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M S Lan

Publications and source records attributed to M S Lan.

49 records · Page 3Linked to original sources
PubMed1994

Molecular cloning and identification of a receptor-type protein tyrosine phosphatase, IA-2, from human insulinoma.

A novel 3.6-kb cDNA, IA-2, with a 2,937-bp open reading frame was isolated from a human insulinoma subtraction library (ISL-153). The predicted amino acid sequence and in vitro-translated product of IA-2 cDNA revealed a 979-amino-acid protein with a pI value of 7.09 and a molecular mass of 105,847 daltons. The protein sequence is consistent with a signal peptide, an extracellular domain, a transmembrane region, and an intracellular domain. The extracellular domain contains an unusual cysteine-rich region following the signal peptide. The intracellular cytoplasmic domain of IA-2 possesses highly conserved regions similar to the catalytic domains found in members of the protein tyrosine phosphatase (PTP) family. Northern blot analysis showed that IA-2 mRNA was expressed in five of five freshly isolated human insulinomas, rat and mouse insulinoma cell lines, and enriched normal mouse islets. It also was found in normal human brain, pituitary, pancreas, and brain tumor cell lines, but not in a variety of other normal or tumor tissues. Based on the sequence and expression data, it appears that IA-2 is a new member of the receptor-type PTP family that is expressed in islet and brain tissues.

Amino Acid Sequence↗
PubMed1993

IA-1, a new marker for neuroendocrine differentiation in human lung cancer cell lines.

IA-1 is a recently isolated novel complementary DNA which encodes a protein of 510 amino acids that contains both a zinc finger DNA-binding domain and a putative prohormone domain. mRNA expression of IA-1 has been found thus far only in tumors of neuroendocrine origin. In this report we describe the expression of IA-1 mRNA in a panel of 64 human lung cancer cell lines. IA-1 mRNA was detected by Northern blot analysis in 97% (30 of 31) of small cell lung cancer cell lines. In contrast, IA-1 mRNA was detected in only 13% (4 of 30) of non-small cell lung cancer cell lines. Nine of the 30 (30%) expressed either chromogranin A mRNA or produced L-dopa decarboxylase. Four of these 9 (44%) had detectable levels of IA-1 mRNA. In most of the lung cancer cell lines examined, IA-1 showed high concordance with the other neuroendocrine markers, L-dopa decarboxylase, and chromogranin A. The one exception was a variant small cell lung cancer cell line which expressed low or nondetectable levels of L-dopa decarboxylase. IA-1 is a candidate marker of neuroendocrine differentiation of human lung tumors.

Biomarkers, Tumor↗
PubMed1992

A novel human insulinoma-associated cDNA, IA-1, encodes a protein with "zinc-finger" DNA-binding motifs.

A subtraction library was constructed from human insulinoma (beta cell tumor) and glucagonoma (alpha cell tumor) cDNA phagemid libraries. Differential screening of 153 clones with end-labeled mRNAs from insulinoma, glucagonoma, and HeLa cells resulted in the isolation of a novel cDNA clone designated IA-1. This cDNA clone has a 2838-base pair sequence consisting of an open reading frame of 1530 nucleotides, which translates into a protein of 510 amino acids with a pI value of 9.1 and a molecular mass of 52,923 daltons. At the 3'-untranslated region there are seven ATTTA sequences between two polyadenylation signals (AATAAA). The IA-1 protein can be divided into two domains based upon the features of its amino acid sequence. The NH2-terminal domain of the deduced protein sequence (amino acids 1-250) has four classical pro-hormone dibasic conversion sites and an amidation signal sequence, Pro-Gly-Lys-Arg. The COOH-terminal domain (amino acids 251-510) contains five putative "zinc-finger" DNA-binding motifs of the form X3-Cys-X2-4-Cys-X12-His-X3-4-His-X4 which has been described as a consensus sequence for members of the Cys2-His2 DNA-binding protein class. Northern blot analysis revealed IA-1 mRNA in five of five human insulinoma and three of three murine insulinoma cell lines. Expression of this gene was undetectable in normal tissues. Additional tissue studies revealed that the message is expressed in several tumor cell lines of neuroendocrine origin including pheochromocytoma, medullary thyroid carcinoma, insulinoma, pituitary tumor, and small cell lung carcinoma. The restricted tissue distribution and unique sequence motifs suggest that this novel cDNA clone may encode a protein associated with the transformation of neuroendocrine cells.

Amino Acid Sequence↗
PubMed1990

Cloning and sequencing of a human pancreatic tumor mucin cDNA.

A monospecific polyclonal antiserum against deglycosylated human pancreatic tumor mucin was used to select human pancreatic mucin cDNA clones from a lambda gt11 cDNA expression library developed from a human pancreatic tumor cell line. The full-length 4.4-kilobase mucin cDNA sequence included a 72-base pair 5'-untranslated region and a 307-base pair 3'-untranslated region. The predicted amino acid sequence for this cDNA revealed a protein of 122,071 daltons containing 1,255 amino acid residues of which greater than 60% were serine, threonine, proline, alanine, and glycine. Approximately two-thirds of the protein sequence consisted of identical 20-amino acid tandem repeats which were flanked by degenerate tandem repeats and nontandem repeat sequences on both the amino-terminal and carboxyl-terminal ends. The amino acid sequence also contained five putative N-linked glycosylation sites, a putative signal sequence and transmembrane domain, and numerous serine and threonine residues (potential O-linked glycosylation sites) outside and within the tandem repeat position. The cDNA and deduced amino acid sequence of the pancreatic mucin sequence was over 99% homologous with a mucin cDNA sequence derived from breast tumor mucin, even though the native forms of these molecules are quite distinct in size and degree of glycosylation.

Amino Acid Sequence↗
PubMed1990

Polypeptide core of a human pancreatic tumor mucin antigen.

This work describes the molecular properties of the polypeptide core of a human pancreatic mucin antigen isolated from a human pancreatic adenocarcinoma cell line, HPAF. Pancreatic tumor mucin was isolated by a combination of molecular sieve chromatography and CsCl/4 M guanidine-HCl density gradient ultracentrifugation. Trifluoromethane sulfonic acid was used to remove carbohydrate units from purified mucin molecules. A rabbit monospecific polyclonal antibody was generated against pancreatic apomucin and reacted with a Mr greater than 200,000 species. The antibody binding data indicated that the rabbit antiserum raised against pancreatic apomucin cross-reacted with a breast mucin synthetic peptide. Northern blot and immunodot blot analyses of various cell line extracts revealed that a tandem repeat sequence and a similar mRNA were detected in both pancreatic and breast mucin-producing cell lines. These results suggest that pancreatic apomucin and breast apomucin share some similarity in tandem repeated nucleic acid and protein sequences.

Adenocarcinoma↗
PubMed1989

Specific, major histocompatibility complex-unrestricted recognition of tumor-associated mucins by human cytotoxic T cells.

We have previously reported the establishment of cytotoxic T-cell lines from pancreatic cancer patients, by continuously stimulating tumor-draining lymph node cells with allogeneic pancreatic tumor cell lines. After the preliminary characterization of their phenotype and tumor specificity, detailed studies performed with one of the cell lines, W.D., show that it recognizes a specific antigen, a large and heavily glycosylated mucin molecule, expressed on pancreatic and breast tumors and tumor cell lines. Although this recognition appears major histocompatibility complex (MHC)-unrestricted, the antigen receptor used by the cytotoxic T cell is the alpha/beta heterodimer, typically found on MHC-restricted T cells. The target antigen is atypical, however, in its ability to directly bind and activate the T cells in the absence of self MHC, presumably by abundant and regularly repeated antigenic epitopes. These findings are important because they demonstrate a specific T-cell response against a human tumor-associated antigen. In addition to pancreatic and breast tumors, various mucin molecules are known to be produced by other tumors of epithelial cell origin and could be expected to stimulate similar T-cell-mediated immune responses.

Adenocarcinoma↗
PubMed1988

Detection of an oncofetal antigen (DU-PAN-2) in sera of patients with non-malignant hepatobiliary diseases and hepatomas.

DU-PAN-2 is a high-molecular-weight glycoprotein defined by a murine monoclonal antibody (MAb) elicited against a human pancreatic adenocarcinoma cell line. This MAb recognizes an oncofetal antigen present on the surface of normal pancreatic and bile-duct epithelium, normal bronchus epithelium, and some adenocarcinomas. Elevated levels of the antigen (greater than 400 U/ml) have been detected in the serum of 79% of patients with adenocarcinoma of the pancreas and in a small percentage of patients with other adenocarcinomas, by means of a competition radioimmunoassay. Here, we have studied DU-PAN-2 antigen levels in sera of patients with a spectrum of hepatobiliary diseases and controls. Serum DU-PAN-2 antigen was elevated in 59% of 112 patients with non-malignant hepatobiliary diseases and in 50% of hepatoma patients. None of 50 healthy controls had elevated serum DU-PAN-2 levels. Patients in every category of hepatobiliary disease studied had elevated median serum DU-PAN-2 levels; the highest median levels were seen in patients with primary biliary cirrhosis (1,296 U/ml) and the lowest in stable cirrhosis (300 U/ml). Elevated serum DU-PAN-2 levels in one patient with primary biliary cirrhosis and in one patient with hepatoma returned to normal following liver transplantation. Serum DU-PAN-2 levels did not correlate well with alkaline phosphatase, 5'-nucleotidase, bilirubin, or alpha-fetoprotein. Using an immunoperoxidase technique on formalin-fixed, deparaffinized liver sections, we showed that DU-PAN-2 MAb reacted heterogeneously with bile-duct epithelium but never stained hepatocytes or hepatoma cells. While serum DU-PAN-2 levels may be useful in detecting and monitoring pancreatic adenocarcinoma, they are not specific for this disease.

Antigens, Neoplasm↗
PubMed1988

Aberrant expression of monoclonal antibody-defined colonic mucosal antigens in inflammatory bowel disease.

Human proximal colon from patients with inflammatory bowel disease and from controls was studied by two techniques to detect tumor-associated antigen expression. A panel of four murine monoclonal antibodies that recognize tumor-associated antigens was used to test purified colonic mucins for epitope expression by radioimmunoassay and to test formalin-fixed, deparaffinized sections of colon by the immunoperoxidase technique. The panel included monoclonal antibodies 19-9, B72.3, DU-PAN-2, and CSLEX1. Colonic mucins were purified from uninvolved surgical specimens by gel filtration with Sepharose 4B and cesium chloride-guanidine hydrochloride density gradient ultracentrifugation. Purified mucins from uninvolved colonic mucosal specimens from 4 of 7 patients with ulcerative colitis expressed one or more of these epitopes by radioimmunoassay, whereas mucins from 6 disease controls did not. Reactivity patterns were heterogeneous. Immunoperoxidase testing demonstrated staining with two or more antibodies in 14 of 18 involved inflammatory bowel disease segments, whereas control sections rarely stained with these antibodies, with the exception of 19-9. Sections of uninvolved mucosa from 4 of 9 patients with ulcerative colitis stained with two or more antibodies. Staining patterns were heterogeneous. The results demonstrate that colonic expression of tumor-associated epitopes occurs frequently in involved segments from both patients with ulcerative colitis and with Crohn's disease, whereas only patients with ulcerative colitis frequently expressed these epitopes in uninvolved segments.

Antibodies, Monoclonal↗
PubMed1987

Molecular characterization of a mucin-type antigen associated with human pancreatic cancer. The DU-PAN-2 antigen.

This work describes the molecular characterization of a human pancreatic cancer-associated antigen defined by a murine monoclonal antibody (DU-PAN-2). DU-PAN-2 antigen was isolated from a pancreatic adenocarcinoma cell line (HPAF) or patient's ascitic fluid, and the antigenic activity was monitored by competitive inhibition radioimmunoassay. Affinity chromatography and CsCl/guanidine HCl density gradient centrifugation were employed to remove other populations of mucin-type glycoproteins and noncovalently associated proteins, respectively. Three electrophoretically distinct components were detected by 1% agarose gel electrophoresis and were resolved by chromatography on Sepharose CL-4B. The major fraction (FII) was subjected to carbohydrate and amino acid analyses. The sum of threonine, serine, proline, glycine, and alanine comprised more than 50% of the amino acid residues. The saccharide units, O-glycosidically linked to the peptide via GalNAc, contained fucose, galactose, GlcNAc, GalNAc, and sialic acid. The total carbohydrate content of FI and FII was 80.8% and 77.4% by weight, respectively. The molecular weight of FII antigen showed two species of molecules of 1.45 X 10(6) and 4.59 X 10(6) by analytical sedimentation equilibrium. DU-PAN-2 antigen was susceptible to neuraminidase, pepsin, Pronase, and papain digestion. These results suggest that both protein components and sialic acid residues may play important roles in the binding of DU-PAN-2 antibody.

Adenocarcinoma↗
PubMed1987

Co-expression of human cancer-associated epitopes on mucin molecules.

This work describes the immunochemical comparison of mucin-like high-molecular-weight glycoproteins associated with human malignancies that are defined by murine MAbs, DU-PAN-2, 19-9, OC-125, B 72.3, and Mov 2. These MAbs were originally elicited to human adenocarcinomas from different organ sites such as pancreas, colon, ovary, and breast, respectively. Although each antibody recognizes an antigen on tumors of the same type as the tumor used for immunization, there is often considerable cross-reactivity with adenocarcinomas from other organ sites. Additionally, these antigens have common properties of large molecular size, high carbohydrate content, and molecular size heterogeneity. Three antigens, CA 19-9, Mov 2, and DU-PAN-2, demonstrated size heterogeneity on agarose gel immunoblotting with their respective antibodies and gave different migration patterns from sera, bile, and pancreatic juice of patients with pancreatic adenocarcinoma. Data from inhibitory double determinant analyses indicated that the DU-PAN-2, CA 19-9, CA 125, TAG-72, and Mov 2 epitopes are distinct and non-cross-reactive. However, immunoblotting and affinity chromatography indicated that both 19-9 and DU-PAN-2 epitopes may be co-expressed on the same mucin molecule in varying proportions.

Adenocarcinoma↗
PubMed1985

Isolation and properties of a human pancreatic adenocarcinoma-associated antigen, DU-PAN-2.

This work describes the molecular properties of a human pancreatic adenocarcinoma-associated mucin-like antigen defined by a murine monoclonal antibody (DU-PAN-2). DU-PAN-2 antigen is a large molecule, readily detected in the body fluids of patients with pancreatic adenocarcinoma and sensitive to neuraminidase treatment and alkaline reduction. The antigen binding activity of the DU-PAN-2 immunoglobulin M antibody is markedly reduced when coupled to an insoluble matrix. Therefore, the antigen was partially purified from the serum and ascites of patients with pancreatic adenocarcinoma by ammonium sulfate fractionation and Affi-Gel-Blue chromatography to remove most of the serum proteins. Noncovalently associated proteins were further separated on CsCl/CsBr density gradients and noncovalently associated lipids removed by organic solvent extraction. DU-PAN-2 antigen was monitored by a solid-phase competition radioimmunoassay. We have been able to detect antigen reactivity and analyze its electrophoretic pattern following transfer from 1% agarose gel onto nitrocellulose paper and immunoblotting with DU-PAN-2 antibody. Antigen was also labeled metabolically with various radioactive monosaccharides and sulfates. Radioimmunoprecipitation of labeled antigen with DU-PAN-2 antibody showed two distinct broad antigen bands consistent with the immunoblotting signals. The heavily glycosylated and polydisperse nature of this antigen and the results of various enzyme treatments suggest that the DU-PAN-2 epitope is expressed on a mucin-like molecule.

Adenocarcinoma↗
PubMed1984

Detection of a pancreatic cancer-associated antigen (DU-PAN-2 antigen) in serum and ascites of patients with adenocarcinoma.

A competition radioimmunoassay was developed, utilizing a murine monoclonal antibody to human pancreatic adenocarcinoma cells. Immunoblotting of a standard antigen preparation from either serum or ascites fluid after electrophoresis in 1% agarose showed that the specific DU-PAN-2 activity resided in two major high molecular weight bands. DU-PAN-2 antigen levels were expressed as arbitrary units based on a standard partially purified antigen preparation. The inhibition curve with standard antigen was reproducible (SD less than 10%) and essentially linear from 25 to 200 units/ml. The mean DU-PAN-2 antigen concentration for the sera from 126 normal individuals was 81 units/ml. Sera from pediatric patients with malignancy had a mean of 127 units/ml, while nasopharyngeal, stage III melanoma, and ovarian carcinoma patients had means of 89, 92, and 119 units/ml, respectively. All values in normal subjects as well as the melanoma, nasopharyngeal, ovarian, and pediatric cancer patients were less than 400 units/ml. Intermediate antigen levels were detected in patients with alimentary tract malignancies. Eight of 20 gastric cancer and 8 of 76 colorectal carcinoma patients and 3 patients with benign or nonmalignant gastrointestinal tract disease had DU-PAN-2 values exceeding 400 units/ml. Ascites fluids from 6/6 and pancreatic juice from 2/2 pancreatic cancer patients had values greater than 750 units/ml. Serum from 68% of the 89 pancreatic cancer patients tested had DU-PAN-2 antigen levels greater than 400 units/ml. The mean serum value in this patient population was 4888 units/ml.

Adenocarcinoma↗