High levels of ceruloplasmin in the serum of transgenic mice developing hepatocellular carcinoma

The Oncopig as an Emerging Model to Investigate Copper Regulation in Cancer

Emerging evidence points to several fundamental contributions that copper (Cu) has to promote the development of human pathologies such as cancer. These recent and increasing identification of the roles of Cu in cancer biology highlights a promising field in the development of novel strategies against cancer. Cu and its network of regulatory proteins are involved in many different contextual aspects of cancer from driving cell signaling, modulating cell cycle progression, establishing the epithelial-mesenchymal transition, and promoting tumor growth and metastasis. Human cancer research in general requires refined models to bridge the gap between basic science research and meaningful clinical trials. Classic studies in cultured cancer cell lines and animal models such as mice and rats often present caveats when extended to humans due to inherent genetic and physiological differences. However, larger animal models such as pigs are emerging as more appropriate tools for translational research as they present more similarities with humans in terms of genetics, anatomical structures, organ sizes, and pathological manifestations of diseases like cancer. These similarities make porcine models well-suited for addressing long standing questions in cancer biology as well as in the arena of novel drug and therapeutic development against human cancers. With the emergent roles of Cu in human health and pathology, the pig presents an emerging and valuable model to further investigate the contributions of this metal to human cancers. The Oncopig Cancer Model is a transgenic swine model that recapitulates human cancer through development of site and cell specific tumors. In this review, we briefly outline the relationship between Cu and cancer, and how the novel Oncopig Cancer Model may be used to provide a better understanding of the mechanisms and causal relationships between Cu and molecular targets involved in cancer.

Reduced Neutrophil Extracellular Trap (NET) Formation During Systemic Inflammation in Mice With Menkes Disease and Wilson Disease: Copper Requirement for NET Release

Neutrophil extracellular traps (NETs) contribute to pathological disorders, and their release was directly linked to numerous diseases. With intravital microscopy (IVM), we showed previously that NETs also contribute to the pathology of systemic inflammation and are strongly deposited in liver sinusoids. Over a decade since NET discovery, still not much is known about the metabolic or microenvironmental aspects of their formation. Copper is a vital trace element essential for many biological processes, albeit its excess is potentially cytotoxic; thus, copper levels are tightly controlled by factors such as copper transporting ATPases, ATP7A, and ATP7B. By employing IVM, we studied the impact of copper on NET formation during endotoxemia in liver vasculature on two mice models of copper excess or deficiency, Wilson (ATP7B mutants) and Menkes (ATP7A mutants) diseases, respectively. Here, we show that respective ATP7 mutations lead to diminished NET release during systemic inflammation despite unaltered intrinsic capacity of neutrophils to cast NETs as tested ex vivo. In Menkes disease mice, the in vivo effect is mostly due to diminished neutrophil infiltration of the liver as unmutated mice with a subchronic copper deficiency release even more NETs than their controls during endotoxemia, whereas in Wilson disease mice, excess copper directly diminishes the capacity to release NETs, and this was further confirmed by ex vivo studies on isolated neutrophils co-cultured with exogenous copper and a copper-chelating agent. Taken together, the study extends our understanding on how microenvironmental factors affect NET release by showing that copper is not a prerequisite for NET release but its excess affects the trap casting by neutrophils.

Differentially expressed serum host proteins in hepatitis B and C viral infections

Hepatitis B virus (HBV) and Hepatitis C virus (HCV) infection often lead to hepatocellular carcinoma (HCC), which is mostly detected in advanced stage. Hence, its early detection is of paramount importance using a biomarker having sensitivity and specificity both. The present study highlights differentially expressed host proteins in response to HBV/HCV infection at different stages. Comparative proteomic study was done by two-dimensional gel electrophoresis followed by mass spectrometry. Sera from each of chronically infected, liver cirrhosis and HCC in HBV or HCV infection along with controls were selected. Analysis of functional association between differentially expressed proteins with viral hepatitis was extensively carried out. Forty-three differentially expressed spots (≥ 1.5 fold; P < 0.05) on two-dimensional gel electrophoresis were corresponded to 28 proteins by mass spectrometry in variable liver diseases. Haptoglobin protein levels were decreased upon disease progression to HCC due to HBV infection. The other proteins expressed differentially are ceruloplasmin, serum paraoxonase 1, retinol binding protein and leucine rich alpha 2 proteins in plasma maybe associated to HBV HCC. Whereas, upregulation of C4a/C4b showed it as a reliable marker in patients with end stage liver disease related to HCV infection. ApolipoproteinA1 levels in liver diseases in both HBV and HCV infection corresponding to healthy controls may be a common marker for early diagnosis and disease monitoring. Protein interaction studies by extensive pathway analysis using bioinformatics tools such as EnrichNet application and STRING revealed significant associations with specific infections.

Use of pleural fluid ceruloplasmin in the differentiation of exudative and transudative pleural effusion

Background:

Differentiating into transudate or exudate is the first step in the evaluation of effusions. Light's criteria is the standard but a significant number of transudates may not be differentiated based on these criteria. Acute phase proteins (APP) are present in plasma, which increase or decrease by about 25% during an acute inflammatory response. Ceruloplasmin (CP) is a positive APP. Hence, this study was done to know the diagnostic value of pleural fluid (pf) CP and pf to serum ceruloplasmin ratio (CPr) to differentiate the pleural effusion (PE) into exudate and transudate as compared to Light's criteria.

Materials and Methods:

Setting: Medical wards of St John's Medical College Hospital, Bangalore.

Design:

Cross-sectional descriptive study. Patients with PE were divided into exudate and transudate by definitive diagnosis. pfCP, CPr and Light's criteria were compared with definitive diagnosis for the differentiation of pf into exudate and transudate.

Results:

The mean value of the pfCP and CPr was found to be significantly different between exudates and transudates. Sensitivity and specificity of pfCP at ≥ 13.34 mg/dl is 89.7% and 83.3%, CPr at ≥ 0.37 is 91.4% and 83.3%, Light's criteria 94.82% and 83.3%, respectively. Light's criteria, pfCP and CPr have similar PPV (98%) with Light's criteria having higher NPV (62.5%) than pfCP (45%) and CPr (50%), respectively. CPr has higher NPV than pfCP.

Conclusions:

pfCP and CPr can differentiate pf into exudate and transudate with comparable PPV to Light's criteria.

A proteomic study of plasma protein changes under extreme physical stress

The Spartathlon race (brisk walking a distance of 246km in less than 36h) was employed as a model of severe physical stress to investigate proteomic alterations in the plasma of athletes at the start (Athens) and finish (Sparta) of the race, as well as 48h after the race (Post). The athletes' plasma was analyzed by 2D gel electrophoresis (2-DE) and the differentially expressed proteins were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS). The ProteoSeek™ Albumin/IgG removal kit and the ProteoMiner™ enrichment kit were utilized to detect medium- and low-abundance proteins, whose expression may be masked due to high-abundance proteins. Our results were confirmed by Western blot and biochemical analyses. Overall fifty-two proteins were differentially expressed between the starting point, the finishing line and two days after the end of the race. Of these, thirty proteins were involved in inflammation, while the rest concerned anti-oxidation, anti-coagulation and iron and vitamin D transport. These results indicate that prolonged physical stress affects circulating stress-related proteins, which might be employed as biomarkers of stress-related diseases.

BIOLOGICAL SIGNIFICANCE

The current study employed the Spartathlon, as a model of prolonged endurance exercise, to identify and isolate putative biomarkers of inflammation under extreme physical stress conditions. These protein quantitative variations may pave the way to exploration and understanding of stress-related physiological processes, the stress response itself and diseases whose onset appears to be linked to stress.

Development of quantitative plasma N-glycoproteomics using label-free 2-D LC-MALDI MS and its applicability for biomarker discovery in hepatocellular carcinoma

There has been rapid progress in the development of clinical proteomic methodologies with improvements in mass spectrometric technologies and bioinformatics, leading to many new methodologies for biomarker discovery from human plasma. However, it is not easy to find new biomarkers because of the wide dynamic range of plasma proteins and the need for their quantification. Here, we report a new methodology for relative quantitative proteomic analysis combining large-scale glycoproteomics with label-free 2-D LC-MALDI MS. In this method, enrichment of glycopeptides using hydrazide resin enables focusing on plasma proteins with lower abundance corresponding to the tissue leakage region. On quantitative analysis, signal intensities by 2-D LC-MALDI MS were normalized using a peptide internal control, and the values linked to LC data were treated with DeView™ software. Our proteomic method revealed that the quantitative dynamic ranged from 10² to 10⁶ pg/mL of plasma proteins with good reproducibility, and the limit of detection was of the order of a few ng/mL of proteins in biological samples. To evaluate the applicability of our method for biomarker discovery, we performed a feasibility study using plasma samples from patients with hepatocellular carcinoma, and identified biomarker candidates, including ceruloplasmin, alpha-1 antichymotrypsin, and multimerin-1.

Regulation of iron metabolism-related genes in diethylnitrosamine-induced mouse liver tumors

BACKGROUND

It has been suggested that the altered iron metabolism in liver tumors, characterized by the iron-deficient phenotype, is of importance for tumor growth.

AIM

This study was performed to elucidate the mechanisms underlying iron deficiency in liver tumors by examining how the liver tumor development affects the expression of iron metabolism-related genes.

METHODS

Iron metabolism reference values were analyzed in the sera of diethylnitrosamine-induced hepatocellular adenoma-bearing mice. Expression of iron metabolism-related genes was analyzed in adenomas and surrounding non-tumor tissues, and a subgroup of adenoma-bearing mice loaded with iron 72h before sacrifice.

RESULTS

Iron content of the adenoma tissues was 2.0-2.5-fold lower compared to surrounding and age-matched control tissues. There was no significant difference in serum iron levels between the adenoma-bearing and control mice, while the adenoma-bearing mice exhibited a 2.4-fold lower level of serum transferrin saturation. Expression of iron metabolism-related genes was dysregulated in the adenomas. Iron loading affected protein expression similarly in the adenomas and surrounding tissues suggesting that iron-responsive regulation of the proteins was not impaired. However, the mRNA expression for ceruloplasmin and divalent metal transporter 1 (DMT1) IRE(+) in the adenomas was altered independently of iron status, and the dysregulation may contribute to diminished iron content.

CONCLUSION

These findings suggest that diethylnitrosamine-induced liver adenoma-bearing mice have abnormal iron metabolism and that dysregulation of iron metabolism-related genes contributes to iron deficiency in the adenomas.

Ceruloplasmin expression by human peripheral blood lymphocytes: a new link between immunity and iron metabolism

Ceruloplasmin (CP) is a multicopper oxidase involved in the acute phase reaction to stress. Although the physiological role of CP is uncertain, its role in iron (Fe) homeostasis and protection against free radical-initiated cell injury has been widely documented. Previous studies showed the existence of two molecular isoforms of CP: secreted CP (sCP) and a membrane glycosylphosphatidylinositol (GPI)-anchored form of CP (GPI-CP). sCP is produced mainly by the liver and is abundant in human serum whereas GPI-CP is expressed in mammalian astrocytes, rat leptomeningeal cells, and Sertolli cells. Herein, we show using RT-PCR that human peripheral blood lymphocytes (huPBL) constitutively express the transcripts for both CP molecular isoforms previously reported. Also, expression of CP in huPBL is demonstrated by immunofluorescence with confocal microscopy and flow cytometry analysis using cells isolated from healthy blood donors with normal Fe status. Importantly, the results obtained show that natural killer cells have a significantly higher CP expression compared to all other major lymphocyte subsets. In this context, the involvement of lymphocyte-derived CP on host defense processes via its anti/prooxidant properties is proposed, giving further support for a close functional interaction between the immune system and the Fe metabolism.

Oncoproteomics of hepatocellular carcinoma: from cancer markers' discovery to functional pathways

Hepatocellular carcinoma (HCC) is a heterogeneous cancer with no promising treatment and remains one of the most prevailing and lethal malignancies in the world. Researchers in many biological areas now routinely identify and characterize protein markers by a mass spectrometry-based proteomic approach, a method that has been commonly used to discover diagnostic biomarkers for cancer detection. The proteomic research platforms span from the classical two-dimensional polyacrylamide gel electrophoresis (2-DE) to the latest Protein Chip or array technology, which are often integrated with the MALDI (matrix-assisted laser-desorption ionization), SELDI (surface-enhanced laser desorption/ionization) or tandem mass spectrometry (MS/MS). New advances on quantitative proteomic analysis (e.g. SILAC, ICAT, and ITRAQ) and multidimensional protein identification technology (MudPIT) have greatly enhanced the capability of proteomic methods to study the expressions, modifications and functions of protein markers. The present article reviews the latest proteomic development and discovery of biomarkers in HCC that may provide insights into the underlying mechanisms of hepatocarcinogenesis and the readiness of biomarkers for clinical uses.