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

In this study, the effect of tumor presence on the concentration of vitamin E in the liver, spleen, and kidney of BALB/c mice was measured, and the influence of the degree of fat saturation was assessed. In mice fed diets deficient in vitamin E, the presence of a transplanted sarcoma in the thigh significantly increased the concentration of the vitamin in all 3 organs. This was true whether the fat was saturated or unsaturated (hydrogenated coconut oil [HCO] or corn oil [CO], respectively). The tumor itself was generally lower in tocopherol than were other tissues of the tumor-bearing host. In mice fed diets containing vitamin E, the tumor increased the vitamin content in some organs but not others. Only in the kidney of tumor-bearing mice fed the HCO +/- E diet was there a significantly decreased content of the vitamin. A comparison of the spleen tocopherol content with mitogenesis by concanavalin A revealed a positive correlation, which explains why the spleens of tumor-bearing mice fed a diet deficient in vitamin E exhibited higher mitogenic activity than the spleens of normal mice fed the same diet (namely, the spleens from tumor-bearing mice had a higher content of tocopherol).
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PMID:Effect of K3T3 sarcomas on tissue concentrations of vitamin E. 716 95

Vitamins are a class of organic compounds that are components of an adequate diet. They or their derivatives function as coenzymes, cellular antioxidants, and/or regulators of gene expression. Fourteen vitamins are recognized in human nutrition (Vitamins A, D, E, K, B1, B2, B6, B12, C, niacin, folacin, pantothenic acid, biotin, choline), with deficiencies or excesses in intake leading to changes in protein, nucleic acid, carbohydrates, fat and/or mineral metabolism. Thus, the integrity of physiological systems, including those associated with detoxification, cellular repair, immune processes, and neural and endocrine function, depends upon the nutritional and vitamin status of the host. For these reasons, it may be anticipated that the adequacy of the vitamin supply to cells and tissues would affect the development, progress, and outcome of cancers. In this review, the definition and functions of and requirements and recommended allowance for vitamins are discussed briefly before exploring the evidence, largely from studies in experimental animals, that indicates the nature of the link between vitamins and cancer. Although evidence based on studies in animal systems reveals that vitamin intake and status can modulate the outcome of experimental carcinogenesis, the findings are often conflicting and difficult to interpret. Furthermore, it is not yet possible to develop a suitable prediction of the role of the individual vitamins in tumor development. The significance of these observations for human nutrition and cancer prevention, particularly in reference to ascorbic acid (vitamin C), vitamin E, and B-complex vitamins is considered. Vitamin A and retinoid compounds are discussed elsewhere in the symposium. The many popular misconceptions and unsound advice concerning vitamins and health, including "fake" vitamins-pangamic acid ("vitamin B15") and laetrile ("vitamin B17")-are also discussed. On the basis of current evidence, it would be inappropriate to recommend either substantial changes in habitual vitamin intakes, as provided by an adequate, well-balanced diet, or promotion of megavitamin intakes, as a means of reducing risk from cancers in the human population. However, a prudent approach toward diet and food habits, as a means of better optimizing the health consequences of our complex lifestyle is to be recommended.
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PMID:Vitamins and cancer prevention: issues and dilemmas. 723 79

Strain A mice were injected with urethan, 3-methylcholanthrene or dimethylnitrosamine and given repeated injections of butylated hydroxytoluene (BHT). This treatment significantly increased multiplicity of lung tumors induced by all 3 carcinogens. Two other antioxidants, butylated hydroxyanisole (BHA) or alpha-tocopherol (vitamin E) did not enhance tumor formation, nor did methylcyclopentadienyl manganese tricarbonyl (MMT), an agent capable of producing cell proliferation in lung. Lungs were more susceptible to the carcinogenic action of urethan 2 weeks following BHT-induced injury, but not during the phase of acute cell proliferation in lung. It is concluded that the effects of BHT on lung tumor development in mice are not related to its properties as an antioxidant or to its capability to produce extensive cell proliferation in lung.
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PMID:Modification of lung tumor development in A/J mice. 728 Nov 95

Epidermoid carcinomas were induced in hamster buccal pouches with use of 7.12 dimethylbenz[a]anthracene (DMBA). In five animals that served as tumor controls (Group 1), right buccal pouches were painted with DMBA (0.5% solution in mineral oil) thrice weekly for 14 weeks. In five animals (Group 2), right buccal pouches were painted with DMBA and reduced glutathione (GSH) was administered systemically by mouth. Five animals (Group 3) received vitamin E instead of glutathione. An additional 20 animals (Groups 4, 5, 6, and 7) were untreated, vehicle, glutathione, and vitamin E controls, respectively. Glutathione and vitamin E were given in doses of 10 mg/kg in 0.5 ml of mineral oil thrice weekly on days alternate to DMBA painting. Treatment by GSH and vitamin E reduced the number and size of tumors that were formed. Histopathologically, there were also fewer sites of dysplasia, carcinoma in situ, and early invasive epidermoid carcinoma than in the tumor control animals. The formalin-fixed and paraffin-embedded buccal pouch sections were stained immunohistochemically with use of monoclonal antibodies for cytokeratins. These included high-molecular-weight keratins (50,000-68,000 mol wt) 10, 13, and 8 (k10, k13, and k8, respectively). Oral carcinomas and dysplastic sites exhibited basal and suprabasal (spinous layer) high levels of k10, k13, and k8 staining. Treatment with GSH or vitamin E increased the suprabasal staining for high-molecular-weight keratins and reduced the protein expression for k10, k13, or k8. This pattern of staining was observed in dysplastic as well as in carcinoma sites. These results indicate that cytokeratin protein expression could contribute to a common biomarker analysis for chemoprevention.
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PMID:Altered cytokeratin expression in carcinogenesis inhibition by antioxidant nutrients. 749 Dec 97

Since the cellular role of the antioxidative vitamins in the formation of foam cells has not yet been studied in detail, we investigated the effect of alpha-tocopherol and ascorbic acid loading of P388D1 macrophage-like cells on their cholesterol and cholesteryl ester levels and their response to the exposure to different lipoproteins. alpha-Tocopherol loading, but not ascorbic acid loading, of P388D1 cells strongly reduced their cellular cholesteryl ester/cholesterol ratio (the crucial indicator of foam cell formation) when fetal calf serum was the only extracellular source of cholesterol. Balance studies suggest that this effect of alpha-tocopherol was mainly due to a reduced uptake of fetal-calf-serum-derived cholesterol. alpha-Tocopherol loading, however, did not reduce the cholesteryl ester/cholesterol ratio when human unmodified low-density lipoprotein (LDL) was added to culture medium containing fetal calf serum. Thus, the uptake of fetal-calf-serum-derived cholesterol was competitively reduced by human LDL, the uptake of which remained unaffected by alpha-tocopherol. Similarly, alpha-tocopherol loading did not prevent cholesteryl ester formation induced by human LDL either oxidized with Cu2+, ultraviolet light or HOCl, or modified by acetylation, aggregation or by malondialdehyde treatment. The present experimental conditions lacked any pro-oxidative burden, since (a) ascorbic acid, either alone or combined with alpha-tocopherol, did not affect cellular cholesteryl ester levels, (b) foam cell formation was not a linear function of the degree of oxidative LDL modification, and (c) alpha-tocopherol lacked specific effects on oxidatively modified LDL. Thus, the reduction of cellular cholesteryl esters by alpha-tocopherol in the absence of human unmodified LDL was hardly due to common antioxidative properties of vitamin E. In conclusion, the present observation that a desirable alpha-tocopherol effect on the cholesteryl ester balance in mouse-tumor-derived P388D1 cells strongly depended on the species of extracellular cholesterol carrier, cautions against premature generalizations of conventional non-human cell culture data.
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PMID:Prevention of cholesteryl ester accumulation in P388D1 macrophage-like cells by increased cellular vitamin E depends on species of extracellular cholesterol. Conventional heterologous non-human cell cultures are poor models of human atherosclerotic foam cell formation. 758 42

Many different antioxidants have been shown to inhibit the induction of cancer by a wide variety of chemical carcinogens and/or radiation at many target sites in mice, rats, and hamsters. Evidence is accumulating that suggests that free radicals are important in all stages of chemical carcinogenesis. Both carcinogens and tumor promoters have also been shown to decrease the cellular activity of superoxide dismutase and catalase. A number of antioxidants and related compounds were tested to determine if they would inhibit either skin tumor initiation, promotion, and/or progression. In terms of skin tumor initiation, BHT, vitamin E and C and CuDIPS have been found to inhibit DMBA skin tumor initiation by approximately 50%. The mechanism of action of these compounds appears to be related to their effect on the metabolism of DMBA, since BHT and CuDIPS do not inhibit the initiating activity of BP-diol-epoxide and MNNG. Although several antioxidants do inhibit skin tumor initiation by procarcinogens, antioxidants are in general much more effective inhibitors of skin tumor promotion. BHT, BHA, parahydroxyanisole, disulfiran, and vitamin E and C inhibit skin tumor promotion by TPA and benzoyl peroxide by greater than 90%. We also determined the effect of free radical scavengers on the progression process. Of the agents tested glutathione and N-acyl dehydroalamines were the most effective in reducing carcinoma incidence. Diethyl maleate, a chemical that reduces glutathione levels, was effective in enhancing progression. In addition overexpression of g-glutamylt-ranspeptidase (GGT) which leads to a reduction in cellular glutathione levels also enhances progression. These results suggest that GGT has a functional role in skin tumor progression, and that a number of antioxidants are either effective inhibitors of skin tumor initiation, promotion, and/or progression.
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PMID:Inhibition of the induction of cancer by antioxidants. 759 4

Precancerous pathological changes of colon was induced by single injection in a short-term and multiple injection in a long-term intraperitoneally with 1,2-dimethylhydrazine (DMH) in NIH mice and Sprague-Dawley rats. And, protective effects of spirulina, germanium-132 and vitamin E on colon aberrant crypts induced by DMH were observed. Results showed either single injection or multiple injection with DMH could induce aberrant crypts in colon. The number of aberrant crypts scattered by short-term single injection was less than that by multiple one, and less of the aberrant crypts foci were formed by short-term single injection. Spirulina powder, germanium-132 and vitamin E all could inhibit the function of aberrant crypts of colon. In the ninth week during multiple injection with DMH, a lot of aberrant crypts of colon had been induced, and a certain amount of aberrant crypts foci had been generated. The number of aberrant crypts and aberrant crypts foci in the animals with tumor increased with the length of DMH injection. In the ninth-, 13th- and 16th-week, respectively, the number of aberrant crypts and aberrant crypts foci was significantly less in animals protected by spirulina than in positive controls (P < 0.01), but there was no significant difference between them during 21st- and 24th-week of injections.
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PMID:[Inhibitive effects of spirulina on aberrant crypts in colon induced by dimethylhydrazine]. 760 Aug 82

The symptomatic postmenopausal woman with breast cancer presents the clinician with a difficult task with respect to hormone replacement therapy (HRT). All of the published meta-analyses have been consistent in showing that there is a slightly increased risk of developing breast cancer in those patients using postmenopausal estrogens for greater than 10 years. However, there have been no published placebo-controlled clinical trials on the effects of HRT in women with a history of breast cancer. Quality of life must be balanced against the theoretical risk of tumor promotion. Assessment of osteoporotic and cardiac risk factors (i.e., smoking, hypertension, family history, hyperlipidemia) should influence the decision. Valid alternatives to estrogen replacement include low-dose progesterones such as Bellergal or vitamin E for hot flashes, and biphosphonates, calcium, anabolic steroids, and calcitonin for osteoporosis.
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PMID:The management of menopausal symptoms in women with breast cancer. 761 Jun 43

This overview of the potential mechanisms of chemopreventive activity will provide the conceptual groundwork for chemopreventive drug discovery, leading to structure-activity and mechanistic studies that identify and evaluate new agents. Possible mechanisms of chemopreventive activity with examples of promising agents include carcinogen blocking activities such as inhibition of carcinogen uptake (calcium), inhibition of formation or activation of carcinogen (arylalkyl isothiocyanates, DHEA, NSAIDs, polyphenols), deactivation or detoxification of carcinogen (oltipraz, other GSH-enhancing agents), preventing carcinogen binding to DNA (oltipraz, polyphenols), and enhancing the level or fidelity of DNA repair (NAC, protease inhibitors). Chemopreventive antioxidant activities include scavenging reactive electrophiles (GSH-enhancing agents), scavenging oxygen radicals (polyphenols, vitamin E), and inhibiting arachidonic acid metabolism (glycyrrhetinic acid, NAC, NSAIDs, polyphenols, tamoxifen). Antiproliferation/antiprogression activities include modulation of signal transduction (glycyrrhetinic acid, NSAIDs, polyphenols, retinoids, tamoxifen), modulation of hormonal and growth factor activity (NSAIDs, retinoids, tamoxifen), inhibition of aberrant oncogene activity (genistein, NSAIDs, monoterpenes), inhibition of polyamine metabolism (DFMO, retinoids, tamoxifen), induction of terminal differentiation (calcium, retinoids, vitamin D3), restoration of immune response (NSAIDs, selenium, vitamin E), enhancing intercellular communication (carotenoids, retinoids), restoration of tumor suppressor function, induction of programmed cell death (apoptosis) (butyric acid, genistein, retinoids, tamoxifen), correction of DNA methylation imbalances (folic acid), inhibition of angiogenesis (genistein, retinoids, tamoxifen), inhibition of basement membrane degradation (protease inhibitors), and activation of antimetastasis genes. A systematic drug development program for chemopreventive agents is only possible with continuing research into mechanisms of action and thoughtful application of the mechanisms to new drug design and discovery. One approach is to construct pharmacological activity profiles for promising agents. These profiles are compared among the promising agents and with untested compounds to identify similarities. Classical structure-activity studies are used to find optimal agents (high efficacy with low toxicity) based on good lead agents. Studies evaluating tissue-specific and pharmacokinetic parameters are very important. A final approach is design of mechanism-based assays and identification of mechanism-based intermediate biomarkers for evaluation of chemopreventive efficacy.
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PMID:Mechanistic considerations in chemopreventive drug development. 761 36

The biological activities of vitamin E are related to the cellular functions and presence of sufficient tissue concentrations of this micronutrient. Most of the stored vitamin E is in the adipose tissue where it appears to be distributed equally. The breast adipose tissue has similar vitamin E concentrations as other parts of the body. The ductal systems also store vitamin E in sufficient concentrations to maintain cellular functions. The milk secreted from the ducts of the breast contains a high concentration of tocopherol. Whereas the normal breast tissue presumably utilizes vitamin E as an antioxidant, tumor tissue appears to handle vitamin E differently. Breast tumors possessing estrogen negative receptors and having poor histological differentiation have lower concentrations of vitamin E than tumors with positive estrogen receptors and well differentiated histology. Since vitamin E is considered the principal, if not sole, chain-breaking lipophilic antioxidant in plasma and tissue, its role as a potential chemopreventive agent in breast cancer should be further investigated. The combination of vitamin E with other cancer chemopreventive agents appears to be a reasonable procedure.
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PMID:Some aspects of vitamin E related to humans and breast cancer prevention. 772 56


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