Ectonucleoside triphosphate diphosphohydrolase type 5 (Entpd5)-deficient mice develop progressive hepatopathy, hepatocellular tumors, and spermatogenic arrest

Cant1 Affects Cartilage Proteoglycan Properties: Aggrecan and Decorin Characterization in a Mouse Model of Desbuquois Dysplasia Type 1

Desbuquois dysplasia type 1 (DBQD1) is a recessive chondrodysplasia caused by mutations in the CANT1 gene, encoding for the Golgi Calcium-Activated Nucleotidase 1 (CANT1). The enzyme hydrolyzes UDP, the by-product of glycosyltransferase reactions, but it might play other roles in different cell types. Using a Cant1 knock-out mouse, we demonstrated that CANT1 is crucial for glycosaminoglycan (GAG) synthesis; however, its impact on the biochemical properties of cartilage proteoglycans remains unknown. Thus, in this work, we characterized decorin and aggrecan from primary chondrocyte cultures and cartilage biopsies of mutant mice at post-natal day 4 by Western blots and further investigated their distribution in the cartilage extracellular matrix (ECM) by immunohistochemistry. We demonstrated that the GAG synthesis defect caused by CANT1 impairment led to the synthesis and secretion of proteoglycans with shorter GAG chains compared with wild-type animals. However, this alteration did not result in the synthesis and secretion of decorin and aggrecan in the unglycanated form. Interestingly, the defect was not cartilage-specific since also skin decorin showed a reduced hydrodynamic size. Finally, immunohistochemical studies in epiphyseal sections of mutant mice demonstrated that the proteoglycan structural defect moderately affected decorin distribution in the ECM.

Adenosine A2A receptor is a tumor suppressor of NASH-associated hepatocellular carcinoma

Inhibition of adenosine A2A receptor (A2AR) is a promising approach for cancer immunotherapy currently evaluated in several clinical trials. We here report that anti-obesogenic and anti-inflammatory functions of A2AR, however, significantly restrain hepatocellular carcinoma (HCC) development. Adora2a deletion in mice triggers obesity, non-alcoholic steatohepatitis (NASH), and systemic inflammation, leading to spontaneous HCC and promoting dimethylbenzyl-anthracene (DMBA)- or diethylnitrosamine (DEN)-induced HCC. Conditional Adora2a deletion reveals critical roles of myeloid and hepatocyte-derived A2AR signaling in restraining HCC by limiting hepatic inflammation and steatosis. Remarkably, the impact of A2AR pharmacological blockade on HCC development is dependent on pre-existing NASH. In support of our animal studies, low ADORA2A gene expression in human HCC is associated with cirrhosis, hepatic inflammation, and poor survival. Together, our study uncovers a previously unappreciated tumor-suppressive function for A2AR in the liver and suggests caution in the use of A2AR antagonists in patients with NASH and NASH-associated HCC.

Differential plasma protein expression after ingestion of essential amino acid-based dietary supplement verses whey protein in low physical functioning older adults

In a recent randomized, double-blind, placebo-controlled trial, we were able to demonstrate the superiority of a dietary supplement composed of essential amino acids (EAAs) over whey protein, in older adults with low physical function. In this paper, we describe the comparative plasma protein expression in the same subject groups of EAAs vs whey. The plasma proteomics data was generated using SOMA scan assay. A total of twenty proteins were found to be differentially expressed in both groups with a 1.5-fold change. Notably, five proteins showed a significantly higher fold change expression in the EAA group which included adenylate kinase isoenzyme 1, casein kinase II 2-alpha, Nascent polypeptide-associated complex subunit alpha, peroxiredoxin-1, and peroxiredoxin-6. These five proteins might have played a significant role in providing energy for the improved cardiac and muscle strength of older adults with LPF. On the other hand, fifteen proteins showed slightly lower fold change expression in the EAA group. Some of these 15 proteins regulate metabolism and were found to be associated with inflammation or other comorbidities. Gene Ontology (GO) enrichment analysis showed the association of these proteins with several biological processes. Furthermore, protein-protein interaction network analysis also showed distinct networks between upregulated and downregulated proteins. In conclusion, the important biological roles of the upregulated proteins plus better physical function of participants in the EAAs vs whey group demonstrated that EAAs have the potential to improve muscle strength and physical function in older adults. This study was registered with ClinicalTrials.gov: NCT03424265 "Nutritional interventions in heart failure."

Heat Shock Alters the Proteomic Profile of Equine Mesenchymal Stem Cells

The aim of this research was to determine the impact of heat stress on cell differentiation in an equine mesenchymal stem cell model (EMSC) through the application of heat stress to primary EMSCs as they progressed through the cell specialization process. A proteomic analysis was performed using mass spectrometry to compare relative protein abundances among the proteomes of three cell types: progenitor EMSCs and differentiated osteoblasts and adipocytes, maintained at 37 °C and 42 °C during the process of cell differentiation. A cell-type and temperature-specific response to heat stress was observed, and many of the specific differentially expressed proteins were involved in cell-signaling pathways such as Notch and Wnt signaling, which are known to regulate cellular development. Furthermore, cytoskeletal proteins profilin, DSTN, SPECC1, and DAAM2 showed increased protein levels in osteoblasts differentiated at 42 °C as compared with 37 °C, and these cells, while they appeared to accumulate calcium, did not organize into a whorl agglomerate as is typically seen at physiological temperatures. This altered proteome composition observed suggests that heat stress could have long-term impacts on cellular development. We propose that this in vitro stem cell culture model of cell differentiation is useful for investigating molecular mechanisms that impact cell development in response to stressors.

Knockdown of ENTPD5 inhibits tumor metastasis and growth via regulating the GRP78/p-eIF-2α/CHOP pathway in serous ovarian cancer

Background

Dysregulation of Ectonucleoside Triphospahate Diphosphohydrolase 5 (ENTPD5) in tumors might be associated with tumor progression, while the role of ENTPD5 in the growth and metastasis of serous ovarian cancer (SOC) is still unclear.

Methods

ENTPD5 expression patterns in ovarian cancer tissues were analyzed by qRT-PCR and immunohistochemistry assay (IHC). Two SOC cell lines, SKOV3 and OVCAR8, were stably transfected with lentivirus to build knockdown and overexpression cell lines. Clone formation assay, collagen gel droplet culture technology, wound healing assay and flow cytometry were used to assess the migration and growth traits of SOC cells. Expression levels of ENTPD5, glucose regulated protein 78 (GRP78), eukaryotic translation initiation factor 2 alpha (eIF-2α), phosphorylated -eIF-2α and, C/EBP homologous protein (CHOP) in SOC cells were detected by Western blot.

Results

Compared to fallopian tube tissues, the expression of ENTPD5 was significantly higher in tumor tissues obtained from SOC patients, and positively correlated with clinical stage and metastasis. ENTPD5 knockdown robustly inhibited cell proliferation, migration, whereas ENTPD5 overexpression elicited the opposite effect on SOC cells. ENTPD5 knockdown arrested cell cycle in G0/G1 phase and increased apoptosis. Importantly, ENTPD5 knockdown was associated with significantly decreased protein levels for GRP78, CHOP, and p-eIF-2α, suggesting possible involvement of ENTPD5 in endoplasmic reticulum stress (ERS).

Conclusions

Our study demonstrates that ENTPD5 knockdown inhibited SOC cell proliferation, migration and restrained the activation of the GRP78/p-eIF-2α/CHOP pathway, which provides a potentially effective therapeutic target for the treatment of SOC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-022-00996-0.

Ectonucleotidases in Inflammation, Immunity, and Cancer

Nucleoside triphosphate diphosphohydrolases (NTPDases) are a family of enzymes that hydrolyze nucleotides such as ATP, UTP, ADP, and UDP to monophosphates derivates such as AMP and UMP. The NTPDase family consists of eight enzymes, of which NTPDases 1, 2, 3, and 8 are expressed on cell membranes thereby hydrolyzing extracellular nucleotides. Cell membrane NTPDases are expressed in all tissues, in which they regulate essential physiological tissue functions such as development, blood flow, hormone secretion, and neurotransmitter release. They do so by modulating nucleotide-mediated purinergic signaling through P2 purinergic receptors. NTPDases 1, 2, 3, and 8 also play a key role during infection, inflammation, injury, and cancer. Under these conditions, NTPDases can contribute and control the pathophysiology of infectious, inflammatory diseases and cancer. In this review, we discuss the role of NTPDases, focusing on the less understood NTPDases 2-8, in regulating inflammation and immunity during infectious, inflammatory diseases, and cancer.

Whole-genome sequencing analysis of the cardiometabolic proteome

The human proteome is a crucial intermediate between complex diseases and their genetic and environmental components, and an important source of drug development targets and biomarkers. Here, we comprehensively assess the genetic architecture of 257 circulating protein biomarkers of cardiometabolic relevance through high-depth (22.5×) whole-genome sequencing (WGS) in 1328 individuals. We discover 131 independent sequence variant associations (P < 7.45 × 10-11) across the allele frequency spectrum, all of which replicate in an independent cohort (n = 1605, 18.4x WGS). We identify for the first time replicating evidence for rare-variant cis-acting protein quantitative trait loci for five genes, involving both coding and noncoding variation. We construct and validate polygenic scores that explain up to 45% of protein level variation. We find causal links between protein levels and disease risk, identifying high-value biomarkers and drug development targets.

The P2X7 Receptor and NLRP3 Axis in Non-Alcoholic Fatty Liver Disease: A Brief Review

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, and its prevalence is reaching epidemic characteristics both in adults and in children. The increase of NAFLD prevalence parallels that of obesity, now representing the major cause of liver inflammation, increasing the risk of cirrhosis and hepatocarcinoma. Furthermore, NAFLD is a risk factor for cardiovascular diseases and type 2 diabetes, two of the major leading causes of morbidity and mortality in western countries. Thus a significant amount of studies have dealt with the evaluation of the possible molecular mechanisms leading to NAFLD and its inflammatory consequences within the liver, the non-alcoholic steatohepatitis, and cirrhosis. The inflammasome is a key player in the inflammation and fibrogenic responses in many different tissues, including the liver. The activation of the NLRP3 inflammasome requires the activation by extracellular adenosine tri-phosphate (ATP) of a specific purinergic receptor named P2X7 located in the target cells, although other pathways have been described. To this regard, extracellular ATP acts as an internal danger signal coming from damaged cells participating in the activation of the inflammatory process, a signaling pathway common to many different tissues. Here, we briefly review the involvement of the P2X7 receptor/inflammasome NLRP3 axis in the pathophysiological events leading to NAFLD and its inflammatory and fibrotic evolutions, reporting the possible therapeutical strategies targeting the P2X7 receptor/NLRP3 inflammasome.

Inhibition of lung cancer cells and Ras/Raf/MEK/ERK signal transduction by ectonucleoside triphosphate phosphohydrolase-7 (ENTPD7)

Background

The aim of this study was to investigate the effects and mechanisms of ectonucleoside triphosphate phosphohydrolase-7 (ENTPD7) on lung cancer cells.

Methods

The expression characteristics of ENTPD7 and its effect on the survival of lung cancer patients were analyzed by referring to The Cancer Genome Atlas (TCGA). Streptavidin-peroxidase (SP) staining was performed to detect the ENTPD7 protein in tumor tissues and adjacent tissues. Plasmid transfection technology was also applied to silence ENTPD7 gene. Crystal violet staining and flow cytometry were performed to determine cell proliferation and apoptosis. Tumor-bearing nude mice model was established to investigate the effect of sh-ENTPD7 on tumors.

Results

The results showed that patients with low levels of ENTPD7 had higher survival rates. ENTPD7 was up-regulated in lung cancer tissues and cells. Down-regulation of the expression of ENTPD7 inhibited proliferation but promoted apoptosis of lung cancer cell. Silencing ENTPD7 also inhibited the expression levels of Ras and Raf proteins and the phosphorylation of mitogen-activated protein kinase (MEK) and extracellular signal-regulated kinase (ERK). Tumor-bearing nude mice experiments showed that silencing ENTPD7 had an inhibitory effect on lung cancer cells.

Conclusions

ENTPD7 was overexpressed in lung cancer cells. Down-regulating ENTPD7 could inhibit lung cancer cell proliferation and promote apoptosis via inhibiting the Ras/Raf/MEK/ERK pathway.

Identifying small molecule probes of ENTPD5 through high throughput screening

Ectonucleoside Triphosphate Diphosphohydrolase 5 (ENTPD5) has been shown to be important in maintaining cellular function in cancer, and its expression is upregulated through multiple, unique pathways in certain cancers, including laryngeal, glioblastoma multiforme, breast, testicular, and prostate. ENTPD5 supports cancer growth by promoting the import of UDP-glucose, a metabolite used for protein glycosylation and hence proper glycoprotein folding, into the ER by providing the counter molecule, UMP, to the ER antiporter. Despite its cancer-supporting function, no small molecule inhibitors of ENTPD5 are commercially available, and few studies have been performed in tissue culture to understand the effects of chemical inhibition of ENTPD5. We performed a high-throughput screen (HTS) of 21,120 compounds to identify small molecule inhibitors of ENPTD5 activity. Two hits were identified, and we performed a structure activity relationship (SAR) screen around these hits. Further validation of these probes were done in an orthogonal assay and then assayed in cell culture to assess their effect on prostate cancer cell lines. Notably, treatment with the novel ENTPD5 inhibitor reduced the amount of glycoprotein produced in treated cells, consistent with the hypothesis that ENTPD5 is important for glycoprotein folding. This work serves as an important step in designing new molecular probes for ENTPD5 as well as further probing the utility of targeting ENTPD5 to combat cancer cell proliferation.

Predicting human disease mutations and identifying drug targets from mouse gene knockout phenotyping campaigns

Two large-scale mouse gene knockout phenotyping campaigns have provided extensive data on the functions of thousands of mammalian genes. The ongoing International Mouse Phenotyping Consortium (IMPC), with the goal of examining all ∼20,000 mouse genes, has examined 5115 genes since 2011, and phenotypic data from several analyses are available on the IMPC website (www.mousephenotype.org). Mutant mice having at least one human genetic disease-associated phenotype are available for 185 IMPC genes. Lexicon Pharmaceuticals' Genome5000™ campaign performed similar analyses between 2000 and the end of 2008 focusing on the druggable genome, including enzymes, receptors, transporters, channels and secreted proteins. Mutants (4654 genes, with 3762 viable adult homozygous lines) with therapeutically interesting phenotypes were studied extensively. Importantly, phenotypes for 29 Lexicon mouse gene knockouts were published prior to observations of similar phenotypes resulting from homologous mutations in human genetic disorders. Knockout mouse phenotypes for an additional 30 genes mimicked previously published human genetic disorders. Several of these models have helped develop effective treatments for human diseases. For example, studying Tph1 knockout mice (lacking peripheral serotonin) aided the development of telotristat ethyl, an approved treatment for carcinoid syndrome. Sglt1 (also known as Slc5a1) and Sglt2 (also known as Slc5a2) knockout mice were employed to develop sotagliflozin, a dual SGLT1/SGLT2 inhibitor having success in clinical trials for diabetes. Clinical trials evaluating inhibitors of AAK1 (neuropathic pain) and SGLT1 (diabetes) are underway. The research community can take advantage of these unbiased analyses of gene function in mice, including the minimally studied 'ignorome' genes.

Ectonucleotidases in Intestinal and Hepatic Inflammation

Purinergic signaling modulates systemic and local inflammatory responses. Extracellular nucleotides, including eATP, promote inflammation, at least in part via the inflammasome upon engagement of P2 purinergic receptors. In contrast, adenosine generated during eATP phosphohydrolysis by ectonucleotidases, triggers immunosuppressive/anti-inflammatory pathways. Mounting evidence supports the role of ectonucleotidases, especially ENTPD1/CD39 and CD73, in the control of several inflammatory conditions, ranging from infectious disease, organ fibrosis to oncogenesis. Our experimental data generated over the years have indicated both CD39 and CD73 serve as pivotal regulators of intestinal and hepatic inflammation. In this context, immune cell responses are regulated by the balance between eATP and adenosine, potentially impacting disease outcomes as in gastrointestinal infection, inflammatory bowel disease, ischemia reperfusion injury of the bowel and liver, autoimmune or viral hepatitis and other inflammatory conditions, such as cancer. In this review, we report the most recent discoveries on the role of ENTPD1/CD39, CD73, and other ectonucleotidases in the regulation of intestinal and hepatic inflammation. We discuss the present knowledge, highlight the most intriguing and promising experimental data and comment on important aspects that still need to be addressed to develop purinergic-based therapies for these important illnesses.

Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5

Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins. A comprehensive pan-cancer analysis revealed a highly significant correlation between p53 GOF mutations and ENTPD5 expression. Mechanistically, mutp53 is recruited by Sp1 to the ENTPD5 core promoter to induce its expression. We show ENTPD5 to be a mediator of mutant p53 GOF activity in clonogenic growth, architectural tissue remodeling, migration, invasion, and lung colonization in an experimental metastasis mouse model. Our study reveals folding of N-glycosylated membrane proteins in the ER as a mechanism underlying the metastatic progression of tumors with mutp53 that could provide new possibilities for cancer treatment.

Dentin Dysplasia in Notum Knockout Mice

Secreted WNT proteins control cell differentiation and proliferation in many tissues, and NOTUM is a secreted enzyme that modulates WNT morphogens by removing a palmitoleoylate moiety that is essential for their activity. To better understand the role this enzyme in development, the authors produced NOTUM-deficient mice by targeted insertional disruption of the Notum gene. The authors discovered a critical role for NOTUM in dentin morphogenesis suggesting that increased WNT activity can disrupt odontoblast differentiation and orientation in both incisor and molar teeth. Although molars in Notum-/- mice had normal-shaped crowns and normal mantle dentin, the defective crown dentin resulted in enamel prone to fracture during mastication and made teeth more susceptible to endodontal inflammation and necrosis. The dentin dysplasia and short roots contributed to tooth hypermobility and to the spread of periodontal inflammation, which often progressed to periapical abscess formation. The additional incidental finding of renal agenesis in some Notum -/- mice indicated that NOTUM also has a role in kidney development, with undiagnosed bilateral renal agenesis most likely responsible for the observed decreased perinatal viability of Notum-/- mice. The findings support a significant role for NOTUM in modulating WNT signaling pathways that have pleiotropic effects on tooth and kidney development.

NTPDase5/PCPH as a new target in highly aggressive tumors: a systematic review

The protooncogene PCPH was recently identified as being the ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5). This protooncogene is converted into an oncogene by a single base pair deletion, resulting in frame change and producing a premature stop codon, leading to a mutated protein (mt-PCPH) with only 27 kDa, which is much smaller than the original 47 kDa protein. Overexpression of the PCPH as well as the mutated PCPH increases the cellular resistance to stress and apoptosis. This is intriguing considering that the active form, that is, the oncogene, is the mutated PCPH. Several studies analyzed the expression of NTPDase5/mt-PCPH in a wide range of tumor cells and evaluated its role and mechanisms in cancer and other pathogenic processes. The main point of this review is to integrate the findings and proposed theories about the role played by NTPDase5/mt-PCPH in cancer progression, considering that these proteins have been suggested as potential early diagnostic tools and therapy targets.

Identification and quantification of the basal and inducible Nrf2-dependent proteomes in mouse liver: biochemical, pharmacological and toxicological implications

The transcription factor Nrf2 is a master regulator of cellular defence: Nrf2 null mice (Nrf2^(−/−)) are highly susceptible to chemically induced toxicities. We report a comparative iTRAQ-based study in Nrf2^(−/−) mice treated with a potent inducer, methyl-2-cyano-3,12-dioxooleana-1,9(11)dien-28-oate (CDDO-me; bardoxolone -methyl), to define both the Nrf2-dependent basal and inducible hepatoproteomes. One thousand five hundred twenty-one proteins were fully quantified (FDR < 1%). One hundred sixty-one were significantly different (P < 0.05) between WT and Nrf2^(−/−) mice, confirming extensive constitutive regulation by Nrf2. Treatment with CDDO-me (3 mg/kg; i.p.) resulted in significantly altered expression of 43 proteins at 24 h in WT animals. Six proteins were regulated at both basal and inducible levels exhibiting the largest dynamic range of Nrf2 regulation: cytochrome P4502A5 (CYP2A5; 17.2-fold), glutathione-S-transferase-Mu 3 (GSTM3; 6.4-fold), glutathione-S-transferase Mu 1 (GSTM1; 5.9-fold), ectonucleoside-triphosphate diphosphohydrolase (ENTPD5; 4.6-fold), UDP-glucose-6-dehydrogenase (UDPGDH; 4.1-fold) and epoxide hydrolase (EPHX1; 3.0-fold). These proteins, or their products, thus provide a potential source of biomarkers for Nrf2 activity. ENTPD5 is of interest due to its emerging role in AKT signalling and, to our knowledge, this protein has not been previously shown to be Nrf2-dependent. Only two proteins altered by CDDO-me in WT animals were similarly affected in Nrf2^(−/−) mice, demonstrating the high degree of selectivity of CDDO-me for the Nrf2:Keap1 signalling pathway.

Biological significance

The Nrf2:Keap1 signalling pathway is attracting considerable interest as a therapeutic target for different disease conditions. For example, CDDO-me (bardoxolone methyl) was investigated in clinical trials for the treatment of acute kidney disease, and dimethyl fumarate, recently approved for reducing relapse rate in multiple sclerosis, is a potent Nrf2 inducer. Such compounds have been suggested to act through multiple mechanisms; therefore, it is important to define the selectivity of Nrf2 inducers to assess the potential for off-target effects that may lead to adverse drug reactions, and to provide biomarkers with which to assess therapeutic efficacy. Whilst there is considerable information on the global action of such inducers at the mRNA level, this is the first study to catalogue the hepatic protein expression profile following acute exposure to CDDO-me in mice. At a dose shown to evoke maximal Nrf2 induction in the liver, CDDO-me appeared highly selective for known Nrf2-regulated proteins. Using the transgenic Nrf2^(−/−) mouse model, it could be shown that 97% of proteins induced in wild type mice were associated with a functioning Nrf2 signalling pathway. This analysis allowed us to identify a panel of proteins that were regulated both basally and following Nrf2 induction. Identification of these proteins, which display a large magnitude of variation in their expression, provides a rich source of potential biomarkers for Nrf2 activity for use in experimental animals, and which may be translatable to man to define individual susceptibility to chemical stress, including that associated with drugs, and also to monitor the pharmacological response to Nrf2 inducers.

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Liver proteomes from WT, Nrf2-null and Nrf2-induced mice were compared by iTRAQ

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Of 1521 proteins quantified, 161 were regulated basally and 43 following induction

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Six proteins were both basally and inducibly regulated, with high dynamic ranges

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In order of fold change, these proteins were CYP2A5, GSTM3, GSTM1, ENTPD5, G6PD, EPHX1

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These proteins may yield translatable biomarkers for clinical development

Cordyceps cicadae induces G2/M cell cycle arrest in MHCC97H human hepatocellular carcinoma cells: a proteomic study

Background

Cordyceps cicadae is a medicinal fungus that is often used for treating cancer. However, the anticancer mechanisms of C. cicadae are largely unknown. This study aims to investigate the anticancer mechanisms of C. cicadae against hepatocellular carcinoma cells in vitro using a proteomic approach.

Methods

Human hepatocellular carcinoma MHCC97H cells were treated with a water extract of C. cicadae (0, 100, 250, 500, and 1000 μg/mL) for 48 h and harvested for cell viability assays. The significant differences in protein expression between control and C. cicadae-treated cells were analyzed by two-dimensional gel-based proteomics coupled with matrix-assisted laser desorption ionization-time of flight mass spectrometry. Flow cytometry analysis was employed to investigate the cell cycle and cell death. The anticancer molecular mechanism was analyzed by whole proteome mapping.

Results

The water extract of C. cicadae (0, 100, 250, 500, and 1000 μg/mL) inhibited the growth of MHCC97H cells in a dose-dependent manner via G2/M phase cell cycle arrest with no evidence of apoptosis. Among the identified proteins with upregulated expression were dynactin subunit 2, N-myc downstream-regulated gene 1, heat shock protein beta-1, alpha-enolase isoform 1, phosphatidylinositol transfer protein, and WD repeat-containing protein 1. Meanwhile, the proteins with downregulated expression were 14-3-3 gamma, BUB3, microtubule-associated protein RP/EB family member 1, thioredoxin-like protein, chloride intracellular channel protein 1, ectonucleoside triphosphate diphosphohydrolase 5, xaa-Pro dipeptidase, enoyl-CoA delta isomerase 1, protein-disulfide isomerase-related chaperone Erp29, hnRNP 2H9B, peroxiredoxin 1, WD-40 repeat protein, and serine/threonine kinase receptor-associated protein.

Conclusion

The water extract of C. cicadae reduced the growth of human hepatocellular carcinoma MHCC97H cells via G2/M cell cycle arrest.

PANDER transgenic mice display fasting hyperglycemia and hepatic insulin resistance

PANcreatic-DERived factor (PANDER, FAM3B) is a novel protein that is highly expressed within the endocrine pancreas and to a lesser degree in other tissues. Under glucose stimulation, PANDER is co-secreted with insulin from the β-cell. Despite prior creation and characterization of acute hepatic PANDER animal models, the physiologic function remains to be elucidated from pancreas-secreted PANDER. To determine this, in this study, a transgenic mouse exclusively overexpressing PANDER from the endocrine pancreas was generated. PANDER was selectively expressed by the pancreatic-duodenal homeobox-1 (PDX1) promoter. The PANDER transgenic (PANTG) mice were metabolically and proteomically characterized to evaluate effects on glucose homeostasis, insulin sensitivity, and lipid metabolism. Fasting glucose, insulin and C-peptide levels were elevated in the PANTG compared with matched WT mice. Younger PANTG mice also displayed glucose intolerance in the absence of peripheral insulin sensitivity. Hyperinsulinemic-euglycemic clamp studies revealed that hepatic glucose production and insulin resistance were significantly increased in the PANTG with no difference in either glucose infusion rate or rate of disappearance. Fasting glucagon, corticosterones, resistin and leptin levels were also similar between PANTG and WT. Stable isotope labeling of amino acids in cell culture revealed increased gluconeogenic and lipogenic proteomic profiles within the liver of the PANTG with phosphoenol-pyruvate carboxykinase demonstrating a 3.5-fold increase in expression. This was matched with increased hepatic triglyceride content and decreased p-AMPK and p-acetyl coenzyme A carboxylase-1 signaling in the PANTG. Overall, our findings support a role of pancreatic β-cell-secreted PANDER in the regulation of hepatic insulin and lipogenenic signaling with subsequent impact on overall glycemia.

Purinergic signalling in the liver in health and disease

Purinergic signalling is involved in both the physiology and pathophysiology of the liver. Hepatocytes, Kupffer cells, vascular endothelial cells and smooth muscle cells, stellate cells and cholangiocytes all express purinoceptor subtypes activated by adenosine, adenosine 5'-triphosphate, adenosine diphosphate, uridine 5'-triphosphate or UDP. Purinoceptors mediate bile secretion, glycogen and lipid metabolism and indirectly release of insulin. Mechanical stress results in release of ATP from hepatocytes and Kupffer cells and ATP is also released as a cotransmitter with noradrenaline from sympathetic nerves supplying the liver. Ecto-nucleotidases play important roles in the signalling process. Changes in purinergic signalling occur in vascular injury, inflammation, insulin resistance, hepatic fibrosis, cirrhosis, diabetes, hepatitis, liver regeneration following injury or transplantation and cancer. Purinergic therapeutic strategies for the treatment of these pathologies are being explored.

Ectonucleotidase expression profile and activity in human cervical cancer cell lines

Cervical cancer is the third most frequent cancer in women worldwide. Adenine nucleotide signaling is modulated by the ectonucleotidases that act in sequence, forming an enzymatic cascade. Considering the relationship between the purinergic signaling and cancer, we studied the E-NTPDases, ecto-5'-nucleotidase, and E-NPPs in human cervical cancer cell lines and keratinocytes. We evaluated the expression profiles of these enzymes using RT-PCR and quantitative real-time PCR analysis. The activities of these enzymes were examined using ATP, ADP, AMP, and p-nitrophenyl-5'-thymidine monophosphate (p-Nph-5'-TMP) as substrate, in a colorimetric assay. The extracellular adenine nucleotide hydrolysis was estimated by HPLC analysis. The hydrolysis of all substrates exhibited a linear pattern and these activities were cation-dependent. An interesting difference in the degradation rate was observed between cervical cancer cell lines SiHa, HeLa, and C33A and normal imortalized keratinocytes, HaCaT cells. The mRNA of ecto-5'-nucleotidase, E-NTPDases 5 and 6 were detectable in all cell lines, and the dominant gene expressed was the Entpd 5 enzyme, in SiHa cell line (HPV16 positive). In accordance with this result, a higher hydrolysis activity for UDP and GDP nucleotides was observed in the supernatant of the SiHa cells. Both normal and cancer cells presented activity and mRNAs of members of the NPP family. Considering that these enzymes exert an important catalytic activity, controlling purinergic nucleotide concentrations in tumors, the presence of ectonucleotidases in cervical cancer cells can be important to regulate the levels of extracellular adenine nucleotides, limiting their effects.

The ENTPD5/mt-PCPH oncoprotein is a catalytically inactive member of the ectonucleoside triphosphate diphosphohydrolase family

Expression of the ENTPD5/mt-PCPH onco-protein and overexpression of the normal ENTPD5/PCPH protein contribute to the malignant transformation of diverse mammalian cell types, and PCPH is mutated and/or deregulated in various human tumor types. Expression of PCPH or mt-PCPH caused similar phenotypes, yet the effects promoted by mt-PCPH expression were consistently and substantially greater. ATP depletion and increased stress‑resistance are phenotypes commonly associated with PCPH and mt-PCPH expression. It was suggested that the intrinsic nucleoside triphosphate diphosphohydrolase (NTPDase) activity of PCPH and mt-PCPH may be responsible for these phenotypes, but direct supporting evidence remains to be established. Results from experiments designed to test such hypothesis demonstrate that, as expected, mt-PCPH expression in human colorectal carcinoma (CRC) cells decreased their ATP levels and conferred resistance to oxaliplatin, a colorectal cancer-relevant chemotherapeutic agent. Using a combination of site-directed mutagenesis, immunoprecipitation methods, in vitro enzyme activity assays and in situ enzyme activity determinations in live cells, this report also demonstrates that the mt-PCPH oncoprotein lacks detectable NTPDase activity, indicating that direct ATP cleavage by mt-PCPH did not cause the ATP depletion observed in mt-PCPH-expressing CRC cells. These results strongly suggest that the mt-PCPH oncoprotein may regulate the cellular energy levels and subsequent chemoresistance by an NTPDase-independent mechanism. Understanding possible alternative mechanisms will be essential to devise strategies for the successful treatment of predictably therapeutically resistant tumors expressing either increased PCPH levels or, particularly, the mt-PCPH oncoprotein.

Disordered purinergic signaling and abnormal cellular metabolism are associated with development of liver cancer in Cd39/ENTPD1 null mice

Liver cancer is associated with chronic inflammation, which is linked to immune dysregulation, disordered metabolism, and aberrant cell proliferation. Nucleoside triphosphate diphosphohydrolase-1; (CD39/ENTPD1) is an ectonucleotidase that regulates extracellular nucleotide/nucleoside concentrations by scavenging nucleotides to ultimately generate adenosine. These properties inhibit antitumor immune responses and promote angiogenesis, being permissive for the growth of transplanted tumors. Here we show that Cd39 deletion promotes development of both induced and spontaneous autochthonous liver cancer in mice. Loss of Cd39 results in higher concentrations of extracellular nucleotides, which stimulate proliferation of hepatocytes, abrogate autophagy, and disrupt glycolytic metabolism. Constitutive activation of Ras-mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR)-S6K1 pathways occurs in both quiescent Cd39 null hepatocytes in vitro and liver tissues in vivo. Exogenous adenosine 5'-triphosphate (ATP) boosts these signaling pathways, whereas rapamycin inhibits such aberrant responses in hepatocytes.

CONCLUSION

Deletion of Cd39 and resulting changes in disordered purinergic signaling perturb hepatocellular metabolic/proliferative responses, paradoxically resulting in malignant transformation. These findings might impact adjunctive therapies for cancer. Our studies indicate that the biology of autochthonous and transplanted tumors is quite distinct.

Entpd5 is essential for skeletal mineralization and regulates phosphate homeostasis in zebrafish

Bone mineralization is an essential step during the embryonic development of vertebrates, and bone serves vital functions in human physiology. To systematically identify unique gene functions essential for osteogenesis, we performed a forward genetic screen in zebrafish and isolated a mutant, no bone (nob), that does not form any mineralized bone. Positional cloning of nob identified the causative gene to encode ectonucleoside triphosphate/diphosphohydrolase 5 (entpd5); analysis of its expression pattern demonstrates that entpd5 is specifically expressed in osteoblasts. An additional mutant, dragonfish (dgf), exhibits ectopic mineralization in the craniofacial and axial skeleton and encodes a loss-of-function allele of ectonucleotide pyrophosphatase phosphodiesterase 1 (enpp1). Intriguingly, generation of double-mutant nob/dgf embryos restored skeletal mineralization in nob mutants, indicating that mechanistically, Entpd5 and Enpp1 act as reciprocal regulators of phosphate/pyrophosphate homeostasis in vivo. Consistent with this, entpd5 mutant embryos can be rescued by high levels of inorganic phosphate, and phosphate-regulating factors, such as fgf23 and npt2a, are significantly affected in entpd5 mutant embryos. Our study demonstrates that Entpd5 represents a previously unappreciated essential player in phosphate homeostasis and skeletal mineralization.

ENTPD5-mediated modulation of ATP results in altered metabolism and decreased survival in gliomablastoma multiforme

Gliomablastoma multiforme (GBM) is the most aggressive of brain cancers in humans. Response to current therapies remains extremely poor, with dismal survival statistics. Recently, the endoplasmic reticulum UDPase, ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5), was identified as a key component in the Akt/phosphatidylinositol 3-kinase/phosphatase and tensin homolog regulatory loop, capable of synergizing aerobic glycolysis and cancer cell proliferation in vitro. Utilizing a novel enhanced acceptor fluorescence-based single-cell adenosine 5'-triphosphate (ATP) biosensor, we analyzed ENTPD5-mediated modulation of cytosolic ATP. Here, ENTPD5-dependent modulation of cellular ATP in GBM results in altered metabolic kinetics in vitro, increasing the catabolic efficiencies of aerobic glycolysis and fatty acid oxidation. Additionally, an upregulation of ENTPD5 in both GBM mouse xenografts and in GBM patient tumors was identified, resulting in dramatically reduced survival. Therefore, these results not only provide new tools to monitor ATP flux and cellular metabolism kinetics but also identified a novel therapeutic target for GBM.

Cellular function and molecular structure of ecto-nucleotidases

Ecto-nucleotidases play a pivotal role in purinergic signal transmission. They hydrolyze extracellular nucleotides and thus can control their availability at purinergic P2 receptors. They generate extracellular nucleosides for cellular reuptake and salvage via nucleoside transporters of the plasma membrane. The extracellular adenosine formed acts as an agonist of purinergic P1 receptors. They also can produce and hydrolyze extracellular inorganic pyrophosphate that is of major relevance in the control of bone mineralization. This review discusses and compares four major groups of ecto-nucleotidases: the ecto-nucleoside triphosphate diphosphohydrolases, ecto-5'-nucleotidase, ecto-nucleotide pyrophosphatase/phosphodiesterases, and alkaline phosphatases. Only recently and based on crystal structures, detailed information regarding the spatial structures and catalytic mechanisms has become available for members of these four ecto-nucleotidase families. This permits detailed predictions of their catalytic mechanisms and a comparison between the individual enzyme groups. The review focuses on the principal biochemical, cell biological, catalytic, and structural properties of the enzymes and provides brief reference to tissue distribution, and physiological and pathophysiological functions.

Colorectal adenoma to carcinoma progression is accompanied by changes in gene expression associated with ageing, chromosomal instability, and fatty acid metabolism

Background

Colorectal cancer develops in a multi-step manner from normal epithelium, through a pre-malignant lesion (so-called adenoma), into a malignant lesion (carcinoma), which invades surrounding tissues and eventually can spread systemically (metastasis). It is estimated that only about 5% of adenomas do progress to a carcinoma.

Aim

The present study aimed to unravel the biology of adenoma to carcinoma progression by mRNA expression profiling, and to identify candidate biomarkers for adenomas that are truly at high risk of progression.

Methods

Genome-wide mRNA expression profiles were obtained from a series of 37 colorectal adenomas and 31 colorectal carcinomas using oligonucleotide microarrays. Differentially expressed genes were validated in an independent colorectal gene expression data set. Gene Set Enrichment Analysis (GSEA) was used to identify altered expression of sets of genes associated with specific biological processes, in order to better understand the biology of colorectal adenoma to carcinoma progression.

Results

mRNA expression of 248 genes was significantly different, of which 96 were upregulated and 152 downregulated in carcinomas compared to adenomas. Classification of adenomas and carcinomas using the expression of these genes showed to be very accurate, also when tested in an independent expression data set. Gene-sets associated with ageing (which is related to senescence) and chromosomal instability were upregulated, and a gene-set associated with fatty acid metabolism was downregulated in carcinomas compared to adenomas. Moreover, gene-sets associated with chromosomal location revealed chromosome 4q22 loss and chromosome 20q gain of gene-set expression as being relevant in this progression.

Concluding remark

These data are consistent with the notion that adenomas and carcinomas are distinct biological entities. Disruption of specific biological processes like senescence (ageing), maintenance of chromosomal instability and altered metabolism, are key factors in the progression from adenoma to carcinoma.

Electronic supplementary material

The online version of this article (doi:10.1007/s13402-011-0065-1) contains supplementary material, which is available to authorized users.

Exploring the elephant: histopathology in high-throughput phenotyping of mutant mice

Recent advances in gene knockout techniques and the in vivo analysis of mutant mice, together with the advent of large-scale projects for systematic mouse mutagenesis and genome-wide phenotyping, have allowed the creation of platforms for the most complete and systematic analysis of gene function ever undertaken in a vertebrate. The development of high-throughput phenotyping pipelines for these and other large-scale projects allows investigators to search and integrate large amounts of directly comparable phenotype data from many mutants, on a genomic scale, to help develop and test new hypotheses about the origins of disease and the normal functions of genes in the organism. Histopathology has a venerable history in the understanding of the pathobiology of human and animal disease, and presents complementary advantages and challenges to in vivo phenotyping. In this review, we present evidence for the unique contribution that histopathology can make to a large-scale phenotyping effort, using examples from past and current programmes at Lexicon Pharmaceuticals and The Jackson Laboratory, and critically assess the role of histopathology analysis in high-throughput phenotyping pipelines.

The GDA1_CD39 superfamily: NTPDases with diverse functions

The first comprehensive review of the ubiquitous "ecto-ATPases" by Plesner was published in 1995. A year later, a lymphoid cell activation antigen, CD39, that had been cloned previously, was shown to be an ecto-ATPase. A family of proteins, related to CD39 and a yeast GDPase, all containing the canonical apyrase conserved regions in their polypeptides, soon started to expand. They are now recognized as members of the GDA1_CD39 protein family. Because proteins in this family hydrolyze nucleoside triphosphates and diphosphates, a unifying nomenclature, nucleoside triphosphate diphopshohydrolases (NTPDases), was established in 2000. Membrane-bound NTPDases are either located on the cell surface or membranes of intracellular organelles. Soluble NTPDases exist in the cytosol and may be secreted. In the last 15 years, molecular cloning and functional expression have facilitated biochemical characterization of NTPDases of many organisms, culminating in the recent structural determination of the ecto-domain of a mammalian cell surface NTPDase and a bacterial NTPDase. The first goal of this review is to summarize the biochemical, mutagenesis, and structural studies of the NTPDases. Because of their ability in hydrolyzing extracellular nucleotides, the mammalian cell surface NTPDases (the ecto-NTPDases) which regulate purinergic signaling have received the most attention. Less appreciated are the functions of intracellular NTPDases and NTPDases of other organisms, e.g., bacteria, parasites, Drosophila, plants, etc. The second goal of this review is to summarize recent findings which demonstrate the involvement of the NTPDases in multiple and diverse physiological processes: pathogen-host interaction, plant growth, eukaryote cell protein and lipid glycosylation, eye development, and oncogenesis.

Extracellular nucleosides and nucleotides regulate liver functions via a complex system of membrane proteins

Nucleosides and nucleotides are now considered as extracellular signalling molecules, like neurotransmitters and hormones. Hepatic cells, amongst other cells, ubiquitously express specific transmembrane receptors that transduce the physiological signals induced by extracellular nucleosides and nucleotides, as well as various cell surface enzymes that regulate the levels of these mediators in the extracellular medium. Here, we cover various aspects of the signalling pathways initiated by extracellular nucleosides and nucleotides in the liver, and discuss their overall impact on hepatic physiology.

The ER UDPase ENTPD5 promotes protein N-glycosylation, the Warburg effect, and proliferation in the PTEN pathway

PI3K and PTEN lipid phosphatase control the level of cellular phosphatidylinositol (3,4,5)-trisphosphate, an activator of AKT kinases that promotes cell growth and survival. Mutations activating AKT are commonly observed in human cancers. We report here that ENTPD5, an endoplasmic reticulum (ER) enzyme, is upregulated in cell lines and primary human tumor samples with active AKT. ENTPD5 hydrolyzes UDP to UMP to promote protein N-glycosylation and folding in ER. Knockdown of ENTPD5 in PTEN null cells causes ER stress and loss of growth factor receptors. ENTPD5, together with cytidine monophosphate kinase-1 and adenylate kinase-1, constitute an ATP hydrolysis cycle that converts ATP to AMP, resulting in a compensatory increase in aerobic glycolysis known as the Warburg effect. The growth of PTEN null cells is inhibited both in vitro and in mouse xenograft tumor models. ENTPD5 is therefore an integral part of the PI3K/PTEN regulatory loop and a potential target for anticancer therapy.

Integrating proteomic and transcriptomic high-throughput surveys for search of new biomarkers of colon tumors

To the search of new colon tumor biomarkers in the transition from normal colon (NC) mucosa to adenoma (AD) and adenocarcinoma (AC), we integrated microarray data with the results of a high-throughput proteomic workflow. In proteomic study, we used a modified isoelectric focusing protocol on strips with an immobilized pH gradient to separate peptides labeled with iTRAQ (isobaric tags for relative and absolute quantitation) tags followed by liquid chromatography-tandem mass spectrometry analysis. Gene expression measurements were done using Affymetrix GeneChip HG-U133plus2 microarrays and quantitative reverse transcriptase PCR (q-RT-PCR). We identified 3,886 proteins with at least two peptides. Of them, 1,061 proteins were differentially expressed [FC ≥ 1.5; FDR ≤ 0.01] in two pair-wise comparisons: AD vs. NC and AC vs. AD while 15 and 23 proteins were progressively up-regulated and down-regulated in the NC/AD/AC sequence, respectively. The quantitative proteomic information was subsequently correlated with microarray data. For a collection of genes with the same direction of changes of both mRNA and protein levels, we obtained 785/853/795 genes in AD vs. NC/AC vs. NC/AC vs. AD comparison, respectively. Further evaluation of sequentially altered gene expression by q-RT-PCR on individual samples of 24 NCs, 42 ADs, and 26 ACs confirmed progressive expression of six genes: biglycan, calumenin, collagen type XII, alpha 1 (COL12A1), monoamine oxidase A (MAOA), ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5), and MOCO sulphurase C-terminal domain-containing 2 (MOSC2). Among them, three continuously down-regulated (MAOA, ENTPD5, and MOSC2) and one continuously overexpressed (COL12A1) are reported, to our best knowledge, for the first time in a connection to colon cancer onset.

Genome-wide mRNA expression analysis of hepatic adaptation to high-fat diets reveals switch from an inflammatory to steatotic transcriptional program

BACKGROUND

Excessive exposure to dietary fats is an important factor in the initiation of obesity and metabolic syndrome associated pathologies. The cellular processes associated with the onset and progression of diet-induced metabolic syndrome are insufficiently understood.

PRINCIPAL FINDINGS

To identify the mechanisms underlying the pathological changes associated with short and long-term exposure to excess dietary fat, hepatic gene expression of ApoE3Leiden mice fed chow and two types of high-fat (HF) diets was monitored using microarrays during a 16-week period. A functional characterization of 1663 HF-responsive genes reveals perturbations in lipid, cholesterol and oxidative metabolism, immune and inflammatory responses and stress-related pathways. The major changes in gene expression take place during the early (day 3) and late (week 12) phases of HF feeding. This is also associated with characteristic opposite regulation of many HF-affected pathways between these two phases. The most prominent switch occurs in the expression of inflammatory/immune pathways (early activation, late repression) and lipogenic/adipogenic pathways (early repression, late activation). Transcriptional network analysis identifies NF-kappaB, NEMO, Akt, PPARgamma and SREBP1 as the key controllers of these processes and suggests that direct regulatory interactions between these factors may govern the transition from early (stressed, inflammatory) to late (pathological, steatotic) hepatic adaptation to HF feeding. This transition observed by hepatic gene expression analysis is confirmed by expression of inflammatory proteins in plasma and the late increase in hepatic triglyceride content. In addition, the genes most predictive of fat accumulation in liver during 16-week high-fat feeding period are uncovered by regression analysis of hepatic gene expression and triglyceride levels.

CONCLUSIONS

The transition from an inflammatory to a steatotic transcriptional program, possibly driven by the reciprocal activation of NF-kappaB and PPARgamma regulators, emerges as the principal signature of the hepatic adaptation to excess dietary fat. These findings may be of essential interest for devising new strategies aiming to prevent the progression of high-fat diet induced pathologies.