Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this report we describe an auto-immunogenic tumor associated high molecular weight glycoprotein (HMW-GP) present on most rat colon carcinomas as detected by syngeneic monoclonal IgM antibodies. The HMW-GP has an apparent molecular weight of more than 10(6) D and carries several epitopes for various lectins, carbohydrate specific mouse monoclonal antibodies and four rat syngeneic monoclonal antibodies. The epitope defined by the 10B 12 rat monoclonal antibody is present in colon carcinoma tissue, but only in very low amounts in normal gastro-intestinal-tissue. The epitope is present at multiple sites on the large molecule and is shown to be sterically related, but not identical to determinants for Dolichos biflorus lectin and a mouse mAB binding to blood group A. The 10B 12 mAB binding is insensitive to boiling, reduction with mercaptoethanol and treatment with trypsin, but abolished by pretreatment of the antigen with sodium periodate or neuraminidase. The epitopes defined by 1 G6 and 1F6 rat monoclonal antibodies are present both in tumor tissue and in normal colon mucosa and the antibody binding is increased after treatment with both neuraminidase and sodium periodate.
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PMID:Recognition of a high molecular weight glycoprotein (HMW-GP) associated with rat colon cancer cells by rat monoclonal antibodies. 280 9

Treatment of the transformed mouse embryo fibroblast cell line AKR-MCA with 1% N,N-dimethylformamide (DMF) resulted in the restoration of a nontransformed phenotype in these cells. In order to determine if an increase in growth inhibitory peptides might be responsible for these changes in growth properties of the DMF-treated AKR-MCA cells we examined the serum-free conditioned medium for its ability to inhibit the anchorage-independent growth of a human colon carcinoma cell line. The extracellular levels of inhibitory activity were two-fold higher in conditioned medium derived from AKR-MCA cells than in AKR-MCA cells grown in 1% DMF (AKR-MCA/DMF). Fractionation of the crude conditioned medium indicated the presence of an Mr 20,000 inhibitory fraction in AKR-MCA/DMF conditioned medium which was reduced in AKR-MCA cells. This Mr 20,000 inhibitory activity was acid and heat stable and sensitive to dithiothreitol and trypsin. In addition to inhibiting the growth of a human colon carcinoma cell line this protein induced colony formation in AKR-2B cells and competed for binding to the transforming growth factor beta (TGF-beta) receptor. Therefore, this Mr 20,000 inhibitory polypeptide induced by DMF is probably TGF-beta. TGF-beta was also shown to inhibit the growth of AKR-MCA cells in monolayer culture.
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PMID:Regulation of growth inhibitory activity in transformed mouse embryo fibroblasts. 288 48

Syngeneic colon carcinoma cells and glioma cells were injected into the portal vein of BD IX rats. After various time periods the animals were sacrificed and the livers and lungs were fixed and prepared for histology. Atypical cells were observed in the liver 4 and 7 days after the injection of tumor cells, whereas distinct colonies of both colon carcinoma and glioma cells were demonstrated after 14 days. Lung metastases of both tumor cell types were seen after 14 and 30 days. Furthermore, injection of glioma and carcinoma cells into the tail vein gave detectable lung metastases after 7 and 4 days respectively. Intraperitoneal injection of tumor cells resulted in the accumulation of large tumor masses, particularly in the mesentery. By in situ perfusions of the liver with tumor cells included in the perfusion medium it was possible to establish that all the tumor cells were arrested in the course of 4 min. In contrast, normal rat leukocytes were not trapped in the liver, whereas trypsin-treated leukocytes were, suggesting the importance of trypsin-sensitive structures for binding to hepatic tissue. The binding of both glioma and carcinoma cells to the liver and the ensuing growth of tumor nodules in this organ indicate a lack of specificity on part of the malignant cell types for metastasis to the liver in the rat. Both tumor cell types colonized the first organ encountered after injection.
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PMID:Colonization of the rat liver by syngeneic tumor cells. An experimental approach by in vivo and in situ studies. 290 Nov 59

Reliable markers to distinguish human colon carcinoma from normal colonic epithelium are needed particularly for poorly differentiated tumors where no useful marker is currently available. To search for markers we constructed cDNA libraries from human colon carcinoma cell lines and screened for clones that hybridize to a greater degree with mRNAs of colon carcinomas than with their normal counterparts. Here we report one such cDNA clone that hybridizes with a 1.2-kilobase (kb) mRNA, the level of which is approximately equal to 9-fold greater in colon carcinoma than in adjacent normal colonic epithelium. Blot hybridization of total RNA from a variety of human colon carcinoma cell lines shows that the level of this 1.2-kb mRNA in poorly differentiated colon carcinomas is as high as or higher than that in well-differentiated carcinomas. Molecular cloning and complete sequencing of cDNA corresponding to the full-length open reading frame of this 1.2-kb mRNA unexpectedly show it to contain all the partial cDNA sequence encoding 135 amino acid residues previously reported for a human laminin receptor. The deduced amino acid sequence suggests that this putative laminin-binding protein from human colon carcinomas consists of 295 amino acid residues with interesting features. Containing only two cysteine residues, the protein does not have consensus sequences for asparagine-linked glycosylation, amphipathic alpha-helix, or the N-terminal leader signal sequences for entry into endoplasmic reticulum, although hydrophobic segments for potential membrane associations exist. There is an unusual C-terminal 70-amino acid segment, which is trypsin-resistant (no lysine or arginine) and highly negatively charged (13 aspartic plus glutamic residues). Within this segment are five repeats of (Asp/Glu)-Trp-(Ser/Thr); two of these are nearly tandem repeats of Thr-Glu-Asp-Trp-Ser-Ala-Xaa-Pro.
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PMID:Increased mRNA expression of a laminin-binding protein in human colon carcinoma: complete sequence of a full-length cDNA encoding the protein. 297 Jun 39

The study of the autologous immune response to cancer avoids the difficulties encountered in the use of xenoantisera and may identify antigens of physiological relevance. However, the low titer and incidence of autologous antibody to melanoma have hampered further evaluation. By utilizing acid dissociation and ultrafiltration of serum, we have been able to augment the detectable autologous immune response to melanoma in the majority of patients studied. In autologous system Y-Mel 84:420, serum S150 demonstrated a rise in titer from 1:32 in native sera to 1:262,044 after dissociation. The antigen detected by S150 was found to be broadly represented on melanoma, glioma, renal cell carcinoma, neuroblastoma, and head and neck carcinoma cell lines. It did not react with bladder or colon carcinoma, fetal fibroblasts, pooled platelets, lymphocytes and red blood cells, or autologous cultured lymphocytes. Using polyacrylamide gel electrophoresis, S150 detects a 66,000-mol wt antigen in spent tissue culture media and serum ultrafiltrate. In cell lysate two bands between 20,000 and 30,000 mol wt are detected by S150. The 66,000-mol wt antigen is sensitive to trypsin digestion and but is resistant to pepsin and heat inactivation. Exposure of spent media to trypsin results in the development of a 24,000-mol wt band that appears to correspond to the antigen detected in the cell lysate. The difference between the antigens detected in the cell lysate as compared with spent media and serum ultrafiltrate may be due to degradation during cell lysis. We conclude that melanoma-associated antigens are present in the serum of patients with melanoma and are shed or secreted by their tumor cells.
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PMID:Isolation and partial characterization of melanoma-associated antigens identified by autologous antibody. 338 49

Platelet function following inoculation of chemically induced carcinoma was evaluated in the rat. The original line of tumor (NGW1) was obtained using N-methyl-N-nitrosoguanidine. After trypsin homogenation a cell suspension of 0.3 X 10(6) viable tumor cells was injected subserosally in the cecum of each animal. Controls received injections of equal volumes of 0.9% NaCl solution or trypsin. The animals were subjected to laparotomy 2, 4, and 6 weeks after inoculation. Platelet function was assessed in vivo by measuring bleeding time and blood loss during mesenteric vessel transection or liver resection upon laparotomy. Hemoglobin, hematocrit, platelet count, activated partial thromboplastin time, platelet aggregation, thromboxane B2, platelet factor 4, and fibrinogen levels were evaluated after sacrifice by exsanguination. Significant decrease in bleeding time and blood loss was observed in animals with local primary tumors as well as in rats with lymph node metastases. Hemoglobin and hematocrit were decreased in the presence of metastases. Platelet count was not changed. Activated partial thromboplastin time was not affected by the presence of tumor. Platelet aggregation in vitro was accelerated in the presence of primary tumor or lymph node metastases, as well as following addition of tumor cells to platelet suspensions. No changes in thromboxane B2 or platelet factor 4 could be registered. Fibrinogen levels were decreased in the presence of liver metastases. Enhancement of primary hemostasis and platelet function in the presence of colon carcinoma in the rat was demonstrated both in vivo and in vitro. Direct or indirect interaction of the tumor cell with thrombocytes may play a role in determining the metastatic potential of the neoplasm.
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PMID:Hemostasis following inoculation and during spreading of colon carcinoma in the rat. 375 13

A line of human colon carcinoma cells, designated MOSER, was established which synthesized tumor-inhibitory factor (TIF) and transforming growth factor (TGF) activity. Both activities were found in serum-free conditioned medium and in cell extracts. The activities coelute on Bio-Gel P-10 in acetic acid, but can be completely separated by reverse-phase high-pressure liquid chromatography. The TIF and TGF activities were acid and heat stable and were sensitive to trypsin and dithiothreitol. MOSER cell TIF prevented the anchorage-independent growth of the more differentiated colon carcinoma cell lines tested but did not affect the less differentiated lines. Using anchorage-dependent growth conditions, the effect of TIF appeared to be noncytotoxic and partially reversible. Purified TGF stimulated the growth of normal rat kidney fibroblasts and the slow-growing CBS colon carcinoma cell line but did not stimulate MOSER cell growth. MOSER cells contain both positive (TGF) and negative (TIF) factors with relative concentrations that may be important parameters in the regulation of cell growth.
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PMID:Identification of endogenous inhibitory growth factors from a human colon carcinoma cell line. 385 17

Some properties and kinetics of synthesis of the carcinoembryonic antigen (CEA-LoVo) produced by an established human colon carcinoma cell line were analyzed. CEA-LoVo was assayed by the method of Chu and Reynoso which was standardized against the activity of the First British Standard for CEA. CEA-LoVo was stable at -20 and 4 degrees C. At 37 degrees C, CEA-LoVo degraded at the rate of 1.4%/day in cell-free supernatants, and at the rate of 6.6%/day in the supernatants of monolayer cultures. CEA-LoVo was sensitive to enzymatic treatment with trypsin (approximately 55% loss)) and extraction of PCA (> 70% loss). The elution profile of CEA-LoVo in Concanavalin A-Sepharose B coincided with that of the First British Standard for CEA. No A or B blood group antigenic activity was noted. Studies employing immunofluorescent and horseradish peroxidase-labeled antibody techniques demonstrated heavy membrane and moderate intracytoplasmic localization. The greatest amount of net synthesis occurred for cells in the stationary phase while CEA-LoVo release occurred maximally in the lag phase.
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PMID:Observations on the synthesis of carcinoembryonic antigen by an established human colonic carcinoma cell line. 625 89

Because tumor-induced platelet aggregation appears to play a role in the development of certain experimental tumor metastases, we examined the mechanism(s) of tumor-induced platelet aggregation as well as the effect of various anti-platelets agents. Two mechanisms for tumor-induced platelets aggregation have been previously described: (1) a mechanism which requires complement, a stable plasma factor, divalent cation and a sialo-lipo-protein vesicular component of the tumor membrane for platelet aggregation; and (2) a mechanism which operates via the generation of thrombin and requires a phospholipid component of the tumor membrane. We now report a new mechanism of tumor-induced platelet aggregation which is shared by three different tumors: a spontaneously metastatic human melanoma, HM29, a murine melanoma, B16F10, and a carcinogen-induced metastatic murine colon carcinoma, CT26. These tumors do not require cell-surface sialic acid or serum complement as does the first mechanism. They do not require cell-surface phospholipid, as do the tumors representing the other two mechanism. They do not aggregate platelets via the generation of thrombin as do tumors representing the second mechanism. These tumors are unique in that they require a trypsin-sensitive surface protein for activity. The ability of the thrombin-generating tumors to aggregate platelets is uniquely sensitive to two highly specific, synthetic thrombin-competitive inhibitors: DAPA and No. 805. The other two groups of tumors are at least 10 times more sensitive to inhibition of platelet aggregation by elevation of cyclic AMP levels (prostacyclin, 6-keto-PGE1, dibutyryl cyclic AMP) and at least 10 times more sensitive to inhibition of prostaglandin synthesis (indomethacin, ibuprofen). Thus, tumor-induced platelet aggregation is heterogeneous with respect to mechanism of action as well as inhibition by anti-platelet pharmacologic agents. Sensitivity to anti-platelet agents correlates with the mechanism by which tumor cells aggregate platelets.
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PMID:A new mechanism for tumor induced platelet aggregation. Comparison with mechanisms shared by other tumor with possible pharmacologic strategy toward prevention of metastases. 629 77

From an established cell culture line obtained from a chemically-induced rat colon carcinoma, two sublines have been selected and isolated according to their susceptibility to trypsin-mediated detachment from plastic surfaces. Subline TR, the most resistant to the detaching effect of trypsin, gave progressive tumors in most of the syngeneic rats in which it was inoculated. Subline TS, which was easily detached by trypsin, also gave tumors in the syngeneic rats, but all these tumors disappeared within 3 or 4 weeks. Both sublines gave progressive tumors when injected into nude mice. This suggests that the parent cell line is heterogeneous and contains cell variants differing in their susceptibility to trypsin-mediated detachment from substrate and their sensitivity to host factors leading to acceptance or rejection of the inoculated tumor cells.
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PMID:Selection by trypsin of two sublines of rat colon cancer cells forming progressive or regressive tumors. 635 55


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