Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A synthetic peptide containing the RGD (Arg-Gly-Asp) sequence is known to inhibit the attachment between cells and the extracellular matrix (ECM) in vitro, and also inhibit experimental pulmonary metastasis of murine melanoma cells in vivo. Prevention of peritoneal seeding by RGD-containing peptides has never previously been discussed. In this study, the inhibition of peritoneal seeding by RGD-containing peptides is examined, using the in vivo experimental peritoneal seeding model with human ovarian cancer cells (JHOC-1). Intraperitoneal (i.p.) inoculation of nude mice with JHOC-1 cells soon resulted in peritoneal seeding in all of the mice. Most of them expired within 4 to 80 weeks, and none survived for as long as 10 weeks. GRGDS (Gly-Arg-Gly-Asp-Ser) sequenced synthetic peptides were administered by i.p. injection after tumor cell inoculation following some regimens, and the changes in body weight and the periods of survival of the peptides-treated and untreated mice were observed. Intraperitoneal administration of 2mg/mouse of GRGDS peptides (every 8 hours, for 4 days, beginning just after tumor cell inoculation) significantly prolonged the survival periods of the tumor implanted mice. In this study, RGD-containing peptides were found to be able to prevent in vivo experimental peritoneal seeding by continual i.p. administration. This might indicate that RGD and integrins plays a critical role in peritoneal seeding as well as in hematogeneous metastasis.
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PMID:RGD-containing peptides inhibit experimental peritoneal seeding of human ovarian cancer cells. 174 66

We examined the binding capacity of anti-metastatic polypeptide containing repetitive Arg-Gly-Asp(RGD) sequence derived from cell binding site of fibronectin, poly(RGD), to the surface of tumor cells. Poly(RGD) competitively inhibited the binding of radiolabeled fibronectin to the cell surface more potently than oligo(RGD) or RGD tripeptide on a molar basis. Compared on a weight basis to oligo(RGD) or RGD peptide, poly(RGD) was more active than the oligo- and monomeric peptide at inhibiting tumor cell adhesion to immobilized fibronectin. The secondary structure of poly(RGD) was predicted to be a beta-turn from the data of CD spectra and its amino acid sequence. These findings suggest that poly(RGD)-mediated inhibition of cell adhesion is due to its potent binding capacity to fibronectin receptors on cell surface probably through its conformational properties.
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PMID:Molecular properties of poly(RGD) and its binding capacities to metastatic melanoma cells. 176 68

We previously showed that the in vivo invasion of a squamous cell carcinoma induced by the intradermal injection of tumor cells was significantly delayed after the IFN-gamma-producing gene transfer to tumor cells. With respect to the mechanism of the delayed invasion, it was suggested that the IFN-gamma might inhibit the adhesion of the cells to extracellular matrices (ECM) and the subsequent locomotion. Thus, we examined the effect of IFN-gamma on the adhesion of Pam-T cells to ECM. The attachment of Pam-T cells to fibronectin (FN) was significantly higher than that to laminin (LN), collagen type I (COL I) or collagen type IV (COL IV) substrata. The attachment to FN was significantly enhanced specifically by the IFN-gamma-treatment of the cells, although the attachment to LN, COL I or COL IV was not altered by IFN-gamma. Neither IFN-alpha nor IFN-beta had any effect on the attachment of Pam-T cells to FN. When Pam-T cells were treated with IFN-gamma together with a neutralizable anti-IFN-gamma antibody, this enhancement was completely abolished. Moreover, the attachment of IFN-gamma-treated Pam-T cells as well as non-treated cells to FN was blocked by the synthetic peptide Arg-Gly-Asp-Ser (RGDS), but not by the control peptide Arg-Gly-Glu-Ser. Based on these results, we conclude that IFN-gamma specifically enhances the adhesiveness of Pam-T cells to FN substrata by the modulation of integrin activity.
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PMID:Modulatory effects of interferon-gamma on the fibronectin receptor function of squamous cell carcinoma cells in vitro. 183 57

Laminin is a large multidomain glycoprotein with diverse biological activities which include stimulation of neurite outgrowth, enhancement of tumor metastasis, and promotion of cell growth, adhesion, and differentiation. A 19 amino acid synthetic peptide derived from the E8 fragment of the laminin A chain (Cys-Ser-Arg-Ala-Arg-Lys-Gln-Ala-Ala-Ser-Ile-Lys-Val-Ala-Val-Ser-Ala-Asp -Arg- NH2) was identified which promotes metastasis and stimulates collagenase IV activity in the culture medium of B16 melanoma cells (Kanemoto et al., 1990). We report that this peptide, here designated LamA2091-2108, is also a potent stimulator of tissue plasminogen activator (t-PA)-catalyzed plasminogen activation, resulting in a 22-fold increase in the kcat/Km of the activation reaction. The activity of purified type I and type IV collagenase was inhibited by LamA2091-2108 with IC50 values of 3 and 43 microM, respectively. These data support an alternative mechanism for the appearance of collagenase activity in the culture media of melanoma cells, namely, that the peptide stimulates plasminogen activation, subsequently generating collagenase activity.
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PMID:Modulation of plasminogen activation and type IV collagenase activity by a synthetic peptide derived from the laminin A chain. 184 24

Albolabrin, a 7.5-kDa cysteine-rich protein isolated from the venom of Trimeresurus albolabris, contains the arginine-glycine-aspartic acid (RGD) cell recognition sequence found in many cell adhesion-promoting extracellular matrix proteins, such as fibronectin and laminin. Albolabrin belongs to a family of RGD-containing peptides, termed disintegrins, recently isolated from the venom of various vipers and discovered to be potent inhibitors of both platelet aggregation and cell-substratum adhesion. Here we report that albolabrin inhibited the attachment of B16-F10 mouse melanoma cells to either fibronectin or laminin absorbed on plastic. When immobilized on plastic, albolabrin promoted B16-F10 melanoma cell attachment; this was inhibited by either RGD-serine (RGDS) or antibodies to integrins, suggesting that albolabrin binds via its RGD amino sequence to integrin receptors expressed on the melanoma cell surface. In an in vivo experimental metastasis system, albolabrin at a concentration of 300-600 nM inhibited C57BL/6 mouse lung colonization by tail vein-injected mouse melanoma cells and was at least 2000 times more active than RGDS in this assay. We propose that albolabrin inhibits tumor cell metastasis by inhibiting integrin-mediated attachment of melanoma cells to RGD-containing components of the extracellular matrix in the mouse lung.
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PMID:Inhibition of murine melanoma cell-matrix adhesion and experimental metastasis by albolabrin, an RGD-containing peptide isolated from the venom of Trimeresurus albolabris. 187 72

The authors report on the influence of plasminogen activators (PA) on implantation of TA3Ha mammary tumor cells in the healing hepatic wounds of syngeneic strain A mice. Intravenously injected TA3Ha cells, although they rarely metastasize to the liver, formed tumors in the hepatic wounds of a significant percent (42%, P less than 0.0001) of mice. The frequency of tumor formation declined as the interval between surgery and tumor cell inoculation was increased. Furthermore, preexposure of cells to fibrinogen, fibronectin, laminin, or peptides containing the arginine-glycine-aspartic acid-serine residues dramatically reduced the frequency of tumor formation in the hepatic wounds. These results indicate that TA3Ha cells interact with fibrinogen-related proteins in the wound to aid their attachment and growth. Because these proteins are susceptible to digestion by plasmin, PA were used in this study to examine whether administration of these drugs to the mice would modulate tumor formation in the liver wounds. Among the PA tested, human plasmin B-chain-streptokinase complex (B-SK) and recombinant tissue plasminogen activator (t-PA) inhibited tumor implantation in a dose-related manner. Administration of 900 units (U) of B-SK or 3300 U of t-PA per mouse reduced the frequency of tumor formation from 42% to 0% (P = 0.02) and 11% (P = 0.02), respectively. The B-SK was complexed with p-nitrophenyl-p-guanidinobenzoate; it did not activate the plasminogen or inhibit tumor formation in the hepatic wounds. Although urokinase activated the plasminogen, it did not inhibit tumor implantation in the hepatic wound. Heparin, an anticoagulant that prevents conversion of fibrinogen to fibrin without being fibrinolytic, had no influence on tumor formation in the hepatic wounds. The PA can generate plasmin that digests the cell attachment proteins in wounds and consequently inhibits tumor cell attachment.
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PMID:Inhibition of tumor implantation at sites of trauma by plasminogen activators. 191 15

A putative tumor suppressor gene, p53, has been shown to be altered in a variety of human tumor types. The primary mechanism of p53 inactivation is believed to be mutation of one allele followed by loss of the second allele. Malignant mesothelioma is a tumor that has been highly associated with exposure to asbestos fibers, which are known to cause chromosomal abnormalities in mesothelial cells. We have examined four mesothelioma cell lines for genetic abnormalities in p53. Cytogenetic analysis revealed that two of the four tumors had abnormalities (numerical and/or structural) of chromosome 17 (the locus of the p53 gene). Restriction fragment length polymorphism analysis using a chromosome 17p-specific probe (pYNZ22) revealed that two tumors had loss of heterozygosity in the region of 17p13. The relative level of p53 mRNA expression was examined by Northern analysis, with one tumor showing negligible expression of p53 mRNA. The complementary DNA of p53 was generated from the three tumors showing detectable mRNA expression, and the region between codons 70 and 319 was amplified by the polymerase chain reaction and sequenced. DNA single-base substitutions were detected in two of the tumor cell lines, each resulting in amino acid substitutions. One tumor had an arginine to histidine substitution at position 175, and one tumor had a glycine to aspartic acid substitution at position 245. The observed mutations took place in regions of high cross-species sequence homology, indicating that these regions may be functionally important. The correlation of chromosomal loss in 17p on the cytogenetic and molecular level along with p53 mRNA expression and DNA sequence data indicate that genetic alterations in p53 could be a feature of malignant mesotheliomas and may reveal an important role of asbestos fibers in tumor suppressor gene inactivation.
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PMID:Genetic alterations of the p53 gene are a feature of malignant mesotheliomas. 191 60

The role of cellular adhesion in regional lymph node metastasis of solid tumors has been investigated. The data reviewed is based on studies in four different tumor models of human, rat and murine origin. An in vitro assay measuring tumor cell attachment to cryostat sections of normal peripheral lymph nodes, obtained from the species of tumor origin was used to compare the adhesion of tumor sublines with different metastatic potentials. A good correlation was found between tumor cell potential to metastasize to regional nodes and the adhesion to the sections in all models studied. The adhesion of all tumor lines could be blocked by Arg-Gly-Asp containing peptides while pretreatment of the cells with antibodies to integrins implicated beta 1 and beta 3 receptor complexes in the adhesion. Ligand binding assays provided indirect evidence that the preferential attachment of the metastatic tumor lines to the frozen sections was mediated via extracellular matrix proteins such as fibronectin, vitronectin and type IV collagen. As these basement membrane proteins have been localized to the outer surfaces of reticular fibers which are known to permeate the lymph node and trasverse the subcapsular sinus it is postulated that tumor cell attachment to these fibers may facilitate and possibly be required for tumor cell retention and growth in the invaded regional nodes.
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PMID:Adhesion mechanisms in lymphatic metastasis. 191 72

Chromogranin-B (CgB), a secretory granule protein, is normally synthesized in a variety of neuroendocrine tissues, including the pancreatic islet alpha-cells. We have demonstrated that rat CgB is expressed and extensively processed by limited proteolysis in a transplantable glucagonoma tumor line. Eight peptides (fragments 1-8) purified by HPLC from acidic tumor extracts were partially sequenced and showed homology to CgB amino acid sequences deduced from rat, mouse, and human cDNA. Similar peptides were not found in insulinomas of common origin. The determined amino acid sequence represents approximately 35% of the rat precursor CgB. Ten of a total of 231 sequenced residues deviated from the published rat cDNA sequence. The differences were clustered in 3 fragments, suggesting allelic polymorphism. Five of the 8 peptides could be derived from the precursor by processing at paired basic amino acids, but processing N-terminally at a single basic residue was also seen. One peptide equivalent to the previously reported C-terminal CgB (CCB) is released by processing at a tribasic segment. Fragment 1 containing the N-terminal sequence Ala-Pro-Val-Asp represents the actual N-terminus of CgB after removal of the putative signal peptide sequence. All processing sites used in glucagonoma tissue to derive the 8 isolated fragments were conserved between murine and human CgB. At least 3 dibasic sites present in rat, but not human, CgB sequence were actually not used. A previously reported CgB-derived pituitary peptide, GAWK, was further processed at a conserved internal dibasic site to yield fragment 6, indicating alternative processing in different tissues. The small undecapeptide, fragment 7, is 100% conserved among murine and human CgB and, thus, may have an important biological function. We conclude that CgB is extensively processed in glucagonoma tissue by limited proteolysis as prohormones at conserved basic residues. The proglucagon-converting enzymes present in transformed alpha-cells are likely candidates to be involved in tissue-specific CgB processing. Distinct biological activities of any of the CgB-derived fragments remain to be identified.
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PMID:Chromogranin-B, a putative precursor of eight novel rat glucagonoma peptides through processing at mono-, di-, or tribasic residues. 195 95

Ductectatic-type mucinous cystic neoplasms of the pancreas constitute a recently recognized new human pancreatic tumor entity. Examination for the presence of point mutations at codon 12 of K-ras by oligonucleotide hybridization in 5 adenomas and 3 carcinomas revealed alteration in 3 and 2, respectively. In 4 of these positive cases, the transition was GGT----GAT (Gly----Asp) with the remaining one, found in a cancer, being GGT----GTT (Gly----Val). In two carcinoma cases, the same point mutation was detected both in the carcinoma area and in a coexisting adenoma component. Thus K-ras point mutation appears to be associated with this particular type of neoplasm in the same manner as observed for typical exocrine pancreas carcinomas. Our study also indicates the possible existence of an adenoma-carcinoma sequence in the evolution of this type of neoplasm and we suggest that K-ras activation may be an important event in the phase of adenoma development.
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PMID:c-Ki-ras point mutations in ductectatic-type mucinous cystic neoplasms of the pancreas. 195 73


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