PubMed Health⌕ Search

Biomedical subjects

F X Real

Publications and source records attributed to F X Real.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cell surface expression of paraneoplastic encephalomyelitis/sensory neuronopathy-associated Hu antigens in small-cell lung cancers and neuroblastomas.

BACKGROUND: Serum from patients with small-cell lung cancer-associated paraneoplastic encephalomyelitis/sensory neuronopathy contains autoantibodies recognizing 35- to 40-kDa nuclear antigens present in neurons, small-cell lung cancers, and some neuroblastomas (anti-Hu). AIM: Because the mechanisms by which Hu autoantibodies may contribute to the paraneoplastic syndrome are largely unknown, we sought to examine if Hu antigens are expressed at the plasma membrane of cultured cells from Hu-expressing tumors. METHODS AND RESULTS: Hu-related molecules of 35 to 41 kDa were detected in the membrane of small-cell lung cancers and neuroblastomas using: (1) immunofluorescence, (2) absorption assays, (3) Western blotting on membrane fractions, and (4) surface biotinylation. The antibodies recognizing these membrane components were specifically absorbed by recombinant HuD protein. There was a perfect correlation between nuclear and membrane Hu expression. To determine the purity of the subcellular fractions, their reactivity with antibodies recognizing the A2 nuclear ribonucleoprotein and the cytoplasmic mitogen-activated protein kinase was examined. None of them was detected in the membrane fractions reactive with sera containing Hu antibodies. CONCLUSIONS: Hu-related antigens can be detected both in the nucleus and the membrane of small-cell lung cancer and neuroblastomas. IMPLICATIONS: These results provide an experimental basis for surface binding-mediated pathogenic mechanisms in paraneoplastic encephalomyelitis/sensory neuronopathy and in Hu-expressing tumors.

Antigens, Surface↗
PubMed1996

Host cell effect upon glycosylation and antigenicity of human respiratory syncytial virus G glycoprotein.

Infection of different human epithelial cell lines with human respiratory syncytial virus (HRSV) revealed significant differences in the electrophoretic mobility of the viral attachment glycoprotein (G). Cell-type specific differences in G protein glycosylation were observed with certain lectins and sugar-specific reagents. Furthermore, substantial changes in the reactivity of the G glycoprotein with anti-G monoclonal antibodies were associated to the infected cell type. Strain-specific epitopes--present in a limited number of HRSV isolates of the same antigenic group--were particularly susceptible to cell-type-specific modifications of the mature G protein. Some of these epitopes, which were either exposed in the unglycosylated precursor or reproduced with synthetic peptides, were nonetheless masked in the mature G protein expressed in certain cell lines. Antigenic and electrophoretic mobility changes of the G glycoprotein were reverted in extracts of HEp-2 cells infected with HRSV grown in other cell types, indicating that phenotypic traits rather than selection of variants were associated to the above stated changes. These results highlight the importance of cell-type-specific modifications for HSRV G glycoprotein antigenicity and raise questions about the actual antigenic structure of this molecule when HRSV replicates in the respiratory tract.

Antibodies, Monoclonal↗
PubMed1996

Isolation of tissue-type plasminogen activator, cathepsin H, and non-specific cross-reacting antigen from SK-PC-1 pancreas cancer cells using subtractive hybridization.

We have used subtractive hybridization to isolate cDNAs overexpressed in SK-PC-1 pancreas cancer cells. Forty-five independent clones corresponding to 11 genes were identified. Their expression in cultured pancreas cancer cells, normal pancreas tissue, and normal exocrine pancreas cultures was examined by Northern blotting. cDNA clones can be grouped into two broad categories: (1) those corresponding to genes expressed at high levels both in tumor cell lines and in primary cultures of normal pancreas, but not in normal tissue (i.e. thymosin beta4(3), cytokeratin 18, beta-actin, pyruvate kinase and mitochondrial genes); and (2) those corresponding to genes expressed at high levels in pancreas cancer cultures but not in normal pancreas tissue or cultured cells (i.e. tissue-type plasminogen activator and cathepsin H). The overexpression of these proteases in pancreas cancers suggests that they play a role in the aggressive biological behavior of this tumor.

Antigens, Neoplasm↗
PubMed1996

Lysosomal alpha-glucosidase: cell-specific processing and altered maturation in HT-29 colon cancer cells.

We have previously described the abnormal localization of resident Golgi proteins and O-glycans in the rough endoplasmic reticulum of mucin-secreting HT-29 M6 colon cancer cells, suggesting altered protein trafficking in these cells [Egea, Francí, Gambús, Lesuffleur, Zweibaum and Real (1993) J. Cell Sci. 105, 819-830]. In the present work, we have chosen lysosomal alpha-glucosidase as a reporter to examine the intracellular traffic of glycoproteins in M6 cells. We have compared the synthesis and processing of alpha-glucosidase in mucin-secreting M6 cells and in Caco-2 colon cancer cells, the latter resembling normal absorptive intestinal epithelium. Our results show that alpha-glucosidase processing and secretion is markedly delayed in M6 cells as compared to Caco-2 cells or normal fibroblasts, and this delay is caused by an accumulation of alpha-glucosidase precursor form in the trans-Golgi network. Furthermore, treatment in Caco-2 cells with brefeldin A led to changes in alpha-glucosidase maturation similar to those observed in untreated M6 cells. To determine whether altered processing occurs in other cultured cells, a panel of cancer cell lines and cultures from normal exocrine pancreas were examined. In pancreas-derived cultures, alpha-glucosidase showed a processing pattern different from that described until now. Only HT-29 cells and HT-29-derived subpopulations displayed a defect in alpha-glucosidase maturation. In conclusion, alpha-glucosidase processing is more diverse than has previously been described; this finding may have tissue-specific functional implications.

Amidohydrolases↗
PubMed1996

Loss of an HLA haplotype in pancreas cancer tissue and its corresponding tumor derived cell line.

A combination of immunohistochemical, biochemical, and recombinant DNA techniques were used to investigate class I expression in 26 pancreatic adenocarcinomas and 6 autologous tumor-derived cells. The prevalence of HLA losses was found to be comparable to that observed in other tumor types (> 35%), using monomorphic and locus-specific antibodies. In one patient, the original tumor tissue, a tumor derived cell line (IMIM-PC-2), and EBV-transformed lymphocytes were available for study. The patient's phenotype was A25, A30, B18, B18. However, A30 allele product could not be detected in the original tumor not in the cultured tumor cells. In addition, A30 allele could not be isolated from cDNA or genomic clones from the cultured tumor cells whereas it was isolated from the autologous lymphoblastoid cell line. Using isoelectric focusing analysis a significant reduction in the B18 heavy chain product was also observed in the tumor cell line, IMIM-PC-2, suggesting the absence of expression of one allele. Further studies revealed loss of heterozygosity at DR and other loci of chromosome 6 and cytogenetic data strongly suggested deletion of a full chromosome 6. This work indicates for the first time that loss of a full HLA haplotype occurs in tumor tissue and suggests that this mechanism may contribute to the progression of human cancer.

Adenocarcinoma↗
PubMed1996

Radiolocalization of squamous lung carcinoma with 131I-labeled epidermal growth factor.

Overexpression of epidermal growth factor receptor (EGFr) in squamous carcinomas has been demonstrated extensively. Preliminary clinical studies have shown that radiolabeled anti-EGFr monoclonal antibodies can localize to these tumors. The aims of this study were to determine the tolerance, pharmacokinetics, and radiolocalization properties of 131I-labeled EGF in patients (n = 9) with advanced squamous lung cancer. Patients' vital signs and symptoms were monitored regularly for 3 days. Daily scintigrams and biological samples for pharmacokinetic analysis were obtained for 3-4 days. 99mTc-labeled human serum albumin was administered to patients with positive tumor scans. Six patients had positive tumor scans, and five of them had received >/=1.0 mg EGF. In all of these cases, tumors were visualized the same day of the infusion, although best tumor-background contrast was obtained at 50-74 h. There were no false-positive images. Whole-body radioactivity retention rose significantly with increasing EGF doses; most labeled EGF was eliminated by urinary excretion. Tumor:normal tissue uptake ratios increased during the course of the study. All patients presented self-limited, dose-related gastrointestinal adverse effects. In conclusion, recombinant 131I-labeled EGF administered i.v. can localize to squamous lung cancer efficiently, can be administered safely to patients, and has more advantageous pharmacokinetic properties than monoclonal antibodies. Further studies are warranted to determine more accurately the potential of EGF and EGF-related peptides in the imaging and/or therapy of EGFr-overexpressing human cancers.

Aged↗
PubMed1995

Characterization of a mucin cDNA clone isolated from HT-29 mucus-secreting cells. The 3' end of MUC5AC?

HT-29 cells resistant to 10(-6) M methotrexate (HT29-MTX) secrete mucins with gastric immunoreactivity (Lesuffleur, T., Barbat, A., Dussaulx, E., and Zweibaum, A. (1990) Cancer Res. 50, 6334-6343). A 3310-base pair mucin cDNA clone (L31) was isolated from an HT29-MTX expression library using a polyclonal serum specific for normal gastric mucosa. It shows a high level of identity (98.6%) to clone NP3a isolated from a nasal polyp cDNA library (Meerzaman, D., Charles, P., Daskal, E., Polymeropoulos, M. H., Martin, B. M., and Rose, M. C. (1994) J. Biol. Chem. 269, 12932-12939). However, as a result of changes in reading frame, the 1042-amino acid deduced peptide contains four regions of a low similarity to the NP3a peptide. The amino acid sequence shows 36.3% similarity to part of the carboxyl-terminal sequence of MUC2 including the so-called D4 domain and 21.3% to the pro von Willebrand factor. A short amino acid sequence is similar to cysteine-rich sequences repeated in tracheobronchial, gastric, and colonic mucin cDNAs. The gene corresponding to L31 is located in the mucin gene cluster on chromosome 11p15.5. The patterns of mRNA expression were indistinguishable from those revealed with the JER58 probe (MUC5AC). Southern blot analysis indicates that the L31 and JER 58 sequences are within 20 kilobase pairs of each other. Together, these results suggest that L31 clone is the 3' end of MUC5AC.

Adult↗
PubMed1995

MUC6 apomucin shows a distinct normal tissue distribution that correlates with Lewis antigen expression in the human stomach.

BACKGROUND & AIMS: Among the human mucin complementary DNAs thus far identified, two (MUC5AC and MUC6) were cloned from stomach libraries. This study examines the distribution of MUC6 in normal tissues and compares it with that of MUC5AC as well as with the expression of Lewis blood group antigens. METHODS: Affinity-purified rabbit antibodies detecting epitopes within the repetitive sequence of MUC5AC and MUC6 were used in enzyme-linked immunosorbent assays and immunohistochemical assays. RNA expression was analyzed by in situ hybridization. Double-labeling immunofluorescence was used to study apomucin and Lewis antigen coexpression. RESULTS: MUC6 is detected in the stomach, colon, gallbladder, and endocervix. Two patterns of staining are observed, perinuclear and diffuse cytoplasmic, possibly reflecting differences in MUC6 glycosylation. Using both immunohistochemical assays and in situ hybridization on stomach tissue sections, MUC6 is expressed mainly in antral mucous cells, whereas MUC5AC is detected mainly in the superficial epithelium and neck glands. In antral mucosa, MUC6+ cells express Lewis(y), whereas MUC5AC+ cells express Lewis(b) and sialyl-Lewis(a). CONCLUSIONS: It was concluded that MUC6 has a distinct tissue distribution pattern, different from that of MUC1-MUC5; MUC5AC and MUC6 are expressed by different cellular populations in normal stomach; and in this tissue, MUC5AC+ cells and MUC6+ cells show different patterns of Lewis antigen expression.

Amino Acid Sequence↗
PubMed1995

In situ hybridization shows distinct patterns of mucin gene expression in normal, benign, and malignant pancreas tissues.

BACKGROUND & AIMS: Northern blotting and immunohistochemistry have shown cell-specific patterns of mucin gene expression in the pancreas and alterations associated with neoplastic transformation. The aim of this study was to determine the presence of mucin transcripts at the single cell level in tissue samples from normal pancreas and benign and malignant pancreatic proliferative lesions. METHODS: In situ hybridization with 35S-labeled oligonucleotides was performed on sections of paraffin-embedded tissues. RESULTS: Acinar cells express only MUC1. Normal pancreatic ducts show homogeneous expression of MUC1 and MUC5B and heterogenous expression of MUC3. MUC2, MUC4, and MUC5AC are generally undetectable in all cells of normal pancreas tissue. Pancreas cancers generally express MUC1, MUC3, MUC4, MUC5B and MUC5AC. Obstructive chronic pancreatitis adjacent to pancreas cancers shows the same pattern of mucin gene expression as normal ducts. In areas of papillary hyperplasia, altered expression of MUC3, MUC5B, and MUC5AC is observed. CONCLUSIONS: In situ hybridization has confirmed that neoplastic transformation of the exocrine pancreas is accompanied by changes in mucin gene expression. Although this type of change is not restricted to cancer cells, the findings of this study suggest that analysis of mucin gene expression may be of value in the differential diagnosis of pancreatic lesions.

Adenocarcinoma↗
PubMed1995

Ki-ras mutations as a prognostic factor in extrahepatic bile system cancer. PANK-ras I Project Investigators.

PURPOSE: To assess the prevalence and prognostic significance of Ki-ras codon 12 mutations in extrahepatic biliary system cancer (EBSC). PATIENTS AND METHODS: Patients diagnosed with EBSC between 1980 and 1990 (N = 111) were selected from two hospitals. DNA was amplified from paraffin-embedded tissues and mutations in codon 12 of Ki-ras were detected using the artificial restriction fragment-length polymorphism (RFLP) technique. RESULTS: Tissue was available from 68.5% of patients. The prevalence of mutations was 41%. There was no association between mutations and clinical and pathologic characteristics; however, mutations in Ki-ras were associated with survival, with a median survival duration of 7.7 months for patients with wild-type Ki-ras and 1.7 months for patients with mutated tumors (hazards ratio [HR] = 1.67; P = .075). Among patients with stage I to II tumors, the chance of dying of patients with the mutation was 7.8 times higher than that of patients without the mutation (P = .087); the corresponding HR for patients with stage III to IV disease was 2.9 (P = .003). After adjusting for age, tumor site, histology, differentiation, and stage, the HR for Ki-ras mutations was 2.12 (P = .026). CONCLUSION: Ki-ras codon 12 mutations are an independent prognostic indicator in patients with EBSC. Mutation detection may be of help in the management of these patients.

Adenocarcinoma↗
PubMed1995

Characterization of mucins and proteoglycans synthesized by a mucin-secreting HT-29 cell subpopulation.

HT-29 cells selected by adaptation to 10(-5) M methotrexate (HT-29 MTX) are a homogeneous cell population producing high amounts of mucin. Intracellular mucins and proteoglycans were isolated from these cells by ultracentrifugation of cell lysates on a cesium bromide gradient and further separated by anion-exchange high performance liquid chromatography. The major mucin fraction isolated was characterized by a high hydroxy amino acid content (40%), a Thr/Ser ratio of 1.52, a high sialic acid content, and a low sulfate content. When the same procedure was applied to undifferentiated HT-29 cells, a minor mucin fraction was isolated which appeared less sialylated and more sulfated. The major proteoglycan species identified in HT-29 MTX cells showed less acidic behavior than the proteoglycan isolated from HT-29 cells. The effect of brefeldin A and the sugar analog GalNAc-alpha-O-benzyl on the synthesis and biochemical properties of mucins synthesized by HT-29 MTX cells was examined. Brefeldin A induced the synthesis of more-sulfated mucins. GalNAc-alpha-O-benzyl treatment resulted in mucins with an increased content of T antigen and a 13-fold lower sialic acid content. We show that GalNAc-alpha-O-benzyl was metabolized by the cells to Gal beta 1-3GalNAc-alpha-O-benzyl, which, in turn, was a potent competitive inhibitor of the O-glycan alpha-2,3-sialyltransferase. These results illustrate the suitability of HT-29 MTX cells as a model to analyse mucin synthesis and sialylation.

Acetylgalactosamine↗
PubMed1995

Hepatocyte growth factor is a potent mitogen for normal human pancreas cells in vitro.

BACKGROUND: Little is known regarding the mechanisms that regulate cell proliferation in the exocrine pancreas. The aim of this study was to analyze the effect of growth factors on normal human exocrine pancreas cultures. EXPERIMENTAL DESIGN: The mitogenic effect of hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), and other growth factors was examined using [3H]-thymidine uptake assays. The phenotype of the cultures was analyzed using a panel of mAb. c-met expression was determined by immunohistochemistry and Western blotting. RESULTS: HGF was the most potent mitogen (concentration range 0.1 to 10 ng/ml), although IGF-1, EGF, and platelet-derived growth factor were also mitogenic in some assays. Combinations of HGF+EGF or HGF+IGF-1 were superior to HGF when used at suboptimal concentrations. Proliferative cultures expressed cytokeratins 7, 8, 18, and 19 and the MUC1 mucin, a phenotype characteristic of normal ductal cells. The 170-kDa precursor and 145-beta chain of c-met were detected in cultured cells with rabbit polyclonal antisera raised against synthetic peptides corresponding to the carboxy-terminal domains of the beta chain. c-met was also detected in the apical membrane of ductal cells in normal pancreas tissue but was generally absent from acinar, centroacinar, and islet cells. CONCLUSIONS: These results suggest that HGF and c-met may play a role in growth regulation in this organ.

Cell Division↗
PubMed1995

New pancreas cancers cell lines that represent distinct stages of ductal differentiation.

BACKGROUND: Most available pancreas cancer cell lines have been in culture for long periods of time, have not been extensively characterized from the cell biology standpoint, or lack differentiated properties. EXPERIMENTAL DESIGN: We have established four new cell lines from ductal pancreatic cancers (IMIM-PC-1, IMIM-PC-2, SK-PC-1, and SK-PC-3). The phenotype and functional properties of the cell lines were analyzed using ultrastructural methods, antibodies detecting cytokeratin polypeptides and mucin epitopes, and cDNA probes of epithelial differentiation markers. RESULTS: IMIM-PC-2 and SK-PC-1 cells grow as a polarized monolayer, form domes, and express all CK polypeptides typical of simple epithelia and the MUC1 mucin. IMIM-PC-1 and SK-PC-3 are morphologically less differentiated and express low or undetectable levels of CK7 and MUC1. By Northern blotting, we found that SK-PC-1 and SK-PC-3 cells express carbonic anhydrase II and that the cystic fibrosis transmembrane regulator was undetectable in the four lines. Secretin induces a marked stimulation of cAMP levels in all cell lines except for SK-PC-3. Cytogenetic analysis demonstrates their human origin. CONCLUSIONS: Levels of CK7 and MUC1 are associated with less differentiated cultures. The new cell lines should be useful tools to study the cell biology of exocrine pancreas cancer.

Antigens↗
PubMed1994

Comparative analysis of mutations in the p53 and K-ras genes in pancreatic cancer.

Mutations in codon 12 of K-ras occur in a high proportion of pancreatic cancer cases. Although there is evidence that p53 mutations also occur in this tumor, few studies have been reported to date and no comparison has been made of K-ras and p53 mutations in the same tissues. Single-strand conformation polymorphism and sequencing of the PCR products were used to determine mutations in p53 gene; to detect mutations in K-ras genes, the artificial restriction fragment length polymorphism (RFLP) approach was used. Eight out of 30 tissues from primary pancreas cancer and 3 of 4 samples from metastases showed p53 mutations. Fifteen out of 17 pancreatic cancer cell lines had p53 mutations. In 2 cases, the same p53 mutation was identified in the original tumor and in a tumor-derived cell line. The majority of p53 mutations were present in exons 5-9 of the gene. Mutations at codon 12 of the K-ras gene were identified in 23/32 pancreas cancer tissues and in 14/17 cell lines. There was no relationship between the types of mutation observed in the 2 genes. In conclusion, mutations in K-ras and p53 genes are common in pancreatic cancer. p53 mutations may occur more frequently in metastatic lesions than in primary tumors, although further work is necessary to investigate this point.

Base Sequence↗
PubMed1994

Differential apomucin expression in normal and neoplastic human gastrointestinal tissues.

BACKGROUND/AIMS: The cloning of genes encoding human mucins is the basis for the study of their normal tissue distribution and the alterations associated with cancer. The aim of this study was to determine the normal and tumor tissue expression of MUC1, MUC2, MUC5B, and MUC5C. METHODS: The reactivity of apomucin-specific antibodies with fresh normal and tumor tissues was analyzed using immunohistochemical techniques. RESULTS: Anti-MUC1 antibodies reacted with most glandular epithelia. Anti-MUC2 antibody was mainly reactive with intestinal goblet cells and cervical mucous cells. Anti-MUC5B was reactive with a wide range of epithelial tissues whereas anti-MUC5C was reactive with stomach, trachea, and endocervix. Double-labeling experiments showed coexpression of MUC1/MUC2 and MUC2/MUC5C in colonic tissue. Multiple apomucins were detected in colon cancers, but no relationship to histochemical mucus stains was observed. CONCLUSIONS: It is concluded that (1) each apomucin shows a distinct tissue expression pattern; (2) multiple apomucins are present in a single tissue and at the single cell level; and (3) altered apomucin expression takes place in pathological colonic tissue.

Amino Acid Sequence↗