BackgroundHepatocellular carcinoma (HCC) is an aggressive malignant disease with poor prognosis. Recent advances suggest the existence of cancer stem cells (CSCs) within liver cancer, which are considered to be responsible for tumor relapse, metastasis, and chemoresistance. However, novel therapeutic approaches for eradicating CSCs are yet to be established. Here, we aimed to identify the role of glutaminase 1 (GLS1) in stemness, and the feasibility that GLS1 serves as a therapeutic target for elimination CSCs as well as the possible mechanism.MethodsPublicly-available data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) was mined to unearth the association between GLS1 and stemness phenotype. Using big data, human tissues and multiple cell lines, we gained a general picture of GLS1 expression in HCC progression. We generated stable cell lines by lentiviral-mediated overexpression or CRISPR/Cas9-based knockout. Sphere formation assays and colony formation assays were employed to analyze the relationship between GLS1 and stemness. A series of bioinformatics analyses and molecular experiments including qRT-PCR, immunoblotting, flow cytometry, and immunofluorescence were employed to investigate the role of GLS1 in regulating stemness in vitro and in vivo.FindingsWe observed GLS1 (both KGA and GAC isoform) is highly expressed in HCC, and that high expression of GAC predicts a poor prognosis. GLS1 is exclusively expressed in the mitochondrial matrix. Upregulation of GLS1 is positively associated with advanced clinicopathological features and stemness phenotype. Targeting GLS1 reduced the expression of stemness-related genes and suppressed CSC properties in vitro. We further found GLS1 regulates stemness properties via ROS/Wnt/β-catenin signaling and that GLS1 knockout inhibits tumorigenicity in vivo.InterpretationTargeting GLS1 attenuates stemness properties in HCC by increasing ROS accumulation and suppressing Wnt/β-catenin pathway, which implied that GLS1 could serve as a therapeutic target for elimination of CSCs.

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide, because recurrence often occurs in most HCC patients undergoing hepatectomy. It is necessary to identify patients with high risk for recurrence and adopt effective therapies. An obstacle to monitor patients at high risk for poor prognosis has been the lack of useful predictive biomarkers. Fortunately, recent progress in system biology allows to screen the biomarkers for HCC prognosis in a high-throughput manner. In this study, we performed systematic Kaplan-Meier survival analysis of the whole mRNA transcriptomics based on the Cancer Genome Atlas project (TCGA) and developed a three-gene prognostic signature composing of three genes UPB1, SOCS2 and RTN3. The model was validated in two independent microarray data sets retrieved from Gene Expression Omnibus (GEO) and the expression pattern of these three predictive genes in HCC was confirmed by western blot and immunohistochemistry with our HCC samples. In conclusion, our results showed that this three-gene signature has prognostic value for HCC patients.

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PP2Acα plays an essential role in the proper termination of LR via the AKT/GSK3β/Cyclin D1 pathway. Our findings enrich the understanding of the molecular mechanism that controls the termination of LR and provides a potential therapeutic target for treating liver injury.