NPRL2 down-regulation facilitates the growth of hepatocellular carcinoma via the mTOR pathway and autophagy suppression.

Hepatocellular carcinoma (HCC) is a highly invasive malignancy. Recently, GATOR1 (Gap Activity TOward Rags 1) complexes have been shown to play an important role in regulating tumor growth. NPRL2 is a critical component of the GATOR1 complex. Therefore, this study used NPRL2 knockdown to investigate how GATORC1 regulates the prognosis and development of HCC via the mammalian target of rapamycin (mTOR) and autophagy signaling pathways. We established HepG2 cells with NPRL2 knockdown using small interfering RNA (siRNA) and short hairpin RNA (shRNA) systems. The siRNA-mediated and shRNA-mediated NPRL2 down-regulation significantly reduced the expression of NPRL2 and two other GATPOR1 complex components, NPRL3 and DEPDC5, in HepG2 cells; furthermore, the efficient down-regulation of NPRL2 protein expression by both the shRNA and siRNA systems enhanced the proliferation, migration, and colony formation in vitro. Additionally, the NPRL2 down-regulation significantly increased HCC growth in the subcutaneous and orthotopic xenograft mouse models. The NPRL2 down-regulation increased the Rag GTPases and mTOR activation and inhibited autophagy in vitro and in vivo. Moreover, the NPRL2 level in the tumors was significantly associated with mortality, recurrence, the serum alpha fetoprotein level, the tumor size, the American Joint Committee on Cancer stage, and the Barcelona Clinic Liver Cancer stage. Low NPRL2, NPRL3, DEPDC5, and LC3, and high p62 and mTOR protein expression in the tumors was significantly associated with disease-free survival and overall survival in 300 patients with HCC after surgical resection. Conclusion: The efficient down-regulation of NPRL2 significantly increased HCC proliferation, migration, and colony formation in vitro, and increased HCC growth in vivo. Low NPRL2 protein expression in the tumors was closely correlated with poorer clinical outcomes in patients with HCC. These results provide a mechanistic understanding of HCC and aid the development of treatments for HCC.

Association of Heavy Alcohol Intake and ALDH2 rs671 Polymorphism With Hepatocellular Carcinoma and Mortality in Patients With Hepatitis B Virus-Related Cirrhosis.

Importance: The role of heavy alcohol intake, aldehyde dehydrogenase 2 gene (ALDH2) rs671 polymorphism, and hepatitis B virus (HBV) infection in hepatocellular carcinoma (HCC) development and mortality remains uncertain. Objective: To investigate the association of heavy alcohol intake, ALDH2 rs671 polymorphism, and HBV infection with HCC development and mortality in patients with cirrhosis. Design, Setting, and Participants: This retrospective cohort study enrolled patients with cirrhosis with heavy alcoholism or/and HBV infection from January 2005 to December 2020. Patients were followed up through June 30, 2021. The current data analysis was performed from August 2021 to April 2022. Patients from 3 tertiary hospitals in Taiwan were enrolled. Exposures: Heavy alcohol intake was defined as consuming more than 80 g of ethanol each day for at least 5 years. Main Outcomes and Measures: The primary end point was newly developed HCC. The secondary end point was overall mortality. Results: Of 1515 patients with cirrhosis (342 with concomitant heavy alcoholism and HBV infection, 796 with HBV infection alone, and 377 with heavy alcoholism alone), 1277 (84.3%) were men, and their mean (SD) age was 49.5 (10.2) years; 746 patients had blood samples collected for ALDH2 rs671 polymorphism analysis. The 10-year cumulative incidences of HCC and mortality were significantly higher in patients with cirrhosis with concomitant HBV infection and alcoholism than in those with HBV infection alone or alcoholism alone. Heavy alcohol intake and the ALDH2 rs671 genotype (GA/AA) were associated with significantly increased risk of HCC and mortality in patients with HBV-related cirrhosis. In patients with cirrhosis with concomitant HBV infection and alcoholism, factors associated with risk of HCC were baseline serum HBV DNA (adjusted hazard ratio [aHR], 3.24; 95% CI, 1.43-7.31), antiviral therapy (aHR, 0.15; 95% CI, 0.05-0.39), alcohol intake (aHR, 1.78; 95% CI, 1.02-3.12), abstinence (aHR, 0.32; 95% CI, 0.18-0.59), and ALDH2 rs671 polymorphism (aHR, 5.61; 95% CI, 2.42-12.90). Factors associated with increased risk of mortality were abstinence (aHR, 0.25; 95% CI, 0.16-0.32), ALDH2 rs671 polymorphism (aHR, 1.58; 95% CI, 1.09-2.26), Child-Pugh class B vs A (aHR, 1.43; 95% CI, 1.13-2.25) and class C vs A (aHR, 1.98; 95% CI, 1.18-3.31), serum albumin (aHR, 0.61; 95% CI, 0.43-0.86), and HCC development (aHR, 1.68; 95% CI, 1.12-2.89). Conclusions and Relevance: These findings suggest that heavy alcohol intake and ALDH2 rs671 polymorphism are associated with significantly increased risk of HCC development and mortality in patients with HBV-related cirrhosis. Patients with these risk factors should be monitored closely for HCC.