Based on an analysis of 1509 patients with HCC in Taiwan, immunization of infants against HBV reduces their risk of developing HCC as children and young adults. Improving HBV vaccination strategies and overcoming risk factors could reduce the incidence of liver cancer.
Glycine N-methyltransferase (GNMT) is a tumor suppressor for hepatocellular carcinoma (HCC). High rates of Gnmt knockout mice developed HCC. Epigenetic alteration and dysregulation of several pathways including wingless-type MMTV integration site (Wnt), mitogen-activated protein kinase (MAPK) and Janus kinase and signal transducer and activator of transcription (JAK-STAT) are associated with HCC development in Gnmt knockout mice. We hypothesized that GNMT may regulate signal transduction through interacting with other proteins directly. In this report, we identified a mammalian target of rapamycin (mTOR) inhibitor (DEP domain containing MTOR-interacting protein [DEPDC6/DEPTOR]) as a GNMT-binding protein by using yeast two-hybrid screening. Fluorescence resonance energy transfer assay demonstrated that the C-terminal half of GNMT interact with the PSD-95/Dlg1/ZO-1 (PDZ) domain of DEPDC6/DEPTOR. Immunohistochemical staining showed that 27.5% (14/51) of HCC patients had higher expression levels of DEPDC6/DEPTOR in the tumorous tissues than in tumor-adjacent tissues, especially among HCC patients with hepatitis B viral infection (odds ratio 10.3, 95% confidence interval [CI] 1.05-11.3) or patients with poor prognosis (death hazard ratio 4.51, 95% CI 1.60-12.7). In terms of molecular mechanism, knockdown of DEPDC6/DEPTOR expression in HuH-7 cells caused S6K and 4E-BP activation, but suppressed Akt. Overexpression of DEPDC6/DEPTOR activated Akt and increased survival of HCC cells. Overexpression of GNMT caused activation of mTOR/raptor downstream signaling and delayed G2/M cell cycle progression, which altogether resulted in cellular senescence. Furthermore, GNMT reduced proliferation of HuH-7 cells and sensitized them to rapamycin treatment both in vitro and in vivo. In conclusion, GNMT regulates HCC growth in part through interacting with DEPDC6/DEPTOR and modulating mTOR/raptor signaling pathway. Both GNMT and DEPDC6/DEPTOR are potential targets for developing therapeutics for HCC.
Nonalcoholic fatty liver disease (NAFLD) is associated with the development of metabolic syndromes and hepatocellular carcinoma (HCC). Cholesterol accumulation is related to NAFLD, whereas its detailed mechanism is not fully understood. Previously, we reported that glycine N-methyltransferase (GNMT) knockout (Gnmt ings and coimmunoprecipitation assays elucidated that the C conserved region (81-105 amino acids) of NPC2 interacts with the carboxyl-terminal fragment (171-295 amino acids) of GNMT. Confocal microscopy demonstrated that when cells were treated with low-density lipoprotein, NPC2 was released from lysosomes and interacts with GNMT in the cytosol. Overexpression of GNMT doubled the half-lives of both NPC2 isoforms and reduced cholesterol accumulation in cells. Furthermore, GNMT was downregulated in the liver tissues from patients suffering with NAFLD as well as from mice fed a high-fat diet, high-cholesterol diet or methionine/choline-deficient diet. In conclusion, our study demonstrated that GNMT regulates the homeostasis of cholesterol metabolism, and hepatic cholesterol accumulation may result from downregulation of GNMT and instability of its interactive protein NPC2. Novel therapeutics for steatohepatitis and HCC may be developed by using this concept.
Background: The main etiologies of hepatocellular carcinoma (HCC) were often hepatitis B virus (HBV) or C and alcohol, rarely autoimmune and biliary diseases. Nonalcoholic fatty liver disease (NAFLD) has been an emerging role that could lead to chronic liver disease, nonalcoholic steatohepatitis, cirrhosis, and eventually HCC in recent years. The aim of our study is to investigate and compare the clinical features of HCC in patients with NAFLD and HBV, including age, gender, cirrhosis, liver function tests, largest tumor size, and cancer stage at the time of diagnosis. The survival outcome was compared between the two groups and the significant predictors of mortality were also analyzed in all patients with HCC. Methods: Most patients with HCC were recruited from the database of Cancer Registries in Taipei City Hospital, Ren-Ai Branch, from 2011 to 2017; and the other patients consecutively from the HCC multidisciplinary conference between January 2018 and December 2019. NAFLD was defined as nonviral hepatitis B (negative HBsAg and either positive anti-HBs or negative anti-HBc), nonviral hepatitis C (negative antihepatitis C virus [HCV]), nonalcoholic (alcohol consumption of <30 g/d for men and <20 g/d for women) liver disease, or present or past histological or ultrasonographic evidence of fatty liver. Totally, 23 NAFLD-related and 156 HBV-related HCC patients were enrolled in our study for further analysis. Results: NAFLD-related HCC patients were significantly older (median age: 70.0 [61.0–79.0] years vs. 63.0 [56.0–72.0] years, p = 0.012) and heavier (median body mass index [BMI]: 26.6 [24.2–30] kg/m2 vs. 24.8 [22.0–27.1] kg/m2, p = 0.044) than those with HBV-related HCC. They were also more susceptible to diabetes mellitus (DM), and 60.9% (14 of 23) of them had this comorbidity compared with 29.5% (46 of 156) of those with HBV-related HCC (p = 0.003). Only 34.8% (8 of 23) and 71.2% (111 of 156) of patients with NAFLD- and HBV-related HCC were cirrhotic, respectively (p = 0.001). However, gender, tobacco use, international normalized ratio, albumin, creatinine, and cholesterol levels were not significantly different between the two groups. Tumor characteristics such as the Barcelona clinic liver cancer stage, largest tumor size, tumor number, extrahepatic metastasis, and treatment modalities had no significant difference between such groups. According to the Kaplan–Meier method analysis, the overall survival was not significantly different between these two patient groups (log-rank test, p = 0.101). To evaluate which patient group would lead to poor prognosis, we analyzed the survival of all patients through multivariate Cox proportional hazard regression after controlling other factors that may influence the hazard ratio. The analysis revealed that NAFLD and HBV infection as the cause of HCC are not risk factors of poor prognosis. Conclusion: In conclusion, our study showed NAFLD-related HCC patients were older, heavier, and more had DM than HBV-related. In addition, more NAFLD-related HCC patients were noncirrhotic than HBV-related. The survival rate was similar between NAFLD and HBV-related HCC patients.
Our findings suggest that the severity of hepatitis C virus (HCV)-related liver injury is associated with patient age at biopsy. Both serum iron indices and hepatic iron deposition show correlation with serum indices of chronic liver disease but are not related to grade and stage of liver histology.
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