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Differential proteomic and tissue expression analyses identify valuable diagnostic biomarkers of hepatocellular differentiation and hepatoid adenocarcinomas
Abstract
The exact discrimination of lesions with true hepatocellular differentiation from secondary tumours and neoplasms with hepatocellular histomorphology like hepatoid adenocarcinomas (HAC) is crucial. Therefore, we aimed to identify ancillary protein-biomarkers by using complementary proteomic techniques (2D-DIGE, label-free MS). The identified candidates were immunohistochemically validated in 14 paired samples of hepatocellular carcinoma (HCC) and non-tumourous liver tissue (NT). The candidates and HepPar1/Arginase1 were afterwards tested for consistency in a large cohort of hepatocellular lesions and NT (n = 290), non-hepatocellular malignancies (n = 383) and HAC (n = 13). Eight non-redundant, differentially expressed proteins were suitable for further immunohistochemical validation and four (ABAT, BHMT, FABP1, HAOX1) for further evaluation. Sensitivity and specificity rates for HCC/HAC were as follows: HepPar1 80.2%, 94.3% / 80.2%, 46.2%; Arginase1 82%, 99.4% / 82%, 69.2%; BHMT 61.4%, 93.8% / 61.4%, 100%; ABAT 84.4%, 33.7% / 84.4%, 30.8%; FABP1 87.2%, 95% / 87.2%, 69.2%; HAOX1 95.5%, 36.3% / 95.5%, 46.2%. The best 2×/3× biomarker panels for the diagnosis of HCC consisted of Arginase1/HAOX1 and BHMT/Arginase1/HAOX1 and for HAC consisted of Arginase1/FABP1 and BHMT/Arginase1/FABP1. In summary, we successfully identified, validated and benchmarked protein biomarker candidates of hepatocellular differentiation. BHMT in particular exhibited superior diagnostic characteristics in hepatocellular lesions and specifically in HAC. BHMT is therefore a promising (panel based) biomarker candidate in the differential diagnostic process of lesions with hepatocellular aspect.
... Additionally, low levels of ABAT transcripts are associated with poor patient survival in mesenchymal glioblastoma [40] as well as progression, recurrence, and reduced patient survival time in hepatocellular carcinoma (HCC) [41]. In fact, ABAT protein is a highly sensitive biomarker for the identification of HCC and hepatoid adenocarcinomas [42]. Recently, high ABAT transcript levels were found to correlate with positive patient outcome in clear cell renal carcinoma, and to decrease cell proliferation and migration while increasing cell death in a kidney cancer cell line model [43]. ...
... High ABAT transcript expression is also favorably prognostic in renal (papillary), liver, and lung cancers (our mining of the Human Protein Atlas, v19.proteinatlas.org [44]), and prevalently expressed in other cancers, such as thyroid carcinoma [42], but is negatively prognostic for patients with esophageal squamous cell carcinoma [45]. ...
Adrenocortical carcinoma (ACC) is a rare but deadly cancer for which few treatments exist. Here, we have undertaken a targeted bioinformatics study of The Cancer Genome Atlas (TCGA) ACC dataset focusing on the 30 genes encoding the γ-aminobutyric acid (GABA) system— an under-studied, evolutionarily-conserved system that is an emerging potential player in cancer progression. Our analysis identified a subset of ACC patients whose tumors expressed a distinct GABA system transcriptome. Transcript levels of ABAT (encoding a key GABA shunt enzyme), were upregulated in over 40% of tumors, and this correlated with several favorable clinical outcomes including patient survival; while enrichment and ontology analysis implicated two cancer-related biological pathways involved in metastasis and immune response. The phenotype associated with ABAT upregulation revealed a potential metabolic heterogeneity among ACC tumors associated with enhanced mitochondrial metabolism. Furthermore, many GABAA receptor subunit-encoding transcripts were expressed, including two (GABRB2 and GABRD) prognostic for patient survival. Transcripts encoding GABAB receptor subunits and GABA transporters were also ubiquitously expressed. The GABA system transcriptome of ACC tumors is largely mirrored in the ACC NCI-H295R cell line, suggesting that this cell line may be appropriate for future functional studies investigating the role of the GABA system in ACC cell growth phenotypes and metabolism.
... Conversely, the downregulation of ABAT promotes the progression of BLBC and resistance to endocrine therapy of inflammatory breast cancer (Jansen et al., 2015). Moreover, ABAT has been identified as a prognostic factor for renal cell carcinoma and hepatic adenocarcinoma (Reis et al., 2015;Lu et al., 2020). Chen et al. (2017) screened six genes related to HCC metastasis and prognosis through a co-expression network analysis, which led to the identification of DAO and ABAT. ...
Background:
Bioinformatics provides a valuable tool to explore the molecular mechanisms underlying pathogenesis of hepatocellular carcinoma (HCC). To improve prognosis of patients, identification of robust biomarkers associated with the pathogenic pathways of HCC remains an urgent research priority.
Methods:
We employed the Robust Rank Aggregation method to integrate nine qualified HCC datasets from the Gene Expression Omnibus. A robust set of differentially expressed genes (DEGs) between tumor and normal tissue samples were screened. Weighted gene co-expression network analysis was applied to cluster DEGs and the key modules related to clinical traits identified. Based on network topology analysis, novel risk genes derived from key modules were mined and biological verification performed. The potential functions of these risk genes were further explored with the aid of miRNA-mRNA regulatory networks. Finally, the prognostic ability of these genes was assessed by constructing a clinical prediction model.
Results:
Two key modules showed significant association with clinical traits. In combination with protein-protein interaction analysis, 29 hub genes were identified. Among these genes, 19 from one module showed a pattern of upregulation in HCC and were associated with the tumor node metastasis stage, and 10 from the other module displayed the opposite trend. Survival analyses indicated that all these genes were significantly related to patient prognosis. Based on the miRNA-mRNA regulatory network, 29 genes strongly linked to tumor activity were identified. Notably, five of the novel risk genes, ABAT, DAO, PCK2, SLC27A2, and HAO1, have rarely been reported in previous studies. Gene set enrichment analysis for each gene revealed regulatory roles in proliferation and prognosis of HCC. Least absolute shrinkage and selection operator regression analysis further validated DAO, PCK2, and HAO1 as prognostic factors in an external HCC dataset.
Conclusion:
Analysis of multiple datasets combined with global network information presents a successful approach to uncover the complex biological mechanisms of HCC. More importantly, this novel integrated strategy facilitates identification of risk hub genes as candidate biomarkers for HCC, which could effectively guide clinical treatments.
... ABAT and ALDH6A1 are proved to be hub genes in association with metastasis risk and prognosis in hepatocellular carcinoma (HCC) [29]. Both of them are down-regulated in HCC [30,31]. Our study identified that loss of ABAT and ALDH6A1 contributes to ccRCC tumor growth. ...
Background:
Clear cell renal cell carcinoma (ccRCC) is a malignancy characterized by metabolic reprogramming. ABAT and ALDH6A1 are metabolic enzymes. In this study, we aim to investigate the associations of ABAT and ALDH6A1 with the malignancy of ccRCC cells.
Methods:
The gene expression levels of ABAT and ALDH6A1 in ccRCC were analyzed from gene expression microarray datasets and RNA sequencing data. Clinical information was analyzed from The Cancer Genome Atlas (TCGA) data. The distributions of ABAT and ALDH6A1 in ccRCC clinical tissues were screened by reverse transcription-quantitative polymerase chain reaction (RT-QPCR) and immunohistochemical assays. The effect of overexpression of ABAT or ALDH6A1 was measured by detecting the cell viability, migration ability, and the ratio of lactate and nicotinamide adenine dinucleotide phosphate (NADPH). Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were carried out to investigate the transcript regulation of HNF4A in ABAT and ALDH6A1.
Results:
Remarkable downregulated ABAT and ALDH6A1 expression levels were observed in ccRCC patients and low expression of ABAT and ALDH6A1 was correlated with poor survival. Overexpression of ABAT or ALDH6A1 significantly attenuated cell proliferation and migration, and impaired lactate production. In ABAT increased ccRCC cells, the ratio of NADPH/NADP+ was reduced. Finally, we demonstrated that ABAT and ALDH6A1 were directly regulated by a tumor suppressor, HNF4A.
Conclusions:
These observations identified HNF4A-regulated low-expressed ABAT and ALDH6A1 as promising diagnostic and prognostic biomarkers for ccRCC.
... Die hepatoide Differenzierung zeigt sich histologisch durch solide-pseudoglanduläre Formationen leberzellähnlicher Zellen CME in-Homozystein-S-Methyltransferase in Hepatozyten und hepatozellulären Tumoren gerichteter Antikörper. Mit sehr hoher Spezifität hilft BHMT bei negativem Färberesultat, ein hepatoides Adenokarzinom von einem HCC mit mehrheitlich positivem Färberesultat zu unterscheiden [32]. Glanduläre Anteile, Schleimbildung und Expression von EpCam schließen ein HCC aus [30]. ...
Die hochauflösende radiologische Schnittbildtechnik führt dazu, dass auch kleine, hochdifferenzierte hepatozelluläre Tumoren zur leberbioptischen Diagnostik gelangen. In Leberzirrhosen sind regeneratorische und dysplastische Knoten gegenüber einem hepatozellulären Karzinom abzugrenzen. In nichtzirrhotischem Lebergewebe besteht die Differenzialdiagnose zum hepatozellulären Adenom, regeneratorischen Knoten, leberzellähnlichen lebereigenen Tumoren sowie zu Lebermetastasen. Die Diagnostik umfasst die Matrixanalyse des tumortragenden Lebergewebes, die histologische Strukturanalyse von Zytomorphologie, Trabekel- und Gefäßbettarchitektur, die immunhistochemische Prüfung einer hepatozellulären Differenzierung und die Typisierung leberzellähnlicher Fremdzellen. Molekularpathologische Untersuchungen können die Dignitätseinschätzung untermauern. Die vorliegende Übersicht liefert einen Leitfaden zur Diagnose hepatozellulärer Karzinome und leberzellähnlicher Tumoren auch an kleinen Biopsien.
... ABAT (4-aminobutyrate aminotransferase) is responsible for catabolism of γ-aminobutyric acid (GABA) (an important and mostly inhibitory neurotransmitter in the central nervous system) into succinic semialdehyde [9]. Reis et al. found that ABAT was a protein biomarker with high sensitivity (84.4%/84.4%) in the diagnosis of hepatocellular differentiation and hepatoid adenocarcinomas [10]. ...
Hepatocellular carcinoma (HCC) has a high incidence and mortality worldwide, and its carcinogenesis and progression are influenced by a complex network of gene interactions. A weighted gene co-expression network was constructed to identify gene modules associated with the clinical traits in HCC (n = 214). Among the 13 modules, high correlation was only found between the red module and metastasis risk (classified by the HCC metastasis gene signature) (R2 = -0.74). Moreover, in the red module, 34 network hub genes for metastasis risk were identified, six of which (ABAT, AGXT, ALDH6A1, CYP4A11, DAO and EHHADH) were also hub nodes in the protein-protein interaction network of the module genes. Thus, a total of six hub genes were identified. In validation, all hub genes showed a negative correlation with the four-stage HCC progression (P for trend < 0.05) in the test set. Furthermore, in the training set, HCC samples with any hub gene lowly expressed demonstrated a higher recurrence rate and poorer survival rate (hazard ratios with 95% confidence intervals > 1). RNA-sequencing data of 142 HCC samples showed consistent results in the prognosis. Gene set enrichment analysis (GSEA) demonstrated that in the samples with any hub gene highly expressed, a total of 24 functional gene sets were enriched, most of which focused on amino acid metabolism and oxidation. In conclusion, co-expression network analysis identified six hub genes in association with HCC metastasis risk and prognosis, which might improve the prognosis by influencing amino acid metabolism and oxidation.
As a chronic metabolic disease affecting epidemic proportions worldwide, the pathogenesis of Nonalcoholic Fatty Liver Disease (NAFLD) is not clear yet. There is also a lack of precise biomarkers and specific medicine for the diagnosis and treatment of NAFLD. Methionine metabolic cycle, which is critical for the maintaining of cellular methylation and redox state, is involved in the pathophysiology of NAFLD. However, the molecular basis and mechanism of methionine metabolism in NAFLD are not completely understood. Here, we mainly focus on specific enzymes that participates in methionine cycle, to reveal their interconnections with NAFLD, in order to recognize the pathogenesis of NAFLD from a new angle and at the same time, explore the clinical characteristics and therapeutic strategies.
Background:
Hepatocellular carcinoma (HCC) is the major type of primary liver cancer. Mice lacking the tumor-suppressive protein phosphatase 2A subunit B56δ (Ppp2r5d) spontaneously develop HCC, correlating with increased c-MYC oncogenicity.
Materials and methods:
We used two-dimensional difference gel electrophoresis-coupled matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to identify differential proteomes of livers from wild-type, non-cancerous and HCC-affected B56δ knockout mice.
Results:
A total of 23 proteins were differentially expressed/regulated in liver between wild-type and non-cancerous knockout mice, and 119 between non-cancerous and HCC knockout mice ('cancer proteins'). Overlap with our reported differential transcriptome data was poor. Overall, 56% of cancer proteins were reported before in HCC proteomics studies; 44% were novel. Gene Ontology analysis revealed cancer proteins mainly associated with liver metabolism (18%) and mitochondria (15%). Ingenuity Pathway Analysis identified 'cancer' and 'gastrointestinal disease' as top hits.
Conclusion:
We identified several proteins for further exploration as novel potential HCC biomarkers, and independently underscored the relevance of Ppp2r5d knockout mice as a valuable hepatocarcinogenesis model.
Hepatoid adenocarcinoma is a rare extrahepatic tumor, which shows morphological and immunohistochemical similarities to hepatocellular carcinoma (HCC). Hence, hepatoid adenocarcinoma can cause diagnostic confusion with HCC. Arginase-1 immunostain has been recently shown to be an excellent marker of normal hepatocytes and is a sensitive and specific marker for HCC. However, the expression of Arginase-1 in hepatoid adenocarcinoma has not been evaluated in detail. 8 cases of hepatoid adenocarcinoma were immunostained with Arginase-1, Hepar-1, Glypican-3, CK7, CK20, CK19, polyclonal Carcinoembryonic Antigen (p-CEA), alpha-fetoprotein (AFP), CDX2, and TTF-1. Albumin in-situ-hybridization (ISH) was performed in 4 cases. All 8 cases were positive for Hepar-1. Arginase-1 was positive in 5 of 8 (62.5%) cases; 2 of these cases showed diffuse staining, while 3 showed patchy staining. Glypican-3, CK7 and AFP were each positive in 4 of 8 (50%) cases. CK19 was positive in 3 of 8 (37.5%) cases. p-CEA showed canalicular staining in 3 of 8 (37.5%) cases and albumin-ISH was positive in 3 of 4 (75%) cases. CDX2 was positive in 2 of 8 (25%) cases, both arising from the stomach. CK20 was positive in 1 of 8 (12.5%) case while TTF-1 was negative in all cases. Hepatoid adenocarcinoma has a similar immunostaining profile as HCC. Arginase-1 expression is common (62.5%) in hepatoid adenocarcinoma and hence it is not useful in distinguishing HCC from hepatoid adenocarcinoma.
Proteomics-based clinical studies have been shown to be promising strategies for the discovery of novel biomarkers of a particular disease. Here, we present a study of hepatocellular carcinoma (HCC) that combines complementary gel-based and LC-MS-based approaches of quantitative proteomics. In our proteomic experiments, we analyzed a set of 14 samples (7 x HCC vs. 7 x non-tumorous liver tissue) with both techniques. Thereby we identified 573 proteins that were differentially expressed between the experimental groups. Among these, only 51 differentially expressed proteins were identified irrespective of the applied approach. Using Western blotting and immunohistochemical analysis the regulation patterns of six selected proteins from the study overlap (inorganic pyrophosphatase 1 (PPA1), tumor necrosis factor type 1 receptor-associated protein 1 (TRAP1), betaine-homocysteine S-methyltransferase 1 (BHMT)) were successfully verified within the same sample set. In addition, the up-regulations of selected proteins from the complements of both approaches (major vault protein (MVP), gelsolin (GSN), chloride intracellular channel protein 1 (CLIC1)) were also reproducible. Within a second independent verification set (n = 33) the altered protein expression levels of MVP and BHMT were further confirmed by Western blots quantitatively analyzed via densitometry. For the other candidates slight but non-significant trends were detectable in this independent cohort. Based on these results we assume that MVP and BHMT have the potential to act as diagnostic HCC biomarker candidates that are worth to be followed in further validation studies.
In the previous guideline, groups were specified for which surveillance was likely to be cost-effective because the hepatocellular carcinoma (HCC) incidence was high enough. New data on defining HCC risk have emerged for hepatitis B virus,1, 2 hepatitis C virus,3 and autoimmune hepatitis.4 Surveillance is deemed cost-effective if the expected HCC risk exceeds 1.5% per year in patients with hepatitis C and 0.2% per year in patients with hepatitis B. Analysis of recent studies show that alpha-fetoprotein determination lacks adequate sensitivity and specificity for effective surveillance (and for diagnosis).5, 6 Thus, surveillance has to be based on ultrasound examination. The recommended screening interval is 6 months. Diagnosis of HCC should be based on imaging techniques and/or biopsy.The 2005 diagnostic algorithm has been validated and the diagnostic accuracy of a single dynamic technique showing intense arterial uptake followed by “washout” of contrast in the venous-delayed phases has been demonstrated.7-9 Contrast-enhanced US may offer false positive HCC diagnosis in patients with cholangiocarcinoma and thus, has been dropped from the diagnostic techniques. The diagnostic algorithm is shown in Fig. 1. The application of dynamic imaging criteria should be applied only to patients with cirrhosis of any etiology and to patients with chronic hepatitis B who may not have fully developed cirrhosis or have regressed cirrhosis. Interpretation of biopsies and distinction between high-grade dysplatic nodules and HCC is challenging. Expert pathology diagnosis is reinforced by staining for glypican 3, heat shock protein 70, and glutamine synthetase, because positivity for two of these three stains confirms HCC.10
Hepatocyte paraffin 1 is a monoclonal antibody that has been developed specifically to react with hepatocytes in routine formalin-fixed and paraffin-embedded surgical pathology tissues. It results in a distinct, granular cytoplasmic staining of hepatocytes but fails to react with bile ducts and nonparenchymal liver cells. The antibody decorates a majority of hepatocellular carcinomas, including fibrolamellar variants. It fails to react with a wide variety of other adult malignancies, with the exception of focal staining in a few gastrointestinal malignancies, including a subpopulation of gastric carcinomas.
Hepatocellular carcinoma (HCC) is a highly malignant tumor, and chronic infection with hepatitis B virus is one of its major risk factors. To identify the proteins involved in HCC carcinogenesis, we used two-dimensional fluorescence DIGE to study the differentially expressed proteins in tumor and adjacent nontumor tissue samples. Samples from 12 hepatitis B virus-associated HCC patients were analyzed. A total of 61 spots were significantly up-regulated (ratio >/= 2, p </= 0.01) in tumor samples, whereas 158 spots were down-regulated (ratio </= -2, p </= 0.01). Seventy-one gene products were identified among these spots. Members of the heat shock protein 70 and 90 families were simultaneously up-regulated, whereas metabolism-associated proteins were decreased in HCC samples. The down-regulation of mitochondrial and peroxisomal proteins in these results suggested loss of special organelle functions during HCC carcinogenesis. Four metabolic enzymes involved in the methylation cycle in the liver were down-regulated in HCC tissues, indicating S-adenosylmethionine deficiency in HCC. Two gene products, glyceraldehyde-3-phosphate dehydrogenase and formimidoyltransferase-cyclodeaminase, were identified from inversely altered spots, suggesting that different isoforms or post-translational modifications of these two proteins might play different roles in HCC. For the first time, the overexpression of Hcp70/Hsp90-organizing protein and heterogeneous nuclear ribonucleoproteins C1/C2 in HCC tissues was confirmed by Western blot and then by immunohistochemistry staining in 70 HCC samples, suggesting their potential as protein tumor markers. In summary, we profiled proteome alterations in HCC tissues, and these results may provide useful insights for understanding the mechanism involved in the process of HCC carcinogenesis.
We have prepared antibodies against porcine liver BHMT, and recently cloned cDNAs encoding the porcine and human enzyme. Porcine tissues were tested for BHMT expression by enzyme activity measurements, and Western analysis. Porcine liver and kidney were the only organs that had immune-detectable levels of BHMT protein, and expressed high levels of enzyme activity. Porcine pancreas, brain, heart, lung, and spleen were essentially devoid of enzyme activity and had no immuno-detectable protein. Both BHMT activity measurements and Western analysis indicate that BHMT is expressed in porcine kidney cortex, and not the medulla. Human tissues were tested for BHMT expression by Northern analysis. Human liver and kidney were the only organs that expressed BHMT mRNA. Human pancreas, brain, heart, skeletal muscle, spleen, and placenta were devoid of BHMT mRNA. BHMT was mapped to human chromosome 5 by PCR amplification using human BHMT-specific primers and chromosome specific human-rodent somatic cell hybrid panels. Refinement of the physical localization of the gene was obtained by screening a yeast artificial chromosome library. Funded by AHA (IL affiliate), and ILSI (N. America).
BACKGROUND & PURPOSE:
Hepatocellular carcinoma (HCC) is a major lethal cancer worldwide. Despite sophisticated diagnostic algorithms, the differential diagnosis of small liver nodules still is difficult. While imaging techniques have advanced, adjuvant protein-biomarkers as glypican3 (GPC3), glutamine-synthetase (GS) and heat-shock protein 70 (HSP70) have enhanced diagnostic accuracy. The aim was to further detect useful protein-biomarkers of HCC with a structured systematic approach using differential proteome techniques, bring the results to practical application and compare the diagnostic accuracy of the candidates with the established biomarkers.
METHODS:
After label-free and gel-based proteomics (n=18 HCC/corresponding non-tumorous liver tissue (NTLT)) biomarker candidates were tested for diagnostic accuracy in immunohistochemical analyses (n=14 HCC/NTLT). Suitable candidates were further tested for consistency in comparison to known protein-biomarkers in HCC (n=78), hepatocellular adenoma (n=25; HCA), focal nodular hyperplasia (n=28; FNH) and cirrhosis (n=28).
RESULTS:
Of all protein-biomarkers, 14-3-3Sigma (14-3-3S) exhibited the most pronounced up-regulation (58.8×) in proteomics and superior diagnostic accuracy (73.0%) in the differentiation of HCC from non-tumorous hepatocytes also compared to established biomarkers as GPC3 (64.7%) and GS (45.4%). 14-3-3S was part of the best diagnostic three-biomarker panel (GPC3, HSP70, 14-3-3S) for the differentiation of HCC and HCA which is of most important significance. Exclusion of GS and inclusion of 14-3-3S in the panel (>1 marker positive) resulted in a profound increase in specificity (+44.0%) and accuracy (+11.0%) while sensitivity remained stable (96.0%).
CONCLUSIONS:
14-3-3S is an interesting protein biomarker with the potential to further improve the accuracy of differential diagnostic process of hepatocellular tumors. This article is part of a Special Issue entitled: Medical Proteomics.
The aim of this study was the identification of novel biomarker candidates for the diagnosis of cholangiocellular carcinoma (CCC) and its immunohistochemical differentiation from benign liver and bile duct cells. CCC is a primary cancer which arises from the epithelial cells of bile ducts and is characterised by high mortality rates due to its late clinical presentation and limited treatment options. Tumorous tissue and adjacent non-tumorous liver tissue from eight CCC patients were analysed by two-dimensional differential in-gel electrophoresis (2D-DIGE) and by mass spectrometry-based label-free proteomics. After data analysis and statistical evaluation of the proteins which were found to be differentially regulated between the two experimental groups (fold change ≥ 1.5; p-value ≤ 0.05), 14 candidate proteins were chosen for determination of the cell type-specific expression profile by immunohistochemistry in a cohort of 14 patients. This confirmed the significant up-regulation of serpin H1, 14-3-3 protein sigma (SFN) and stress-induced phosphoprotein 1 (STIP1) in tumorous cholangiocytes in comparison to normal hepatocytes and non-tumorous cholangiocytes, whereas some proteins were detectable specifically in hepatocytes. Since STIP1 exhibited both sensitivity and specificity of 100%, an immunohistochemical verification examining tissue sections of 60 CCC patients was performed. This resulted in a specificity of 98% and a sensitivity of 64%. We therefore conclude that this protein should be considered as potential diagnostic biomarker for CCC in an immunohistochemical application, possibly in combination with other candidates from this study in the form of a biomarker panel. This could improve the differential diagnosis of CCC and benign bile duct diseases as well as metastatic malignancies in the liver.
Das sog. CUP-Syndrom (,,carcinoma of unknown primary“) stellt den diagnostizierenden Arzt und den betroffenen Patient vor eine große Herausforderung. Mittels differenzierter pathologischer Diagnostik kann zunächst die Morphologie genauer beschrieben, durch ergänzende immunhistochemische Untersuchungen können weitere Eigenschaften identifiziert und somit eine mögliche Zuordnung zu einem Primärgewebe erreicht werden. Dadurch wird die Suche nach einem latenten Primärtumor erleichtert, und Möglichkeiten zur Therapieoptimierung werden erschlossen. Als letzter Schritt können molekularbiologische Untersuchungen das diagnostische Repertoire erweitern.
Arginase-1 is an enzyme that catalyzes the hydrolysis of arginine to ornithine and urea in the urea cycle. In normal tissues, arginase-1 is primarily expressed in hepatocytes. Recent investigations have reported that the vast majority of hepatocellular carcinomas express this marker, but it is found only rarely in nonhepatocellular tumors. Owing to its restricted expression in hepatocellular carcinomas, arginase-1 has proved to be a useful immunohistochemical marker for assisting in distinguishing between these tumors and other neoplasms with which they may be confused.
Breast-cancer subtypes present with distinct clinical characteristics. Therefore, characterization of subtype-specific proteins may augment the development of targeted therapies and prognostic biomarkers. To address this issue, mass spectrometry-based secretome analysis of eight breast cancer cell lines, corresponding to the three main breast cancer subtypes was performed. More than 5,200 non-redundant proteins were identified with twenty-three, four, and four proteins identified uniquely in basal, HER2-neu amplified and luminal breast cancer cells, respectively. An in silico mRNA analysis using publicly available breast cancer tissue microarray data was carried out as a preliminary verification step. In particular, the expression profiles of 15 out of 28 proteins included in the microarray (from a total of 31 in our subtype-specific signature) showed significant correlation with estrogen receptor expression. A mass spectrometry-based analysis of breast cancer tissues was undertaken to verify the results at the proteome level. Eighteen out of 31 proteins were quantified in the proteomes of estrogen receptor positive and negative breast cancer tissues. Survival analysis using microarray data was performed to examine the prognostic potential of these selected candidates. Three proteins correlated with estrogen receptor status at both mRNA and protein levels: ABAT, PDZK1 and PTX3, with the former showing significant prognostic potential.
Hepatoid adenocarcinoma (HAC) is a rare but important special type of extrahepatic adenocarcinoma with clinicopathological presentation mimicking hepatocellular carcinoma (HCC), and prompt and correct diagnosis can be a challenge, especially in endemic areas with a high incidence of HCC. To date, HAC has only been reported in case series or single case reports, so we aimed to review the clinicopathological characteristics of HAC to obtain a more complete picture of this rare form of extrahepatic adenocarcinoma. All the articles about HAC published from 2001 to 2011 were reviewed, and clinicopathological findings were extracted for analysis. A late middle-aged male with high serum α-fetoprotein and atypical image finding of HCC should raise the suspicion of HAC, and characteristic pathological immunohistochemical stains can help with the differential diagnosis. Novel immunohistochemical markers may be useful to clearly differentiate HAC from HCC. Once metastatic HAC is diagnosed, the primary tumor origin should be identified for adequate treatment. The majority of HAC originates from the stomach, so panendoscopy should be arranged first.
The distinction of hepatocellular carcinoma (HCC) from metastatic tumor in the liver often presents a diagnostic challenge that carries significant impact on prognostication and therapy. The number of diagnostically useful immunohistochemical markers of hepatocytes is limited to hepatocyte paraffin antigen (HepPar-1), polyclonal carcinoembryonic antigen, and CD10, with α-fetoprotein and glypican-3 labeling HCCs. Arginase-1 (Arg-1) is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of arginine to ornithine and urea. We used immunohistochemistry to compare the sensitivity of Arg-1 to that of HepPar-1 in 151 HCCs. We found that the overall sensitivities of Arg-1 and HepPar-1 are 96.0% and 84.1%, respectively. The sensitivities of Arg-1 in well, moderately, and poorly differentiated HCCs are 100%, 96.2%, and 85.7%, respectively, whereas, in comparison, HepPar-1 demonstrated sensitivities of 100%, 83.0%, and 46.4% for well, moderately, and poorly differentiated tumors, respectively. There were no HCCs in our study that were reactive for HepPar-1 but nonreactive for Arg-1. We also examined Arg-1 expression in nonhepatocellular tumors, including many that are potential mimics of HCC (renal cell carcinomas, neuroendocrine tumors, melanomas, gastric adenocarcinomas, and adrenocortical carcinomas) and found that only 2 non-HCC tumors were reactive for Arg-1. Arg-1 represents a sensitive and specific marker of benign and malignant hepatocytes that may ultimately prove to be a useful diagnostic tool in routine surgical pathology practice.
A patient with primary gastric adenocarcinoma with extremely high serum alpha-fetoprotein (AFP) levels (12,000 ng/ml) is described. Histologically, foci strongly resembling hepatocellular carcinoma with hyaline globules were noted. Within tumor cells, AFP was identified with both light and electron microscopy, showing the production of AFP by tumor cells themselves. Furthermore, 88% of serum AFP combined with Concanavalin A (ConA), revealing that it was hepatic-type AFP and not germcell-type. Localization of alpha-I-antitrypsin within tumor cells was also noted. Ultrastructural study showed that there were two types of structures corresponding to periodic acid-Schiff (PAS)-positive globules, one of which, the proteinaceous material in intracytoplasmic lumina, was found to contain AFP. Among gastric adenocarcinomas with a high serum AFP level (several thousand or more ng/ml of AFP), foci resembling hepatocellular carcinomas have been reported by several investigators. Those gastric carcinomas, together with the current case, may constitute a clinicopathologic entity, hepatoid adenocarcinoma of the stomach.
Hepatoid adenocarcinoma (HAC) is a rare and aggressive extrahepatic tumour, morphologically mimicking hepatocellular carcinoma (HCC). However, immunophenotype and location are heterogeneous. We report the case of a 21-year-old man with HAC of the peritoneal cavity and summarize data from the 261 HAC cases published so far. The most common HAC locations were stomach (63%), ovaries (10%), lung (5%), gallbladder (4%), pancreas (4%), and uterus (4%). With the exception of gallbladder HAC, there was a male predominance (M:F = 2.4:1). Median age was 65 years (range 21-88). Fatigue, weight loss, abdominal masses, and pain were common findings. One-year survival was 55% and median overall survival 11 months (range 0.1-102). The outstanding diagnostic feature of HAC is positivity for alphafetoprotein (AFP) (88%), HepPar1 (63%), and EpCAM antibodies HEA125 or MOC31 which show no reactivity with hepatocytes. Due to the beneficial effect of sorafenib in HCC and strong activation of EGFR, ERK1 and AKT1, our patient received sorafenib. Despite temporary clinical improvement, he died 6 months after the diagnosis. The diagnostic panel of HAC should include AFP, HepPar1, and EpCAM antibodies. EpCAM reactivity excludes HCC. HAC has a poor prognosis.
"Cancer of unknown primary (site)" (CUP) represents a frequent and often difficult task for diagnostic histopathology. In the initial CUP situation, immunohistochemistry, which is relatively cost-efficient and non-burdensome for the patient, contributes substantially to the targeted search for and identification of the primary tumor. It may be performed in a two-step algorithm (keratins as the first step, group and selective markers as the second step). However, in true CUP syndrome--a heterogeneous disease whose etiology and pathogenesis is still poorly understood--the primary tumor is rarely identified, and the immunohistochemical marker profile is often anomalous. Nevertheless, immunohistochemistry remains the most important special method, aiming at the phenotypical classification and particularly the identification of certain favorable therapy-responsive subsets. Novel methods for subtyping of CUP based on the analysis of gene expression profiles need to be further evaluated before their possible diagnostic application. Future basic and clinical research is required to unravel the still enigmatic tumor biology of the CUP syndrome and to improve the hitherto very unfavorable prognosis by developing new efficient therapy regimens.
cDNA encoding human 4-aminobutyrate aminotransferase (aminobutyrate:2-oxoglutarate aminotransferase) was prepared by polymerase chain reaction using mRNA from human neuroblastoma cells as the template and oligonucleotides synthesized on the basis of the information obtained from direct protein sequencing. The cDNA-deduced sequence enabled peptides, sequenced by automated Edman degradation, to be aligned for confirmation of the complete primary structure. The results are compared with the recently published sequence of the rat enzyme deduced entirely from DNA sequencing [Medina-Kauwe, L. K., Tillakaratne, N. J. K., Wu, J.-Y. & Tobin, A. J. (1994) J. Neurochem. 62, 1267-1275]. Although the sequences are almost identical for most of their length, they differ in a segment of 36 residues. Almost complete identity of the two sequences is established if it is assumed that a frame-shift error was introduced into the reported rat cDNA sequence. The human cDNA was used to probe for the presence of 4-aminobutyrate aminotransferase mRNA in human tissues and a significant transcript was found in heart, placenta and in tissues usually associated with the expression of this enzyme.
It has been known for at least 50 years that alterations in methionine metabolism occur in human liver cirrhosis. However, the molecular basis of this alteration is not completely understood. In order to gain more insight into the mechanisms behind this condition, mRNA levels of methionine adenosyltransferase (MAT1A), glycine methyltransferase (GNMT), methionine synthase (MS), betaine homocysteine methyltransferase (BHMT) and cystathionine beta-synthase (CBS) were examined in 26 cirrhotic livers, five hepatocellular carcinoma (HCC) tissues and ten control livers.
The expression of the above-mentioned genes was determined by quantitative RT-PCR analysis. Methylation of MAT1A promoter was assessed by methylation-sensitive restriction enzyme digestion of genomic DNA.
When compared to normal livers MAT1A, GNMT, BHMT, CBS and MS mRNA contents were significantly reduced in liver cirrhosis. Interestingly, MAT1A promoter was hypermethylated in the cirrhotic liver. HCC tissues also showed decreased mRNA levels of these enzymes.
These findings establish that the abundance of the mRNA of the main genes involved in methionine metabolism is markedly reduced in human cirrhosis and HCC. Hypermethylation of MAT1A promoter could participate in its reduced expression in cirrhosis. These observations help to explain the hypermethioninemia, hyperhomocysteinemia and reduced hepatic glutathione content observed in cirrhosis.
Betaine-homocysteine S-methyltransferase (BHMT) has been shown to be expressed at high levels in the livers of all vertebrate species tested. It has also been shown to be abundant in primate and pig kidney but notably very low in rat kidney and essentially absent from the other major organs of monogastric animals. We recently showed by enzyme activity and Western analysis that pig kidney BHMT was only expressed in the cortex and was absent from the medulla. Using immunohistochemical detection, we report here that in human, pig, and rat kidney, BHMT is expressed in the proximal tubules of the cortex. Immunohistochemical staining for BHMT in human, pig, and rat liver indicate high expression in hepatocytes. The staining patterns are consistent with cytosolic expression in both organs.
Hydroxyacid oxidase 1 (Hao1) is a liver-specific peroxisomal enzyme that oxidizes glycolate to glyoxylate with concomitant production of H2O2. In Hao1 messenger RNA (mRNA), an iron-responsive element (IRE) homologous to the sequence recognized by iron regulatory proteins (IRP), key regulators of iron homeostasis, is present, but the involvement of iron in Hao1 regulation remains unclear. In this study, we found a reduction of Hao1 mRNA content in livers of rats with chronic dietary iron overload, which showed decreased IRP activity and higher ferritin expression as expected, but also induction of heme oxygenase (HO-1), a marker of oxidative damage, and lipid peroxidation. Hao1 mRNA levels were not altered significantly in livers of rats administered doses of iron sufficient to induce ferritin expression and to repress IRP activity, but not to activate HO-1 and to promote lipid peroxidation, as well as in the liver of iron-deficient rats. These observations were not consistent with a post-transcriptional down-regulation of Hao1 by iron through the IRE/IRP pathway and suggested an effect of reactive oxygen species (ROS). Indeed, a marked decrease of Hao1 mRNA was observed in the liver of rats subjected to oxidative stress induced by either glutathione depletion or postischemic reperfusion. Nuclear run-on analysis showed an effect of ROS at the transcriptional level. In conclusion, down-regulation of Hao1 expression during oxidative stress may provide a mechanism to prevent excessive H2O2 formation in liver peroxisomes and may represent the prototype of a poorly recognized but potentially relevant response to oxidative injury involving down-regulation of ROS-producing enzymes.
Proteome analysis of human hepatocellular carcinoma tissues was conducted using two-dimensional difference gel electrophoresis coupled with mass spectrometry. Paired samples from the normal and tumor region of resected human liver were labeled with Cy3 and Cy5, respectively while the pooled standard sample was labeled with Cy2. After analysis by the DeCyder software, protein spots that exhibited at least a two-fold difference in intensity were excised for in-gel tryptic digestion and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. A total of 6 and 42 proteins were successfully identified from the well- and poorly-differentiated samples, respectively. The majority of these proteins are related to detoxification/oxidative stress and metabolism. Three down-regulated metabolic enzymes, methionine adenosyltransferase, glycine N-methyltransferase, and betaine-homocysteine S-methyltransferase that are involved in the methylation cycle in the liver are of special interest. Their expression levels, especially, methionine adenosyltransferase, seemed to have a major influence on the level of S-adenosylmethionine (AdoMet), a vital intermediate metabolite required for the proper functioning of the liver. Recent work has shown that chronic deficiency in AdoMet in the liver results in spontaneous development of steatohepatitis and hepatocellular carcinoma, and hence the down-regulation of hepatic methionine adenosyltransferase in our hepatocellular carcinoma samples is in line with this observation. Moreover, when a comparison is made between the differentially expressed proteins from our human hepatocellular carcinoma samples and from the liver tissues of knockout mice deficient in methionine adenosyltransferase, there is a fairly good correlation between them.
Unlabelled:
Hepatocellular adenomas (HCA) with activated beta-catenin present a high risk of malignant transformation. To permit robust routine diagnosis to allow for HCA subtype classification, we searched new useful markers. We analyzed the expression of candidate genes by quantitative reverse transcription polymerase chain reaction QRT-PCR followed by immunohistochemistry to validate their specificity and sensitivity according to hepatocyte nuclear factor 1 alpha (HNF1alpha) and beta-catenin mutations as well as inflammatory phenotype. Quantitative RT-PCR showed that FABP1 (liver fatty acid binding protein) and UGT2B7 were downregulated in HNF1alpha-inactivated HCA (P <or= 0.0002); GLUL (glutamine synthetase) and GPR49 overexpression were associated with beta-catenin-activating mutations (P <or= 0.0005), and SAA2 (serum amyloid A2) and CRP (C-reactive protein) were upregulated in inflammatory HCA (P = 0.0001). Immunohistochemistry validation confirmed that the absence of liver-fatty acid binding protein (L-FABP) expression rightly indicated HNF1alpha mutation (100% sensitivity and specificity), the combination of glutamine synthetase overexpression and nuclear beta-catenin staining were excellent predictors of beta-catenin-activating mutation (85% sensitivity, 100% specificity), and SAA hepatocytic staining was ideal to classify inflammatory HCA (91% sensitivity and specificity). Finally, a series of 93 HCA was unambiguously classified using our 4 validated immunohistochemical markers. Importantly, new associations were revealed for inflammatory HCA defined by SAA staining with frequent hemorrhages (P = 0.003), telangiectatic phenotype (P < 0.001), high body mass index, and alcohol intake (P <or= 0.04). Previously described associations were confirmed and in particular the significant association between beta-catenin-activated HCA and hepatocellular carcinomas (HCC) at diagnosis or during follow-up (P < 10(-5)).
Conclusion:
We refined HCA classification and its phenotypic correlations, providing a routine test to classify hepatocellular adenomas using simple and robust immunohistochemistry.
Hepatocyte paraffin 1 (Hep Par 1), a murine monoclonal antibody, is widely used in surgical pathology practice to determine the hepatocellular origin of neoplasms. However, identity of the antigen for Hep Par 1 is unknown. The aim of this study was to characterize the Hep Par 1 antigen. To identify the antigen, immunoprecipitation was used to isolate the protein from human liver tissue, and a distinct protein band was detected at approximately 165 kDa. The protein band was also present in small intestinal tissue, but was not present in several other non-liver tissues nor in three human hepatocellular carcinoma cell lines, Huh-7, HepG2, and LH86. The protein was purified and analyzed by mass spectrometry. It was identified as carbamoyl phosphate synthetase 1 (CPS1). CPS1 is a rate-limiting enzyme in urea cycle and is located in mitochondria. We demonstrated that hepatoid tumors (gastric and yolk sac) were immunoreactive with both Hep Par 1 antibody and anti-CPS1 antibody, further confirming the results of mass spectrometric analysis. We found that the three human hepatocellular carcinoma cell lines do not express either CPS1 RNA or protein. We confirmed that the gene was present in these cell lines, suggesting that suppression of CPS1 expression occurs at the transcriptional level. This finding may have relevance to liver carcinogenesis, since poorly differentiated hepatocellular carcinomas exhibit poor to absent immunoreactivity to Hep Par 1. In conclusion, we have identified the antigen for Hep Par 1 antibody as a urea cycle enzyme CPS1. Our results should encourage further investigation of potential role that CPS1 expression plays in liver pathobiology and carcinogenesis.
WHO Classification of Tumours of the Digestive System
- P Bioulac-Sage
- C Balabaud
- I Wanless
Bioulac-Sage P, Balabaud C, Wanless I. WHO Classification of Tumours of
the Digestive System. 4th ed. Lyon: IARC, 2010; 200–4.