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M Dietel

Publications and source records attributed to M Dietel.

At least 73 records · Page 4Linked to original sources
PubMed2000

Uroplakin III is a highly specific and moderately sensitive immunohistochemical marker for primary and metastatic urothelial carcinomas.

Uroplakins are specific differentiation products of terminally differentiated superficial urothelial cells. We tested the value of a new commercially available monoclonal antibody against uroplakin III (clone AU 1) as a paraffin-reactive immunohistochemical marker for primary and metastatic urothelial carcinomas. The study cases included 67 urothelial carcinomas of the urinary tract (35 primary tumors, 32 metastases) and 318 nonurothelial carcinomas, as well as 5 benign Brenner tumors and 2 transitional cell carcinomas of the ovaries. Uroplakin III was detected in 21 (60%) of the primary urothelial carcinomas and 17 (53%) of the metastases, resulting in an overall sensitivity of 0.57. The studied Brenner tumors also were immunoreactive for uroplakin III. All other studied carcinomas were consistently uroplakin III-negative (specificity 1.00). We found the new monoclonal antibody AU 1 against uroplakin III to be a highly specific paraffin-reactive immunohistochemical marker for urothelial tumors with a moderate sensitivity for the identification of primary and metastatic urothelial carcinomas.

Aged↗
PubMed2000

[beta-Catenine as a genomic target of high-grade microsatellite instability in colorectal cancer].

AIMS: Various inherited and acquired alterations affecting the genes and gene products of the WNT pathway appear to be involved in the different molecular routes leading to colorectal cancer (CRC). This study was initiated to investigate the prevalence of somatic mutations in the beta-catenin gene (CTNNB1) and the associated pathology in CRC with defective DNA mismatch repair. METHODS: Paraffin and/or frozen sections of 33 primary CRC (including any liver and lymph node metastases present) with high-grade microsatellite instability (MSI-H; i.e. with > or = 5 unstable microsatellite markers of 10 tested) were polytopically fractionated by microdissection. Genomic and c-DNA samples were sequenced across exons 2-4 of CTNNB1 and the expression patterns of beta-catenin (beta-C) analyzed by immunohistology and Western blotting. RESULTS: Seven somatic mutations affecting phosphorylation sites of exon 3 (2 deletions also encompassing parts of either intron 2 or exon 4 [delta X2/3 bzw. delta X3/4] and 5 missense mutations [2 x T41A, 2 x S45F, S45P]) were identified. Two mutations (delta X3/4 and S45F) were concordantly present in CRC primaries and their respective metastases whereas the S45P mutation was restricted to a hepatic metastasis. In the delta X2/3 CRC primary only a shortened 66 kD CTNNB1 gene product was present while its associated liver metastasis showed a total loss of beta-C expression. CONCLUSIONS: Both exon 3 and the entire locus coding for beta-C are somatically altered in approximately 20% of CRC with MSI-H at different stages of tumor progression. Thus CTNNB1 appears to be a genomic target for complex oncogenic mutations and deletional processes in a substantial fraction of this molecular subset of CRC.

Cadherins↗
PubMed1999

Involvement of the c-erbB-2 oncogene product in the EGF-induced cell motility of SK-OV-3 ovarian cancer cells.

The epidermal growth factor (EGF) induces the rapid formation of dendritic processes and the dissociation of SK-OV-3 ovarian cancer cells. The SK-OV-3 cell line is characterized by over-expression of the c-erbB-2 oncogene product (p185(c-erbB-2)). To investigate the role of p185(c-erbB-2) in cell motility, a c-erbB-2-specific single-chain antibody was expressed in SK-OV-3 cells using a retroviral expression vector. Eight individual clones expressing the single chain antibody were isolated. These clones have prominent retention of the cell-surface p185(c-erbB-2). The EGF-induced morphologic changes and cell motility of the single-chain-antibody-expressing clones were strongly inhibited, as observed in cell dissociation and in transmigration experiments. However, the suppression of p185(c-erbB-2) does not inhibit the motility signal elicited by 12-O-tetradecanoyl-phorbol-13-acetate. These data indicate that the c-erbB-2 oncogene product is essential to mediate the motility signal of EGF to SK-OV-3 ovarian cancer cells. The enhancement of tumor-cell motility may be partially responsible for the unfavorable prognosis of ovarian cancer with over-expression of c-erbB-2.

Cell Movement↗
PubMed1999

Atypical multidrug resistance: breast cancer resistance protein messenger RNA expression in mitoxantrone-selected cell lines.

BACKGROUND: Human cancer cell lines grown in the presence of the cytotoxic agent mitoxantrone frequently develop resistance associated with a reduction in intracellular drug accumulation without increased expression of the known drug resistance transporters P-glycoprotein and multidrug resistance protein (also known as multidrug resistance-associated protein). Breast cancer resistance protein (BCRP) is a recently described adenosine triphosphate-binding cassette transporter associated with resistance to mitoxantrone and anthracyclines. This study was undertaken to test the prevalence of BCRP overexpression in cell lines selected for growth in the presence of mitoxantrone. METHODS: Total cellular RNA or poly A+ RNA and genomic DNA were isolated from parental and drug-selected cell lines. Expression of BCRP messenger RNA (mRNA) and amplification of the BCRP gene were analyzed by northern and Southern blot hybridization, respectively. RESULTS: A variety of drug-resistant human cancer cell lines derived by selection with mitoxantrone markedly overexpressed BCRP mRNA; these cell lines included sublines of human breast carcinoma (MCF-7), colon carcinoma (S1 and HT29), gastric carcinoma (EPG85-257), fibrosarcoma (EPF86-079), and myeloma (8226) origins. Analysis of genomic DNA from BCRP-overexpressing MCF-7/MX cells demonstrated that the BCRP gene was also amplified in these cells. CONCLUSIONS: Overexpression of BCRP mRNA is frequently observed in multidrug-resistant cell lines selected with mitoxantrone, suggesting that BCRP is likely to be a major cellular defense mechanism elicited in response to exposure to this drug. It is likely that BCRP is the putative "mitoxantrone transporter" hypothesized to be present in these cell lines.

Antineoplastic Agents↗
PubMed1999

Expression of DNA repair proteins hMSH2, hMSH6, hMLH1, O6-methylguanine-DNA methyltransferase and N-methylpurine-DNA glycosylase in melanoma cells with acquired drug resistance.

Malignant melanoma is well known for its primary unresponsiveness to chemotherapy. The mechanisms conferring this intrinsic resistance are unclear. In this study, we investigated the role of genes involved in DNA repair in a panel of human melanoma cell variants exhibiting low and high levels of resistance to 4 commonly used drugs in melanoma treatment, i.e., vindesine, etoposide, fotemustine and cisplatin. We show that in melanoma cells exhibiting resistance to cisplatin, etoposide and vindesine, the nuclear content of each of the DNA mismatch repair (MMR) proteins hMLH1, hMSH2 and hMSH6 was reduced by 30-70%. A decreased expression level of up to 80% of mRNAs encoding hMLH1 and hMSH2 was observed in drug-resistant melanoma cells selected for cisplatin, etoposide and fotemustine, while vindesine-selected cells showed only moderate reduction. In melanoma cells that acquired resistance to fotemustine, the amount of nuclear MMR proteins was nearly unaltered, whereas the activity of O6-methylguanine-DNA methyltransferase (MGMT) was considerably enhanced. Activity of N-methylpurine-DNA glycosylase (MPG) was not significantly altered in any of the drug-resistant melanoma cells. Our data indicate that modulation of both MMR components and MGMT expression level may contribute to the drug-resistant phenotype of melanoma cells.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Increased expression of epidermal fatty acid binding protein, cofilin, and 14-3-3-sigma (stratifin) detected by two-dimensional gel electrophoresis, mass spectrometry and microsequencing of drug-resistant human adenocarcinoma of the pancreas.

In order to study possible mechanisms leading to chemoresistance in pancreatic adenocarcinoma we examined the global protein expression of pancreatic cancer cells in vitro. We used a cell culture model derived from the adenocarcinoma of the pancreas (EPP85-181P). A classical multidrug-resistant subline, EPP85-181RDB, selected in presence of daunorubicin, and an atypical multidrug-resistant cell variant, EPP85-181RNOV, selected in presence of mitoxantrone, were analyzed using two-dimensional electrophoresis. After staining and image analysis, spots of interest were isolated using preparative two-dimensional electrophoresis and subjected to mass spectrometry and microsequencing. Three proteins, E-FABP, cofilin, and 14-3-3-sigma (stratifin), were overexpressed in chemoresistant cell lines. Cofilin was present in both multidrug in chemoresistant cell lines. Cofilin was present in both multidrug-resistant cell lines. E-FABP and 14-3-3-sigma (stratifin) was found to be overexpressed only in the mitoxantrone-selected atypical multidrug-resistant cell line. The possible significance of these findings is discussed.

14-3-3 Proteins↗
PubMed1999

Search for novel proteins involved in the development of chemoresistance in colorectal cancer and fibrosarcoma cells in vitro using two-dimensional electrophoresis, mass spectrometry and microsequencing.

In search of novel mechanisms that may lead to the development of chemoresistance of malignant tumors of the large bowel we used two-dimensional electrophoresis to identify proteins that were overexpressed in colorectal and fibrosarcoma cell lines that were resistant towards mitoxantrone. This cytostatic drug is known to lead to atypical multidrug resistance, i.e., the classical mechanism of multidrug resistance (MDR) accompanied by the overexpression of P-glycoprotein (P-gp) is ineffective. Using mass spectrometry and microsequencing we found adenine phosphoribosyl transferase and breast cancer specific gene 1 (BCSG1) overexpressed in the resistant colorectal tumor cell line. In the chemoresistant fibrosarcoma cell line we found two proteins that were overexpressed. One was identified as Rho-guanine dinucleotide phosphate (Rho-GDP) dissociation inhibitor and the other had sequence homologies with yeast protein yer-7. The putative role of these proteins is discussed.

Antineoplastic Agents↗
PubMed1999

Involvement of the DNA mismatch repair system in antineoplastic drug resistance.

Different types of antineoplastic drugs, such as the alkylating agents busulfan, N-methyl-N'-nitro-N-nitrosoguanidine, N-methyl-N-nitrosourea, procarbazine and temozolomide, the antimetabolites, mercaptopurine and 6-thioguanine, the platinum compounds carboplatin and cisplatin, the anthracycline doxorubicin and the epipodophyllotoxine etoposide act by damaging DNA directly or indirectly. Increasing evidence has shown that tumours could acquire resistance to these drugs by loss of DNA-mismatch repair (MMR) activity. This phenomenon is caused by a decreased MMR-dependent stimulation of signal-transduction pathways causing programmed cell death. Simultaneously, the mutation rate in MMR-deficient tumours is increasing, which could lead to additional secondary drug/resistance phenotypes to other antineoplastic agents. In addition to this, an enhanced mutation rate may contribute to increased phenotypic variation and therefore the clinical aggressiveness of primary tumours and their metastases.

Animals↗
PubMed1999

Effect of follicular cells on calcitonin gene expression in thyroid parafollicular cells in cell culture.

Expression of calcitonin (CT) gene in thyroid parafollicular cells involves alternate formation of CT mRNA or CGRP mRNA. High amounts of CT mRNA are formed only in thyroid gland and formation of CGRP mRNA dominates in the remaining organs. Apart from paracrine and endocrine factors, mRNA formation on the CT gene seems to be affected also by direct contacts with other cells present in the thyroid gland, in which parafollicular cells are located next to follicular cells. The present study aimed at examining whether thyroid follicular cells affect formation of mRNAs for CT and CGRP in parafollicular cells. The studies were performed in cell cultures. A parafollicular cell line (TT cells) and a follicular cell line (F6BTY cells) served as the experimental model. For comparison, co-cultures with fibroblasts, 3T3 cells, and malignant melanoma, MM cells, were also examined. CT gene expression was examined at the level of mRNAs (in situ hybridization and morphometric studies) and at the level of hormones (immunocytochemistry, morphometric studies and radioimmunological estimation of hormone levels in the medium). The immunocytochemical and hybridocytochemical studies, in line with morphometry studies, demonstrated that F6BTY and 3T3 cells were capable of affecting mRNA production for CT and CGRP and that they changed the ratio of CGRP/CT secretion by TT cells, as a sequel of contact between the two cell types and due to mediation of secreted substances. On the other hand, the malignant melanoma MM cells showed no effect on the secretion ratio. Our study seems to indicate that control of mRNA formation from CT gene may involve not only humoral factors but also direct contacts with other cells, which may explain differences in expression of the gene between cells localized in different organs.

Calcitonin↗
PubMed1999

Suppression of the c-erbB-2 gene product decreases transformation abilities but not the proliferation and secretion of proteases of SK-OV-3 ovarian cancer cells.

The overexpression of the c-erbB-2 oncogene product has been reported in approximately 20-30% of human ovarian cancers and has been correlated with a poor prognosis in ovarian cancer patients. To investigate the function of p185(c-erbB-2) in human ovarian cancer cells, a c-erbB-2-specific single-chain antibody (scFv-5R) was expressed in the c-erbB-2-overexpressing SK-OV-3 cell line using a retroviral expression vector. Eight individual clones expressing the single-chain antibody were isolated. These clones have a prominent retention of the cell surface p185(c-erbB-2). In this study we compared the proliferation rate, the anchorage-independent growth, the secretion of matrix metalloproteases and of the urokinase-type plasminogen activator. The clones expressing the c-erbB-2 single-chain antibody, the control cells harbouring the empty vector and the parental SK-OV-3 cells they all had similar proliferation rates in the presence of 10% serum and secreted similar amounts of matrix metalloproteases and of the urokinase-type plasminogen activator. However, the expression of the c-erbB-2 oncogene product offers a strong growth advantage under serum-reduced conditions with 1% serum. In contrast to the parental SK-OV-3 and empty vector control cells, the scFv-5R-expressing clones were not able to grow anchorage-independently. These findings suggest that c-erbB-2 enhances transformation abilities of SK-OV-3 ovarian cancer cells without affecting the secretion of proteases and the proliferation of SK-OV-3 ovarian cancer cells in the presence of high concentrations of serum.

Antineoplastic Agents↗
PubMed1999

Immunohistochemical detection of CD10 with monoclonal antibody 56C6 on paraffin sections.

We tested a total of 174 paraffin-embedded hematolymphoid neoplasias to determine whether CD10 can be specifically and sensitivity detected on paraffin sections using monoclonal antibody 56C6 after epitope retrieval. For 32 cases, results of CD10 detection by immunohistochemistry were compared with flow cytometric data. In only 1 case of follicle center lymphoma, divergent staining results were found with the detection of CD10 by flow cytometry but not by immunohistochemistry. Altogether, 22 of 28 follicle center lymphomas, 2 of 6 hairy cell leukemias, 14 of 34 diffuse large B-cell lymphomas, 3 of 3 Burkitt lymphomas, 4 of 5 precursor B-lineage acute lymphoblastic leukemias, and 2 of 4 T-lymphoblastic lymphomas were CD10+. Decalcification of bone marrow biopsy specimens did not diminish the staining intensity. All other cases, including 10 acute myeloid leukemias and a range of low-grade B-cell lymphomas, were CD10-. CD10 is reliably detectable with antibody 56C6 on paraffin sections using epitope retrieval. The antibody is especially useful for the subclassification of acute leukemias and low-grade B-cell lymphomas.

Antibodies, Monoclonal↗
PubMed1999

Spectrum of congenital heart defects and extracardiac malformations associated with chromosomal abnormalities: results of a seven year necropsy study.

OBJECTIVE: To analyse the spectrum of congenital heart malformations, the frequency of extracardiac malformations, and the proportion of chromosome aberrations among fetuses sent for necropsy. MATERIAL: Necropsies were performed on 815 fetuses-448 induced abortions (55%), 220 spontaneous abortions (27%), and 147 stillbirths (18%)-during a seven year period (1991-97) in the department of pathology of the Charité Medical Centre in Berlin. A congenital heart defect was identified in 129 cases (16%). For all 129 fetuses, karyotyping and an ultrasound examination had been performed. RESULTS: Congenital heart defects were present in 22% of induced abortions (99 cases), 9% of spontaneous abortions (20 cases), and 7% of stillbirths (10 cases). The heart malformations were classified into 13 categories. A fetus with more than one defect was included only in the category of the most serious defect. The malformations in order of frequency were: ventricular septal defect (VSD) (28%), atrioventricular septal defect (AVSD) (16%), hypoplastic left heart (HLH) (16%), double outlet right ventricle (DORV) (12%), coarctation of the aorta (CoA) (6%), transposition of the great arteries (TGA) (4%), aortic valve stenosis (AoVS) (4%), tetralogy of Fallot (TOF) (3%), truncus arteriosus communis (TAC) (3%), pulmonary valve stenosis/pulmonary valve atresia (PaVS/PaVA) (3%), tricuspid atresia (TA) (3%), single ventricle (SV) (1.5%), and atrial septal defect (ASD) (0.5%). The most common congenital heart defects were VSD, AVSD, HLH, and DORV, which made up 72% of all the cases. In 11 cases the heart defect was isolated (no other cardiovascular or extracardiac malformations present), 85 cases (66%) were associated with additional cardiac malformations, 85 cases (66%) were associated with extracardiac malformations, and chromosome anomalies were detected in 43 cases (33%). CONCLUSIONS: Fetal congenital heart malformations are common. These defects are often associated with other cardiovascular and extracardiac malformations, as well as with chromosome anomalies. Complex heart defects such as AVSD, HLH, and DORV are frequent in fetuses, as they often lead to spontaneous abortion or stillbirth or, after prenatal diagnosis, to deliberate termination of pregnancy.

Abortion, Spontaneous↗
PubMed1999

Microsatellite alterations in serum DNA of patients with colorectal cancer.

Cell-free DNA in the blood of cancer patients has been shown to harbor microsatellite alterations frequently matching those of the primary tumors. The aim of this study was to assess the prevalence of allelic loss and instability of serum DNA microsatellites in colorectal cancers. DNA extracted from preoperative sera and microdissected tumors of 27 patients with colorectal adenocarcinoma were allelotyped for nine markers on chromosome arms 1p, 5q, 8p, 12p, 15q, 17p, 17q, and 18q. In all tumors, expression of MLH1 and MSH2 was explored immunohistochemically. Microsatellite alterations comprising loss of heterozygosity (LOH) or microsatellite instability (MSI) were present in 26 of 27 (96%) tumors and in 16 of 27 (59%) serum samples. Using stringent criteria, serum MSI was significantly (p < 0.02) more detectable than serum LOH. Of the three patients with high-grade MSI (more than two unstable loci) present in tumor and serum DNA, two had MSH2-negative tumors on immunohistochemical testing. No significant association of tumor stage or clinical outcome with serum microsatellite alterations of LOH or MSI type could be demonstrated. Although the DNA-shedding phenotype of tumors remains to be elucidated, its detection by serum DNA microsatellite analysis seems to be useful for the diagnosis and monitoring of neoplasms, including colorectal cancers with and without MSI.

Adenocarcinoma↗
PubMed1998

Increased expression of annexin I and thioredoxin detected by two-dimensional gel electrophoresis of drug resistant human stomach cancer cells.

The therapy of advanced cancer using chemotherapy alone or in combination with radiation or hyperthermia yields an overall response rate of about 20-50%. This success is often marred by the development of resistance to cytostatic drugs. Our aim was to study the global analysis of protein expression in the development of chemoresistance in vitro. We therefore used a cell culture model derived from the gastric carcinoma cell line EPG 85-257P. A classical multidrug-resistant subline EPG85-257RDB selected to daunorubicin and an atypical multidrug-resistant cell variant EPG85-257RNOV selected to mitoxantrone, were analysed using two-dimensional electrophoresis in immobilized pH-gradients (pH 4.0-8.0) in the first dimension and linear polyacrylamide gels (12%) in the second dimension. After staining with coomassie brilliant blue, image analysis was performed using the PDQuest system. Spots of interest were isolated using preparative two-dimensional electrophoresis and subjected to microsequencing. A total of 241 spots from the EPG85-257RDB-standard and 289 spots from the EPG85-257RNOV-standard could be matched to the EPG85-257P-standard. Microsequencing after enzymatic hydrolysis in gel, mass spectrometric data and sequencing of the peptides after their fractionation using microbore HPLC identified that two proteins annexin I and thioredoxin were overexpressed in chemoresistant cell lines. Annexin I was present in both the classical and the atypical multidrug-resistant cells. Thioredoxin was found to be overexpressed only in the atypical multidrug-resistant cell line.

Annexin A1↗
PubMed1998

Antisense phosphorothioate oligodeoxynucleotide down-regulation of the insulin-like growth factor I receptor in ovarian cancer cells.

The insulin-like growth factors (IGF-I and IGF-II) play a key role in cellular proliferation and are involved in cellular transformation. The expression of the IGF-I receptor has been demonstrated in a variety of human tumor cell lines including ovarian cancer cells. Phosphorothioate antisense oligodeoxynucleotides (S-ODNs) were analyzed for their potential to suppress the IGF-I receptor in the NIH: OVCAR-3 ovarian cancer cell line. The application of the antisense S-ODN reduced potently the cell growth of unstimulated NIH:OVCAR-3 cells, whereas sense and mismatch S-ODNs were without any effect. This effect resembled that of the monoclonal antibody (MAb) alphaIR-3. In contrast to the antisense compound, this MAb only partially inhibited the IGF-I-induced proliferation of ovarian cancer cells. The concentration of the antisense S-ODN to exhibit an identical inhibition of cell proliferation was reduced to 50 nM when the oligonucleotides were delivered by the cationic lipid formulation lipofectin. The specificity of the antisense S-ODN action was confirmed by reduction of the receptor protein and of the receptor mRNA, as assayed by flow cytometry and by Northern blot hybridizations. Our data demonstrate the potency of antisense S-ODNs to target the IGF-I receptor message and show that antisense strategies against the IGF-I receptor may provide new strategies for the therapy of ovarian cancer.

Cell Division↗
PubMed1998

Distinct regions of allelic imbalance on chromosome 10q22-q26 in squamous cell carcinomas of the lung.

The genetic mechanisms underlying the progression to the metastatic phenotype of lung cancer are poorly understood. We recently showed that small cell lung cancer (SCLC) and metastasizing squamous cell carcinomas are characterized by an increased incidence of allelic loss on chromosome 10q. In the present study we performed a deletion mapping using 24 polymorphic markers on chromosome 10q22-q26 in 39 squamous cell carcinomas (SCC) of the lung identifying 14 metastatic carcinomas (74%) and three non-metastatic SCC (15%) with allelic imbalance. The allelotype analysis indicated three regions of allelic loss that were clustered at the loci Afm086/D10S541, D10S185 and D10S1782/D10S169. A localized microsatellite instability was observed in two carcinomas for the markers D10S1686 and D10S1782. In addition the PTEN/MMAC1 gene was analysed by direct DNA sequencing and Southern blot analysis in 25 and 28 carcinomas, respectively, without detecting any genomic alterations. Similarly, no altered transcript was detected in 15 tumor cell lines and 20 primary tumors by Northern blot analysis or RT-PCR. In summary, three distinct regions of allelic imbalance were identified suggesting that multiple tumor suppressor genes on chromosome 10q contribute to tumor progression and metastases formation of lung cancer.

Alleles↗