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

The growth behavior of the two human colon tumor cell lines (SW 480, primary and SW 620, metastatic), originating from the same patient, was studied in six different serum-free media (SFM) [GF3, Chee's essential medium plus insulin, transferrin and selenium; GF3F, GF3 plus fetuin; GF4, GF3 plus linoleic acid-BSA; GF5, GF4 plus fetuin; GF5E, GF5 plus EGF; GF5T, GF5 plus triiodothyronine]. SW 480 grew in all of the SFM. In contrast, SW 620 grew only in four SFM. The cells did not grow in GF3 and GF4. When grown in SFM, SW 480 attached much more firmly to the dishes than SW 620 as determined by the time required to detach the cells with trypsin-EDTA (SW 480, greater than 20 min and SW 620, less than 5 min). It was speculated that SW 480 cells excrete proteins in SFM which influence attachment and growth of the cells. Growth behavior of SW 480 cells which did not grow in GF3, was studied using GF3 medium and SW 480 substratum dishes. SW 620 cells readily attached to the SW 480 substratum dishes and grew. Furthermore, when SW 620 cells were grown on substratum prepared from serum-supplemented medium incubated in the absence of cells (serum substratum), the cell growth was comparable to the cell growth on SW 480 substratum in GF3. Substratum from SW 480 cells and the serum substratum were compared for their components using SDS-PAGE system. The SW 480 substratum contains many more components than serum substratum. A protein band at 60 kD appears to be common in both SW 480 and serum substrata.
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PMID:Proteins excreted by primary human colon carcinoma cells (SW 480) promote spreading and growth of metastatic human colon carcinoma cells (SW 620) in serum-free medium. 262 Feb 93

The association between the concentration of selenium in serum and the risk of degenerative processes of the cardiovascular apparatus or of neoplastic disease remains still uncertain. An inaccurate selection of the study populations, and above all the lack of age, sex and area of residence specific reference values could have contributed to create confusion on the biological relevance of selenium in human diseases. In our present work the serum selenium levels for the Italian population have been studied, adopting standardized methods. The study population (4201 adult subjects and 1217 children) was derived from samples of populations previously enrolled in epidemiological preventive programs. The mean observed values for the various adult populations examined varied between 87 and 93 micrograms/l and resulted approximately 5 micrograms/l higher than the mean observed values in ten European countries. The mean observed values for the paediatric population (less than 15 years of age) were slightly lower (78-83 micrograms/l). A decreasing trend of the values with age, above 60 years, especially in males, has been observed. No significant difference has been observed for sex and geographic area of residence. A preliminary study of the variations of the serum selenium levels during certain diseases has shown a sharp reduction in children with phenylketonuria and undergoing dietary restrictions, in subject with active systemic Lupus erythematosus, and in certain neoplasias.
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PMID:Age and sex specific reference serum selenium levels estimated for the Italian population. 262 51

We have previously reported that the potent tumor-promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA) and a factor from fetal calf serum (FCS) markedly enhance the transformation of mouse C3H 10T1/2 and Rat 6 fibroblasts, when added to cultures following transfection with plasmid pT24 DNA that contains an activated c-Ha-ras oncogene. In the present study, we examined possible enhancing or inhibiting effects of various chemicals on the transformation of Rat 6 fibroblasts by T24 DNA when tested in the presence of calf serum, calf serum plus TPA or FCS. We found that, like TPA, the chemicals mezerein, 1-oleoyl-2-acetylglycerol, and phospholipase C increased the yield of T24-induced foci, thus further implicating protein kinase C as a critical constituent in this process. Low concentrations (10(-6)-10(-7)M) of retinoic acid (both trans and 13-cis) also stimulated cell transformation. Several compounds inhibited T24-induced transformation. These included nontoxic concentrations of the calcium ionophore A23187, indomethacin, and epsilon-amino-n-caproic acid. Compounds that failed to exert a significant reproducible effect included vasopressin, vitamin D3, selenium, antipain, Bowman-Birk inhibitor, vitamin B12, epidermal growth factor, platelet-derived growth factor, insulin, and transferrin. These findings suggest that this simple in vitro system might be useful for detecting enhancers and inhibitors of ras oncogene-induced cell transformation and also elucidating their mechanisms of action.
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PMID:Effects of various chemical agents on the transformation of rat fibroblasts by an activated c-Ha-ras oncogene. 266 19

Findings from animal tumor models and epidemiologic investigations of humans have identified selenium as a possible anticarcinogenic nutrient. Recent evidence, however, indicates that under some circumstances high levels of selenium can actually enhance experimental tumorigenesis.
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PMID:Possible enhancement of carcinogenesis by selenium in an animal tumor model. 267 17

Selenium is an essential trace element in humans and animals. Its only established function in humans is the antioxidant activity of glutathione peroxidase, a selenoenzyme. Severe prolonged deficiency may cause a fatal cardiomyopathy. Iatrogenic causes of selenium deficiency include parenteral and enteral nutrition. Low plasma selenium is also found in malabsorption, cystic fibrosis, rheumatoid arthritis, neoplasia, and other varied clinical disorders. Death has resulted from a single massive ingestion of selenium, while chronic excessive intake causes skin, nail, and hair pathology. Extreme geographical variation in population blood and urine selenium levels and a marked age-specific variation in population reference intervals are important factors in understanding selenium nutrition. Nutritional requirements, biological availability, and metabolism are discussed in relation to geographical, age, and method variability. Sampling, processing procedures, and methods for selenium quantitation are reviewed. Selenium content in different biological matrices and reference values for pediatric, adult, and obstetric populations are provided.
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PMID:Selenium: clinical significance and analytical concepts. 269 Aug 56

The influence of selenium on cis-diamminedichloroplatinum(II) (c-DDP) nephrotoxicity in mice and rats was assessed, using single doses of both compounds. Sodium selenite, 2 mg of selenium per kg, given 1 h before c-DDP, greatly reduced blood urea nitrogen and creatinine levels and morphological kidney damage in both BALB/c mice and Wistar rats, while administration 1 h after c-DDP did not. Liver toxicity of selenium was evaluated by measuring serum glutamic pyruvate transaminase and serum glutamic oxalate transaminase and by routine histology. No liver damage was observed in animals treated with sodium selenite, 2 mg of selenium per kg, and physiological saline or c-DDP. Pretreatment with sodium selenite did not reduce the antitumor activity of c-DDP against MPC 11 plasmacytoma or Prima breast tumor in BALB/c mice. The present results indicate that sodium selenite may provide protection against c-DDP nephrotoxicity, when it is given before c-DDP. Moreover, selenium has an antineoplastic activity against several tumors. The combination of these qualities may open new perspectives in cancer chemotherapy.
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PMID:Selenium-induced protection against cis-diamminedichloroplatinum(II) nephrotoxicity in mice and rats. 272 Jun 62

The radiation response of drug-resistant variants of the human tumor breast cancer cell line MCF-7 has been investigated. Two sublines, one resistant to adriamycin (ADRR) and the other to melphalan (MLNR), have been selected by exposure to stepwise increasing concentrations of the respective drugs. ADRR cells are 200-fold resistant to adriamycin and cross-resistant to a number of other drugs and are characterized by the presence of elevated levels of selenium-dependent glutathione peroxidase and glutathione-S-transferase. MLNR cells are fourfold resistant to melphalan and cross-resistant to some other drugs. The only mechanism of drug resistance established for MLNR cells to date is an enhancement of DNA excision repair processes. While the spectrum of drug resistance and the underlying mechanisms differ for the two sublines, their response to radiation is qualitatively similar. Radiation survival curves for ADRR and MLNR cells differ from that for wild-type cells in a complex manner with, for the linear-quadratic model, a decrease in the size of alpha and an increase in the size of beta. There is a concomitant decrease in the size of the alpha/beta ratio which is greater for ADRR cells than for MLNR cells. Analysis of results using the multitarget model gave values of D0 of 1.48, 1.43, and 1.67 Gy for MCF-7 cells are not a consequence of cell kinetic differences between these sublines. Results of split-dose experiments indicated that for both drug-resistant sublines the extent of sublethal damage repair reflected the width of the shoulder on the single-dose survival curve. For MCF-7 cells in the stationary phase of growth, the drug-resistant sublines did not show cross-resistance to radiation; however, delayed subculture following irradiation of stationary-phase cultures increased survival to a greater extent for ADRR and MLNR cells than for wild-type cells.
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PMID:Radiation response of drug-resistant variants of a human breast cancer cell line. 272 77

There is evidence that selenium and zinc are involved in malignant neoplasia. The exact role of these trace elements, however, is not completely understood. For this reason, we studied circulating levels of selenium and zinc in relation to food intake and nutritional status in 14 patients with head and neck cancer. Six patients without cancer served as controls. The patients with cancer were in different stages of disease. They were untreated or in an initial phase of oncologic treatment. Five of these patients were severely cachectic according to weight loss and nutritional status, which included body mass index, anthropometric values, and serum albumin level. These patients also demonstrated decreased circulating levels of selenium and zinc. Plasma glutathione peroxidase (selenium-dependent enzyme) activity, however, was not significantly different when the cachectic patients with cancer were compared with controls. We found that the plasma selenium level was positively correlated to both short-term and long-term selenium intake when all 20 patients were accounted for. However, no significant correlation could be shown between plasma selenium and serum albumin levels. Although only one patient demonstrated a plasma value below the reference value, serum zinc was positively correlated to the serum albumin level. We conclude that plasma selenium concentrations are essentially related to food intake but not necessarily to weight loss. Low circulating levels of zinc are, rather, associated with the catabolic state of the patient with cancer.
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PMID:Circulating levels of selenium and zinc in relation to nutritional status in patients with head and neck cancer. 276 24

The objective of this study was to determine whether DNA synthesis induced in the livers of female rats treated with ethinyl estradiol (EE) was due to direct effects of this synthetic estrogen on hepatocytes. Hepatocytes, obtained by collagenase perfusion from female Lewis rats, were cultured in serum-free medium containing low or no phenol red and supplemented with insulin, transferrin, and selenium. When present at 10-15 microM for the initial 30 h of culture, EE caused a subsequent 2-2.7-fold increase in hepatocyte DNA synthesis. Pretreatment of the hepatocytes with EE during the first 30 h of culture caused an EE concentration-dependent enhancement of their subsequent DNA synthetic response to epidermal growth factor (EGF). Pretreatment with EE shifted the EGF dose-response curve, causing a dramatic enhancement of the response to EGF beginning at 2 ng EGF/ml. The response to a saturating (25 ng/ml) dose of EGF was also greatly enhanced. Determination of the effect of EE on hepatocyte surface EGF receptors revealed that the increased responsiveness of DNA synthesis to EGF was accompanied by a twofold increase in EGF receptor number per cell. These results indicate that EE has direct, growth-related effects on hepatocytes which may contribute to liver growth induced in vivo by this tumor promoter.
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PMID:Effects of the liver tumor promoter ethinyl estradiol on epidermal growth factor-induced DNA synthesis and epidermal growth factor receptor levels in cultured rat hepatocytes. 278 53

Serum selenium (Se) levels were measured before, during and after high-dose induction chemotherapy in 70 patients with acute non-lymphocytic leukemia (ANLL). Pre-treatment serum Se levels were lower in patients than in controls (0.082 +/- 0.033 micrograms/ml versus 0.097 +/- 0.035 micrograms/ml, P less than 0.01). Pretreatment serum Se correlated inversely with the absolute peripheral blast cell count (R = -0.62, P less than 0.001) and other measurements of the tumor burden. Seven days after the initiation of chemotherapy, serum Se increased significantly in proportion to the initial tumor burden (P less than 0.01). Thereafter, serum Se levels remained essentially normal in patients entering a complete remission while decreasing gradually in failures. In conclusion, these data do not lend support to the hypothesis that a low selenium status enhances the risk of developing ANLL, but indicate that serum Se levels in patients with acute leukemia are mostly dependent on tumor activity.
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PMID:Relationship of serum selenium levels to tumor activity in acute non-lymphocytic leukemia. 280 30


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