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

Pretreatment of mouse skin in vivo with indomethacin prevents the stimulation of epidermal cell proliferation caused by either removal of the horny layer or by application of phorbol ester TPA. The stimulatory effect of phorbol ester "TI8" is only partially inhibited, whereas the drug indomethacin has no effect on the proliferative response to skin massage or the hyperplasiogenic reaction induced by phorbol ester 4-0-methyl-TPA. These results show that depending on the stimulus, epidermal cell proliferation and hyperplasia can proceed either via an indomethacin sensitive or via an indomethacin insensitive pathway, and that indomethacin sensitivity is neither related to the hyperplasiogenic nor the tumor-promoting efficiency of the stimulus. Although TPA and 4-0-methyl-TPA are structurally closely related phorbol esters, they have different mechanisms of mitogenic action.
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PMID:The effect of indomethacin on cell proliferation induced by chemical and mechanical means in mouse epidermis in vivo. 45 37

We evaluated assays of Tissue Polypeptide Antigen in serum and urine, as an index to the presence of cancer. In the assay, serum, which is first absorbed with human albumin-labeled sheep erythrocytes, or untreated urine (diluted with an equal volume of TPA-free serum) is incubated with antibody specific to Tissue Polypeptide Antigen and then reacted with sheep erythrocytes labeled with Tissue Polypeptide Antigen. We found an increased concentration of Tissue Polypeptide Antigen in the serum of 378 of 513 (74%) and in the urine of 49 of 77 (64%) patients with cancer, as compared with 40/112 (36%) and 7/29 (24%), respectively, for individuals with benign neoplasms. Normal individuals were defined as those with less than 0.09 unit of the antigen per milliliter of specimen. Concentrations exceeding this were found in 2/67 (3%) sera and 6/56 (11%) urines from supposedly normal persons. Tissue Polypeptide Antigen was found in above-normal concentrations in patients with cancer, regardless of neoplasm type and extension, with a higher proportion of abnormal values in patients with distal metastases.
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PMID:A preliminary evaluation of tissue polypeptide antigen in serum or urine (or both) of patients with cancer or benign neoplasms. 65 73

Within the last 10 years numerous new and typical exogenous cocarcinogens were identified chemically as well as biologically and characterized biochemically as initiation or tumor promoters. They are highly irritant diterpene esters of plant origin. Promoters of this type were recently detected also in the Euphorbiacea Croton flavens L., the multiple use of which for stimulants according to local habits was previously held responsible for the unusually high rate of esophageal cancer on Curacao. This detection confirms for the first time that in the etiology of human cancer besides solitary carcinogens (first-order carcinogenic risk factors) also cocarcinogens of the promoter type have to be considered (second-order carcinogenic risk factors). -- The active principles of the diterpene ester type are the strongest promoters known so far; they are noninitiators and nonmutagens. Of the manyfold biochemical activities of these promoters the three most actual are: the TPA molecule does not require activation by metabolic alteration, it releases very rapidly prostaglandin E2 from cellular membranes and it activates latent DNA-viral genoms.
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PMID:[Co-carcinogens or modulators of carcinogenesis. New aspects of the etiology of human tumors and of the molecular mechanisms of carcinogenesis]. 74 37

We present data from experiments designed to investigate the role of DNA interstrand cross-links induced by exposure to 8-MOP plus UVR and skin carcinogenesis. 8-MOP was administered topically to two strains of hairless mice, SKH:hairless-1 and HRS/J/An1, which were then exposed to UV light sources with emission in the range of 1) 300-400, 2) 320-400, and 3) predominantly 365 nm. We found no strain dependency for DNA cross-link production, but a marked strain-dependent difference in tumor susceptibility was noted. Only a small strain-dependent difference occurred in tumor incidence when TPA was administered after exposure to 8-MOP and 320-400 nm. These results suggest that the events concerned with tumor promotion are dependent on strain. Because the most effective tumorigenic wavelength spectrum was 300-400 nm, we investigated the possibility of interaction between lesions induced by the 300- to 320-nm wavelengths and the psoralen photoadducts. In the course of this experiment, we found that the tumorigenic effect was also dependent on the time interval between exposures to 8-MOP plus 365-nm light.
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PMID:Photosensitized reactions and carcinogenesis. 75 79

Skin tumors are produced in rats, mice, and humans by exposure to UV light. We developed a mouse embryo fibroblast line C3H/10T1/2, which can be transformed by chemical carcinogens, X-irradiation, UV radiation, and oncornavirus. When we irradiated these cells with 10, 25, 50, 100, 150, or 200 ergs/mm2 of UV light, neither transformation nor cytotoxicity was observed at the two lower doses. When the irradiated cells were cultured in medium containing 0.1 micrograms TPA/1 ml (a potent tumor promoter) starting from 0-120 hours after irradiation, a high frequency of transformation was always produced. When the cells were initiated with subeffective concentrations of 0.1 micrograms MCA/ml followed by UV radiation at different intervals, no transformation occurred; however, these initiated cells were transformed after TPA treatment. When we treated the cells with multiple exposures to UV light, no transformation occurred then nor when the cells were treated with TPA followed by UV irradiation at different intervals. Thus UV in our system acts as a pure initiator in the two-stage process of oncogenic transformation.
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PMID:Ultraviolet light in the oncogenic transformation of cultured C3H/10T1/2 mouse embryo cells. 75 81

Diaplacental initiation with the carcinogens DMBA or urethane followed by topical treatment of mice of F-1 generation with the tumor promotor TPA led to the formation of benign and malignant tumors on the back skin and also in various internal organs. (This system constitutes a modified 2-stage experiment based on the early schemes of Berenblum and Mottram.) Application of either the carcinogens or the tumor promoter alone did not lead to the formation of tumors within one year. The highest skin papilloma yield was obtained with mice initiated with DMBA from the 16--19th day of fetal life. The highest total tumor yield was obtained after initiation from day 18--21st. The combination urethane/TPA also promoted the formation of tumors of the skin and other organs. The significance of this modified prenatal-postnatal initiation/promotion scheme in human pathology is discussed.
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PMID:Diaplacental carcinogenesis: initiation with the carcinogens dimethylbenzanthracene (DMBA) and urethane during fetal life and postnatal promotion with the phorbol ester TPA in a modified 2-stage Berenblum/Mottram experiment. 82 81

Mouse epidermis can be induced to undergo sequential waves of proliferation and keratinization by treatment with the tumor promoter TPA (12-O-tetradecanoyl-phorbol-13-acetate). This model system offers a unique possibility to study the synthesis of differentiation-specific proteins in the epidermis. During these studies it could be shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis that several previously undetected proteins appear in the epidermis during the phase of differentiation. These have been fractionated according to solubility in 1 M phosphate buffer, pH 7.0, or 0.1 M sodium citrate buffer, pH 2.6. Of the soluble proteins, a band of approximate molecular weight 13,500 (band 1) appears early during the differentiative phase (24 hr after treatment with TPA). Another previously undetected protein of approximate molecular weight 27,000 (band 2) appears in the soluble fraction after 48 hr, at a time when many of the typical manifestations of increased keratinization can be observed. Both of these soluble proteins, although not detectable in normal adult mouse epidermis, are shown to be present in newborn mouse epidermis, which demonstrates histologically a well-developed layer of keratinizing and cornified cells. In addition, by separation of neonatal and TPA-treated adult mouse epidermis into "basal" and "cornified" layers, it could be demonstrated that these two proteins are localized exclusively in the upper layer of the epidermis.
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PMID:The synthesis of specific proteins in adult mouse epidermis during phases of proliferation and differentiation induced by the tumor promoter TPA, and in basal and differentiating layers of neonatal mouse epidermis. 95 Apr 89

Constitutional loss or inactivation of one copy of a tumor-suppressor gene, as exemplified by hereditary retinoblastoma, increases the propensity for malignancies by reducing the number of events necessary for the complete loss of the negative regulatory function. We developed a selectable mutation assay employing a human lymphoblastoid cell line (LCL) derived from a heterozygous carrier of 2,8-dihydroxyadenine urolithiasis, adenine phosphoribosyltransferase (APRT) deficiency, for dissecting the second step in loss-of-function mutations and for determining the potential of physical and chemical agents for producing such mutations. The mode of mutational events arising in the wild-type allele of the functionally heterozygous APRT gene resembled that reported for tumor-suppressor genes in malignancies in that mitotic non-disjunctions or recombinations as well as deletions prevailed. Ultraviolet light (UV) was much less efficient in inducing these types of mutations than ionizing radiation. A group of autosomal recessive cancer-prone diseases, including xeroderma pigmentosum (XP), has been characterized as being more susceptible to genomic insults, owing to some defects in DNA processing, such as replication, repair, or recombination. This increased genomic instability may accelerate the gain-of-function mutation at a proto-oncogene and/or the loss-of-function mutation at a tumor-suppressor gene. XP complementation group A (XP-A) LCLs were extremely sensitive to UV-mutagenesis at the hypoxanthine phosphoribosyltransferase (HPRT) locus even at equicytotoxic doses. Some unique mechanism may operate in UV-mutagenesis in XP-A. We have succeeded for the first time in rendering XP-A cells tumorigenic in athymic mice by applying multiple exposures to UV and subsequent treatment with TPA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Molecular bases for hereditary cancer-prone diseases. 129 55

Flow cytometry revealed the dynamic nature of polyclonal whole serum naturally occurring IgG and IgM antibody binding to the syngeneic murine T cell lymphomas SL2-5, L5178Y-F9 and the in vitro selected high natural antibody binding variant L5178Y-F9 TPA/NAb+3. This was particularly evident at physiological conditions where the temperature was 37 degrees C and the concentration of reactive serum natural antibodies (NAb) was high. Lower binding was observed at 37 versus 4 degrees C, or after raising the temperature from 4 to 37 degrees C, a procedure which was associated with an augmented loss of 125I-surface-labelled material from cells incubated in NAb compared to cells exposed to growth media. Even at 4 degrees C, NAb binding exhibited biphasic kinetics suggesting a loss of surface-bound NAb and a subsequent cycle of NAb uptake. The increased intravenous liver metastasis potential of the high NAb binding L5178Y-F9 TPA/NAb+3 corresponded with its higher total loss of 125I-surface-labelled material when incubated in NAb at 37 degrees C, and with its extensive loss of NAb binding when the temperature was raised from 4 to 37 degrees C. These observations are consistent with the idea that molecules released from the cell may contribute to the higher metastasis. This thinking was supported by the increased metastasis of tumor cells injected intravenously, either with serum in which they had been preincubated at 37 degrees C or into mice treated with supernatants from tumor cells incubated in NAb.
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PMID:Polyclonal natural antitumor antibody binding dynamics: preferential release of surface membrane molecules and increased metastasis. 129 33

The relatively small concentrations required for in vivo bioactivity of diterpene ester skin irritants and promoters (approximately 10 nmol per animal; approximately 10 nM in cell cultures) has discouraged studies of EPR spectra of bioactive, TPA-analogous, spin-labeled phorbol-12,13-diesters [(n,m)PA] bound to their membrane receptors, protein kinases C (PKC). To meet the requirements of present EPR spectrometers, particulate fraction from mouse brain containing at least 25 x 10(-12) mol of receptors/mg protein (PKC species) were employed together with certain (n,m)PA selected to give an optimal ratio of specific to non-specific binding. For selection and optimization of experimental conditions, a theoretical model was developed that considers all characteristic parameters of the system. By fitting the model calculations to the experimental data of competitive agonist displacement from the particulate fraction of tritium-labeled TPA, the dissociation constants Kd for four selected (n,m)PA used as antagonists were determined. Optimal experimental conditions are met by (5,6)PA and by (5,8)PA, in that for both compounds the relative amount of displaced (n,m)PA is in accordance with the predictions derived from the model. Moreover, the model turned out also to be reliable for samples containing either small or large amounts of membranes. To obtain an EPR spectrum of an agonist bound to brain particulate fraction, the (5,6)PA was used. It shows a broad EPR spectrum typical for an immobilized molecule. The spectrum changes if an excess of TPA is added to the system; the slight differences in shape are due to displacement of (5,6)PA from specific receptor sites by non-labeled TPA and show up as a decreased central peak amplitude. This is the first time that the agonist/receptor interaction of a diterpene ester type irritant and tumor promoter has been demonstrated by direct spectroscopic measurement.
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PMID:Spin-labeled phorbol esters and their interactions with cellular membranes--V. Electron paramagnetic resonance of spin-labeled phorbol-12,13-diesters bound to their receptors in mouse brain particulate fraction. 131 Sep 6


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