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 number of plasticizers and lipid-lowering drugs induce peroxisomes and cause hepatocellular carcinoma in rodents by mechanisms which remain unknown. In this study, seven structurally dissimilar peroxisome proliferating agents were shown to uncouple oxidative phosphorylation in isolated rat liver mitochondria. For example, perfluorooctanoate (0.5 mM) increased succinate-induced (state 4) mitochondrial respiration by over 50% while stimulation of state 3 respiration with ADP was minimal (i.e., uncoupling occurred). Interestingly, compounds which are potent carcinogens in vivo (e.g., Wy-14,643 and perfluorooctanoate) were more powerful uncouplers of oxidative phosphorylation in vitro than weak tumor-causing agents (e.g., valproate). Uncoupling also occurred in vivo. Basal rates of oxygen uptake in perfused livers from chronically treated rats were increased from 137 +/- 7 mumol g-1/h in pair-fed controls to 153 +/- 5 mumol g-1/h after 2.5 months of feeding Wy-14,643 (0.1% w/v in diet). Concomitantly, rates of urea synthesis from ammonia, a process highly dependent on ATP supply, were reduced almost completely from 104 +/- 10 mumol g-1/h to 13 +/- 6 mumol g-1/h. Bile flow, another energy-dependent process, was also reduced significantly by treatment with Wy-14,643 in vivo for 24 h. Taken together, these data indicate that energy supply for cellular processes such as urea synthesis and bile flow was disrupted in vivo due to uncoupling of oxidative phosphorylation by Wy-14,643. It is proposed that peroxisomal proliferators accumulate in the liver where they uncouple mitochondrial oxidative phosphorylation and interfere with cellular energetics.
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PMID:Several nongenotoxic carcinogens uncouple mitochondrial oxidative phosphorylation. 139 Aug 25

The potential of the immune system to inhibit or stimulate tumor growth is a vivid example of the "two-edged sword" nature of immune responses. Our results provide evidence that this dual capacity can be attributed, in part, to the dual pathways of arginine metabolism exhibited by intratumor macrophages. Specifically, i.p. tumor rejection in P815-preimmunized mice is accompanied by an upshift in intratumor macrophage arginine metabolism to the nitric oxide (NO) synthase pathway that yields citrulline and NO. A rapid and marked local increase in IFN-gamma (both mRNA and protein) in preimmunized mice during tumor rejection suggests that this cytokine plays a role in up-regulating nitric oxide production in vivo. Unlike tumor rejection, progressive i.p. P815 tumor growth in naive mice is associated with a marked decline in the production of citruline/NO by intratumor macrophages. Examination of macrophage arginine metabolism via arginase revealed a pattern opposite that of NO synthase. The local production of ornithine/urea markedly increases during progressive tumor growth whereas arginase activity decreases during tumor rejection. Inasmuch as nitric oxide inhibits tumor cell replication whereas ornithine is the precursor of polyamines required for cell replication, these results are consistent with the conclusion that the pathway macrophages use to metabolize arginine can influence the type of host immune responses against cancer and other conditions.
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PMID:Macrophage arginine metabolism and the inhibition or stimulation of cancer. 140 10

Intrathecal administration of ACNU ((1-4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitroso urea hydrochloride) had a remarkable chemotherapeutic effect in a rat model of meningeal gliomatosis. This effect was evaluated in rats with meningeal gliomatosis induced by an intracisternal inoculation of rat C6 glioma cells. The median survival time of the rats treated with a single dose of intrathecal ACNU (1 mg/kg) on Day 1 or Day 3 after tumor inoculation was significantly prolonged by 35.7% to 42.9% or 25.0% to 28.6%, respectively, as compared with that of the control animals. Meningeal gliomatosis rat models treated intrathecally with ACNU (1 mg/kg) 5 days after tumor inoculation or intravenously with ACNU (15 mg/kg) both failed to prolong the survival time of the animals. These findings suggest that intrathecal chemotherapy with a low dose of ACNU is effective in the early stages of meningeal gliomatosis, whereas intravenous chemotherapy with a high dose of ACNU is always ineffective.
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PMID:Intrathecal chemotherapy with ACNU in a meningeal gliomatosis rat model. 140 22

During the last years interest has focused on the trophic effect of gastrin in colorectal carcinomas. Some reports indicated an increased serum level of gastrin in patients with colorectal adenomas or carcinomas. In a prospective study in 261 patients submitted to colonoscopy fasting serum gastrin concentrations were determined. 91 patients served as control, 89 patients had one or more adenomas, 55 patients suffered from a colorectal carcinoma, 17 had a benign, postoperative stenosis of the colon, and 9 had a chronic inflammatory bowel disease. All patients fulfilled the following criteria: No regular drug intake, no previous gastric or small bowel operation, no known ulcer disease, no abnormalities in serum calcium, creatinine, triglycerides, cholesterol and blood urea. Mean gastrin level was 86.63 +/- 23.8 pg/ml in the control, 84.57 +/- 25.1 pg/ml in the adenoma group and 84.6 +/- 24.4 pg/ml in the carcinoma group. No difference of serum gastrin levels were observed regarding sex, age, tumor stage and localisation.
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PMID:[Serum gastrin level in patients with colorectal adenoma or carcinoma]. 141 56

Mouse monoclonal antibodies against human (beta 1-4)galactosyl-transferase (GalT) purified from human ovarian tumor effusion fluids were prepared and characterized. GalT purified from normal human plasma showed a single diffused band in nondenaturing polyacrylamide gel electrophoresis, but GalT purified from human ovarian tumor effusion fluids showed several oligomeric bands and a monomeric band in nondenaturing polyacrylamide gel electrophoresis. These oligomeric bands were dissociated into monomer by urea treatment and polymerized by a 2-mercaptoethanol treatment. Nine monoclonal antibodies (MAb) were prepared by immunization of purified GalT from human ovarian tumor effusion fluids and classified into three groups. Type I MAbs (MAb8611, MAb8913, and MAb8919) reacted only to the GalT monomer. Type II MAbs (MAb4880, MAb8507, and MAb8628) reacted to both the GalT monomer and the GalT polymer. Type III MAbs (MAb7907, MAb8513, and MAb8677) reacted only to the GalT polymer. These MAbs except MAb7907 could recover GalT enzyme activity from effusion fluids by immunoprecipitation. A fraction passed through MAb8513 affinity chromatography still showed reactivity to MAb8919, demonstrating that an epitope of MAb8513 resides on a minor part of GalT. A sandwich immunoassay (MAb8513-MAb8628HRP) was developed, and serum samples from ovarian cancer patients and benign ovarian patients were tested. The levels of sandwich immunoassay of serum samples from cancer were elevated significantly compared to those from benign and did not necessarily correlate to total GalT enzyme activity in serum samples. These results suggested that MAb8513 (Type III) might recognize a unique GalT associated with tumor (GAT).
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PMID:Mouse monoclonal antibodies which recognize a human (beta 1-4)galactosyl-transferase associated with tumor in body fluids. 142 58

Previous metabolic studies in rats have suggested in vivo formation of the acrolein-glutathione (acrolein-GSH) adduct following administration of the highly reactive alpha, beta-unsaturated aldehyde acrolein. Early studies by several investigators demonstrated that similar compounds such as alpha, beta-unsaturated aldehyde-cysteine adducts have toxic (carcinostatic) activity against Ehrlich ascites tumor cells implanted in mice. The current studies investigated the in vivo toxicity associated with the acrolein-GSH adduct in the male Sprague-Dawley rat. The 1:1 acrolein-GSH adduct was synthesized and characterized by physical-chemical methods. Rats given the acrolein-GSH adduct intravenously at 0.5 or 1 mmol/kg developed nephrotoxicity characterized by glucosuria, proteinuria, elevation in serum urea nitrogen, and gross and histologic changes of the kidney. The toxicity was not affected by pretreatment of rats with pyrazole, an alcohol dehydrogenase inhibitor; disulfiram, an inhibitor of aldehyde dehydrogenases; or probenecid, a renal organic anion transport inhibitor. Administration of a similar but nonaldehydic glutathione conjugate, S-n-propylglutathione, did not result in nephrotoxicity in the rat. The nephrotoxicity induced by the acrolein-GSH adduct was inhibited by acivicin, a gamma-glutamyl-transpeptidase inhibitor. These results indicate that the acrolein-GSH adduct requires processing through the first step of the renal mercapturic acid synthesis pathway to be activated to a toxic species.
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PMID:Nephrotoxicity of the 1:1 acrolein-glutathione adduct in the rat. 147 Nov 52

The highly (ASML) and non metastatic (AS) variants of the rat tumor BSp73 were compared with respect to cell surface carbohydrate proteins. Fluorescence labelling with lectins (ConA, MPA, PNA, SBA, UEA-I, WGA) revealed a differentiated carbohydrate pattern at the cell surface of these cell lines. The highly metastatic variant was significantly more glycosylated with respect to galactosyl, mannosyl and N-acetylgalactosylamine residues; fucosyl residues were exclusively expressed in the metastatic variant. Examination of isolated plasma membrane fractions showed quantitative differences with respect to glycosylated proteins separated on polyacrylamide gels. A 30 kDa glycoprotein (GP30-ASML) dominant in the metastatic variant was further characterized. Various detergents (CHAPS, Nonidet, SDS, Triton X-100) and urea extracted it exclusively from the highly metastatic variant. GP30-ASML is a predominantly O-glycosylated single polypeptide chain with terminal N-acetylgalactosamine and galactosyl residues; its molecular weight determined by SDS-PAGE is 30 kDa and its isoelectric point is 7.8. Immunofluorescence localization experiments with monoclonal antibodies specific for GP30-ASML and polyclonal antibodies raised against GP30-ASML showed this protein at the cell surface and in the lysosomal compartment of both cell lines; exclusively in the non metastatic variant it was also found in the nuclear membrane. The function of this protein is still unknown.
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PMID:Cell surface glycosylation and characterization of a differentially expressed glycoprotein in metastatic and non metastatic cell lines of the rat BSp73 tumor. 150 18

In GH4C1 rat pituitary cells, cell swelling stimulates prolactin (PRL) secretion by increasing Ca2+ influx through nifedipine-sensitive Ca2+ channels; however, the mechanism by which cell swelling opens Ca2+ channels is still unclear. To evaluate the role of protein kinase C (PKC) in this phenomenon, we studied the effect of down-regulating PKC by 12-h pretreatment with phorbol ester or by treatment with H-7, a protein kinase C inhibitor. Cell swelling induced by either 27% medium hyposmolarity or 80 mM isotonic urea caused a prompt rise in both [Ca2+]i and PRL secretion in otherwise untreated control GH4C1 cells. Removal of medium Ca2+ enhanced the osmotically induced cell swelling but prevented the increase in [Ca2+]i and PRL secretion. Both PKC down-regulation and H-7 suppressed the cell swelling-induced increases in [Ca2+]i concentration and PRL secretion, although they enhanced the induced cell volume expansion. Our data indicate that in GH4C1 cells PKC plays an important positive modulating role in the osmotic opening of plasmalemma Ca2+ channels, a critical component of the early transduction chain by which cell swelling causes PRL secretion in tumor-derived clonal pituitary cells.
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PMID:Protein kinase C modulates cell swelling-induced Ca2+ influx and prolactin secretion in GH4C1 cells. 151 83

A number of highly lipophilic dineodecanoato(trans-R,R- and trans-S,S-1,2-diaminocyclohexane) platinum (II) complexes were entrapped in multilamellar vesicles composed of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidyl-glycerol at a molar ratio of 7:3. The entrapment efficiency and stability of liposomal platinum (L-Pt) preparations was greater than 90%. The subacute mouse LD50 of L-Pt preparations tested ranged from 60 to 104 mg/kg. All L-Pt preparations tested had no significant nephrotoxicity at the LD50 dose except for L-Pt 5, which caused renal dysfunctions (as evidenced by elevated blood urea nitrogen levels) at the LD50 dose. L-Pt preparations had shown good in vivo antitumor activity against i.p. L1210 leukemia when an optimal dose was administered i.p. to mice on days 1, 5 and 9 (% T/C 230-300; cisplatin 220). L-Pt preparations were also markedly active, by the i.p. route, against L1210 leukemia resistant to cisplatin (% T/C 237-355; cisplatin 112). All L-Pt preparations exhibited significant antitumor activity against B16 melanoma when administered i.p. on day 1 (% T/C 144-155; cisplatin 161). L-Pt 1, 3 and 5 were all tested by the i.v. route on days 4, 8 and 12 against M5076 reticulosarcoma, but none of these preparations showed any significant antitumor activity against this tumor system (% T/C 120-127; cisplatin 173). Current studies aimed at optimizing the liposomal formulation of these compounds should result in the selection of a single isomeric L-Pt formulation for clinical development.
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PMID:Toxicity and efficacy studies on a series of lipid-soluble dineodecanoato(trans-R,R- and trans-S,S-1,2-diaminocyclohexane) platinum (II) complexes entrapped in liposomes. 152 98

In HeLa cells transcription of the c-jun gene is activated strongly and rapidly by ultraviolet (UV) irradiation and, to a somewhat lesser extent, by treatment with phorbol ester tumor promoters. In the same cells UV and phorbol esters only marginally enhance the abundance of RNA transcribed from the jun D gene and from the gene coding for the serum response factor (which in turn acts on the UV and phorbol ester response element of the c-fos gene). In contrast to c-jun, jun B transcription is induced more efficiently by phorbol ester than by UV irradiation, suggesting that the members of the jun family are differently regulated. The promoter of c-jun carries two enhancer elements resembling AP-1 binding sites: the jun1 UV response element (URE-71 TGACATCA -64) and the jun2 URE (-190 TTACCTCA-183). These elements act independently in the UV induced expression of c-jun. In the context of the complete c-jun promoter they seem not to be required for c-jun induction by phorbol esters. When fused to the Herpes simplex thymidine kinase promoter, however, the isolated elements mediate induction by both UV and phorbol esters. UV and phorbol ester treatment of cells increases the binding of transcription factors to both elements. Both elements bind factors different in modification or/and constitution from AP-1, the heterodimeric transcription factor composed of c-Fos and c-Jun that controls the activity of the UV and phorbol ester response element (-72 TGAGTCA-66) of the human collagenase gene.
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PMID:Ultraviolet-radiation induced c-jun gene transcription: two AP-1 like binding sites mediate the response. 156 Dec 39


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