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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue transglutaminase is a Ca(2+)-dependent enzyme that catalyzes the formation of protein cross-links by an acyl transfer reaction. Recent reports have suggested that tissue transglutaminase is induced by tumor progression and apoptosis. In this study we immunohistochemically investigated a series of gliomas by using an antiserum against a dodecapeptide from the COOH-terminal of tissue transglutaminase. Among the gliomas the presence of positive immunoreactivity tended to increase in malignant counterparts. It is also noteworthy to mention that glioblastoma cells surrounding the zonal necrosis in a palisade fashion were strongly immunolabeled. The degenerating products in tumor cells, such as round granulated bodies, were primarily immunopositive, whereas Rosenthal fibers were negative. Dying cells through apoptosis in the metastatic brain tumors could be easily recognized by the presence of tissue transglutaminase. In conclusion, tissue transglutaminase may therefore be valuable in the prognostic characterization of gliomas with respect to the detection of dying cells. However, the appearance of tissue transglutaminase-positive neoplastic cells was not limited to apoptotic bodies but could also be detected in necrobiotic cell nests.
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PMID:An immunohistochemical study of tissue transglutaminase in gliomas with reference to their cell dying processes. 752 29

Differentiation therapy is an attractive option for the treatment of superficial, localized neoplastic lesions of the skin. Topical application of agents that induce differentiation could selectively inhibit tumor cell growth, inducing a program of cell death with the production of cross-linked protein envelopes as the terminal event of this process at the skin surface, effectively eliminating the neoplastic phenotype. The nonspecific kinase inhibitor staurosporine induces cornified envelope assembly in neoplastic keratinocytes and causes tumor regression (A. A. Dlugosz and S. H. Yuspa, Cancer Res., 51: 4677-4684, 1991). In pursuit of less toxic agents, specific tyrosine kinase inhibitors were tested for the ability to induce differentiation in keratinocyte-derived cells. Of a range of inhibitors tested, only MC was able to induce cross-linked protein and consequent cell death in mouse and human primary normal keratinocytes, 308 neoplastic mouse keratinocytes, HPV-18-infected immortalized human keratinocytes, and human lines SQCC-Y1 (squamous carcinoma) and A431 (epidermoid carcinoma). MC increased cross-linked protein in a dose-dependent manner (0.05-1 mM). To confirm differentiation, MC-treated mouse primary normal keratinocytes were tested for activation of the endogenous cross-linking enzyme transglutaminase, but no association was found between transglutaminase activity and MC-induced protein cross-linking. MC also induced protein cross-linking in the fibroblast cell line NIH3T3 and in B16 melanoma cells, in which cornified envelope assembly is not part of the differentiation process. This cross-linking occurred at 4 degrees C, suggesting a nonphysiological process. Western blot analysis of an in vitro assay with purified EGF receptor showed that MC was able to cross-link the receptor. As in NIH3T3 cells, DTT inhibited cross-linking, suggesting that oxidation of MC or an acceptor group may be required for this effect. Thus, MC does not induce differentiation by a physiological mechanism in epithelial cells but causes chemical protein cross-linking into cornified envelope-like structures at high concentration.
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PMID:The erbstatin analogue methyl 2,5-dihydroxycinnamate cross-links proteins and is cytotoxic to normal and neoplastic epithelial cells by a mechanism independent of tyrosine kinase inhibition. 758 35

The proto-oncogene pim-1 was expressed in nine human tissues (including epidermis) examined by Northern blotting. Expression of pim-1 was also observed in a number of carcinoma-derived keratinocyte lines in addition to strains derived from normal epidermis. With the exception of a squamous carcinoma line that exhibits little differentiated character in culture (SCC-4), where it was not detected, pim-1 expression was substantially higher after confluence than during log-phase growth in each case. The differentiation marker keratinocyte transglutaminase showed the same pattern of expression as pim-1 in relation to confluence in each of the cell lines and strains studied. The influences on pim-1 mRNA levels of several known effectors of keratinocyte differentiation were studied in the squamous carcinoma line SCC-9. pim-1 mRNA was stimulated by hydrocortisone and suppressed by the tumor promoter tetradecanoyl phorbol acetate. pim-1 mRNA was also regulated by calcium ion concentration in the culture medium, with expression being threefold higher in 0.15 mM than in 0.03 mM calcium ion. Keratinocyte transglutaminase was regulated similarly by these effectors. Thus pim-1 expression was associated with keratinocyte differentiation in these cultured cells.
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PMID:Differentiation-associated expression of the proto-oncogene pim-1 in cultured human keratinocytes. 759 47

Retinoids elicit biological responses by activating a series of nuclear receptors. Six retinoid receptors belonging to two families are currently known: retinoic acid receptors (RAR alpha,beta,and gamma) and retinoid X receptors (RXR alpha,beta,and gamma). Stilbene retinoid analogs of retinoic acid (RA), such as (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)prope n-1- yl]benzoic acid (TTNPB, 1) and (E)-4-[2-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphthalenyl)pro pen-1- yl]benzoic acid (3-methyl-TTNPB, 2), display differential RAR and RXR activities, depending on the substituent at C3 of the naphthalene ring. We report here structural modifications of the benzoate moiety of 2 that result in analogs with greater RXR selectivity as well as those with pan-agonist (activate both RAR and RXR receptors) activities, analyze the structural features that impart receptor selectivity, and describe a stereoselective method for the synthesis of these analogs. The biological activities associated with the RAR and RXR receptors were examined by testing representative examples with different receptor activation profiles for their ability to induce tissue transglutaminase (Tgase) activity in a human promyelocytic leukemia cell line (HL-60 cdm-1) and to inhibit tumor-promoter-induced ornithine decarboxylase (ODC) activity in hairless mouse skin. These results suggest that RAR agonists and RXR agonists may have different therapeutic applications. Finally, we show that RXR agonists are significantly reduced in teratogenic potency relative to RAR agonists and may therefore have significant advantages in clinical practice.
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PMID:Synthesis and structure-activity relationships of stilbene retinoid analogs substituted with heteroaromatic carboxylic acids. 763 43

Somatic cell hybrid cell lines derived from the fusion of human squamous carcinoma cells (FaDu-Hyg) with human keratinocytes were used to examine the relationships between cell differentiation and tumorigenicity. Treatment of the parental keratinocytes or the two hybrid cell lines with the combination of calcium and fetal bovine serum increased the expression of the envelope precursor, involucrin, 4- to 8-fold, whereas it remained unchanged in FaDu-Hyg cells. Similarly, calcium- and serum-treated keratinocytes and the two hybrid cell lines displayed a 7- to 13-fold increase of the activity of membrane-associated type I transglutaminase, whereas transglutaminase activity in FaDu-Hyg cells did not change appreciably. FaDu-Hyg cells were tumorigenic in vivo, but tumorigenicity was suppressed in both hybrid cell lines. Analysis of additional tumor cell lines indicated that the expression of transglutaminase I and involucrin are under separate genetic control and that loss of transglutaminase activity can result either from a lack of protein or from a defect in the activation step. Thus, keratinization of squamous epithelial cells appears to be controlled by several different recessive genes, which cosegregate with but are probably only partly identical with the genes that suppress tumor formation in vivo.
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PMID:Restoration of differentiation and suppression of tumorigenicity in somatic cell hybrids of human squamous carcinoma cells and keratinocytes. 769 77

Several lines of evidence indicate that immunoglobulin-bound prolactin found in human serum is not a conventional complex between an anti-prolactin antibody and prolactin but a different type of association of prolactin with the Fab portion of IgG heavy chains. The complex of prolactin with IgG was purified from serum by anti-human prolactin affinity chromatography and was shown to contain close to 1 mole of N epsilon-(gamma-glutamyl)lysine crosslinks per mole of complex, a characteristic feature in structures crosslinked by transglutaminase. Interestingly, the complex caused a proliferation of cells from a subset of patients with chronic lymphocytic leukemia, while it was inactive in a cell proliferation prolactin bioassay. By contrast, human prolactin stimulated the proliferation of cells in the bioassay but had no effect on the complex-responsive cells from the patients. Competition studies with prolactin and free Fc fragment of IgG demonstrated a necessity for engaging both the prolactin and the immunoglobulin receptors for proliferation. More importantly, competition for the growth response by free prolactin and IgG suggests both possible reasons for the slow growth of this neoplasm as well as avenues for control of the disease.
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PMID:Prolactin-immunoglobulin G complexes from human serum act as costimulatory ligands causing proliferation of malignant B lymphocytes. 772 52

12-Deoxyphorbol-13-phenylacetate (dPP) is the prototype for a new class of phorbol derivatives that function as protein kinase C (PKC) activators with potent anti-tumor-promoting activity. To explore the mechanism of action of dPP, we have conducted detailed analyses of the translocation and down-regulation patterns of individual PKC isozymes in mouse primary keratinocytes upon dPP treatment. PKC-alpha, -delta, and -epsilon were very quickly (within 2-5 min) translocated from the soluble fraction to the Triton X-100-soluble particulate fraction. PKC-delta and -epsilon were translocated with 2 orders of magnitude higher potency than was PKC-alpha. After translocation, PKC-alpha, -delta, -eta, and -epsilon were down-regulated; the down-regulation of PKC-epsilon contrasts with its retention after phorbol-12-myristate-13-acetate or bryostatin treatment. As was the case with translocation, dPP down-regulated the novel PKC isozymes (delta, epsilon, and eta) with 2 orders of magnitude higher potency (ED50, about 1-2 nM), compared with PKC-alpha (ED50, about 100 nM). dPP induced transglutaminase activity, ornithine decarboxylase activity, and cornification with potencies similar to that for PKC-alpha translocation. On the other hand, dPP caused inhibition of EGF binding with a potency similar to that for the translocation of the novel PKC isozymes. Although the generality of its selectivity in different cell types remains to be determined, at least in keratinocytes dPP is a powerful tool for dissecting the involvement of the classical and novel PKC isozymes in biological responses. The unique regulatory pattern of PKC-epsilon could contribute to the anti-tumor-promoting activity of dPP.
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PMID:Differential regulation by anti-tumor-promoting 12-deoxyphorbol-13-phenylacetate reveals distinct roles of the classical and novel protein kinase C isozymes in biological responses of primary mouse keratinocytes. 787 33

A widespread from of transglutaminase, tissue transglutaminase, has been identified in a number of mammalian cell types, both normal and transformed cells; its biological role is not well understood. We investigated the effect of experimentally induced colon cancer on transglutaminase activity in the rat. Azoxymethane (15 mg/kg for six weeks), given by a course of weekly intraperitoneal injections, produces tumors almost exclusively confined to the intestinal tract. Transglutaminase activity was assayed on tissue homogenates both during the period of treatment and, when the cancer had developed, on tumor tissue and on microscopically uninjured adjacent tissue. A transient proliferative phase was present in the intestine during azoxymethane treatment: in this phase we found a coincidentally increased transglutaminase levels. Transglutaminase activity in tumors of both small and large intestine was significantly higher than in adjacent tissue. Immunohistochemistry revealed higher levels of transglutaminase in tumors, mainly localized in the extracellular matrix, than in adjacent tissues, where it was widely distributed. The present study shows that transglutaminase, besides its potential role in intracellular process during early proliferative phase of carcinogenesis, may also play an important role in matrix processing during tumor growth and differentiation.
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PMID:Transglutaminase in azoxymethane-induced colon cancer in the rat. 789 66

A soluble tissue type transglutaminase (TGases; R-glutaminylpeptide:amine gamma-glutamyltransferase, E.C.2.3.2.13) belonging to a group of widely distributed enzymes which catalyze the reaction between a gamma-carboxyamide group of a protein-bound glutamine residue and various amino groups was characterized in cell lines derived from human pancreatic carcinoma. The enzyme activity was measured by incorporation of [3H]putrescine into N,N-dimethylcasein. It showed a strong dependency on Ca2+, which could not be replaced by Mg2+ but was 80% inhibited by 0.7 mM Mg2+ in the presence of optimal Ca2+ concentration (7 mM). The Km-value in regard to putrescine was 2.6 mM. After centrifugation of cell homogenates at 105,000g 95% of the enzyme activity was found in the supernatant indicating that the TGase in pancreatic tumor cells is soluble. This was further substantiated by immunohistochemistry showing a homogeneous cytoplasmic distribution of the TGase in pancreatic tumor cells. Molecular sieve chromatography and Western blot analysis using an antibody against TGase II from human erythrocytes revealed a molecular mass of 80 kDa. In Northern blots with a cDNA of TGase II from mouse macrophages a single transcript approximately 3.4 kbp in size was detected. Polymerase chain reaction analysis using primers for the coding and 3'-non-coding regions showed in each case a single product with the size expected from the human cDNA of TGase II. Taken these data together, we conclude that human pancreatic adenocarcinoma cells express the soluble tissue type TGase II.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of a transglutaminase expressed in human pancreatic adenocarcinoma cells. 790 Oct 19

Human colorectal tumor cells expressing differing metastatic potential and tissue transglutaminase (TGA) activity were tested for the ability of various pharmacological agents to enhance TGA activity. The most effective stimulant was tetradecanoylphorbol-13-acetate (TPA), which in human colon carcinoma cells (SW620) caused a 5-fold, protein synthesis dependent increase in activity over 3 days. In WiDr and SW480 cells TGA activity was less susceptible to induction by TPA, possibly owing to the higher basal levels of TGA. Retinoic acid and a synthetic retinoid, [RO 15-1570; (E)-4-[2(5,6,7,8-tetramethylnaphthalene-2-yl)propen-1-yl] benzenesulphonyl-ethane)], also induced TGA activity to a lesser extent in SW620 cells, whereas other differentiation inducers [sodium butyrate and hexamethylene bis-acetamide (HMBA)] were ineffective. In LS174T cells, TGA activity was resistant to induction by all of the agents. The synthetic retinoid (RO 15-1570) inhibited in vitro invasiveness of SW620 cells, however, TPA treatment or addition of exogenous TGA did not inhibit invasiveness of these cells. Hence, the invasive behavior of a metastatic human colon tumor cell line (SW620) does not appear to be dependent on the TGA activity which the cells express. The anti-invasive activity of the retinoid in SW620 cells therefore may be mediated by some other mechanism.
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PMID:Pharmacological alterations of cellular transglutaminase activity and invasiveness in human colorectal carcinoma cells. 790 10


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