Overexpression of glutamine synthetase in human primary liver cancer

Hub genes, key miRNAs and interaction analyses in type 2 diabetes mellitus: an integrative in silico approach

Diabetes is a rising global metabolic disorder and leads to long-term consequences. As a multifactorial disease, the gene-associated mechanisms are important to know. This study applied a bioinformatics approach to explore the molecular underpinning of type 2 diabetes mellitus through differential gene expression analysis. We used microarray datasets GSE16415 and GSE29226 to identify differentially expressed genes between type 2 diabetes and normal samples using R software. Following that, using the STRING database, the protein-protein interaction network was constructed and further analyzed by Cytoscape software. The EnrichR database was used for Gene Ontology and pathway enrichment analysis to explore key pathways and functional annotations of hub genes. We also used miRTarBase and TargetScan databases to predict miRNAs targeting hub genes. We identified 21 hub genes in type 2 diabetes, some showing more significant changes in the PPI network. Our results revealed that GLUL, SLC32A1, PC, MAPK10, MAPT, and POSTN genes are more important in the PPI network and can be experimentally investigated as therapeutic targets. Hsa-miR-492 and hsa-miR-16-5p are suggested for diagnosis and prognosis by targeting GLUL, SLC32A1, PC, MAPK10, and MAPT genes involved in the insulin signaling pathway. Insight: Type 2 diabetes, as a rising global and multifactorial disorder, is important to know the gene-associated mechanisms. In an integrative bioinformatics analysis, we integrated different finding datasets to put together and find valuable diagnostic and prognostic hub genes and miRNAs. In contrast, genes, RNAs, and enzymes interact systematically in pathways. Using multiple databases and software, we identified differential expression between hub genes of diabetes and normal samples. We explored different protein-protein interaction networks, gene ontology, key pathway analysis, and predicted miRNAs that target hub genes. This study reported 21 significant hub genes and some miRNAs in the insulin signaling pathway for innovative and potential diagnostic and therapeutic purposes.

Glutamine synthetase and hepatocellular carcinoma

Glutamine synthetase (GS) is an enzyme that converts ammonia and glutamate to glutamine using adenosine triphosphate. GS is expressed in the brain, kidney, and liver tissues under normal physiological conditions. GS is involved in abnormal lipid metabolism of the liver by catalyzing de novo synthesis of glutamine, thereby inducing liver inflammation. Metabolic dysfunction-associated steatotic liver diseases (MASLD), such as Metabolic Associated Fatty Liver Disease and Metabolic Associated Steato Hepatitis, are considered risk factors for HCC. GS may also be involved in the development and progression of hepatocellular carcinoma (HCC) through other signaling pathways, including the rapamycin (mTOR) and Wnt/β-catenin signaling pathways. Furthermore, the correct combination of HSP70, GPC3, and GS can improve the accuracy and precision of HCC diagnosis. However, the prognostic value of GS in different HCC populations remains controversial. The expression of GS affects the sensitivity of HCC cells to radiotherapy and chemotherapy. In addition, immunotherapy has been approved for the treatment of advanced HCC. This article delves into the development and application of GS in HCC, laying a theoretical foundation for the subsequent exploration of GS as a potential target for treating HCC.

HCC biomarkers - state of the old and outlook to future promising biomarkers and their potential in everyday clinical practice

Hepatocellular carcinoma (HCC) is one of the most common and deadly tumors worldwide. Management of HCC depends on reliable biomarkers for screening, diagnosis, and monitoring of the disease, as well as predicting response towards therapy and safety. To date, imaging has been the established standard technique in the diagnosis and follow-up of HCC. However, imaging techniques have their limitations, especially in the early detection of HCC. Therefore, there is an urgent need for reliable, non/minimal invasive biomarkers. To date, alpha-fetoprotein (AFP) is the only serum biomarker used in clinical practice for the management of HCC. However, AFP is of relatively rather low quality in terms of specificity and sensitivity. Liquid biopsies as a source for biomarkers have become the focus of clinical research. Our review highlights alternative biomarkers derived from liquid biopsies, including circulating tumor cells, proteins, circulating nucleic acids, and exosomes, and their potential for clinical application. Using defined combinations of different biomarkers will open new perspectives for diagnosing, treating, and monitoring HCC.

Glutamine Synthetase Contributes to the Regulation of Growth, Conidiation, Sclerotia Development, and Resistance to Oxidative Stress in the Fungus Aspergillus flavus

The basic biological function of glutamine synthetase (Gs) is to catalyze the conversion of ammonium and glutamate to glutamine. This synthetase also performs other biological functions. However, the roles of Gs in fungi, especially in filamentous fungi, are not fully understood. Here, we found that conditional disruption of glutamine synthetase (AflGsA) gene expression in Aspergillus flavus by using a xylose promoter leads to a complete glutamine deficiency. Supplementation of glutamine could restore the nutritional deficiency caused by AflGsA expression deficiency. Additionally, by using the xylose promoter for the downregulation of AflgsA expression, we found that AflGsA regulates spore and sclerotic development by regulating the transcriptional levels of sporulation genes abaA and brlA and the sclerotic generation genes nsdC and nsdD, respectively. In addition, AflGsA was found to maintain the balance of reactive oxygen species (ROS) and to aid in resisting oxidative stress. AflGsA is also involved in the regulation of light signals through the production of glutamine. The results also showed that the recombinant AflGsA had glutamine synthetase activity in vitro and required the assistance of metal ions. The inhibitor molecule L-α-aminoadipic acid suppressed the activity of rAflGsA in vitro and disrupted the morphogenesis of spores, sclerotia, and colonies in A. flavus. These results provide a mechanistic link between nutrition metabolism and glutamine synthetase in A. flavus and suggest a strategy for the prevention of fungal infection.

Implications of a Neuronal Receptor Family, Metabotropic Glutamate Receptors, in Cancer Development and Progression

Cancer is the second leading cause of death, and incidences are increasing globally. Simply defined, cancer is the uncontrolled proliferation of a cell, and depending on the tissue of origin, the cancer etiology, biology, progression, prognosis, and treatment will differ. Carcinogenesis and its progression are associated with genetic factors that can either be inherited and/or acquired and are classified as an oncogene or tumor suppressor. Many of these genetic factors converge on common signaling pathway(s), such as the MAPK and PI3K/AKT pathways. In this review, we will focus on the metabotropic glutamate receptor (mGluR) family, an upstream protein that transmits extracellular signals into the cell and has been shown to regulate many aspects of tumor development and progression. We explore the involvement of members of this receptor family in various cancers that include breast cancer, colorectal cancer, glioma, kidney cancer, melanoma, oral cancer, osteosarcoma, pancreatic cancer, prostate cancer, and T-cell cancers. Intriguingly, depending on the member, mGluRs can either be classified as oncogenes or tumor suppressors, although in general most act as an oncogene. The extensive work done to elucidate the role of mGluRs in various cancers suggests that it might be a viable strategy to therapeutically target glutamatergic signaling.

Adipocytic Glutamine Synthetase Upregulation via Altered Histone Methylation Promotes 5FU Chemoresistance in Peritoneal Carcinomatosis of Colorectal Cancer

The development of resistance to 5-fluorouracil (5FU) chemotherapy is a major handicap for sustained effective treatment in peritoneal carcinomatosis (PC) of colorectal cancer (CRC). Metabolic reprogramming of adipocytes, a component of the tumor microenvironment and the main composition of peritoneum, plays a significant role in drug resistance of PC, with the mechanisms being not fully understood. By performing metabolomics analysis, we identified glutamine (Gln), an important amino acid, inducing resistance to 5FU-triggered tumor suppression of CRC-PC through activating mTOR pathway. Noteworthily, genetic overexpression of glutamine synthetase (GS) in adipocytes increased chemoresistance to 5FU in vitro and in vivo while this effect was reversed by pharmacological blockage of GS. Next, we showed that methionine metabolism were enhanced in amino acid omitted from CRC-PC of GS transgenic (Tg^GS) mice, increasing intracellular levels of S-carboxymethy-L-cys. Moreover, loss of dimethylation at lysine 4 of histone H3 (H3k4me2) was found in adipocytes in vitro, which may lead to increased expression of GS. Furthermore, biochemical inhibition of lysine specific demethylase 1 (LSD1) restored H3k4me2, thereby reducing GS-induced chemoresistance to 5FU. Our findings indicate that GS upregulation-induced excessive of Gln in adipocytes via altered histone methylation is potential mediator of resistance to 5FU chemotherapy in patients with CRC-PC.

USP15 antagonizes CRL4CRBN-mediated ubiquitylation of glutamine synthetase and neosubstrates

Targeted protein degradation by the ubiquitin-proteasome system represents a new strategy to destroy pathogenic proteins in human diseases, including cancer and neurodegenerative diseases. The immunomodulatory drugs (IMiDs) thalidomide, lenalidomide, and pomalidomide have revolutionized the treatment of patients with multiple myeloma (MM) and other hematologic malignancies, but almost all patients eventually develop resistance to IMiDs. CRBN, a substrate receptor of CUL4-RBX1-DDB1-CRBN (CRL4^CRBN) E3 ubiquitin ligase, is a direct target for thalidomide teratogenicity and antitumor activity of IMiDs (now known as Cereblon E3 ligase modulators: CELMoDs). Despite recent advances in developing potent CELMoDs and CRBN-based proteolysis-targeting chimeras (PROTACs), many questions apart from clinical efficacy remain unanswered. CRBN is required for the action of IMiDs, but its protein expression levels do not correlate with intrinsic resistance to IMiDs in MM cells, suggesting other factors involved in regulating resistance to IMiDs. Our recent work revealed that the CRL4^CRBN-p97 pathway is required for degradation of natural substrate glutamine synthetase (GS) and neosubstrates. Here, I show that USP15 is a key regulator of the CRL4^CRBN-p97 pathway to control stability of GS and neosubstrates IKZF1, IKZF3, CK1-α, RNF166, GSPT1, and BRD4, all of which are crucial drug targets in different types of cancer. USP15 antagonizes ubiquitylation of CRL4^CRBN target proteins, thereby preventing their degradation. Notably, USP15 is highly expressed in IMiD-resistant cells, and depletion of USP15 sensitizes these cells to lenalidomide. Inhibition of USP15 represents a valuable therapeutic opportunity to potentiate CELMoD and CRBN-based PROTAC therapies for the treatment of cancer.

MYC Rules: Leading Glutamine Metabolism toward a Distinct Cancer Cell Phenotype

Simple Summary

In the last decade, metabolic reprogramming has emerged as a driving characteristic of cancer cells. The MYC oncogene, a transcription factor, has become of growing interest as a fundamental driver of differential cancer cell metabolism. Furthermore, the non-essential amino acid glutamine is deemed to be an important nutrient for cancer cells. In fact, glutamine can integrate into a wide variety of metabolic pathways, from energy metabolism to nucleotide synthesis. This review offers a comprehensive and specific overview of recent discoveries in the regulation of MYC oncogene activation on glutamine metabolism in cancer cells.

Abstract

Metabolic reprogramming and deregulated cellular energetics are hallmarks of cancer. The aberrant metabolism of cancer cells is thought to be the product of differential oncogene activation and tumor suppressor gene inactivation. MYC is one of the most important oncogenic drivers, its activation being reported in a variety of cancer types and sub-types, among which are the most prevalent and aggressive of all malignancies. This review aims to offer a comprehensive overview and highlight the importance of the c-Myc transcription factor on the regulation of metabolic pathways, in particular that of glutamine and glutaminolysis. Glutamine can be extensively metabolized into a variety of substrates and be integrated in a complex metabolic network inside the cell, from energy metabolism to nucleotide and non-essential amino acid synthesis. Together, understanding metabolic reprogramming and its underlying genetic makeup, such as MYC activation, allows for a better understanding of the cancer cell phenotype and thus of the potential vulnerabilities of cancers from a metabolic standpoint.

Two Metabolomics Phenotypes of Human Hepatocellular Carcinoma in Non-Alcoholic Fatty Liver Disease According to Fibrosis Severity

Non-Alcoholic Fatty Liver Disease (NAFLD) is considered as the forthcoming predominant cause for hepatocellular carcinoma (HCC). NAFLD-HCC may rise in non-cirrhotic livers in 40 to 50% of patients. The aim of this study was to identify different metabolic pathways of HCC according to fibrosis level (F0F1 vs. F3F4). A non-targeted metabolomics strategy was applied. We analyzed 52 pairs of human HCC and adjacent non-tumoral tissues which included 26 HCC developed in severe fibrosis or cirrhosis (F3F4) and 26 in no or mild fibrosis (F0F1). Tissue extracts were analyzed using ¹H-Nuclear Magnetic Resonance spectroscopy. An optimization evolutionary method based on genetic algorithm was used to identify discriminant metabolites. We identified 34 metabolites differentiating the two groups of NAFLD-HCC according to fibrosis level, allowing us to propose two metabolomics phenotypes of NAFLD-HCC. We showed that HCC-F0F1 mainly overexpressed choline derivatives and glutamine, whereas HCC-F3F4 were characterized by a decreased content of monounsaturated fatty acids (FA), an increase of saturated FA and an accumulation of branched amino acids. Comparing HCC-F0F1 and HCC-F3F4, differential expression levels of glucose, choline derivatives and phosphoethanolamine, monounsaturated FA, triacylglycerides were identified as specific signatures. Our metabolomics analysis of HCC tissues revealed for the first time two phenotypes of HCC developed in NAFLD according to fibrosis level. This study highlighted the impact of the underlying liver disease on metabolic reprogramming of the tumor.

Glutamate receptor ionotropic, kainate 1 serves as a novel tumor suppressor of colorectal carcinoma and predicts clinical prognosis

Colorectal cancer (CRC) is one of the most malignant cancers worldwide. However, the mechanisms of initiation and development of CRC are still largely unclear. The present study aimed to investigate the biological function and prognosis of glutamate receptor ionotropic, kainate 1 (GRIK1) in CRC. GRIK1 expression levels were analyzed in tissue microarrays containing 80 primary CRC samples using immunohistochemistry (IHC). The association between GRIK1 expression levels, clinicopathological factors and the prognosis was also investigated using Spearman's correlation analysis and Kaplan-Meier analysis, respectively. After genetic knockdown or overexpression of GRIK1, invasion/migration assays, proliferation assay, soft agar/colony formation assays, western blotting, reverse transcription-quantitative PCR and tumor xenograft models were used to investigate the function of GRIK1 both in vitro in two CRC cell lines, HCT116 and SW620, and in vivo. The results revealed that the expression levels of GRIK1 were significantly downregulated in CRC samples. Furthermore, IHC analysis indicated that the downregulated expression levels of GRIK1 were significantly associated with lymph node status and tumor size. In addition, patients with CRC with low GRIK1 expression levels demonstrated a consistently poor overall survival. The overexpression of GRIK1 inhibited the proliferation, colony formation, migration, invasion and epithelial-mesenchymal transition of HCT116 cells in vitro. In contrast, the genetic knockdown of GRIK1 promoted the proliferative, colony forming, migratory and invasive abilities of SW620 cells in vitro. Moreover, the overexpression of GRIK1 inhibited tumor growth, and liver and lung metastasis of CRC in vivo. In conclusion, the findings of the present study suggested that GRIK1 may serve as a tumor suppressor in CRC, and upregulated expression levels of GRIK1 may predict an improved prognosis for patients with CRC.

NASH, Fibrosis and Hepatocellular Carcinoma: Lipid Synthesis and Glutamine/Acetate Signaling

Primary liver cancer is predicted to be the sixth most common cancer and the fourth leading cause of cancer mortality worldwide. Recent studies identified nonalcoholic fatty liver disease (NAFLD) as the underlying cause in 13-38.2% of patients with hepatocellular carcinoma unrelated to viral hepatitis and alcohol abuse. NAFLD progresses to nonalcoholic steatohepatitis (NASH), which increases the risk for the development of liver fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD is characterized by dysregulation of lipid metabolism. In addition, lipid metabolism is effected not only in NAFLD, but also in a broad range of chronic liver diseases and tumor development. Cancer cells manipulate a variety of metabolic pathways, including lipid metabolism, in order to build up their own cellular components. Identifying tumor dependencies on lipid metabolism would provide options for novel targeting strategies. This review article summarizes the research evidence on metabolic reprogramming and focuses on lipid metabolism in NAFLD, NASH, fibrosis, and cancer. As alternative routes of acetyl-CoA production for fatty acid synthesis, topics on glutamine and acetate metabolism are included. Further, studies on small compound inhibitors targeting lipid metabolism are discussed. Understanding reprogramming strategies in liver diseases, as well as the visualization of the metabolism reprogramming networks, could uncover novel therapeutic options.

Metabolic Signaling Cascades Prompted by Glutaminolysis in Cancer

Simple Summary

Within the last few years, accumulating evidences suggest the involvement of altered metabolisms in human diseases including cancer. Metabolism is defined as the sum of biochemical processes in living organisms that produce and consume energy. Tumor growth requires restructuring of cellular metabolism to meet the increasing demand for building blocks to support the ever-increasing cancer cell numbers. The principle of perturbed metabolism in tumors is known for 50–60 years, it regains greater appreciation within the last few years with the realization that there is interdependency between metabolism and all aspects of cellular function including regulation and control of cell growth. Tumor cells do not need stimulation signals from the surrounding environment to promote cell proliferation; in some cases, the tumor cells can generate their own growth signals. In order to support the continuous tumor cell growth even under stressful conditions, a change in metabolism is necessary to fulfill the continuous demand for energy and building blocks. A better understanding of the relationship between tumor environment and altered cell metabolisms will provide valuable insights to design innovative approaches to limit the supply of energy and macromolecules for the treatment of cancer including melanoma.

Abstract

Aberrant glutamatergic signaling has been implicated in altered metabolic activity and the demand to synthesize biomass in several types of cancer including melanoma. In the last decade, there has been a significant contribution to our understanding of metabolic pathways. An increasing number of studies are now emphasizing the importance of glutamate functioning as a signaling molecule and a building block for cancer progression. To that end, our group has previously illustrated the role of glutamatergic signaling mediated by metabotropic glutamate receptor 1 (GRM1) in neoplastic transformation of melanocytes in vitro and spontaneous development of metastatic melanoma in vivo. Glutamate, the natural ligand of GRM1, is one of the most abundant amino acids in humans and the predominant excitatory neurotransmitter in the central nervous system. Elevated levels of glutaminolytic mitochondrial tricarboxylic acid (TCA) cycle intermediates, especially glutamate, have been reported in numerous cancer cells. Herein, we highlight and critically review metabolic bottlenecks that are prevalent during tumor evolution along with therapeutic implications of limiting glutamate bioavailability in tumors.

The Significance of Circulating Tumor Cells in Patients with Hepatocellular Carcinoma: Real-Time Monitoring and Moving Targets for Cancer Therapy

Hepatocellular carcinoma (HCC) is ranked as the sixth most common cancer around the world. With the emergence of the state-of-the-art modalities lately, such as liver transplantation, image-guided ablation, and chemoembolization, the death rate is still high due to high metastasis rate after therapy. Observation by biannual ultrasonography allows effective diagnosis at an early stage for candidates with no extrahepatic metastasis, but its effectiveness still remains unsatisfactory. Developing a new test with improved effectiveness and specificity is urgently needed for HCC diagnosis, especially for patients after first line therapy. Circulating tumor cells (CTCs) are a small sub-population of tumor cells in human peripheral blood, they release from the primary tumor and invade into the blood circulatory system, thereby residing into the distal tissues and survive. As CTCs have specific and aggressive properties, they can evade from immune defenses, induce gene alterations, and modulate signal transductions. Ultimately, CTCs can manipulate tumor behaviors and patient reactions to anti-tumor treatment. Given the fact that in HCC blood is present around the immediate vicinity of the tumor, which allows thousands of CTCs to release into the blood circulation daily, so CTCs are considered to be the main cause for HCC occurrence, and are also a pivotal factor for HCC prognosis. In this review, we highlight the characteristics and enrichment strategies of CTCs, and focus on the use of CTCs for tumor evaluation and management in patients with HCC.

Functional Analysis of a Glutamine Biosynthesis Protein from a Psychrotrophic Bacterium, Cryobacterium soli GCJ02

A putative glutamine synthetase (GS) was detected in a psychrophilic bacterium, Cryobacterium soli GCJ02. For gaining greater insight into its functioning, the gene was cloned and expressed in a heterologous host, Escherichia coli. The monomer enzyme with a molecular weight of 53.03 kDa was expressed primarily in cytosolic compartment. The enzyme activity was detected using glutamate and ATP. The optimum conditions of its biosynthesis were observed to be 60 °C and pH value 7.5. Its thermostability was relatively high with a half-life of 50 min at 40 °C. GS activity was enhanced in the presence of metal ions such as Mg²⁺ and Mn²⁺, whereas Fe²⁺, Cu²⁺ and Ca²⁺ proved inhibitory. The consensus pattern [EXE]-D-KP-[XGXGXH] in the GS lies between residues 132 and 272. The catalytic active sites consisting of EAE and NGSGMH were verified by site-directed mutagenesis. Based on the analysis of the consensus pattern, the GS/glutamate synthase cycle of C. soli GCJ02 is expected to contribute to the GS synthesic activity.

Glutamine synthetase promotes tumor invasion in hepatocellular carcinoma through mediating epithelial-mesenchymal transition

AIM

Glutamine synthetase (GS) levels increase gradually with the development of hepatocellular carcinogenesis. In this study, we aimed to investigate the clinical significance of GS and the underlying mechanism of GS promoting hepatocellular carcinoma (HCC) invasion.

METHODS

Serum concentration of GS and α-fetoprotein (AFP) in HCC patients, liver cirrhosis patients, and healthy individuals were detected. The GS-mRNA level and its prognostic value were explored in an independent HCC cohort from The Cancer Genome Atlas database. GS expression in HCC tissue and matched para-tumor tissue was determined. The effect of GS on HCC invasion was assessed in vitro and in vivo.

RESULTS

The serum GS and AFP level in HCC patients was higher than that in healthy controls and liver cirrhosis patients. The area under the receiver operating characteristic curve for HCC diagnosis was 0.848 and 0.861 for GS and AFP, respectively. The area under the receiver operating characteristic curve of GS for diagnosis of AFP-negative HCC was 0.913. Combining GS with AFP achieved a diagnostic sensitivity and specificity of 82.5% and 93%, respectively. The GS level was higher in tumor tissues than that in para-tumor tissues. High GS expression was associated with poor prognosis of moderately differentiated HCC patients. In vitro, GS exerted an influence on HCC cell migration by mediating epithelial-mesenchymal transition. The lung and liver metastatic model of HCC further confirmed that GS expression affected the invasion of HCC cells in vivo.

CONCLUSIONS

GS is a useful biomarker for HCC diagnosis, especially for AFP-negative patients. In addition, GS affects HCC metastasis through mediating epithelial-mesenchymal transition.

New Labyrinth Microfluidic Device Detects Circulating Tumor Cells Expressing Cancer Stem Cell Marker and Circulating Tumor Microemboli in Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is one of the most lethal cancers with a high mortality and recurrence rate. Circulating tumor cell (CTC) detection offers various opportunities to advance early detection and monitoring of HCC tumors which is crucial for improving patient outcome. We developed and optimized a novel Labyrinth microfluidic device to efficiently isolate CTCs from peripheral blood of HCC patients. CTCs were identified in 88.1% of the HCC patients over different tumor stages. The CTC positivity rate was significantly higher in patients with more advanced HCC stages. In addition, 71.4% of the HCC patients demonstrated CTCs positive for cancer stem cell marker, CD44, suggesting that the major population of CTCs could possess stemness properties to facilitate tumor cell survival and dissemination. Furthermore, 55% of the patients had the presence of circulating tumor microemboli (CTM) which also correlated with advanced HCC stage, indicating the association of CTM with tumor progression. Our results show effective CTC capture from HCC patients, presenting a new method for future noninvasive screening and surveillance strategies. Importantly, the detection of CTCs with stemness markers and CTM provides unique insights into the biology of CTCs and their mechanisms influencing metastasis, recurrence and therapeutic resistance.

Mitochondrial determinants of chemoresistance

Chemoresistance constitute nowadays the major contributor to therapy failure in most cancers. There are main factors that mitigate cell response to therapy, such as target organ, inherent sensitivity to the administered compound, its metabolism, drug efflux and influx or alterations on specific cellular targets, among others. We now know that intrinsic properties of cancer cells, including metabolic features, substantially contribute to chemoresistance. In fact, during the last years, numerous reports indicate that cancer cells resistant to chemotherapy demonstrate significant alterations in mitochondrial metabolism, membrane polarization and mass. Metabolic activity and expression of several mitochondrial proteins are modulated under treatment to cope with stress, making these organelles central players in the development of resistance to therapies. Here, we review the role of mitochondria in chemoresistant cells in terms of metabolic rewiring and function of key mitochondria-related proteins.

Diagnostic Value of Glypican3, Heat Shock Protein 70 and Glutamine Synthetase in Hepatocellular Carcinoma Arising in Cirrhotic and Non-Cirrhotic Livers

BACKGROUND AND OBJECTIVES

Histopathological distinction of various nodular lesions in liver with sufficient sensitivity and specificity is a challenge even in an expert set up. The panel of immunohistochemical markers composed of glutamine synthetase (GS), Glypican3 (GPC3) and heat shock protein 70 (HSP70) was recommended by the International Consensus Group for Hepatocellular Neoplasia group for the differentiation of high grade dysplastic nodule and early hepatocellular carcinoma (HCC). The panel has been extensively validated in the western population. This study aims to test this panel on Indian population on resected, explanted and autopsy cirrhotic and non-cirrhotic liver specimens of HCC.

METHODOLOGY

This study was conducted on 39 such liver specimens (12 cirrhotic, 12 pre-cirrhotic and 11 non-cirrhotic, non-fibrotic livers), including 35 cases of HCC over a period of 12 years. Immunohistochemistry was performed with antibodies against GS, GPC3 and HSP70 on the sections containing both malignant and dysplastic nodules.

RESULTS

The diagnostic yield depended upon the nature of background liver pathology and was found to be high for only those HCCs arising in cirrhotic background, when positivity of any two markers was taken to be in favor of HCC (sensitivity-58.33%; specificity-100%). GS had a sensitivity and Negative predictive value of 100% for HCCs arising in cirrhotic livers.

CONCLUSIONS

Strong positivity for GS is a highly sensitive marker for HCC in a cirrhotic background regardless of the differentiation of the tumor in Indian population. This may be due to preferential activation of Wnt pathway in Indian patients with cirrhosis. The sensitivity of the panel was too low for detecting HCCs arising in non-cirrhotic livers, even in the pre-cirrhotic chronically inflamed livers, even though the specificity was high. GPC3 and HSP70 appear to be useful as individual markers for HCCs arising in non-cirrhotic livers.

High expression of glutamate-ammonia ligase is associated with unfavorable prognosis in patients with ovarian cancer

Glutamate-ammonia ligase (GLUL), which is also called GS (glutamine synthetase), is the enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-dependent reaction. Here, we found higher expression of GLUL in the ovarian cancer patients was associated with worse disease-free survival (DFS) and overall survival (OS). In addition, GLUL was heterogeneously expressed in various ovarian cancer cells. The mRNA and protein expression levels of GLUL in NIH:OVCAR-3 and ES-2 cells were obviously higher than that in the other types of ovarian cancer cells. Knockdown of GLUL in NIH:OVCAR-3 or ES-2 cells could significantly decrease the proliferation ability. Furthermore, GLUL knockdown markedly inhibited the p38 MAPK signaling pathway in NIH:OVCAR-3 or ES-2 cells. Our findings suggest that decreasing expression of GLUL may be a new approach that can be used for ovarian cancer treatment.

Concomitant use of heat-shock protein 70, glutamine synthetase and glypican-3 is useful in diagnosis of HBV-related hepatocellular carcinoma with higher specificity and sensitivity

Hepatocellular carcinoma is the third leading cause of cancer-related death worldwide and late diagnosis is the main cause of death in HCC patients. In this study expression patterns of HSP70, GPC3 and GS and their relationships with pathogenesis of HCC in Iranian patients were investigated. The expression of HSP70, GPC3 and GS were determined by immunohistochemistry and quantitative real-time PCR (q-PCR) methods, using 121 cases from patients with HBV alone, HCC without HBV, HBV+HCC and 30 normal tissues as control group. HSP70, GPC3 and GS were expressed in higher levels in HBV-related HCC samples compared to HBV alone group. The results showed that the labeling index of HSP70, GPC3 and GS are correlated with immunohistochemical and molecular expressions of HSP70, GPC3 and GS. The sensitivity and specificity for HCC diagnosis were 43.4% and 89.7% for HSP70, 64.3% and 90.4% for GPC3, and 60.7% and 94.3% for GS, respectively. The sensitivity and specificity of the panels with 3, 2 and 1 positive markers, regardless of which one, were 21.6% and 100%, 51.3% and 100% and 93.4% and 80.5% respectively. The current study demonstrated an association between HSP70, GPC3 and GS expressions and HBV-related HCC in our population. It was concluded that HSP70, GPC3 and GS expressions could be useful biomarkers for increasing the specificity and sensitivity of HCC diagnosis to acceptable level. Also, proper combinations of these 3 markers could improve diagnostic accuracy.

The biology of Hepatocellular carcinoma: implications for genomic and immune therapies

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is a leading cause of cancer-related death worldwide. It is highly refractory to most systemic therapies. Recently, significant progress has been made in uncovering genomic alterations in HCC, including potentially targetable aberrations. The most common molecular anomalies in this malignancy are mutations in the TERT promoter, TP53, CTNNB1, AXIN1, ARID1A, CDKN2A and CCND1 genes. PTEN loss at the protein level is also frequent. Genomic portfolios stratify by risk factors as follows: (i) CTNNB1 with alcoholic cirrhosis; and (ii) TP53 with hepatitis B virus-induced cirrhosis. Activating mutations in CTNNB1 and inactivating mutations in AXIN1 both activate WNT signaling. Alterations in this pathway, as well as in TP53 and the cell cycle machinery, and in the PI3K/Akt/mTor axis (the latter activated in the presence of PTEN loss), as well as aberrant angiogenesis and epigenetic anomalies, appear to be major events in HCC. Many of these abnormalities may be pharmacologically tractable. Immunotherapy with checkpoint inhibitors is also emerging as an important treatment option. Indeed, 82% of patients express PD-L1 (immunohistochemistry) and response rates to anti-PD-1 treatment are about 19%, and include about 5% complete remissions as well as durable benefit in some patients. Biomarker-matched trials are still limited in this disease, and many of the genomic alterations in HCC remain challenging to target. Future studies may require combination regimens that include both immunotherapies and molecularly matched targeted treatments.

Progression of Hepatic Adenoma to Carcinoma in Ogg1 Mutant Mice Induced by Phenobarbital

The carcinogenic potential of phenobarbital (PB) was assessed in a mouse line carrying a mutant Mmh allele of the Mmh/Ogg1 gene encoding the enzyme oxoguanine DNA glycosylase (Ogg1) responsible for the repair of 8-hydroxy-2′-deoxyguanosine (8-OHdG). Mmh homozygous mutant (Ogg1^−/−) and wild-type (Ogg1^+/+) male and female, 10-week-old, mice were treated with 500 ppm PB in diet for 78 weeks. Hepatocellular carcinomas (HCCs) were found in PB-treated Ogg1^−/− mice, while Ogg1^+/+ animals developed only hepatocellular adenomas (HCAs) at the same rate. This was coordinated with PB-induced significant elevation of 8-OHdG formation in DNA and cell proliferation in adjacent liver of Ogg1^−/− mice. Proteome analysis predicted activation of transcriptional factor Nrf2 in the livers and HCAs of PB-administered Ogg1^+/+ mice; however, its activation was insufficient or absent in the livers and HCCs of Ogg1^−/− mice, respectively. Significant elevation of phase I and II metabolizing enzymes was demonstrated in both Ogg1^−/− and Ogg1^+/+ animals. Treatment of Ogg1^−/− mice with PB resulted in significant elevation of cell proliferation in the liver. These results indicate that PB induced progression from HCA to HCC in Ogg1^−/− mice, due to persistent accumulation of DNA oxidative base modifications and suppression of Nrf2-mediated oxidative stress response, resulting in significant elevation of cell proliferation.

GLUL Promotes Cell Proliferation in Breast Cancer

Glutamate-ammonia ligase (GLUL) belongs to the glutamine synthetase family. It catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-dependent reaction. Here, we found higher expression of GLUL in the breast cancer patients was associated with larger tumor size and higher level of HER2 expression. In addition, GLUL was heterogeneously expressed in various breast cancer cells. The mRNA and protein expression levels of GLUL in SK-BR-3 cells were obviously higher than that in the other types of breast cancer cells. Results showed GLUL knockdown in SK-BR-3 cells could significantly decrease the proliferation ability. Furthermore, GLUL knockdown markedly inhibited the p38 MAPK and ERK1/ERK2 signaling pathways in SK-BR-3 cells. Thus, GLUL may represent a novel target for selectively inhibiting p38 MAPK and ERK1/ERK2 signaling pathways and the proliferation potential of breast cancer cells. J. Cell. Biochem. 118: 2018-2025, 2017. © 2016 Wiley Periodicals, Inc.

Glutamine Triggers Acetylation-Dependent Degradation of Glutamine Synthetase via the Thalidomide Receptor Cereblon

Cereblon (CRBN), a substrate receptor for the cullin-RING ubiquitin ligase 4 (CRL4) complex, is a direct protein target for thalidomide teratogenicity and antitumor activity of immunomodulatory drugs (IMiDs). Here we report that glutamine synthetase (GS) is an endogenous substrate of CRL4(CRBN). Upon exposing cells to high glutamine concentration, GS is acetylated at lysines 11 and 14, yielding a degron that is necessary and sufficient for binding and ubiquitylation by CRL4(CRBN) and degradation by the proteasome. Binding of acetylated degron peptides to CRBN depends on an intact thalidomide-binding pocket but is not competitive with IMiDs. These findings reveal a feedback loop involving CRL4(CRBN) that adjusts GS protein levels in response to glutamine and uncover a new function for lysine acetylation.

Roles of Combined Glypican-3 and Glutamine Synthetase in Differential Diagnosis of Hepatocellular Lesions

BACKGROUND

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer and thirdly leading cause of cancer-related death worldwide. The estimated risk of hepatocellular carcinoma is 15 to 20 times as high among persons infected with HCV as it is among those who are not infected, with most of the excess risk limited to those with advanced hepatic fibrosis or cirrhosis. Glypican3 (GPC3) plays a key role in relation to signaling with growth factors, regulating the proliferative activity of cancer cells. Glutamine synthetase (GS) catalyzes the synthesis of glutamine from glutamate and ammonia in the mammalian liver. GS was suggested as a specific marker for tracing cell lineage relationships during hepatocarcinogenesis. In normal liver, GS expression is seen in pericentral hepatocytes, but not by midzonal or periportal hepatocytes. In HCC, strong and diffuse GS expression in seen in tumor cells.

RESULTS

Glypican3 immunopositvity was highly specific and sensitive indicator for hepatocellular carcinoma as well as glutamine synthetase which was found to be a sensitive and specific indicator for development of hepatocellular carcinoma when compared to cirrhosis, liver cell dyspalsia and metastatic carcinomas. Statistical analysis revealed a significant association between GPC3 and GS with tumor size (P=0.003, p=0.006, respectively). Diffuse staining significantly associated with large tumor size while, focal and mixed staining was detected more with small tumor size. Studying the relation with tumor grade also revealed significant association between diffuse GPC3 and GS staining with high tumor grade. Diffuse staining was detected in 91.7% and 100% respectively of poorly differentiated specimens and only in 33.3% and 22.2% of well differentiated specimens.

CONCLUSIONS

While using GPC3 and GS to screen for premalignant hepatic lesions remains controversial, our data suggest that GPC3 and GS may be a reliable diagnostic immunomarkers to distinguish HCC from benign hepatocellular lesions. However, negative immunostaining should not exclude the diagnosis of HCC.

Role of biopsy sampling for diagnosis of early and progressed hepatocellular carcinoma

The current guidelines for the diagnosis of hepatocellular carcinoma (HCC) recommend liver biopsy for hepatic nodules which do not demonstrate the typical features of HCC on imaging. Thus, while not all HCCs are biopsied for histological confirmation, the nodules that pathologists now encounter on biopsy specimens are frequently well-differentiated early HCCs. This paper reviews the pathological features of HCC and its precursor lesions on liver biopsy specimens, with special emphasis on the differential diagnosis between well-differentiated HCCs and high-grade dysplastic nodules, and discusses the different roles of liver biopsy in diagnosis and management of early and progressed HCC. The potential role of liver biopsy for the development of molecular markers to predict prognosis and response to targeted therapy is also discussed.

Molecular cloning and characterization of glutamine synthetase, a tegumental protein from Schistosoma japonicum

Glutamine synthetase catalyzes the synthesis of glutamine, providing nitrogen for the production of purines, pyrimidines, amino acids, and other compounds required in many pivotal cellular events. Herein, a full-length cDNA encoding Schistosoma japonicum glutamine synthetase (SjGS) was isolated from 21-day schistosomes. The entire open reading frame of SjGS contains a 1,095-bp coding region corresponding to 364 amino acids with a calculated molecular weight of 40.7 kDa. NCBIP blast shows that the putative amino acid of SjGS contains a classic β-grasp domain and a catalytic domain of glutamine synthetase. The relative mRNA expression of SjGS was evaluated in 7-, 13-, 21-, 28-, 35-, and 42-day worms of S. japonicum in the final host and higher expression at day 21, and 42 worms were observed. This protein was also detected in worm extracts using Western blot. Immunofluorescence studies indicated that the SjGS protein was mainly distributed on tegument and parenchyma in 28-day adult worms. The recombinant glutamine synthetase with a molecular weight of 45 kDa was expressed in Escherichia coli and purified in its active form. The enzyme activity of the recombinant protein was 3.30 ± 0.67 U.μg-1. The enzyme activity was highly stable over a wide range of pH (6-9) and temperature (25-40 °C) under physiological conditions. The transcription of SjGS was upregulated in praziquantel-treated worms at 2-, 4-, and 24-h posttreatment compared with the untreated control. As a first step towards the clarification of the role of glutamine synthetase in schistosome species, we have cloned and characterized cDNAs encoding SjGS in S. japonicum, and the data presented suggest that SjGS is an important molecule in the development of the schistosome.

Multidisciplinary Canadian consensus recommendations for the management and treatment of hepatocellular carcinoma

Globally, hepatocellular carcinoma (hcc) is the third most common cause of death from cancer, after lung and stomach cancer. The incidence of hcc in Canada is increasing and is expected to continue to increase over the next decade. Given the high mortality rate associated with hcc, steps are required to mitigate the impact of the disease. To address this challenging situation, a panel of 17 hcc experts, representing gastroenterologists, hepatologists, hepatobiliary surgeons, medical oncologists, pathologists, and radiologists from across Canada, convened to provide a framework that, using an evidence-based approach, will assist clinicians in optimizing the management and treatment of hcc. The recommendations, summarized here, were developed based on a rigorous methodology in a pre-specified process that was overseen by the steering committee. Specific topics were identified by the steering committee and delegated to a group of content experts within the expert panel, who then systematically reviewed the literature on that topic and drafted the related content and recommendations. The set of recommendations for each topic were reviewed and assigned a level of evidence and grade according to the levels of evidence set out by the Centre for Evidence-based Medicine, Oxford, United Kingdom. Agreement on the level of evidence for each recommendation was achieved by consensus. Consensus was defined as agreement by a two-thirds majority of the 17 members of the expert panel. Recommendations were subject to iterative review and modification by the expert panel until consensus could be achieved.

Expression level of glutamine synthetase is increased in hepatocellular carcinoma and liver tissue with cirrhosis and chronic hepatitis B

Studies have suggested that glutamine synthetase (GS) is a potential marker of hepatocellular carcinoma (HCC). We aimed to evaluate the expression of GS in non-malignant liver tissue and serum GS levels in HCC, liver cirrhosis (LC), chronic hepatitis B (CHB), five kinds of extrahepatic diseases patients and healthy subjects. Immunohistochemistry (IHC) was used to assess GS expression in 260 liver tissue samples (from 120 HCC, 90 CHB stage 4, and 50 CHB stage 1-3 patients). Enzyme-linked immunosorbent assays of 325 samples (from 100 healthy donors, 33 CHB stage 1-3, 43 CHB stage 4, 111 HCC, and 45 extrahepatic diseases patients) were used to further analyze GS levels in serum. IHC studies showed the expression of GS in 70% of HCC patients, 46.7% of CHB stage 4 patients and 38% of CHB stage 1-3 patients. The χ(2) tests showed significant difference between HCC samples and non-tumor tissues (P = 0.001 for HCC vs. CHB stage 4, P = 0.000 for HCC vs. CHB). Consistent with this, serum GS levels are increased in HCC and CHB stage 1-4 patients. There are significant differences among all samples (P = 0.000 for all), except CHB stage 1-3 versus CHB stage 4 (P = 0.552). Based on multiple linear regressions, HCC, CHB stage 1-4 and AFP were significantly associated with serum GS levels. In addition, in HCC group, TNM and Child-Pugh were significantly associated with GS levels. Expression of GS is increased in HCC, LC, and CHB. It may be a new serum marker for liver disease.

Update on precursor and early lesions of hepatocellular carcinomas

CONTEXT

There is increasing evidence to support a multistep model of the process of human hepatocarcinogenesis. Precursor lesions are characterized by the appearance of dysplastic lesions in the form of microscopic dysplastic foci and macroscopic dysplastic nodules. There are 2 types of small hepatocellular carcinoma (HCC) (≤2 cm in diameter): (1) early HCC with an indistinct margin and (2) progressed HCC with a distinct margin. Pathologic diagnostic criteria for early HCC have recently been set up based on a consensus between Eastern and Western pathologists.

OBJECTIVE

To review the nomenclature, pathology, and biomarkers of precursor and early lesions of HCC.

DATA SOURCES

Literature review and illustrations from case materials were used.

CONCLUSIONS

Dysplastic foci are composed of large and small cell changes. Small cell change is considered to be a more advanced precursor lesion than large cell change, and large cell change is a rather heterogeneous lesion that may represent both reactive change and true dysplasia. Dysplastic nodules can be categorized as low or high grade according to the degree of atypia. High-grade dysplastic nodules have been reported to show molecular changes similar to HCC and have a high risk of malignant transformation. Early HCC, which may correspond to microinvasive carcinomas of other organs, is a well-differentiated HCC, and differential diagnosis between early HCC and high-grade dysplastic nodule is difficult. Identification of stromal invasion and application of a panel of markers (glypican-3, heat shock protein 70, and glutamine synthetase) is helpful for diagnosis of early HCC. Detection of precursor lesions of HCC is important in recognizing patients with higher risk of developing HCC, and diagnosis of early HCC can improve patient survival by allowing for early and adequate treatment.

Molecular pathology of hepatic neoplasms: classification and clinical significance

Recent technological advances have enabled investigators to characterize the molecular genetics and genomics of hepatic neoplasia in remarkable detail. From these studies, an increasing number of molecular markers are being identified that correlate with clinically important tumor phenotypes. This paper discusses current knowledge relevant to the molecular classification of epithelial primary hepatic tumors that arise in adults, including focal nodular hyperplasia (FNH), hepatocellular adenoma (HCA), hepatocellular carcinoma (HCC), cholangiocarcinoma (CC), and combined HCC-CC. Genetic analysis has defined molecular subtypes of HCA that are clinicopathologically distinct and can be distinguished through immunohistochemistry. Gene expression studies have identified molecular signatures of progression from dysplastic nodules (DNs) to early HCC in cirrhosis. Analyses of the mutational spectra, chromosomal aberrations and instability, transcriptomics, and microRNA profiles of HCC have revealed the existence of biologically distinct subtypes of this common malignancy, with prognostic implications. Molecular characterization of biliary and hepatic progenitor cell phenotypes in liver cancer has shed new light on the histogenesis of these tumors and has focused attention on novel therapeutic targets. In coming years, the molecular classification of hepatic neoplasms will be increasingly valuable for guiding patient care, as targeted therapies for liver cancer are developed and brought into clinical practice.

Assessment of stromal invasion for correct histological diagnosis of early hepatocellular carcinoma

Stromal invasion (invasive growth of tumor tissue into portal tracts and fibrous septa) is now recognized as the most important finding in the diagnosis of the well-differentiated type of early hepatocellular carcinomas (HCCs). In differentiating stromal invasion from pseudoinvasion (benign hepatic tissue in fibrous stroma), the following 5 items are useful: (1) macroscopic or panoramic views of the histological specimen, (2) the amount of fibrous components of stroma, (3) destruction of the structure of portal tracts, (4) loss of reticulin fibers around cancer cells, and (5) cytokeratin 7 immunostaining for ductular proliferation. Knowledge of stromal invasion is also useful for a better understanding of the vasculature (hypovascular HCCs) and histological features (fatty change) of early HCCs. Invasion of preexisting arteries and portal veins causes hypo-vascularity of HCCs. Further, hypovascularity causes fatty change as a hypoxic change of cancer tissues.

Hepatocellular carcinoma – from macroscopy to molecular pathology

A hepatocellularis carcinoma (HCC) igen rossz prognózisú daganat, azonban diagnosztikája és kezelése területén az utóbbi években jelentős előrehaladás történt. Mindehhez hozzájárult a HCC molekuláris patogenezisének mélyebb megismerése. A cirrhosis talaján kialakult HCC praemalignus elváltozásai a nagy regeneratív nodulus, az alacsony („low”) és magas („high”) fokozatú diszplasztikus nodulus. Mikroszkóposan a WHO trabecularis (micro-, macrotrabecularis), acinaris (pseudoglandularis,), scirrhosus és szolid formát különít el, speciális altípusként a világos sejtes, fibrolamellaris és kevert cholangiohepatocellularis szöveti forma ismert. Ezen szövettani típusok prognosztikai jelentősége vitatott. A fibrolamellaris, fiatalokban előforduló, nem cirrhoticus HCC-t jobb prognózisúnak tartják, bár valószínű, hogy ez annak a következménye, hogy ezen típust cirrhosis nem kíséri. A diagnózist segíthetik egyes, a szérumban és a daganatban is kimutatható tumormarkerek, így a jól ismert alfa-fetoprotein (AFP) mellett a glipikán-3 és a survivin, az újabban leírt agrin és claudinok, valamint a májsejteredetet bizonyító hepatocytaspecifikus antigén (HSA). Újabban az úgynevezett mikro-RNS-ek diagnosztikus jelentősége, elsősorban a májsejtspecifikus mir-122-é is felmerült. A HCC molekuláris osztályozása, a kezelés irányait is megszabó barcelonai beosztás (BCLC) mellett, kulcsfontosságú molekuláris eltérések alapján csoportosítja a HCC-t. Számos olyan molekuláris alteráció észlelhető, amely minden HCC-ben megfigyelhető, míg egyes eltérések csak bizonyos tumorokban detektálhatók.

The application of markers (HSP70 GPC3 and GS) in liver biopsies is useful for detection of hepatocellular carcinoma

BACKGROUND/AIMS

Liver biopsy for hepatocellular carcinoma (HCC) detection is largely restricted to small hepatocellular lesions, which are often morphologically challenging, requiring careful distinction between dysplastic nodules (high-grade) and well-differentiated HCC.

METHODS

We investigated the diagnostic accuracy of a panel of markers (HSP70 GPC3 and GS), previously tested in resection specimens, in a series of liver biopsies of large regenerative nodules (n=13), low-grade dysplastic nodules (n=21), high-grade dysplastic nodules (n=50), very well-differentiated (VWD) (n=17), well-differentiated (WD-G1) (n=40) and G2-3 (n=35) HCC.

RESULTS

Almost all cases of large regenerative and low-grade dysplastic nodules did not stain while high-grade dysplastic nodules showed 1 marker (22%) but never 2 or 3. For HCC detection the overall accuracy of marker combination was 60.8% (3 markers) and 78.4% (2 markers) with 100% specificity. When restricted to VWD+WD-G1 HCC the accuracy was 57% (3 markers) and 72.9% (2 markers) with 100% specificity.

CONCLUSIONS

This panel proved useful to detect well-differentiated HCC in biopsy. Two immunoreactive markers (out of 3) are recommended as the most valuable diagnostic combination for HCC detection. The diagnostic accuracy of the panel could be improved using additional markers, as suggested by studies of expression profiling in other human models.

Bidirectional transport of amino acids regulates mTOR and autophagy

Amino acids are required for activation of the mammalian target of rapamycin (mTOR) kinase which regulates protein translation, cell growth, and autophagy. Cell surface transporters that allow amino acids to enter the cell and signal to mTOR are unknown. We show that cellular uptake of L-glutamine and its subsequent rapid efflux in the presence of essential amino acids (EAA) is the rate-limiting step that activates mTOR. L-glutamine uptake is regulated by SLC1A5 and loss of SLC1A5 function inhibits cell growth and activates autophagy. The molecular basis for L-glutamine sensitivity is due to SLC7A5/SLC3A2, a bidirectional transporter that regulates the simultaneous efflux of L-glutamine out of cells and transport of L-leucine/EAA into cells. Certain tumor cell lines with high basal cellular levels of L-glutamine bypass the need for L-glutamine uptake and are primed for mTOR activation. Thus, L-glutamine flux regulates mTOR, translation and autophagy to coordinate cell growth and proliferation.

Discovery of candidate genes and pathways that may help explain fertility cycle stage dependent post-resection breast cancer outcome

Breast cancer relapse and death occur more often and sooner among young pre-menopausal women. Breast cancer resected during luteal phase cures about a quarter more women than if the operation is performed during follicular phase. We have identified candidate breast cancer gene signatures that may point to the potential mechanisms of cycle stage-dependent surgical cure. We performed whole murine genome microarrays on mammary tumors resected during pre-ovulatory (diestrus, follicular) and post-ovulatory (estrus, luteal) phases of the estrous cycle with known post-surgical cure or relapse (pulmonary metastasis) outcome. A set of genes whose expressions are differentially modulated by fertility cycle stage of tumor resection and also associate with prognosis were identified. These identified genes were validated by qRT-PCR. From two independent microarray studies, we identified 90 genes in mammary tumors whose expressions change significantly (up to 100-fold) across the estrous cycle, 69 genes that are associated with cure/relapse independent of cycle stage at resection, and 24 genes that change significantly (up to 12-fold) across the estrous cycle and also associate with the outcome. The mRNA expression patterns of these 24 identified genes were 100% validated by qRT-PCR in the same samples. We have identified candidate breast cancer genes and pathways that may point to the potential mechanisms by which the post-resection breast cancer outcome is influenced by the menstrual cycle phase of cancer resection. Since human breast cancer outcome is influenced by the menstrual cycle phase of breast cancer resection, we consider this study in a mouse breast cancer model to be a proof of principle that such signatures may well exist in human premenopausal breast cancer. It remains to be determined in human breast cancer whether woman to woman and/or tumor to tumor variability will mask cycle phase dependent and outcome predictive genomic signatures in human premenopausal breast cancer. The pathways identified by these studies are potential targets for the development of peri-surgical neoadjuvant therapies, which may delay or prevent relapse by preventing dormant micrometastatic tumor cells from escaping that dormant state post-operatively.

Histological features of early hepatocellular carcinomas and their developmental process: for daily practical clinical application : Hepatocellular carcinoma

Based on clinical and pathological experience, indistinct margin-type hepatocellular carcinomas (HCCs) were considered to be typical early-stage HCCs with good prognosis. For histological diagnosis, the assessment of stromal invasion (tumor invasion into portal tracts and fibrous septa) is very important. In differentiating stromal invasion from pseudoinvasion (benign hepatic tissue in the fibrous stroma), the following 5 items are useful: (1) macroscopic or panoramic views of the histological specimen, (2) amount of fibrous components of the stroma, (3) destruction of the structure of portal tracts, (4) loss of reticulin fibers around cancer cells, and (5) cytokeratin 7 immunostaining for ductular proliferation. Parenchymal features of early HCCs are summarized as follows: (1) thin trabecular structure, (2) hypercellularity, (3) hyperstainability of cytoplasm, and (4) microacinar formation. Detailed understanding of the total biopsy procedure and various difficult lesions is necessary for a correct biopsy diagnosis. Evaluation of noncancerous tissue is also required to attain a better understanding of the developmental process and clinical stages of HCCs.

Deficiency of manganese superoxide dismutase in hepatocytes disrupts zonated gene expression in mouse liver

The liver acinus displays a physiological periportal to perivenous oxygen gradient. This gradient was implicated to use reactive oxygen species (ROS) as mediators for the zonal gene expression. Mitochondria use oxygen and produce ROS, therefore they may contribute to the zonation of gene expression. To further elucidate this, we used the Cre-loxP system to generate a hepatocyte-specific null mutation of the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) in mice. We found that ROS levels were enhanced in livers of MnSOD(-/-) mice which were reduced in size and displayed signs of liver failure such as intracellular protein droplets, increased apoptotic bodies and Bax levels as well as multinuclear hepatocytes. Further, the zonation of glutamine synthetase, glucokinase and phosphoenolpyruvate carboxykinase was no longer preserved. We conclude that deficiency of mitochondrial MnSOD initiates a dysregulation of zonated gene expression in liver.

Diagnostic value of HSP70, glypican 3, and glutamine synthetase in hepatocellular nodules in cirrhosis

Hepatocellular nodules in cirrhosis include regenerative (large regenerative, LRN) and dysplastic (low and high grade, LGDN and HGDN) nodules, early and grade 1 HCC (eHCC-G1), and overt HCC. The differential diagnosis may be particularly difficult when lesions such as HGDN and eHCC-G1 are involved. We investigated the diagnostic yield of a panel of 3 putative markers of hepatocellular malignancy such as HSP70, glypican 3 (GPC3), and glutamine synthetase (GS). We selected 52 surgically removed nonmalignant nodules (15 LRNs, 15 LGDNs, 22 HGDNs) and 53 HCCs (10 early, 22 grade 1, and 21 grade 2-3) and immunostained them for HSP70, GPC3, and GS. The sensitivity and specificity of the individual markers for the detection of eHCC-G1 were 59% and 86% for GS, 69% and 91% for GPC3, and 78% and 95% for HSP70. We identified 2 main phenotypes: (1) all negative, seen in 100% LRN and LGDN, 73% HGDN and 3% eHCC-G1; (2) all positive, a feature detected in less than half the eHCC-G1. Using a 3-marker panel, when at least 2 of them, regardless which, were positive, the sensitivity and specificity for the detection of eHCC-G1 were respectively 72% and 100%; the most sensitive combination was HSP70+/GPC3+ (59%) when a 2-marker panel was used.

CONCLUSION

The adopted panel of 3 markers is very helpful in distinguishing eHCC-G1 from dysplastic nodules arising in cirrhosis.

Hepatocellular expression of glutamine synthetase: an indicator of morphogen actions as master regulators of zonation in adult liver

Glutamine synthetase (GS) has long been known to be expressed exclusively in pericentral hepatocytes most proximal to the central veins of liver lobuli. This enzyme as well as its peculiar distribution complementary to the periportal compartment for ureogenesis plays an important role in nitrogen metabolism, particularly in homeostasis of blood levels of ammonium ions and glutamine. Despite this fact and intensive studies in vivo and in vitro, many aspects of the regulation of its activity on the protein and on the genetic level remained enigmatic. Recent experimental advances using transgenic mice and new analytic tools have revealed the fundamental role of morphogens such as wingless-type MMTV integration site family member signals (Wnt), beta-catenin, and adenomatous polyposis coli in the regulation of this particular enzyme. In addition, novel information concerning the structure of transcription factor binding sites within regulatory regions of the GS gene and their interactions with signalling pathways could be collected. In this review we focus on all aspects of the regulation of GS in the liver and demonstrate how the new findings have changed our view of the determinants of liver zonation. What appeared as a simple response of hepatocytes to blood-derived factors and local cellular interactions must now be perceived as a fundamental mechanism of adult tissue patterning by morphogens that were considered mainly as regulators of developmental processes. Though GS may be the most obvious indicator of morphogen action among many other targets, elucidation of the complex regulation of the expression of the GS gene could pave the road for a better understanding of the mechanisms involved in patterning of liver parenchyma. Based on current knowledge we propose a new concept of how morphogens, hormones and other factors may act in concert, in order to restrict gene expression to small subpopulations of one differentiated cell type, the hepatocyte, in different anatomical locations. Although many details of this regulatory network are still missing, and an era of exciting new discoveries is still about to come, it can already be envisioned that similar mechanisms may well be active in other organs contributing to the fine-tuning of organ-specific functions.

Characterization of HULC, a novel gene with striking up-regulation in hepatocellular carcinoma, as noncoding RNA

BACKGROUND & AIMS

Recent studies have highlighted the role of noncoding RNAs (ncRNAs) in carcinogenesis, and suggested that this class of genes might be used as biomarkers in cancer. We searched the human genome for novel genes including ncRNAs related to hepatocellular carcinoma (HCC).

METHODS

An HCC-specific gene library was generated and screened for deregulated genes with 46 HCCs, 4 focal nodular hyperplasias, and 7 cirrhoses utilizing cDNA arrays. Sequencing of library clones identified a novel ncRNA as the most up-regulated gene in HCC. This gene was also cloned from different monkeys and characterized by quantitative RT-PCR, Northern blot analysis and in situ hybridization. Structural and functional studies included comparative sequence and protein expression analyses, quantitative RT-PCR of polysomal preparations, and siRNA-mediated knockdown experiments.

RESULTS

The most up-regulated gene in HCC named highly up-regulated in liver cancer (HULC) was characterized as a novel mRNA-like ncRNA. HULC RNA is spliced and polyadenlyated, and resembles the mammalian LTR transposon 1A. It does not contain substantial open reading frames, and no native translation product was detected. HULC is present in the cytoplasm, where it copurifies with ribosomes. siRNA-mediated knockdown of HULC RNA in 2 HCC cell lines altered the expression of several genes, 5 of which were known to be affected in HCC, suggesting a role for HULC in post-transcriptional modulation of gene expression.

CONCLUSIONS

HULC is the first ncRNA with highly specific up-regulation in HCC. Because HULC was detected in blood of HCC patients, a potential use as novel biomarker can be envisaged.

Molecular Profiling of Hepatocellular Carcinoma in Mice with a Chronic Deficiency of HepaticS-Adenosylmethionine: Relevance in Human Liver Diseases

S-adenosylmethionine arises as a central molecule in the preservation of liver homeostasis as a chronic hepatic deficiency results in spontaneous development of steatohepatitis and hepatocellular carcinoma. In the present work, we have attempted a comprehensive analysis of proteins associated with hepatocarcinogenesis in MAT1A knock out mice using a combination of two-dimensional electrophoresis and mass spectrometry, to then apply the resulting information to identify hallmarks of human HCC. Our results suggest the existence of individual-specific factors that might condition the development of preneoplastic lesions. Proteomic analysis allowed the identification of 151 differential proteins in MAT1A-/- mice tumors. Among all differential proteins, 27 changed in at least 50% of the analyzed tumors, and some of these alterations were already detected months before the development of HCC in the KO liver. The expression level of genes coding for 13 of these proteins was markedly decreased in human HCC. Interestingly, seven of these genes were also found to be down-regulated in a pretumoral condition such as cirrhosis, while depletion of only one marker was assessed in less severe liver disorders.