Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epithelial cell loss was induced in the descending colon of the rat by temporary ischaemia to investigate whether this would lead to an increase in crypt cell proliferation. Shortly after the temporary ischaemia the number of cells per crypt was markedly reduced, and it was shown that the cell loss occurred mainly from the non-proliferating upper half of the crypt. The number of cells per crypt reached control values again after 24-48 h. There was a marked increase in proliferative activity, as reflected by the labelling index after 3HTdR and by the mitotic index, with peak values at 16 and 24 h after ischaemia. After 48 h the proliferative indices were normal again. The increase in crypt cell proliferation was characterized by an increase in the labelling index as well as in the mitotic index per crypt cell position. No enlargement of the proliferative cell compartment in the crypt was observed. It is most likely then that the increase in crypt cell proliferation was brought about by a shortening of the cell cycle, since the growth fraction in the lower half of the crypt approaches 1.0. The possible implications of the present data for the control of colonic cell proliferation and colonic carcinogenesis are discussed.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979
PMID:Epithelial cell kinetics in the descending colon of the rat. I. The effect of ischaemia-induced epithelial cell loss. 4 96

Plasmids containing the luciferase gene from the firefly (Photinus pyralis) fused to the Chinese hamster metallothioneine I promoter (ChMTI) were microinjected into the pronuclei of medaka (Oryzias latipes) eggs, which were then artificially inseminated. Evidence of integration into the genome was gained from observation of germ-line transmission in a mendelian fashion from the F1 to the F2 generation. However, gene expression (light emission) could not be demonstrated in the established transgenic line. In a separate program, transient expression of gene constructs containing the luciferase gene fused to various promoters was compared in medaka embryos. Plasmids were microinjected into pronuclei, and homogenates from 3-day-old embryos were measured for light emission using a luminometer. Among the various promoters tested (SV40, RSV-LTR, ChMTI, HSP70, and mouse albumin), the highest levels of luciferase gene expression were observed in gene constructs containing ChMTI and HSP70 gene promoters. Expression in these two constructs was significantly increased following administration of ZnSO4 or heat treatment, respectively. Plasmids were also introduced into goldfish fibroblast-like cells in vitro, in which enzymatically active luciferase was transiently expressed. Assaying for expression of luciferase provided a rapid and sensitive method for monitoring promoter activity. The potential usefulness of this fish species for cancer research is discussed based on accumulated information from carcinogenesis studies.
Mol Mar Biol Biotechnol
PMID:Firefly luciferase gene transmission and expression in transgenic medaka (Oryzias latipes). 130 22

Although oncogenes and tumor suppressor genes have been implicated in carcinogenesis and tumor progression, their relationship to the development of genomic instability has not been elucidated. To examine this role, we transfected oncogenes (polyomavirus middle [Py] and large T [MT and LT]) and adenovirus serotype 5 E1A) into two NIH 3T3-derived cell lines, EN/NIH 2-4 and EN/NIH 2-20. Both cell lines contain two stable integrants of a variant of the retrovirus vector pZipNeoSV(x)1 that has been modified by deletion of the enhancer elements from the long terminal repeats. DNA rearrangements activating the silent neomycin phosphotransferase gene (neo) present in these integrants were identified by selection of cells in the antibiotic G418. Whereas control-transfected EN/NIH cell lines do not yield G418-resistant subclones (GRSs), a fraction of oncogene-transfected EN/NIH 2-4 (8 of 19 Py MT, 5 of 17 Py LT, and 11 of 19 E1A) and 2-20 (7 of 15 Py MT) cell lines gave rise to GRSs at differing frequencies (0.33 x 10(-6) to 46 x 10(-6) for line 2-4 versus 0.11 x 10(-6) to 1.3 x 10(-6) for line 2-20) independent of cell generation time. In contrast, a distinctly smaller fraction of mutant Py MT-transfected EN/NIH cell lines (1 of 10 MT23, 1 of 10 MT1015, and 0 of 10 MT59b) resulted in GRSs. Southern analysis of DNA from selected oncogene-transfected GRSs demonstrated genomic rearrangements of neo-containing cellular DNA that varied in type (amplification and/or novel fragments) and frequency depending on the specific oncogene and EN/NIH cell line used in transfection. Furthermore, only one of the two neo-containing genomic loci present in both EN/NIH cell lines appeared to be involved in these genomic events. In addition to effects related to the genomic locus, these observations support a role for oncogenes in the development of genetic changes associated with tumor progression.
Mol Cell Biol 1992 Jan
PMID:Oncogenes result in genomic alterations that activate a transcriptionally silent, dominantly selectable reporter gene (neo). 130 88

Retrotransposition has been well documented as a significant source of mutagenesis in diverse eukaryotic organisms, including humans. Insertions of retrotransposons within or in close proximity to transcription units cause many spontaneous mutations, and have been implicated as a source of heritable genetic defects and as a cause of carcinogenesis. The mechanisms by which retrotransposon insertions produce mutant phenotypes are diverse and, in many cases, not fully understood. A model transcriptional system was utilized to test the effects of copia retrotransposon-derived sequence insertions upon gene expression in different cellular environments. The results of these experiments indicate that retrotransposon insertions within nontranslated regions of a transcription unit inhibit gene expression by at least two concurrently acting mechanisms: 1) transcriptional interference due to an active internal promoter and, 2) trans RNA hybridization interactions between transcripts containing complementary retrotransposon sequences.
Cell Mol Biol 1992 Apr
PMID:The effects of retrotransposon-derived sequence insertions on gene expression in a model system. 131 15

Chronic treatment of hamsters with estradiol for several months has previously been shown to decrease the specific content of cytochrome P450 in the kidney, a target of hormonal carcinogenesis, but not in liver. The reason for this decrease in metabolic enzyme activity is unknown and has been examined in this investigation. We now report that the decrease in specific content of renal cytochrome P450 by 73% in response to estradiol was not affected by co-treatment with tamoxifen for 1 month. The subcutaneous infusion of 250 micrograms/day estradiol for 7 days lowered renal cytochrome P450 by 71% from control values and was therefore used for further mechanistic studies. This treatment decreased renal activities of estradiol 2- or 4-hydroxylase by 77 to 80%, of 7-ethoxycoumarin-O-deethylase by 66% of control values, respectively, and completely eliminated aryl hydrocarbon hydroxylase activities, whereas liver enzymes remained unaffected. After 7 days of infusion of estradiol, fluorescent products of lipid peroxidation were more than doubled in hamster kidney but remained unchanged in liver. The possibility of enzyme destruction by binding of estradiol 2,3-quinone to metabolizing enzymes was investigated in vitro. In the presence of 2-hydroxyestradiol, cumene hydroperoxide, and microsomes, conditions known to favor the oxidation of the steroid to quinone, the binding of catechol estrogen metabolite to microsomal protein increased 60 fold over control values in the absence of cofactor. Purified rat liver cytochrome P450c also oxidized 2-hydroxyestradiol to 2,3-estradiol quinone. The rate of oxidation was linear for the first 2-3 min, but thereafter decreased with time.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1992 Mar 04
PMID:Target organ-specific inactivation of drug metabolizing enzymes in kidney of hamsters treated with estradiol. 131 25

Cervical carcinogenesis is a multistep process that appears to be initiated by infection of squamous epithelial cells in the cervix with one of a limited number of human papillomavirus (HPV) types. However, the mechanisms involved in the evolution of benign, HPV-induced lesions to malignancy have not yet been fully elucidated. Transforming growth factor-beta (TGF-beta), a multifunctional growth factor produced by cells in the skin, inhibits the proliferation of foreskin and cervical keratinocytes in vitro. We examined the effects of TGF-beta on growth and virus early-gene expression in cell lines immortalized by two HPV types associated with cervical carcinogenesis as well as the expression of TGF-beta 1 mRNA transcripts in normal and HPV-positive cells in vivo and in vitro. We found that normal and HPV-positive cells expressed similar levels of TGF-beta 1 mRNAs and exhibited similar patterns of responsiveness to three isoforms of TGF-beta in both monolayer and modified organotypic cultures. Of particular interest is our finding that the expression of the E6 and E7 early viral transforming regions of both HPV16 and HPV18 was reversibly and rapidly inhibited by TGF-beta. In one HPV16-positive cell line examined in detail, inhibition of HPV expression required protein synthesis and occurred at the level of transcription. HPV-immortalized cells selected for resistance to in vitro differentiation signals remained sensitive to TGF-beta-mediated growth inhibition. These results, showing that both growth and virus gene expression in HPV-transformed cells were responsive to TGF-beta, suggest that endogenous growth factors produced by different cell types in squamous epithelium may play a role in the progression of cervical neoplasia.
Mol Carcinog 1992
PMID:Regulation of growth and gene expression in human papillomavirus-transformed keratinocytes by transforming growth factor-beta: implications for the control of papillomavirus infection. 132 88

Gene amplification contributes to carcinogenesis by enhancing proto-oncogene activity and causing chromosomal instability. The ease of detecting amplified tumor-virus sequences has encouraged use of this system as a surrogate for studying the molecular events involved in endogenous gene amplification. We report here a new system for studying carcinogen-induced amplification of both endogenous and viral sequences in the SV40-transformed human keratinocyte line AG06. Treatment with carcinogens induced a transient dose-dependent amplification of the integrated SV40 sequences. The amplified sequences appeared in the extrachromosomal fraction. Treatment of these cells with carcinogens prior to methotrexate (MTX) selection increased the frequency of MTX-resistant colonies, 67% of which exhibited dihydrofolate reductase (dhfr) amplification. The abilities of five carcinogens with different DNA-damaging activities (the DNA-damaging agents N-methyl-N-nitro-N-nitrosoguanidine, mitomycin C (MMC), ultraviolet light C, and X-rays and the non-DNA-damaging agent arsenite) to induce SV40 and dhfr amplification at concentrations that result in 50% clonal survival were compared. All four DNA-damaging carcinogens (as well as growth arrest) were able to elicit some SV40 amplification, but responses varied markedly, from 1.8-fold for X-rays to sevenfold to eightfold for MMC. There was no correlation between the ability to elicit the two amplification responses. Arsenite, which did not induce SV40 amplification, was the best inducer of MTX resistance. These results point to different controls involved in the induction of viral and dhfr amplification. The signal for amplification of viral genes may be triggered by DNA damage and growth arrest, whereas amplification of dhfr, and perhaps other endogenous sequences, seems to be triggered by other signals as well.
Mol Carcinog 1992
PMID:Differential susceptibility to carcinogen-induced amplification of SV40 and dhfr sequences in SV40-transformed human keratinocytes. 133 30

Rate constants of 8-oxy-dGMP (8-hydroxy-dGMP) formation upon incubating dGMP in H2O solutions at different temperatures were determined with differential UV-spectroscopy. Extrapolation of rate constant values obtained at elevated temperatures to 37 degrees C gives k = 5.8 x 10(-10) s-1.M-1. The activation energy for the process was estimated to be 24 kcal/mole. In D2O solutions essential lowering of the activation energy (13 kcal/mole) and rising of rate constant (k = 3.7 x 10(-9) s-1.M-1 at 37 degrees C) were observed. The strong influence of D2O on the process points to the possible participation of singlet oxygen in a heat-induced formation of 8-oxy-dGMP. The obtained values of rate constants and activation energy induced by heat show that of all types of DNA damages currently known such as single strand scission, depurination, cytosine deamination and oxidation of guanyl residues to the 8-oxo-derivatives- the last process seems to be the strongest damage of DNA resulting in such biological consequences as mutagenesis, carcinogenesis and aging.
Mol Biol (Mosk)
PMID:[Kinetics of formation of 8-oxy-2'-deoxyguanosine-5'-monophosphate under the effect of heat: determination of rate constants and activation energy]. 133 39

Carcinogenesis is a multistage process that has been characterized both by the activation of cellular oncogenes and by the loss of function of tumor suppressor genes. Colorectal cancer has been associated with the activation of ras oncogenes and with the deletion of multiple chromosomal regions including chromosomes 5q, 17p, and 18q. Such chromosome loss is often suggestive of the deletion or loss of function of tumor suppressor genes. The candidate tumor suppressor genes from these regions are, respectively, MCC and/or APC, p53, and DCC. In order to further our understanding of the molecular and genetic mechanisms involved in tumor progression and, thereby, of normal cell growth, it is important to determine whether defects in one or more of these loci contribute functionally in the progression to malignancy in colorectal cancer and whether correction of any of these defects restores normal growth control in vitro and in vivo. To address this question, we have utilized the technique of microcell-mediated chromosome transfer to introduce normal human chromosomes 5, 17, and 18 individually into recipient colorectal cancer cells. Additionally, chromosome 15 was introduced into SW480 cells as an irrelevant control chromosome. While the introduction of chromosome 17 into the tumorigenic colorectal cell line SW480 yielded no viable clones, cell lines were established after the introduction of chromosomes 15, 5, and 18. Hybrids containing chromosome 18 are morphologically similar to the parental line, whereas those containing chromosome 5 are morphologically distinct from the parental cell line, being small, polygonal, and tightly packed. SW480-chromosome 5 hybrids are strongly suppressed for tumorigenicity, while SW480-chromosome 18 hybrids produce slowly growing tumors in some of the animals injected. Hybrids containing the introduced chromosome 18 but was significantly reduced in several of the tumor reconstitute cell lines. Introduction of chromosome 5 had little to no effect on responsiveness, whereas transfer ot chromosome 18 restored responsiveness to some degree. Our findings indicate that while multiple defects in tumor suppressor genes seem to be required for progression to the malignant state in colorectal cancer, correction of only a single defect can have significant effects in vivo and/or in vitro.
Mol Cell Biol 1992 Mar
PMID:Progression of colorectal cancer is associated with multiple tumor suppressor gene defects but inhibition of tumorigenicity is accomplished by correction of any single defect via chromosome transfer. 134 43

The c-erbB-2/neu gene encodes a transmembrane protein of 185 kDa (p185) with tyrosine kinase activity and extensive sequence homology to epidermal growth factor receptor. Amplification and overexpression of the c-erbB-2/neu gene has been shown in certain human tumors and is postulated to be important in human carcinogenesis. High levels of expression of the c-erbB-2/neu gene have been reported in non-small-cell lung cancer (NSCLC) cell lines and primary tumors from the United States. Since geographical and cultural factors may contribute to the development of certain types of cancer, we examined p185 examined p185 expression in 120 tumors from Chinese patients with lung cancers of different cell types and used immunohistochemical staining to determine the extent and general significance of p185 expression in human primary lung cancer. Our results demonstrate that 58.8% of the NSCLCs expressed p185 and that expression of p185 was observed only in NSCLC and not in small-cell lung cancers. Thirty-three of 41 adenocarcinomas and 24 of 55 squamous cell carcinomas among the NSCLCs examined were found to express p185 at levels different from those of normal lung. For the squamous cell carcinomas, p185 expression was correlated with lymph node metastasis (P less than 0.01), but for the adenocarcinomas, it was not (P greater than 0.05). In addition, expression of p185 in NSCLC was significantly more frequent in patients in advanced clinical stages. Our findings indicate that p185 expression is a frequent event and a general phenomenon in NSCLC and is correlated with poor clinical prognostic indicators, suggesting that expression of p185 may be of potential prognostic importance in NSCLC.
Mol Carcinog 1992
PMID:Overexpression of the c-erbB-2/neu-encoded p185 protein in primary lung cancer. 135 Jan 98


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