Biomedical subjects

Günther Ernst

Publications and source records attributed to Günther Ernst.

11 recordsLinked to original sources

PubMed2007

Identification of specific protein markers in microdissected hepatocellular carcinoma.

At present, the molecular mechanisms of hepatocellular carcinogenesis are not well-understood, and hepatocellular carcinoma (HCC) stays one of the most frequent and high-risk metastatic visceral neoplasms worldwide. For the identification of tumor-relevant proteins, we analyzed microdissected cells from nontumorous liver tissue (n = 28) and tissue derived from hepatic tumor center (n = 25), as well as tumor margin (n = 23). We unequivocally identified 53 proteins from hepatic tumor tissues by peptide fingerprint mapping and SELDI mass spectrometry that were separated using two-dimensional gel electrophoresis. Among a number of signals that were detected as significantly different in the protein profiling analysis, we identified for the first time ferritin light subunit (FLS) and adenylate kinase 3 alpha-like 1 (AK3), showing decreased expressions in hepatic tumor, as well as biliverdin reductase B (BVRB) that was upregulated in HCC. The use of ProteinChip technology in combination with tissue microdissection gives insight of the complex changes occurring at the protein level in hepatocellular cancer associated with tumor development and progression and resulted in three new potential diagnostically useful markers.

Biomarkers↗

PubMed2006

Convergence of the proteomic pattern in cancer.

MOTIVATION: On the histological level the differentiation of normal epithelial tissues is well known. The phenomenon of dedifferentiation, which occurs as cells develop towards malignancy is also well described. To identify an epithelial tumor-specific proteomic profile as well as to measure the proximities between we used data from tumor tissue and adjacent normal tissue microdissected from head and neck and colon cancer samples which were analyzed using ProteinChip technology and performed a bioinformatic meta-analysis on the resulting four complex datasets. RESULTS: All four groups could be identified based on their proteomic signatures and the tumor tissues were found to be more similar to one another than to the normal epithelial tissue from which they progressed. This study shows at the proteomic level that changes in the histological features of tumors as compared to the tissues from which they arise are reflected in the convergence of proteomic pattern during the development to cancer.

Cell Differentiation↗

PubMed2006

Detection and identification of heat shock protein 10 as a biomarker in colorectal cancer by protein profiling.

Although colorectal cancer is one of the best-characterized tumors with regard to the multistep progression, it remains one of the most frequent and deadly neoplasms. For a better understanding of the molecular mechanisms behind the process of tumorigenesis and tumor progression, changes in protein expression between microdissected normal and tumorous colonic epithelium were analyzed. Cryostat sections from colorectal tumors, adenoma tissue, and adjacent normal mucosa were laser-microdissected and analyzed using ProteinChip Arrays. The derived MS profiles exhibited numerous statistical differences. One peak showing significantly high expression in the tumor was purified by reverse-phase chromatography and SDS-PAGE. The protein band of interest was passively eluted from the gel and identified as heat shock protein 10 (HSP 10) by tryptic digestion, peptide mapping, and MS/MS analysis. This tumor marker was further characterized by immunohistochemistry. Analysis of HSP 10-positive tissue by ProteinChip technology confirmed the identity of this protein. This work demonstrates that biomarker in colorectal cancer can be detected, identified, and assessed by a proteomic approach comprising tissue microdissection, protein profiling, and immunological techniques. In our experience, histological defined microdissected tissue areas should be used to identify proteins that might be responsible for tumorigenesis.

Biomarkers, Tumor↗

PubMed2006

Different expression of calgizzarin (S100A11) in normal colonic epithelium, adenoma and colorectal carcinoma.

The aim of the study was to detect proteomic markers usable to distinguish colorectal carcinoma from colon adenoma for a better understanding of the molecular mechanisms in the process of tumourigenesis. Therefore, we microdissected colon carcinoma tissue, epithelial colon adenoma tissue as well as normal adjacent colon epithelium and determined protein profiles by SELDI-TOF MS. A multitude of significantly different signals was detected. For their identification colon biopsis were lysed and subjected to a two-dimensional gel electrophoresis for separation. Subsequently, we identified nearly 100 proteins by tryptic digestion, peptide fingerprint mapping and database search. Calgizzarin (S100A11; S100C) identified by peptide fingerprint mapping correlated very well with a significantly differentially expressed signal found in prior protein profiling. Using an immunodepletion assay we confirmed the identity of this signal as calgizzarin. To localise calgizzarin in tissues we performed immunohistochemistry. For further confirmation of the identity of calgizzarin we re-analysed IHC-positive as well as IHC-negative tissue sections on ProteinChip arrays. This work demonstrates that biomarkers in colorectal cancer can be detected, identified and assessed by a proteomic approach comprising tissue-microdissection, protein profiling and immunological techniques.

Adenoma↗

PubMed2005

Proteohistography--direct analysis of tissue with high sensitivity and high spatial resolution using ProteinChip technology.

On the proteomic level, all tissues, tissue constituents, or even single cells are heterogeneous, but the biological relevance of this cannot be adequately investigated with any currently available technique. The analysis of proteins of small tissue areas by any proteomic approach is limited by the number of required cells. Increasing the number of cells only serves to lower the spatial resolution of expressed proteins. To enhance sensitivity and spatial resolution we developed Proteohistography. Laser microdissection was used to mark special areas of interest on tissue sections attached to glass slides. These areas were positioned under microscopic control directly on an affinity chromatographic ProteinChip Array so that cells were lysed and their released proteins bound on a spatially defined point. The ProteinChip System, surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS), allows the laser to be steered to up to 215 distinct positions across the surface of the spot, enabling a high spatial resolution of measured protein profiles for the analyzed tissue area. Protein profiles of the single positions were visually plotted over the used tissue section to visualize distribution proteohistologically. Results show that the spatial distribution of detectable proteins could be used as a Proteohistogram for a given tissue area. Consequently, this procedure can provide additional information to both a matrix-assisted laser desorption/ionization (MALDI)-based approach and immunohistochemistry, as it is more sensitive, highly quantitative, and no specific antibody is needed. Hence, proteomic heterogeneity can be visualized even if proteins are not known or identified.

Carcinoma, Hepatocellular↗

PubMed2005

Discovery and identification of alpha-defensins as low abundant, tumor-derived serum markers in colorectal cancer.

BACKGROUND & AIMS: Although colorectal cancer is one of the best characterized tumors with regard to the multistep genetic progression, it remains one of the most frequent and deadly neoplasms in Western countries. This is mainly due to the fact that, up to now, no clinically relevant serum markers could be established in an early routine diagnostic procedure. METHODS: We comparatively analyzed microdissected normal and tumorous colonic epithelium by ProteinChip technology to detect proteins specific for the tumor directly in the tissue. Immunohistochemistry (IHC) was used for the in situ localization of the discovered proteins, and an ELISA was performed to quantify these proteins in serum. RESULTS: By this approach, we found and identified alpha-defensins 1-3 (HNP1-3) to be more highly expressed in the tumor than in normal epithelium. These findings could be confirmed by IHC. Detection of these peptides in the corresponding serum samples was subsequently performed with ELISA, resulting in an average sensitivity of 69% and specificity of 100% for the recognition of colorectal cancer when using the HNP1-3 level in the serum of the patients. CONCLUSIONS: The direct analysis of microdissected tissue for the discovery of tumor-specific markers followed by the specific detection of these markers in serum by antibody-based methods proved to be a successful strategy in this study. Therefore, we can conclude that these promising markers would not have been found in serum without the information gained through the analysis of microdissected tissue by ProteinChip technology.

Adenoma↗

PubMed2005

Identification of proteins from colorectal cancer tissue by two-dimensional gel electrophoresis and SELDI mass spectrometry.

We investigated protein profiles obtained from colorectal tumor tissue and adjacent normal mucosa to identify tumor specific changes. Protein extracts of biopsis were separated by two-dimensional gel electrophoresis and >40 low-molecular mass proteins were identified by peptide fingerprinting using surface-enhanced laser desoption/ionization mass spectrometry (SELDI-MS). Among these, PACAP protein, hnrnp A1, flavin reductase, calgizzarin, NDK B (NM23-H2), cyclophilin A and smooth muscle protein 22-alpha showed significantly differential abundancy in the analyzed specimens. In addition, immunohistochemical analysis of tissue distribution and subcellular localization of some of the differentially expressed proteins demonstrated alterations in subcellular protein distribution. Further investigations are in progress to assess whether these differentially expressed proteins are associated with tumor development and tumor progression.

Colorectal Neoplasms↗

PubMed2004

A technical triade for proteomic identification and characterization of cancer biomarkers.

Biomarkers are needed to elucidate the biological background and to improve the detection of cancer. Therefore, we have analyzed laser-microdissected cryostat sections from head and neck tumors and adjacent mucosa on ProteinChip arrays. Two differentially expressed proteins (P = 3.34 x 10(-5) and 4.6 x 10(-5)) were isolated by two-dimensional gel electrophoresis and identified as S100A8 (calgranulin A) and S100A9 (calgranulin B) by in-gel proteolytic digestion, peptide mapping, tandem mass spectrometry analysis, and immunodepletion assay. The relevance of these single marker proteins was evaluated by immunohistochemistry. Positive tissue areas were reanalyzed on ProteinChip arrays to confirm the identity of these proteins. As a control, a peak with low P was identified as calgizzarin (S100A11) and characterized in the same way. This technical triade of tissue microdissection, ProteinChip technology, and immunohistochemistry opens up the possibility to find, identify, and characterize tumor relevant biomarkers, which will allow the movement toward the clonal heterogeneity of malignant tumors. Taking this approach, proteins were identified that might be responsible for invasion and metastasis.

Biomarkers, Tumor↗

PubMed2004

Proteomic profiling in microdissected hepatocellular carcinoma tissue using ProteinChip technology.

At present, the molecular mechanisms of hepatocellular carcinogenesis are not well understood. It is known, however, that cancer development and progression are accompanied by profound changes at the cellular and subcellular level, involving RNA/DNA and protein structure and function. Therefore, high-throughput, proteomic techniques targeting these biological molecules may provide novel insights into HCC genesis and prognosis. We characterized tissue protein profiles from 10 HCC patients using ProteinChip technology (SELDI) which is able to detect minute amounts of proteins and moreover to analyze complex protein pattern. Therefore, after histopathological examination, proteins from kryostat sections of non-tumorous hepatic tissue as well as from central and peripheral tumor areas were isolated from complete histological sections or from selected and microdissected tissue areas. Analysis on the SAX and WCX ProteinChip Arrays revealed 14-26, and 25-29 differentially expressed peaks respectively, which characterized non-tumorous and tumor tissue (p< or =0.05). One feature which allows differentiation between central tumor and peripheral tumor regions could only be detected in microdissected tissue. Using ProteinChip technology in combination with tissue microdissection it is possible to investigate complex changes at the protein level in hepatocellular cancer associated with tumor development and progression.

Biomarkers, Tumor↗

PubMed2002

Molecular characterization of head and neck tumors by analysis of telomerase activity and a panel of microsatellite markers.

Head and neck cancer is a frequent malignancy with a complex, and up to now not clear etiology. The reactivation of telomerase activity and losses or gains of specific chromosomal regions, which point to deletions of tumor suppressor genes or amplification of oncogenes are supposed to be the molecular processes during the development and progression of head and neck cancer. Therefore, we analyzed telomerase activity and microsatellite markers using a genome wide panel of 28 microsatellite markers in 38 head and neck squamous-cell carcinomas (HNSCC). Our microsatellite marker set included distinct chromosomal areas that all likely harbor genes contributing to the carcinogenesis of HNSCC. DNA or protein lysates were obtained from primary tumors and compared to peripheral lymphocytes or corresponding normal tissue. At least one genomic alteration [loss of heterozygosity (LOH), or microsatellite instability (MSI)] was found in 31 of the 38 cases (82%). Most frequently we detected an LOH in the chromosomal region 9p12-21 where at least the tumor suppressor genes (TSG) p16INK4A, p14ARF and p15INKB are localized. The comparison between grade two and grade three tumors showed a highly changed frequency of LOH in the chromosomal region 7q31, where a putative TSG is predicted. Telomerase activity was present in 31/37 (83.8%) tumor samples independent of the histopathological staging and grading of the tumors. These molecular characterizations of HNSCC may be a further hint for the involvement of additional, so far unknown, TSGs in the tumor progression and will elucidate the regulation of telomerase.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Characterization of pepsinogen C as a potential biomarker for gastric cancer using a histo-proteomic approach.

We analyzed 74 cryostat sections of central gastric tumor, tumor margin, and normal gastric epithelium using ProteinChip Arrays and SELDI-TOF MS. One peak was significantly down-regulated in tumor tissue (P = 1.43 x 10(-6)) and identified as pepsinogen C using MS/MS analysis and immunodepletion. This signal was further characterized by immunohistochemistry. This work demonstrates that differentially expressed signals can be identified and assessed using a proteomic approach comprising tissue-microdissection, protein profiling, and immunohistochemistry.

Biomarkers↗