion exacerbated steatohepatitis by inhibiting autophagy. Mechanistically, COX1 directly interacted with WD repeat domain, phosphoinositide interacting 2 (WIPI2), which was crucial for autophagosome maturation. Adeno-associated virus (AAV)-mediated rescue of WIPI2 reversed the impaired autophagic flux and improved NASH phenotypes in Cox1^Δhepa mice, indicating that COX1 deletion-mediated steatohepatitis was partially dependent on WIPI2-mediated autophagy. In conclusion, we demonstrated a novel role of COX1 in hepatic autophagy that protected against NASH by interacting with WIPI2. Targeting the COX1-WIPI2 axis may be a novel therapeutic strategy for NASH.