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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ionizing radiation is a carcinogen that is known to induce malignant transformation of C3H/10T1/2 fibroblasts in vitro. Radiation is also known to induce c-myc expression and protease inhibitors that suppress radiation transformation reduce myc and fos gene expression. The antiproliferative protein kinase inhibitor 2-aminopurine has been shown to selectively inhibit serum induced c-fos and c-myc expression in human hemopoetic cells. The myc and fos oncogenes are thought to play a role in the regulation of cell proliferation and may be involved in early stages of carcinogenesis. We determined the ability of 2-aminopurine to affect x-ray-induced transformation in C3H/10T1/2 cells in vitro and its effect on myc and fos gene expression in these cells. Treatment with 2-aminopurine (5 x 10(-4) M) resulted in a 50-100% reduction in transformation yield when C3H/10T1/2 cells were irradiated with 6 Gy of x-irradiation. The 2-aminopurine had to be present during the post-confluent stage of cell growth in order to exert its inhibitory effect. Treatment of cells with 2-aminopurine significantly reduced the level of myc gene expression; the inhibitory effect of 2-aminopurine on fos gene expression in these cells was not statistically significant.
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PMID:Inhibition of x-ray induced transformation and effect on myc and fos gene expression by the nucleotide analog, 2-aminopurine. 779 90

Current basic research on tumorigenesis suggests that the accumulation of multiple genetic defects underlies the progression of initiated cells toward malignancy. Molecular abnormalities associated with primary brain tumors include a wide variety of changes in tumor-suppressor genes, proto-oncogenes and growth factors. A well-known tumor-suppressor gene, p53 gene, is located on the short arm (p) of chromosome 17 and consists of 11 exons transcribed into a 2.2-2.5 kb messenger (m) RNA that encode for a 53 kDa protein. Its alterations are associated with carcinogenesis of astrocytic tumors. Recent evidence suggests also that the p53 protein may function through promoting the expression of the recently discovered gene, WAF1/Cipl. Loss of chromosome 10 was frequently observed in glioblastoma. Southern blot analysis of glioblastomas revealed that 72% have the chromosome 10 loss and that 38% had amplification of the epidermal growth factor receptor (EGFR) gene. Autocrine stimulation of cell growth requires the presence of both growth factors and their receptors. Other genetic alterations in gliomas include elevated expression of the c-myc, Ha-ras, and c-fos oncogenes with a trend to increase in higher malignant grades.
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PMID:Molecular changes involved in the carcinogenesis of brain tumors. 788 30

Antioxidant and antipromotional effects of the soybean isoflavone genistein have been studied in HL-60 cells and the mouse skin tumorigenesis model. Effects of structure-related flavone/isoflavones on hydrogen peroxide (H2O2) production by 12-O-tetradecanoylphorbol-13-acetate (TPA)-activated HL-60 cells and superoxide anion (O2-) generation by xanthine/xanthine oxidase were compared. Of tested isoflavones, genistein is the most potent inhibitor among TPA-induced H2O2 formation by (dimethyl sulfoxide) DMSO-differentiated HL-60 cells, daidzein is second, and apigenin and biochanin A show little effect. In contrast, genistein, apigenin, and prunectin are equally potent in inhibiting O2- generation by xanthine/xanthine oxidase, with daidzein showing a moderate inhibitory effect and biochanin A exhibiting no effect. These results suggest that the antioxidant properties of isoflavones are structurally related and the hydroxy group at Position 4' is crucial in both systems. Dietary administration of 250 ppm genistein for 30 days significantly enhances the activities of antioxidant enzymes in the skin and small intestine of mice. Further studies show that genistein significantly inhibits TPA-induced proto-oncogene expression (c-fos) in mouse skin in a dose-dependent manner. In a two-stage skin carcinogenesis study, low levels of genistein (1 and 5 mumol) significantly prolong tumor latency and decrease tumor multiplicity by approximately 50%. We conclude that genistein's antioxidant properties and antiproliferative effects may be responsible for its anticarcinogenic effect. Its high content in soybeans and relatively high bioavailability favor genistein as a promising candidate for the prevention of human cancers.
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PMID:Antioxidant and antipromotional effects of the soybean isoflavone genistein. 789 86

The SV40 T-antigen-transfected human thyroid cell line SGHTL-34 was used to investigate the effect of thyrotropin (TSH), insulin-like growth factor-1 (IGF-1) and epidermal growth factor (EGF) on c-fos and c-erbB/EGF receptor (EGF-R) mRNA expression and their role in human thyroid cell proliferation. EGF caused a transient 8- and 4-fold increase in c-fos mRNA level after 30 min in serum/hormone-deprived and in logarithmically growing cells, respectively. EGF was only mitogenic in the presence of serum, as measured by 3H-thymidine incorporation and cell counting. TSH had no detectable effect on c-fos mRNA expression and no mitogenic effect on the SGHTL-34 cells. IGF-1 showed no effect alone or in combination with EGF or TSH on either proliferation or c-fos mRNA expression. Our data suggest that increased c-fos mRNA levels are part of the mitogenic pathway, but are insufficient to engender a mitogenic response. SGHTL-34 cells produced high levels of transforming growth factor-alpha (TGF-alpha) and c-erbB/EGF-R mRNA, also seen in thyroid papillary carcinomas. The TGF-alpha protein was detected in conditioned medium from the SGHTL-34 cells, indicating that TGF-alpha may function as an autocrine growth factor. Our data show that the c-erbB/EGF-R mRNA level is regulated by growth factors and hormones in the SGHTL-34 cell line. The SGHTL-34 cells may therefore represent a useful model system for studying the role of TGF-alpha and EGF-R in thyroid carcinogenesis.
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PMID:Growth requirements and oncogene expression in the human thyroid cell line SGHTL-34. 790 43

Previous studies have indicated that excision repair genes, such as ERCC1, or early response genes, such as c-fos, may play a significant role in regulating cellular responses to cisplatin (CDDP) by mediating DNA synthesis and repair pathways. This present study aimed to determine whether altered gene expression mediated CDDP resistance expressed in two human tumour sublines following their in vitro exposure to fractionated X-irradiation, not to the drug itself. These sublines, designated SuSa/DXR10 and SKOV-3/DXR10, established respectively from a testicular teratoma cell line (SuSa) or an ovarian carcinoma cell line (SKOV-3), expressed stable 3.1- and 2-fold levels of CDDP resistance, as judged by clonogenic assay. Both sublines expressed c-fos, c-myc and thymidylate synthase (TS) RNA constitutively, but at comparable levels to their parental counterparts. Whilst the ovarian carcinoma cells inherently expressed markedly higher levels (30- to 50-fold) of the excision repair gene ERCC1 than the teratoma cells, only the teratoma DXR10 subline showed an increased level of expression of ERCC1 mRNA relative to their parental cells. Expression of the ERCC3/XPB gene encoding a repair helicase, however, was similar in all the lines tested. The results suggest that CDDP resistance may be mediated by different mechanisms in these DXR10 sublines from those previously identified in drug-selected CDDP-resistant human ovarian A2780/DDP cells.
Carcinogenesis 1994 Sep
PMID:Gene expression in X-irradiated human tumour cell lines expressing cisplatin resistance and altered DNA repair capacity. 792 2

The neoplastic transformation of cultured rat liver epithelial cells by various means has consistently been associated with the development of resistance to the mito-inhibitory effect of transforming growth factor beta (TGF-beta), suggesting that such phenotype plays a mechanistic role during the transformation of these cells. We have studied the induction of the "TGF-beta-resistant" phenotype in a clonal strain of early passage WB-F344 normal cultured rat liver epithelial cells, the proliferation of which was markedly inhibited by TGF-beta. The control WB cells in continuous culture slowly developed TGF-beta resistance. However, when the same cells were exposed to step-wise increases of TGF-beta concentration in their culture medium, the development of TGF-beta resistance was accelerated. Cells which had been grown in medium containing 1 ng/ml TGF-beta developed colony-forming capacity in soft agar containing epidermal growth factor. Cells which were grown in media containing 5 and 10 ng/ml TGF-beta demonstrated a low level of colony-forming efficiency in soft agar medium without added epidermal growth factor and tumorigenicity in isogeneic rats. These TGF-beta-resistant cells also exhibited progressively increasing levels of expression of the c-fos and and myc mRNA, and increased resistance to the cytotoxicity of Adriamycin and melphalan. The latter phenomenon was accompanied by an increase in the mdr-1 mRNA expression, cellular glutathione level, and glutathione S-transferase activity. The results suggest that chronic exposure to high concentration of TGF-beta promotes the spontaneous neoplastic transformation of cultured rat liver epithelial cells, and that this process may represent one of the mechanisms of cellular adaptation for induction of the multidrug-resistant phenotype during the carcinogenesis of epithelial cells.
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PMID:Transforming growth factor beta 1 promotes spontaneous transformation of cultured rat liver epithelial cells. 795 58

Expression of c-jun protein (c-Jun) was observed in normally proliferating JB6 cells but not in confluent cells. Reduction of the serum concentration from 5% to 2% in the cell culture medium caused JB6 cells to enter a quiescent non-proliferating state and down-regulated the expression of c-Jun. Treatment of quiescent JB6 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10 ng/ml) for 24 h markedly stimulated the formation of c-Jun and caused morphological changes. Treatment of JB6 cells with TPA for 48 h resulted in transformed foci with mixed cell populations. Although some cells in these foci expressed high levels of c-Jun, many other cells did not. The increased expression of c-Jun and morphological changes observed at 24 h after treatment of JB6 cells with TPA (10 ng/ml) was inhibited by curcumin (10 nmol/ml). Treatment of JB6 cells with 2.5, 5 or 10 nmol curcumin/ml inhibited the formation of TPA-induced anchorage-independent colonies that grow in soft agar by 31%, 43% and 77%, respectively. Although inhibition of cell proliferation was not observed with 2.5 nmol curcumin/ml, higher concentrations did inhibit cell proliferation. Topical application of 5 nmol TPA to the backs of CD-1 mice once a day for 5 days caused epidermal hyperplasia and the levels of c-Jun were increased in the suprabasal layer of the epidermis and in the muscle layer of the dermis. This treatment also increased c-fos protein (c-Fos) expression in the muscle layer, but there was little or no increase in the expression of c-Fos in the basal or suprabasal layer of the epidermis. Topical application of 10 mumol curcumin together with 5 nmol TPA once a day for 5 days strongly inhibited TPA-induced epidermal hyperplasia and c-Jun and c-Fos expression. A single application of 180 mJ/cm2 of ultraviolet B light (UVB) to the backs of SKH-1 mice caused epidermal hyperplasia and expression of c-Fos and c-Jun in the muscle layer of the dermis and of c-Fos in the suprabasal layer of the epidermis. Maximum effects were observed at 6 days after UVB exposure. Application of 10 mumol curcumin to mouse skin twice a day for 5 days immediately after UVB exposure had only a small/variable inhibitory effect on UVB-induced increases in the expression of c-Fos and c-Jun and on epidermal hyperplasia.(ABSTRACT TRUNCATED AT 400 WORDS)
Carcinogenesis 1994 Oct
PMID:Effect of curcumin on 12-O-tetradecanoylphorbol-13-acetate- and ultraviolet B light-induced expression of c-Jun and c-Fos in JB6 cells and in mouse epidermis. 795 78

To analyze the role of cell proliferation in phenolic compound-induced rat forestomach carcinogenesis, early forestomach histopathological changes as well as oncogene expression and reversibility of early forestomach lesions were examined in F344 male rats. For the analysis of early lesions, five animals each were treated with butylated hydroxyanisole (BHA), caffeic acid, sesamol, or 4-methoxyphenol in the diet, each at a dose of 2%, and killed for histopathological examination after 12 hr, 1, 3, or 7 days. For oncogene analysis, three animals each were treated with BHA for 15, 30 min, 1, 3, 6, or 24 hr and then sacrificed. In the reversibility study, groups of animals were treated with BHA, caffeic acid, sesamol or 4-methoxyphenol for 24 weeks, and basal diet alone was supplied for a further 24-week period. Animals were killed at 24 and 48 weeks and forestomach epithelium was examined histopathologically. DNA synthesis increased within 12 hr to 3 days after commencement of chemical treatment in all cases. Toxicity and cell proliferation became evident subsequent to increase in DNA synthesis in each case. Elevated expression of c-fos and c-myc oncogenes was demonstrated 15 min after beginning treatment with BHA. In the reversibility study, although most of the proliferative lesions induced by these antioxidants regressed after cessation of chemical treatment, some dysplastic lesions were still observed at week 48. The results indicate that these phenolic compounds act primarily as mitogens in rat forestomach epithelium, with regeneration due to toxicity further enhancing cell proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cell proliferation and forestomach carcinogenesis. 801 96

The induction of c-fos and c-myc expression in the pyloric mucosa of 8-week-old F344 male rats after oral administration of the glandular stomach carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), or the tumor-promoter, taurocholate, was examined by Northern blotting. MNNG at doses of 5-50 mg/kg body weight dose-dependently induced transient increase of up to 30-fold c-fos expression with a maximum after 30 min, and of 8-fold c-myc expression with a maximum after 3 h. It also induced up to 3-fold increase in S-phase cells in the proliferation zone of the pyloric mucosa after 16 h. Similar effects were observed with sodium taurocholate at doses of 200-800 mg/kg body weight. These results suggest that c-fos and c-myc oncogenes play a role in stomach carcinogenesis.
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PMID:Induction of c-fos and c-myc oncogene expression in the pyloric mucosa of rat stomach by N-methyl-N'-nitro-N-nitrosoguanidine and taurocholate. 806 19

We have shown previously that overexpression of c-Ha-ras, v-mos or c-fos increases the spontaneous level of chromosomal aberrations and gene mutations in NIH 3T3 cells, and that reduction of the Fos protein level inhibits aberration induction by c-Ha-ras and v-mos and also by irradiation with ultraviolet light (van den Berg et al., Mol. Carcinogenesis, 4, 460-466). In order to examine whether fos is also involved in DNA recombination, thymidine kinase (tk) deficient human osteosarcoma cells containing two versions of the herpes simplex virus tk gene inactivated by base insertion were either transiently or stably transfected with various fos expression plasmids. The frequency of tk+ revertants was significantly enhanced both upon transient transfection with RSV-promoter-fos gene constructs and by stimulation of Fos synthesis in stably transfected cells harbouring an inducible metallothionein promoter-fos construct. No such increases were observed in cells transfected with plasmids containing a truncated version of c-fos. The data indicate that c-fos is involved in generating various types of genetic changes including homologous recombination; a role of c-fos in genetic instability may contribute to its action in tumor promotion and progression.
Carcinogenesis 1993 May
PMID:Overexpression of c-fos increases recombination frequency in human osteosarcoma cells. 809 16


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