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T M Gress

Publications and source records attributed to T M Gress.

At least 37 records · Page 2Linked to original sources
PubMed1999

Strategies for the detection of disease genes in pancreatic cancer.

The present review summarizes our strategies aimed at identifying and characterizing genetic alterations occurring at the transcriptional and chromosomal level in pancreatic cancer. To study transcriptional alterations we have used a number of techniques including modified versions of differential hybridizations and cDNA RDA (representational difference analysis). These approaches have led to the identification of more than 500 genes with differential expression in pancreatic cancer. To study chromosomal aberrations occurring in pancreatic cancer tissues we used comparative genomic hybridization (CGH). This allowed the identification of a number of chromosomal regions containing putative tumor suppressor genes or oncogenes. Genes isolated in both approaches represent potential new disease genes for pancreatic cancer and are at present being characterized by individual or serial analysis.

Amino Acid Sequence↗
PubMed1999

Expression and differential regulation of connective tissue growth factor in pancreatic cancer cells.

CTGF is an immediate early growth responsive gene that has been shown to be a downstream mediator of TGFbeta actions in fibroblasts and vascular endothelial cells. In the present study hCTGF was isolated as immediate early target gene of EGF/TGFalpha in human pancreatic cancer cells by suppression hybridization. CTGF transcripts were found in 13/15 pancreatic cancer cell lines incubated with 10% serum. In 3/7 pancreatic cancer cell lines EGF/TGFalpha induced a significant rise of CTGF transcript levels peaking 1-2 h after the start of treatment. TGFbeta increased CTGF transcript levels in 2/7 pancreatic cancer cell lines after 4 h of treatment and this elevation was sustained after 24 h. Only treatment with TGFbeta was accompanied by a parallel induction of collagen type I transcription. 15/19 human pancreatic cancer tissues were shown to overexpress high levels of CTGF transcripts. CTGF transcript levels in pancreatic cancer tissues and nude mouse xenograft tumors showed a good correlation to the degree of fibrosis. In situ hybridization and the nude mouse experiments revealed that in pancreatic cancer tissues, fibroblasts are the predominant site of CTGF transcription, whereas the tumor cells appear to contribute to a lesser extent. We conclude that CTGF may be of paramount importance for the development of the characteristic desmoplastic reaction in pancreatic cancer tissues.

Animals↗
PubMed1999

Use of representational difference analysis to study the effect of TGFB on the expression profile of a pancreatic cancer cell line.

It has been shown that TGFBs, their receptors, or downstream targets show genetic alterations in pancreatic cancer. This study was designed to identify transcriptional alterations induced by prolonged treatment of pancreatic cancer cell lines with TGFB. The TGFB-responsive PANC-1 cell line was treated with 10-ng/ml TGFB1 for 24 hr. cDNA representational difference analysis was used to generate subtracted hybridization probes enriched for TGFB regulated genes. These probes were hybridized on gridded arrays of cDNA clones containing genes differentially expressed in pancreatic cancer. Twenty-seven distinct cDNA clones were shown to be TGFB target genes. Eleven genes were upregulated by TGFB and were associated with extracellular matrix composition and formation, including genes usually transcribed by cells of mesenchymal origin only. Transcript levels of 16 genes were downregulated by TGFB and could mainly be classified into markers of epithelial differentiation and genes involved in the transcriptional and translational machinery. In conclusion, a 24-hr treatment of PANC-1 cells with TGFB induced a loss of epithelial and a gain of mesenchymal markers. As in other tumors, this epithelial-mesenchymal transdifferentiation may be of general importance during pancreatic carcinogenesis, and may participate, e.g., in the development of the desmoplastic reaction or the acquisition of an invasive phenotype of pancreatic tumor cells. This study demonstrates the usefulness of cDNA RDA and gridded clone libraries to study the effect of signaling cascades on the expression profile of tumor cells. Similar approaches may be helpful in the context of the genome project for the characterization of novel genes. Genes Chromosomes Cancer 26:70-79, 1999.

Cell Division↗
PubMed1999

Expression of the highly conserved RNA binding protein KOC in embryogenesis.

The human KOC gene which is highly expressed in cancer shows typical structural features of an RNA binding protein. We analyzed the temporal and spatial expression pattern of KOC in mouse embryos at different gestational ages. The expression of KOC seems to be ubiquitous at early stages. During advanced gestation highest KOC expression occurs in the gut, pancreas, kidney, and in the developing brain. The expression pattern of KOC was compared to its Xenopus homologue Vg1-RBP during frog development. Similar expression was found in these organs suggesting an important functional role of the homologous proteins in embryonic development.

Amino Acid Sequence↗
PubMed1999

Invasion and metastasis in pancreatic cancer.

Understanding the molecular mechanisms of invasion and metastasis is crucial for the development of novel therapeutic strategies to treat metastases. Considerable studies revealed that the establishment of metastasis is the final outcome of a series of processes such as tumor growth, angiogenesis, tumor cell detachment and invasion of extracellular matrix. Each step of this multistep process is essential for tumor cell survival and establishment of secondary lesions and is regulated by interactions of tumor cells with host microenvironment. This review is focused on the molecular mechanisms involved in the regulation of this processes. The central role of adhesion molecules and ECM degrading proteinases in disruption of cell-cell and cell-ECM associations as well as degradation of extracellular matrix and basement membranes is emphasized.

Cell Adhesion↗
PubMed1999

Novel technology for detection of genomic and transcriptional alterations in pancreatic cancer.

AIM: The present review summarizes our strategies aimed at identifying and characterizing genetic alterations occurring at the transcriptional and chromosomal level in pancreatic cancer. METHODS: To study transcriptional alterations we have used a number of techniques including modified versions of differential hybridizations and cDNA-RDA (representational difference analysis). Comparative genomic hybridization (CGH) was used to study chromosomal aberrations occurring in pancreatic cancer tissues. RESULTS: The study of transcriptional alterations led to the identification of more than 500 genes with differential expression in pancreatic cancer. The sum of these alterations represented the first expression profile characteristic for pancreatic tumors. The CGH analysis allowed the identification of a number of chromosomal regions containing putative tumor suppressor genes or oncogenes. These regions are presently being characterized at the molecular level. In a first approach the myb-oncogene was identified as the relevant oncogene of an amplification on 6q occurring in up to 10% of pancreatic cancer patients. CONCLUSIONS: Genes isolated in both approaches represent potential new disease genes for pancreatic cancer and are at present being characterized by individual or serial analysis.

Chromosome Aberrations↗
PubMed1999

A phase II study of weekly 24-h infusion of high-dose 5-fluorouracil in advanced pancreatic cancer.

No single agent or combination chemotherapy protocol, with the exception of gemcitabine, has so far proven superior to standard bolus 5-fluorouracil regimes for the treatment of advanced pancreatic cancer. The present phase II trial was designed to study whether the effectivity of 5-fluorouracil can be improved with a weekly high-dose 5-fluorouracil schedule. 26 patients with cytologically or histologically verified, metastasized (n = 21) or locally advanced (n = 5) previously untreated adenocarcinoma of the pancreas were included in this study. Treatment consisted of weekly applications of 2,600 mg/m2 5-fluorouracil as 24-h infusion on days 1, 8, 15, 22, 29, 36. Treatment was repeated at day 50 and was continued until disease progression. Primary endpoints of the study were response rates and toxicity, secondary endpoints were survival and clinical benefit in terms of performance status, body weight and analgesia consumption. Toxicity of the regimen was mild with only four instances of grade-3 toxicity. Response rates were 8% (95% CI = 1.2-13.7) with two partial remissions. Improvement of at least one parameter of clinical benefit for > or = four weeks was observed for 11.5% of the study patients. The most prominent effect was a transient stabilization of objective tumor measurements (48% [95% CI = 27.8-68.7]) and individual parameters of clinical benefit (50-75%). Median survival was 248 days (95% CI = 164-459) for all patients included in the study. The present study indicates that the high-dose 5-fluorouracil regimen shows weak activity in advanced pancreatic cancer which seems comparable to gemcitabine.

Adenocarcinoma↗
PubMed1998

The product of the mammalian orthologue of the Saccharomyces cerevisiae HBS1 gene is phylogenetically related to eukaryotic release factor 3 (eRF3) but does not carry eRF3-like activity.

We describe here the cloning and sequencing of human and mouse cDNAs encoding a putative GTP binding protein. Sequence comparison shows that these cDNAs (named eRFS) are likely to represent the orthologues of the yeast Saccharomyces cerevisiae HBS1 gene and that the C-terminal domains of the encoded proteins share structural features with eukaryotic elongation factor eEF-1A and release factor 3 (eRF3) families. The phylogenetic analysis suggests that eRFS proteins and Hbs1p form a cluster of orthologous sequences branching with the eRF3 family. Nevertheless, in yeast, the human eRFS protein and Hbs1p do not complement eRF3/Sup35p thermosensitive mutation and do not interact with eRF1.

Amino Acid Sequence↗
PubMed1998

[Diagnosis of a "hereditary pancreatitis" by the detection of a mutation in the cationic trypsinogen gene].

HISTORY AND CLINICAL FINDINGS: A 71-year-old woman was admitted with the suspected diagnosis of pancreatic carcinoma. As a child she had had repeated attacks of abdominal pain of undetermined cause. When aged 48 years she had developed diabetes mellitus. Her now 42-year-old daughter had from the age of 9 years suffered from repeated attacks of acute pancreatitis that had finally led to chronic pancreatitis. The patient's 15-year-old grandchild was having recurrent bouts of abdominal pain. INVESTIGATIONS: Imaging procedures revealed calcifications in the pancreas and an infiltrating space-occupying lesion, about 3 cm in diameter, in the head of the pancreas with lymph node and liver metastases. Cytological analysis of material aspirated from the space-occupying mass showed typical findings of ductal pancreatic carcinoma. FURTHER TESTS, TREATMENT AND COURSE: At first the patient's course was not typical for a genetically-determined disease, but the family history raised the suspicion of hereditary pancreatitis. A genetic test (Afl-III-RFLP test) demonstrated the mutation Arg 117 His in the cationic trypsinogen gene in all diseased or symptomatic family members. The patient died of the complications of the pancreatic cancer. CONCLUSION: Genetic tests are valuable in the diagnosis of hereditary pancreatitis, because the increased cancer risk can be met by frequent examinations in affected family members.

Abdominal Pain↗
PubMed1998

Identification of a new tumour-associated antigen TM4SF5 and its expression in human cancer.

In a previous large-scale screening for differentially expressed genes in pancreatic cancer, a gene was identified that was highly overexpressed in pancreatic cancer encoding a novel putative tetraspan transmembrane protein highly homologous to the tumour-associated antigen L6. Using a radiation hybrid panel the identified human gene named TM4SF5 (transmembrane 4 superfamily member 5) was localized to chromosome 17 in the region 17p13.3. The cloned TM4SF5 cDNA has a 32bp 5'-untranslated region (UTR), a 591bp open reading frame (ORF) and a 85bp 3'UTR. The predicted TM4SF5 protein with 197 amino acids contains three NH2-terminal hydrophobic transmembrane regions, followed by an extracellular hydrophilic domain containing two potential N-linked glycosylation sites and a COOH-terminal hydrophobic transmembrane region. These structural features are shared by the L6 antigen and a number of related cell surface proteins associated with cell growth. TM4SF5 was overexpressed in pancreatic cancer tissues as compared to both normal pancreas and chronic pancreatitis tissues, and was detected at high levels in other tumour tissues. Although the precise function of TM4SF5 remains to be elucidated it may be useful in a clinical setting for tumour diagnosis and/or therapy. This hypothesis is supported by the strong homology to the L6 antigen, which has proved promising in immunological, therapeutic and diagnostic approaches.

Amino Acid Sequence↗
PubMed1998

Cloning of a new Kunitz-type protease inhibitor with a putative transmembrane domain overexpressed in pancreatic cancer.

In a previous large scale screen for differentially expressed genes in pancreatic cancer, we identified a gene highly overexpressed in cancer encoding a novel putative transmembrane protein with two Kunitz-type serine protease inhibitor domains. The identified gene named kop (Kunitz domain containing protein overexpressed in pancreatic cancer) was assigned to chromosome 19 in the region 19q13.1. Kop was detected at high levels in pancreatic cancer cell lines and was overexpressed in pancreatic cancer tissues as compared to both, normal pancreas and chronic pancreatitis tissues. Being a member of the Kunitz-type serine protease inhibitor family, this new gene may participate in tumour cell invasion and metastasis and in the development of the marked desmoplastic reaction typical for human pancreatic cancer tissues. In this context, the fact that kop has a putative transmembrane domain may have functional implications of particular interest.

Adenocarcinoma↗
PubMed1998

Isolation of differentially expressed genes by combining representational difference analysis (RDA) and cDNA library arrays.

The difference products (DP) of representational difference analyses (RDA) were used as hybridization probes on cDNA arrays. The effectivity of RDA products obtained with increasing driver/tester ratios (DP 1 = 100:1, DP 2 = 800:1 and DP 3 = 400,000:1) to isolate differentially expressed genes was compared with the effectivity of conventional differential hybridizations. Pacreatic cancer and control tissues were used as a test system to isolate differentially expressed genes. The use of RDA products as hybridization probes showed two major advantages: (i) a reliable identification of true differential signals; and (ii) only one autoradiograph had to be analyzed, which eliminated the need for a laborious subtraction of signal intensities obtained with different cDNA probes. Increasing driver/tester ratios in iterative rounds of RDA delivered more specific results, though the total yield of differential clones was gradually reduced. In this situation, the intermediate RDA product DP 2 provided the best compromise.

Blotting, Northern↗
PubMed1997

Cloning of novel transcripts of the human guanine-nucleotide-exchange factor Mss4: in situ chromosomal mapping and expression in pancreatic cancer.

In a previous large-scale analysis of gene expression in pancreatic cancer using gridded arrays of cDNA libraries and differential hybridizations, a gene that was a homolog to human mss4 was identified. Mss4 is a guanine-nucleotide-exchange factor for the Sec4/ Ypt1/Rab family of small GTP-binding proteins involved in the regulation of intracellular vesicular transport. By fluorescence in situ hybridization the human mss4 gene was assigned to chromosome 1q32-q41. Northern blot analysis revealed that three mss4 mRNA species are transcribed in human tissues of 780, 1200, and 2800 bp in length, respectively. Cloning and sequencing of the human mss4 transcripts from a pancreatic cancer cDNA library revealed that these mRNA species differ in the length of the 3-untranslated region and are probably due to the alternate use of polyadenylation sites. All mRNA species were detected at moderate to high levels in pancreatic cancer cell lines and were overexpressed in pancreatic cancer tissue compared to both normal pancreas and chronic pancreatitis tissue. However, the 1200-bp transcript was the Mss4 mRNA species with the highest level of expression in more than 50% of tumor cells and tissues. High levels of expression were found as well in other human tumor tissues. Mss4 as guanine-exchange factor required in the regulation of intracellular transport may be of importance for the function and growth of human tumor cells. However, the precise role of mss4 in human tumor cells is unknown and remains to be elucidated.

Amino Acid Sequence↗
PubMed1997

Characterization of a high copy number amplification at 6q24 in pancreatic cancer identifies c-myb as a candidate oncogene.

In a recent study designed to identify chromosomal aberrations in pancreatic cancer tissues using comparative genomic hybridization, a high copy number amplification on 6q was detected. To identify the most likely candidate oncogene, the extension of the amplification in pancreatic cancer tissues and cell lines was determined by Southern blot analysis. Exon trapping was performed with DNA from a yeast artificial chromosome clone containing the complete minimally amplified region. Only fragments from two genes, namely, the c-myb oncogene and a novel gene, were shown to be amplified. The c-myb proto-oncogene was amplified in 10% of the pancreatic carcinoma tissues and in the pancreatic cancer cell line PC2. Interestingly, the c-myb oncogene was overexpressed not only in the amplified samples but also in the majority of the examined pancreatic cancer tissues and cell lines, suggesting that amplification is only one of the mechanisms leading to overexpression. In contrast, the novel gene, which was called human eRF3b (eukaryotic release factor 3b), seems to be only coamplified with c-myb. Genetic alterations of c-myb were mainly found in advanced tumors, indicating a possible correlation to tumor progression and aggressive tumor phenotypes.

Adenocarcinoma↗
PubMed1997

Cloning of a gene highly overexpressed in cancer coding for a novel KH-domain containing protein.

In a previous large scale screen for differentially expressed genes in pancreatic cancer, we identified a gene highly overexpressed in cancer encoding a novel protein with four K-homologous (KH) domains. KH-domains are found in a subset of RNA-binding proteins, including pre-mRNA-binding (hnRNP) K protein and the fragile X mental retardation gene product (FMR1). By fluorescence in situ hybridization (FISH) the identified gene named koc (KH domain containing protein overexpressed in cancer) was assigned to chromosome 7p11.5. Two pseudogenes were localised on chromosome 6 and 11. The cloned koc cDNA has a 250 bp 5'-UTR, a 1740 bp ORF and a 2168 bp 3'-UTR. The AU-rich 3'-untranslated region of koc contains eight AUUUA and four AUUUUUA reiterated motifs. The deduced koc protein with 580 amino-acids has a relative molecular mass (Mr) of approximately 65,000 (65 K). The koc transcript is highly overexpressed in pancreatic cancer cell lines and in pancreatic cancer tissue as compared to both, normal pancreas and chronic pancreatitis tissue. High levels of expression were as well found in tissue samples of other human tumours. As the KH domain has been shown to be involved in the regulation of RNA synthesis and metabolism, we speculate that koc may assume a role in the regulation of tumour cell proliferation by interfering with transcriptional and or posttranscriptional processes. However, the precise role of koc in human tumour cells is unknown and remains to be elucidated.

Amino Acid Sequence↗
PubMed1997

Identification of genes with specific expression in pancreatic cancer by cDNA representational difference analysis.

cDNA representational difference analysis (cDNA-RDA) is a polymerase-chain-reaction-coupled subtractive and kinetic enrichment procedure for the isolation of differentially expressed genes. In this study, the technique was used to isolate novel genes specifically expressed in pancreatic cancer. cDNA-RDA was done on cDNA reverse transcribed from a poly(A)+ mRNA pool made from 10 cancer tissues (tester) by using as a driver a cDNA from a poly(A)+ mRNA pool made from a combination of 10 tissues of chronic pancreatitis and 10 healthy pancreatic tissues. The use of chronic pancreatitis in addition to healthy pancreas mRNA in the driver preparation eliminated the influence of stromal tissue components present as contamination in the cancer-specific preparations. Such cDNA-RDA led to the isolation of 16 distinct, cancer-specific gene fragments. These were confirmed to be overexpressed in pancreatic cancer tissues by Northern blot analysis. Sequence analysis revealed homologies to five genes previously implicated in the carcinogenesis of the pancreas or other tissues. Eleven fragments had no significant homology to any known gene and thus represent novel candidate disease genes. The experiments demonstrate that cDNA-RDA is a reproducible and highly efficient method for the identification of novel genes with cancer-specific expression.

Annexin A3↗
PubMed1997

Extracellular matrix is reduced by inhibition of transforming growth factor beta1 in pancreatitis in the rat.

BACKGROUND & AIMS: Regeneration from cerulein-induced pancreatitis is accompanied by a transient synthesis and deposition of extracellular matrix components in the rat pancreas. The pleiotropic transforming growth factor (TGF)-beta1 has been suggested to regulate extracellular matrix remodeling during regeneration from acute pancreatitis. The present study was designed to verify this hypothesis by investigating the effect of TGF-beta1 inhibition. METHODS: Experimental acute pancreatitis was induced in rats by supramaximal doses of cerulein. The biological activity of TGF-beta1 was inhibited by injections of neutralizing TGF-beta1 antibody. Changes in the content of extracellular matrix proteins, TGFs, and their messenger RNA concentrations were monitored. RESULTS: TGF-beta1 expression in pancreatic cells was suppressed after induction of acute pancreatitis by the application of neutralizing TGF-beta1 antibody. Immunochemical analysis showed a clear reduction of extracellular matrix formation during the regeneration of the pancreas in antibody-treated animals. The hydroxyproline content and the concentration of collagen types I and III, fibronectin on protein, and messenger RNA level were significantly reduced in the pancreas of treated animals. CONCLUSIONS: These results provide evidence that TGF-beta1 is involved in the regulation of extracellular matrix remodeling in the rat pancreas during regeneration from acute pancreatitis.

Acute Disease↗