Cancer cells possess a unique metabolic phenotype that allows them to preferentially utilize glucose through aerobic glycolysis. This phenomenon is referred to as the “Warburg effect.” Accumulating evidence suggests that microRNAs (miRNAs), a class of small noncoding regulatory RNAs, interact with oncogenes/tumor suppressors and induce such metabolic reprograming in cancer cells. To systematically study the metabolic roles of miRNAs in cancer cells, we developed a gain‐of‐function miRNA screen in HeLa cells. Subsequent investigation of the characterized miRNAs indicated that miR‐199a‐5p acts as a suppressor for glucose metabolism. Furthermore, miR‐199a‐5p is often down‐regulated in human liver cancer, and its low expression level was correlated with a low survival rate, large tumor size, poor tumor differentiation status, high tumor‐node‐metastasis stage and the presence of tumor thrombus of patients. MicroRNA‐199a‐5p directly targets the 3′‐untranslated region of hexokinase 2 (HK2), an enzyme that catalyzes the irreversible first step of glycolysis, thereby suppressing glucose consumption, lactate production, cellular glucose‐6‐phosphate and adenosine triphosphate levels, cell proliferation, and tumorigenesis of liver cancer cells. Moreover, HK2 is frequently up‐regulated in liver cancer tissues and associated with poor patient outcomes. The up‐regulation of hypoxia‐inducible factor‐1α under hypoxic conditions suppresses the expression of miR‐199a‐5p and promotes glycolysis, whereas reintroduction of miR‐199a‐5p interferes with the expression of HK2, abrogating hypoxia‐enhanced glycolysis. Conclusion: miR‐199a‐5p/HK2 reprograms the metabolic process in liver cancer cells and provides potential prognostic predictors for liver cancer patients. (Hepatology 2015;62:1132‐1144)

It is widely accepted that chronic hepatitis B virus (HBV) infection is the result of an ineffective antiviral immune response against HBV infection. Our previous study found that the hepatitis B surface Ag (HBsAg) was related to decreased cytokine production induced by the TLR2 ligand (Pam3csk4) in PBMCs from chronic hepatitis B patients. In this study, we further explored the mechanism involved in the inhibitory effect of HBsAg on the TLR2 signaling pathway. The results showed that both Pam3csk4-triggered IL-12p40 mRNA expression and IL-12 production in PMA-differentiated THP-1 macrophage were inhibited by HBsAg in a dose-dependent manner, but the production of IL-1β, IL-6, IL-8, IL-10, and TNF-α was not influenced. The Pam3csk4-induced activation of NF-κB and MAPK signaling were further examined. The phosphorylation of JNK-1/2 and c-Jun was impaired in the presence of HBsAg, whereas the degradation of IκB-α, the nuclear translocation of p65, and the phosphorylation of p38 and ERK-1/2 were not affected. Moreover, the inhibition of JNK phosphorylation and IL-12 production in response to Pam3csk was observed in HBsAg-treated monocytes/macrophages (M/M_Φs) from the healthy donors and the PBMCs and CD14-positive M/M_Φs from chronic hepatitis B patients. Taken together, these results demonstrate that HBsAg selectively inhibits Pam3csk4- stimulated IL-12 production in M/M_Φs by blocking the JNK–MAPK pathway and provide a mechanism by which HBV evades immunity and maintains its persistence.

Metabolic reprogramming is often observed in carcinogenesis, but little is known about the aberrant metabolic genes involved in the tumorigenicity and maintenance of stemness in cancer cells. Sixty‐seven oncogenic metabolism‐related genes in liver cancer by in vivo CRISPR/Cas9 screening are identified. Among them, acetyl‐CoA carboxylase 1 (ACC1), aldolase fructose‐bisphosphate A (ALDOA), fatty acid binding protein 5 (FABP5), and hexokinase 2 (HK2) are strongly associated with stem cell properties. HK2 further facilitates the maintenance and self‐renewal of liver cancer stem cells. Moreover, HK2 enhances the accumulation of acetyl‐CoA and epigenetically activates the transcription of acyl‐CoA synthetase long‐chain family member 4 (ACSL4), leading to an increase in fatty acid β‐oxidation activity. Blocking HK2 or ACSL4 effectively inhibits liver cancer growth, and GalNac‐siHK2 administration specifically targets the growth of orthotopic tumor xenografts. These results suggest a promising therapeutic strategy for the treatment of liver cancer.