PubMed Health⌕ Search

Biomedical subjects

Andreas Teufel

Publications and source records attributed to Andreas Teufel.

17 recordsLinked to original sources

Digestive cancers: mechanisms, therapeutics and management.

Cancers of the digestive system are major contributors to global cancer-associated morbidity and mortality, accounting for 35% of annual cases of cancer deaths. The etiologies, molecular features, and therapeutic management of these cancer entities are highly heterogeneous and complex. Over the last decade, genomic and functional studies have provided unprecedented insights into the biology of digestive cancers, identifying genetic drivers of tumor progression and key interaction points of tumor cells with the immune system. This knowledge is continuously translated into novel treatment concepts and targets, which are dynamically reshaping the therapeutic landscape of these tumors. In this review, we provide a concise overview of the etiology and molecular pathology of the six most common cancers of the digestive system, including esophageal, gastric, biliary tract, pancreatic, hepatocellular, and colorectal cancers. We comprehensively describe the current stage-dependent pharmacological management of these malignancies, including chemo-, targeted, and immunotherapy. For each cancer entity, we provide an overview of recent therapeutic advancements and research progress. Finally, we describe how novel insights into tumor heterogeneity and immune evasion deepen our understanding of therapy resistance and provide an outlook on innovative therapeutic strategies that will shape the future management of digestive cancers, including CAR-T cell therapy, novel antibody-drug conjugates and targeted therapies.

Humans↗

Genome-wide analysis of factors regulating gene expression in liver.

In recent decades, multiple individual genes have been studied with respect to their level of expression in liver tissue and in many cases substantial progress has been made in identifying individual factors promoting gene expression in liver. However, the overall picture is still undefined and general rules or factors regulating gene expression in liver have not yet been established. Thus, a genome-wide screen for factors regulating gene expression in liver is of high interest, as it may reveal common regulatory mechanisms for most genes highly expressed in liver. These factors represent potential new targets in liver disease associated with differential gene expression. Using a novel bioinformatics approach, we have performed a genome-wide, bioinformatic screen to identify genetic factors regulating gene expression in liver. As the expression of an individual gene is generally driven by its promoter activity, we compared the level of expression to individual promoter sequences. Expression data of 15,704 individual genes in 12 tissues were obtained from a normal tissue microarray dataset. The genes were subsequently divided into two groups, according to whether or not their highest expression level was found in liver tissue. Scanning 1000 bp upstream of the transcription start of each individual gene and using the PromoterScan algorithm, we were able to identify a total of 7042 promoters containing a total of 241,984 transcription factors. To eliminate the possibility that currently unknown transcription factors may be crucial to liver expression regulation, we investigated all possible nucleotide combinations of 8 bp and 10 bp which we reasoned may serve as novel binding sites for transcription factors. In both screens we did not detect any significant, biologically relevant differences in numbers of transcription factors and binding sites between the two groups. Furthermore, we excluded possible differences in distribution of TATA-boxes or CpG islands as well as differences in nucleotide composition of RNA sequences or amino acid composition of transcribed protein sequences. We conclude that the existence of central, superordinated regulatory factors in liver gene expression is unlikely and that expression of individual genes in liver is more likely to be dependent on individual combinations of regulating factors for each gene.

Algorithms↗

Genetic association of autoimmune hepatitis and human leucocyte antigen in German patients.

AIM: To report on our large German collective and updated data of 142 patients with autoimmune hepatitis (AIH) type 1. METHODS: Key investigations performed were liver biopsy, serum autoantibodies as well as serum markers such as IgG and elevated transaminases. Antinuclear antigen (ANA) and smooth muscle antigen (SMA) autoantibodies characterized type 1 AIH. Type 3 (AIH) was solely characterized by the occurrence of soluble liver antigen/liver-pancreas antigen (SLA/LP) autoantibodies either with or without ANA or SMA autoantibodies. RESULTS: Most prevalent HLAs were A2 (68 patients, 48%), B8 (63 patients, 44%), C7 (90 patients, 63%), DR3 (49 patients, 38%), DR4 (49 patients, 38%) and DQ2 (42 patients, 30%). Compared to the Italian and North American patients, we found fewer patients with a DQ2 subtype. Furthermore, the B8-DR3-DQ2 human leucocyte antigen (HLA) was also less prominent compared to the North American patients. However, prevalences of B8, DR3, DR4, DR7, DR11 and DR13 were comparable to the Italian and North American patients. Furthermore, we report on an additional subgroup of patients with SLA/LP positive AIH. Generally, in this subgroup of patients the same HLA subtypes were favoured as the AIH type 1. CONCLUSION: Although HLA subtypes were comparable between these three collectives, the German patients were distinct from the Italian and North American patients with respect to DQ2 and from the North American patients with respect to B8-DR3-DQ2 HLA. A clinical correlation, e.g. difference in severity or treatability of AIH type 1, has yet to be determined.

Autoantigens↗

Characterization of human gene encoding SLA/LP autoantigen and its conserved homologs in mouse, fish, fly, and worm.

AIM: To approach the elusive function of the SLA/LP molecule, we have characterized genomic organization and conservation of the major antigenic and functional properties of the SLA/LP molecule in various species. METHODS: By means of computational biology, we have characterized the complete SLA/LP gene, mRNA and deduced protein sequences in man, mouse, zebrafish, fly, and worm. RESULTS: The human SLA/LP gene sequence of approximately 39 kb, which maps to chromosome 4p15.2, is organized in 11 exons, of which 10 or 11 are translated, depending on the splice variant. Homologous molecules were identified in several biological model organisms. The various homologous protein sequences showed a high degree of similarity or homology, notably at those residues that are of functional importance. The only domain of the human protein sequence that lacks significant homology with homologous sequences is the major antigenic epitope recognized by autoantibodies from autoimmune hepatitis (AIH) patients. CONCLUSION: The SLA/LP molecule and its functionally relevant residues have been highly conserved throughout the evolution, suggesting an indispensable function of the molecule. The finding that the only non-conserved domain is the dominant antigenic epitope of the human SLA/LP sequence, suggests that SLA/LP autoimmunity is autoantigen-driven rather than being driven by molecular mimicry.

Adaptor Proteins, Signal Transducing↗

Actin binding LIM protein 3 (abLIM3).

LIM domain proteins were demonstrated to play key roles in various biological processes such as embryonic development, cell lineage determination, and cancer differentiation. Actin binding LIM protein 1 (abLIM1) was reported to be localized in a genomic region often deleted in human cancers and suggested to be involved in axon guidance. Recently, existence of a second family member was reported, actin binding LIM protein 2. By means of computational biology and comparative genomics, we now characterized an additional, third member of the actin binding LIM protein subgroup, actin binding LIM protein 3 (abLIM3). The human mRNA sequence was previously annotated as differentially regulated in hepatoblastoma compared to normal livers. Conservation of key structural features of abLIM1 and abLIM2, four LIM domains and a VHD domain, suggested comparable biological function of abLIM3 as a linker between actin cytoskeleton and cell signaling pathways. AbLIM3 was found to be conserved in vertebrates, as orthologous sequences were characterized for mouse, fish, and frog. In addition, we report the existence of abLIM2 orthologs in fish and frog, suggesting a similar degree of evolutionary conservation. The intracellular localization of the abLIM3 protein was predicted to be nuclear by means of Reinhardt's neural network and the k-nearest neighbor algorithm. The corresponding abLIM3 gene was localized to chromosome 5q32 and spanned 119 kb, organized in 24 exons. An RT-PCR based expression profile available from the human unidentified gene-encoded (HUGE) database demonstrated highest expression for abLIM3 in heart, lung, liver, and brain/cerebellum accompanied by lower expression in multiple other tissues. Furthermore, abLIM3 was expressed in fetal liver, CNS, and spinal cord.

Amino Acid Sequence↗

Current bioinformatics tools in genomic biomedical research (Review).

On the advent of a completely assembled human genome, modern biology and molecular medicine stepped into an era of increasingly rich sequence database information and high-throughput genomic analysis. However, as sequence entries in the major genomic databases currently rise exponentially, the gap between available, deposited sequence data and analysis by means of conventional molecular biology is rapidly widening, making new approaches of high-throughput genomic analysis necessary. At present, the only effective way to keep abreast of the dramatic increase in sequence and related information is to apply biocomputational approaches. Thus, over recent years, the field of bioinformatics has rapidly developed into an essential aid for genomic data analysis and powerful bioinformatics tools have been developed, many of them publicly available through the World Wide Web. In this review, we summarize and describe the basic bioinformatics tools for genomic research such as: genomic databases, genome browsers, tools for sequence alignment, single nucleotide polymorphism (SNP) databases, tools for ab initio gene prediction, expression databases, and algorithms for promoter prediction.

Computational Biology↗

New chemotherapeutic strategies in colorectal cancer.

Since colorectal cancer is the second most prevalent cancer worldwide, its treatment remains a major challenge for researchers, gastroenterologists and oncologists. Despite curative resections, half of all patients diagnosed with colorectal cancer die because of their underlying disease. Integral chemotherapeutic components of standard regimens are 5-fluorouracil (5-FU), its modulation by folinic acid and irinotecan or oxaliplatin. All these drugs sequentially given have results in terms of median overall survival of more than 20 months in the palliative treatment of advanced colorectal cancer. Oral fluoropyrimidines, currently under clinical investigation, are likely to substitute continuous 5-FU. Inhibitors of growth factor receptors or their signaling may further prolong disease-free and overall survival rates. Preliminary evidence exists that improved adjuvant and neoadjuvant chemotherapy strategies may further improve the prognosis, mainly because more patients are able to go for primary or secondary surgery with curative intent.

Administration, Oral↗

Characterization of OEBT, a LIM protein.

LIM Proteins have been demonstrated to play key roles in pattern formation during embryonic development, cell lineage determination, and cancer differentiation. These proteins are characterized by their conserved LIM domain, which functions as a specific protein-binding site. Recently, two new members of the LIM protein family, PRICKLE1 and PRICKLE2, were characterized in silico and demonstrated to be human orthologues of the Drosophila prickle proteins. We report on an additional member of this protein family, overexpressed breast tumor protein (OEBT). The corresponding gene was mapped to human chromosome 6p22.31. Orthologues in mouse and rat with 72 and 54% identities on a protein level were identified and the corresponding genes were mapped to mouse chromosome 17 and rat chromosome 9. The protein displays two LIM domains, as well as a PET domain, and was predicted to be localized in the nucleus. Expression of human OEBT was analyzed in silico, and the corresponding RNA was annotated to be highly expressed in a broad range of tissues. ESTs from several malignant tissue differentiations point towards a possible role of OEBT in cancer differentiation.

Adaptor Proteins, Signal Transducing↗

In silico characterization of LZTS3, a potential tumor suppressor.

Members of the leucine zipper tumor suppressor (LZTS) protein family are thought to play roles in cell growth modulation. The two currently known members were identified by analyzing genomic and chromosomal alterations reported to be either involved or deleted in various types of cancer, suggesting a causative relationship. By means of computational biology, we have now identified a novel member of the LZTS protein family named LZTS3. The corresponding gene was localized to chromosome 20p13 and consisted of three exons. The novel LZTS3 protein demonstrated a high similarity to LAPSER1/LZTS2 and FEZ1/LZTS1, two members of the LZTS family. The conserved FEZ1 domain contains a leucine zipper motif similar to the cAMP-responsive activating transcription factor 5. As FEZ1 inhibits cancer cell growth through the regulation of mitosis and its alteration resulted in abnormal cell growth, the LZTS3 protein was expected to have similar functions during cancer differentiation. Furthermore, the protein was conserved in vertebrates, as orthologs could be identified in mouse, rat, and zebrafish. The intracellular localization of the LZTS3 protein was predicted to be nuclear by means of Reinhardt's neural network and the k-nearest neighbor algorithm. An RT-PCR-based expression profile available from the human unidentified gene-encoded (HUGE) database demonstrated the highest expression in the brain and kidney, accompanied by lower expression in multiple other tissues.

Amino Acid Sequence↗

In silico characterization of an Iroquois family-related homeodomain protein.

Homeobox genes have been demonstrated to play important roles during cancer differentiation and embryonic development. The subset of Iroquois-related homeobox genes (IRXs) have furthermore been demonstrated to be involved in several embryonic developmental processes such as patterning of the anterior-posterior and dorso-ventral axis, as well as specific regions of the central nervous system, and differentiation of the otic vesicle, branchial epithelium, and limbs. We have characterized a novel homeodomain protein and corresponding gene by means of computational biology. Since the protein sequence displayed high similarity to the human IRX proteins, the newly identified homeodomain protein was named Iroquois family related homeodomain protein (IFRX). The IFRX protein sequence was found to be highly conserved in vertebrates. The corresponding IFRX gene was located on chromosome 10p12.1 and is organized in seven exons. The protein is predicted to be localized to the nucleus, supporting evidence for a functional role as a transcription factor, as suggested by the existence of a homeodomain. Preliminary expression profiling by biocomputational means predicted a rather broad expression profile with expression in the bone marrow, brain, heart, kidney, liver, lung, pancreas, prostate, skeletal muscle, spinal cord, spleen and thymus. However, expression in several tissues seemed to be low. In addition, approximately one third of all available EST sequences were obtained from embryonic tissues, suggesting that IFRX has a role in embryonic development.

Amino Acid Sequence↗

LASS6, an additional member of the longevity assurance gene family.

Longevity assurance genes (LAGs) represent a subgroup of the homeobox gene family. Five mammalian homologs have been reported, and the corresponding proteins have previously been investigated with respect to their key role in ceramide synthesis. However, members of the LAG family have been shown to be involved in cell growth regulation and cancer differentiation. In an effort to characterize additional members of the LAG family, we have screened the latest releases of genomic databases and report on the bioinformatic characterization of yet another member, LAG1 longevity assurance homolog 6 (LASS6). Like other LAG family members, the LASS6 protein contained a homeodomain and LAG1 domain. In phylogenetic analyses, it displayed highest homology to LASS5. The corresponding gene was localized to human chromosome 2q24.3, spanning a rather large genomic region of 318 kb. Orthologous sequences in mouse and zebrafish suggested a conservation of LASS6 in vertebrates as the protein and corresponding genomic sequences were highly conserved. LASS6 expression was analyzed in silico, and the gene was shown to be broadly expressed in a wide range of tissues. Furthermore, available microarray data suggested a role in cancer differentiation and early embryonic development.

Amino Acid Sequence↗

Irinotecan plus folinic acid/continuous 5-fluorouracil as simplified bimonthly FOLFIRI regimen for first-line therapy of metastatic colorectal cancer.

BACKGROUND: Combination therapy of irinotecan, folinic acid (FA) and 5-fluorouracil (5-FU) has been proven to be highly effective for the treatment of metastatic colorectal cancer. However, in light of safety and efficacy concerns, the best combination regimen for first-line therapy still needs to be defined. The current study reports on the bimonthly FOLFIRI protocol consisting of irinotecan with continuous FA/5-FU in five German outpatient clinics, with emphasis on the safety and efficiency, quality of life, management of delayed diarrhea, and secondary resection of regressive liver metastases. METHODS: A total of 35 patients were treated for metastatic colorectal cancer. All patients received first-line treatment according to the FOLFIRI regimen, consisting of irinotecan (180 mg/m2), L-FA (200 mg/m2) and 5-FU bolus (400 mg/m2) on day 1, followed by a 46-h continuous infusion 5-FU (2400 mg/m2). One cycle contained three fortnightly administrations. Staging was performed after 2 cycles. Dosage was reduced at any time if toxicity NCI CTC grade III/IV was observed. Chemotherapy was administered only to diarrhea-free patients. RESULTS: The FOLFIRI regimen was generally well tolerated. It was postponed for one-week in 51 of 415 applications (12.3%). Dose reduction was necessary in ten patients. Grade III/IV toxicity was rare, with diarrhea (14%), nausea/vomiting (12%), leucopenia (3%), neutropenia (9%) and mucositis (3%). The overall response rate was 31% (4 CR and 7 PR), with disease control in 74%. After primary chemotherapy, resection of liver metastases was achieved in three patients. In one patient, the CR was confirmed pathologically. Median progression-free and overall survival were seven and 17 months, respectively. CONCLUSIONS: The FOLFIRI regimen proved to be safe and efficient. Outpatient treatment was well tolerated. Since downstaging was possible, combinations of irinotecan and continuous FA/5-FU should further be investigated in neoadjuvant protocols.

Adenocarcinoma↗

FoxP4, a novel forkhead transcription factor.

Forkhead proteins have been demonstrated to play key roles in embryonic development, cell cycle regulation, and oncogenesis. We report the characterization of a new forkhead transcription factor, which is a member of the FoxP subfamily. In adult tissues FoxP4 is expressed in heart, brain, lung, liver, kidney, and testis. By Northern hybridization, very low levels of FoxP4 expression were found as early as E7 during embryonic development. Embryonic expression was highest at E11 and subsequently decreased at E15 and E17. In situ hybridization revealed expression of FoxP4 in the developing lung and gut, suggesting a role for FoxP4 during the development of these organs. In addition, FoxP4 was found to be significantly reduced in patients with kidney tumors. Lastly, FoxP4 matches an uncharacterized human EST that has previously been shown to be down-regulated in larynx carcinoma.

Amino Acid Sequence↗

Functional ablation of the mouse Ldb1 gene results in severe patterning defects during gastrulation.

The LIM domain-binding protein 1 (Ldb1) is found in multi-protein complexes containing various combinations of LIM-homeodomain, LIM-only, bHLH, GATA and Otx transcription factors. These proteins exert key functions during embryogenesis. Here we show that targeted deletion of the Ldb1 gene in mice results in a pleiotropic phenotype. There is no heart anlage and head structures are truncated anterior to the hindbrain. In about 40% of the mutants, posterior axis duplication is observed. There are also severe defects in mesoderm-derived extraembryonic structures, including the allantois, blood islands of the yolk sack, primordial germ cells and the amnion. Abnormal organizer gene expression during gastrulation may account for the observed axis defects in Ldb1 mutant embryos. The expression of several Wnt inhibitors is curtailed in the mutant, suggesting that Wnt pathways may be involved in axial patterning regulated by Ldb1.

Animals↗

Frcp1 and Frcp2, two novel fibronectin type III repeat containing genes.

The fibronectin type III (FNIII) repeat is one of three structural motifs originally identified in the fibronectin protein and has been well characterized in recent years. The consensus sequence has since been found in many different proteins including receptors and cell adhesion molecules. We report the cloning and expression analysis of Frcp1 and Frcp2, two members of a new FNIII repeat containing gene family. During embryonic development both genes are primarily expressed in the brain. In adult tissues, Frcp1 is strongly expressed in the liver and Frcp2 in the heart.

Amino Acid Sequence↗

Mbx, a novel mouse homeobox gene.

The homeobox gene Mbxis thought to play important roles in the development of eyes and tectum in zebrafish. We isolated mouse Mbx cDNA and analyzed its expression pattern during early mouse embryogenesis. Expression is predominantly restricted to the midbrain region at E9.5. At subsequent stages of development, Mbx transcripts were also found in the forebrain in addition to midbrain. Thus, the Mbx gene provides a useful molecular marker for early mouse midbrain development and may play a critical role in brain development.

Amino Acid Sequence↗

Treatment of advanced gastric cancer with etoposide, folinic acid, and fluorouracil in the clinical setting: efficacy of therapy and value of serum tumor markers.

The combination of etoposide, folinic acid, and 5-fluorouracil (5-FU) (ELF regimen) has been proved to be an active chemotherapy in patients with advanced gastric cancer. The aim of this study was to confirm the efficacy in the clinical setting and to correlate response with different parameters like serum tumor markers. We treated 60 patients with advanced gastric cancer with 120 mg/m2 etoposide, 300 mg/m2 folinic acid, and 500 mg/m2 5-FU, on d 1-3. The cycle was repeated on d 21. Objective response was obtained in 23% of all patients with measurable disease. Stable disease was obtained in 37%. The tumor-growth-control rate in patients with proximal carcinoma was significantly higher than in those with distal carcinoma (85% vs 48%, p = 0.04). Median survival for all patients was 8.0 mo (95% confidence interval [CI] 7.0-8.5). In responsive patients, survival was more than two-fold longer than in patients with progressive disease. The administration of ELF could be performed safely on an outpatient basis. Toxicity was rather mild. The most frequently elevated serum tumor marker was CA 72-4 (55% of the patients). An elevated level of carcinoembryonic antigen before treatment was significantly correlated with progressive disease. A more than two-fold elevation of at least one marker under treatment was significantly correlated to progressive disease (p < 0.002). A reduction of at least one marker under treatment was significantly correlated to tumor growth control (p < 0.00015). The results of the present trial confirm the efficacy and low toxicity of the ELF regimen in advanced gastric carcinoma. Serum tumor markers proved suitable parameters for assessing response to treatment.

Adult↗