Oncogenic Roles of Laminin Subunit Gamma-2 in Intrahepatic Cholangiocarcinoma via Promoting EGFR Translation.

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal biliary epithelial cancer in the liver. Here, Laminin subunit gamma-2 (LAMC2) with important oncogenic roles in iCCA is discovered. In a total of 231 cholangiocarcinoma patients (82% of iCCA patients) across four independent cohorts, LAMC2 is significantly more abundant in iCCA tumor tissue compared to normal bile duct and non-tumor liver. Among 26.3% of iCCA patients, LAMC2 gene is amplified, contributing to its over-expression. Functionally, silencing LAMC2 significantly blocks tumor formation in orthotopic iCCA mouse models. Mechanistically, it promotes EGFR protein translation via interacting with nascent unglycosylated EGFR in the endoplasmic reticulum (ER), resulting in activated EGFR signaling. LAMC2-mediated EGFR translation also depends on its interaction with the ER chaperone BiP via their C-terminus. Together LAMC2 and BiP generate a binding "pocket" of nascent EGFR and facilitate EGFR translation. Consistently, LAMC2-high iCCA patients have poor prognosis in two iCCA cohorts. LAMC2-high iCCA cells are highly sensitive to EGFR tyrosine kinase inhibitors (TKIs) treatment both in vitro and in vivo. Together, these data demonstrate LAMC2 as an oncogenic player in iCCA by promoting EGFR translation and an indicator to identify iCCA patients who may benefit from available EGFR-targeted TKIs therapies.

Blocking hepatocarcinogenesis by a cytochrome P450 family member with female-preferential expression.

OBJECTS: The incidence of hepatocellular carcinoma (HCC) shows an obvious male dominance in rodents and humans. We aimed to identify the key autosomal liver-specific sex-related genes and investigate their roles in hepatocarcinogenesis. DESIGN: Two HCC cohorts (n=551) with available transcriptome and metabolome data were used. Class comparisons of omics data and ingenuity pathway analysis were performed to explore sex-related molecules and their associated functions. Functional assays were employed to investigate roles of the key candidates, including cellular assays, molecular assays and multiple orthotopic HCC mouse models. RESULTS: A global comparison of multiple omics data revealed 861 sex-related molecules in non-tumour liver tissues between female and male HCC patients, which denoted a significant suppression of cancer-related diseases and functions in female liver than male. A member of cytochrome P450 family, CYP39A1, was one of the top liver-specific candidates with significantly higher levels in female vs male liver. In HCC tumours, CYP39A1 expression was dramatically reduced in over 90% HCC patients. Exogenous CYP39A1 significantly blocked tumour formation in both female and male mice and partially reduced the sex disparity of hepatocarcinogenesis. The HCC suppressor role of CYP39A1 did not rely on its known P450 enzyme activity but its C-terminal region, by which CYP39A1 impeded the transcriptional activation activity of c-Myc, leading to a significant inhibition of hepatocarcinogenesis. CONCLUSIONS: The liver-specific CYP39A1 with female-preferential expression was a strong suppressor of HCC development. Strategies to up-regulate CYP39A1 might be promising methods for HCC treatment in both women and men in future.

MiR-125b Loss Activated HIF1α/pAKT Loop, Leading to Transarterial Chemoembolization Resistance in Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Transarterial chemoembolization (TACE) is a standard locoregional therapy for patients with hepatocellular carcinoma (HCC) patients with a variable overall response in efficacy. We aimed to identify key molecular signatures and related pathways leading to HCC resistance to TACE, with the hope of developing effective approaches in preselecting patients with survival benefit from TACE. APPROACH AND RESULTS: Four independent HCC cohorts with 680 patients were used. MicroRNA (miRNA) transcriptome analysis in patients with HCC revealed a 41-miRNA signature related to HCC recurrence after adjuvant TACE, and miR-125b was the top reduced miRNA in patients with HCC recurrence. Consistently, patients with HCC with low miR-125b expression in tumor had significantly shorter time to recurrence following adjuvant TACE in two independent cohorts. Loss of miR-125b in HCC noticeably activated the hypoxia inducible factor 1 alpha subunit (HIF1α)/pAKT loop in vitro and in vivo. miR-125b directly attenuated HIF1α translation through binding to HIF1A internal ribosome entry site region and targeting YB-1, and blocked an autocrine HIF1α/platelet-derived growth factor ß (PDGFß)/pAKT/HIF1α loop of HIF1α translation by targeting the PDGFß receptor. The miR-125b-loss/HIF1α axis induced the expression of CD24 and erythropoietin (EPO) and enriched a TACE-resistant CD24-positive cancer stem cell population. Consistently, patients with high CD24 or EPO in HCC had poor prognosis following adjuvant TACE therapy. Additionally, in patients with HCC having TACE as their first-line therapy, high EPO in blood before TACE was also noticeably related to poor response to TACE. CONCLUSIONS: MiR-125b loss activated the HIF1α/pAKT loop, contributing to HCC resistance to TACE and the key nodes in this axis hold the potential in assisting patients with HCC to choose TACE therapy.

Loss of miR-192-5p initiates a hyperglycolysis and stemness positive feedback in hepatocellular carcinoma.

BACKGROUND: Emerging studies revealed that cancer stem cells (CSCs) possessed peculiar metabolic properties, which however remained largely unknown in hepatocellular carcinoma (HCC). Genetic silencing of liver-abundant miR-192-5p was a key feature for multiple groups of CSC-positive HCCs. We thus aimed to investigate essential metabolic features of hepatic CSCs via using HCCs with miR-192-5p silencing as a model. METHODS: Datasets from two independent HCC cohorts were used. Data integration analyses of miR-192-5p with metabolome and mRNA transcriptome data in HCC Cohort 1 were performed to investigate miR-192-5p related metabolic features, which was further validated in Cohort 2. Cellular and molecular assays were performed to examine whether and how miR-192-5p regulated the identified metabolic features. Co-culture systems consisting of HCC cells and LX2 (human hepatic stellate cell line) or THP1 (human monocyte cell line) were established to explore effects of the identified metabolic properties on stemness features of HCC cells via interacting with co-cultured non-tumor cells. RESULTS: High levels of glycolysis-related metabolites and genes were present in HCCs with low miR-192-5p and CSC-positive HCCs in two independent HCC cohorts. miR-192-5p knockout cells displayed CSC features and miR-192-5p loss led to an enhanced glycolytic phenotype via upregulating three bona fide targets, GLUT1 and PFKFB3 (two glycolytic enzymes) and c-Myc (regulating glycolytic genes' expression). Meanwhile, c-Myc suppressed miR-192-5p transcription, ensuring a low-miR-192-5p/high-c-Myc loop to maintain hyperglycolysis. Moreover, over-produced lactic acid from hyperglycolytic HCC cells stimulated the ERK phosphorylation of co-cultured LX2 and THP1 non-tumor cells partially via NDRG3 and MCT1, which in turn promoted cell malignancy and stemness of HCC cells. Consistently, HCC patients with low level of miR-192-5p in their tumor tissues and high level of NDRG3 or MCT1 in their non-tumor tissues had the shortest overall survival. CONCLUSIONS: In CSC-positive HCCs, miR-192-5p loss enhanced glycolysis and over produced lactate might further increase HCC malignant features via interacting with environmental non-tumor cells.

Transcriptome integration analysis in hepatocellular carcinoma reveals discordant intronic miRNA-host gene pairs in expression.

Intronic miRNAs, residing in intronic regions of host genes, are thought to be co-transcribed from their host genes and present consistent expression patterns with host genes. Recent studies reported a few intronic miRNAs with discordant expression with their host genes. We therefore aimed to understand the expression pattern of intronic miRNAs and their host genes in hepatocellular carcinoma (HCC) and reveal possible associated molecular mechanisms. Our genome wide integration analysis of miRNA and mRNA transcriptomes, in three dataset from 550 patients with HCC, found that a large amount of miRNA-host gene pairs were discordantly expressed. Consistent results were also revealed in 775 breast cancer patients. Further, most of HCC-related intronic miRNAs were predicted to have distinct upstream regulators and independent proximal promoter signals from host genes. The discordant expression of representative pairs, miR-26s/CTDSPs, was validated experimentally. We have also identified the independent transcriptional start site, promoter signal, and transcriptional factor of miR-26b from its host gene. Collectively, discordant expression of intronic miRNAs and their host genes was relatively ubiquitous and the intronic miRNA "independent transcription" may partially contribute to such a phenotype.

Single tumor-initiating cells evade immune clearance by recruiting type II macrophages.

Tumor infiltrated type II (M2) macrophages promote tumorigenesis by suppressing immune clearance, promoting proliferation, and stimulating angiogenesis. Interestingly, macrophages were also found to enrich in small foci of altered hepatocytes containing liver tumor-initiating cells (TICs). However, whether and how TICs specifically recruit macrophages and the function of these macrophages in tumor initiation remain unknown due to technical difficulties. In this study, by generating genetically defined liver TICs, we demonstrate that TICs actively recruit M2 macrophages from as early as the single-cell stage. Elimination of TIC-associated macrophages (TICAMs) abolishes tumorigenesis in a manner dependent on the immune system. Mechanistically, activation of the Hippo pathway effector Yes-associated protein (YAP) underlies macrophage recruitment by TICs. These results demonstrate for the first time that macrophages play a decisive role in the survival of single TICs in vivo and provide a proof of principle for TIC elimination by targeting YAP or M2 macrophages.