Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A deletion mutant of the human melanoma-associated ME491 antigen gene starting at the first intron (lambda R31) differentially mediates the antigen expression depending on the cell type. Cryptic promoter activity residing in a 270-base-pair (bp) fragment of the first intron was examined by primer extension analysis and recombinant chloramphenicol acetyltransferase (CAT) assay. The cryptic promoter, further localized within a 153-bp fragment (fr153BN), exerted its effect in Ltk- and H-ras-transformed NIH3T3 (3T3-Hras) but not in parental NIH3T3 cells. The results suggested that the cryptic promoter was associated with a novel ras-responsive positive regulatory element, since fr153BN did not contain an AP-1-binding sequence motif, known as the ras-responsive enhancer element. The cryptic promoter activity of fr153BN was suppressed by an upstream 121-bp fragment (fr121SB) which contained a consensus sequence motif for binding of a repressor protein, GC factor, and regions showing sequence similarity with putative cis-acting repressor elements found in the vimentin gene. The degree of the suppression was greater in 3T3-Hras than in Ltk- cells. These positive and negative regulatory elements may be differentially involved in the regulation of ME491 antigen expression depending on the cell type.
Jpn J Cancer Res 1991 Nov
PMID:Activation and suppression of a cryptic promoter in the intron of the human melanoma-associated ME491 antigen gene. 175 82

The hst gene is exclusively expressed in undifferentiated embryonal carcinoma cell lines and at a limited stage of embryonal development. Two DNase I-hypersensitive sites were mapped in the 3' region (approximately 3.5 and 4.5 kb downstream of the translational initiation site) of the human hst gene, irrespective of the presence or absence of hst mRNA in the cells. A DNA fragment containing one of these DNase I-hypersensitive sites (at around 3.5 kb relative to the translational initiation site) showed enhancer activity when tested by chloramphenicol acetyltransferase (CAT) assay. These results strongly suggest that an enhancer element(s) exists in the third exon of the hst and that the expression of the hst may be regulated by the presence or absence of a putative protein factor(s) which binds to the enhancer.
Jpn J Cancer Res 1991 Nov
PMID:Regulation of human hst expression by an enhancer element residing in the third exon. 183 54

A deletion in an Alu repetitive sequence in the fifth intron of the c-sis gene of meningioma patients was previously described (M. Smidt et al., J. Clin. Invest., 86:1151-1157, 1990). The authors analyzed the structure of this intron in DNA from peripheral blood leukocytes and tumor samples of 86 patients with sporadic meningiomas. After amplifying these DNA sequences by the polymerase chain amplification reaction, the authors failed to find any cases with deletions. They also analyzed the effects on the expression of c-sis of the fifth intron with or without the deletion. A c-sis expression clone with an SV40 promoter was modified by adding introns 4, 5, and 6, and the resulting clones were used to examine the expression of c-sis mRNA in A172, NIH3T3, and Cos-7 cells. Northern blots showed that the quantity of message was not changed when the introns were present and that the size of the message was not changed by the deletion in the fifth intron. The effect of the fifth intron Alu sequence on the c-sis promoter was also tested using clones with chloramphenicol acetyltransferase as a reporter gene in A172 and Cos-7 cells. The c-sis promoter was not affected by the fifth intron Alu sequence with or without the deletion and in either orientation. There were also no effects when cells were stimulated by phorbol 12-myristate 13-acetate or the regulatory gene Tax from human T-lymphotropic virus type 1. These data do not support a role for deletions in the fifth c-sis intron in the development of most sporadic meningiomas.
Cancer Res 1991 Aug 15
PMID:Structure and expression of the c-sis gene and its relationship to sporadic meningiomas. 186 50

Human HeLa cells resistant to cisplatin were established by stepwise selection. The selected cells showed a 15- to 20-fold cisplatin resistance (CPR) at the dose level resulting in 50% inhibition. These cells were cross-resistant to mitomycin C, melphalan, and ethyl methanesulfonate but not to Adriamycin, colchicine, or vinblastine. The expression of cisplatin-damaged plasmid DNA carrying the bacterial chloramphenicol acetyltransferase (CAT) gene after its transfection into CPR cells was enhanced by approximately 3-fold. This did not correlate with the degree of CPR. However, the development of the CPR phenotype paralleled the enhanced CAT activity. The addition of aphidicolin (an inhibitor of DNA alpha-polymerase) to CPR cells effectively diminished the enhanced CAT activity and CPR. These studies have identified an enhanced host cell reactivation of the damaged plasmid in the acquisition of CPR, suggesting that DNA repair is a potential mechanism for the development of CPR phenotype in human cells.
Cancer Res 1991 Jan 15
PMID:Enhanced host cell reactivation of damaged plasmid DNA in HeLa cells resistant to cis-diamminedichloroplatinum(II). 189 14

Different portions of the 5'-upstream region of the mouse DNA polymerase beta gene were combined with bacterial chloramphenicol acetyltransferase (CAT) gene of the CAT vector. Transfection of these recombinant plasmids into mouse NIH/3T3 cells has revealed that each of the previously identified two negatively acting regions (silencers I and II) of this gene consists of multiple sub-domains. The distal silencer (silencer I) at around -1.5 kb consists of four sub-domains (-1852 to -1667, -1663 to -1616, -1564 to -1525 and -1355 to -1257). The promoter-proximal silencer (silencer II) at around -0.5 kb consists of two functional domains (-681 to -523 and -490 to -447) separated by a neutral region of 33 base pairs. Silencer II functioned efficiently when silencer I was deleted. Conversely, the distal silencer I functioned efficiently when silencer II was deleted. Thus, these silencers functioned redundantly to each other in NIH/3T3 cells. Nucleotide sequence analysis revealed no extensive sequence similarity between these two silencers. Significant sequence similarity is present between a distal portion of silencer II and the c-myc gene silencer, and also between a proximal portion of silencer II and the mouse F9 cell-specific silencer. A protein factor(s) that specifically bound to the silencer elements was detected in nuclear extracts of NIH/3T3 cells and mouse liver in which DNA polymerase beta was expressed at a rather low level. The same binding factor(s) can bind to both silencer I and II regions, although its affinity for silencer II is much higher than that for silencer I.
Jpn J Cancer Res 1991 Jan
PMID:Organization of mouse DNA polymerase beta gene silencer elements and identification of the silencer-binding factor(s). 190 Feb 71

A method for measuring nucleotide excision repair in response to UV irradiation and chemical-induced DNA damage has been developed, validated, and field tested in cultured human lymphocytes. The methodology is amenable to population-based screening and should facilitate future epidemiological studies seeking to investigate associations between DNA repair proficiency and cancer susceptibility. The impetus for such endeavors derives from the suggestion that the high incidence of skin cancer in the genetic disorder xeroderma pigmentosum is manifested as a result of the reduced capacity of patients' cells to repair DNA damaged by UV-mimetic agents. For the assay, damaged, nonreplicating, recombinant plasmid DNA harboring a chloramphenicol acetyltransferase (cat) reporter gene is introduced into lymphocytes by using a DEAE-dextran/DNA complex short-term transfection conditions. Excision repair of the damaged bacterial cat gene is monitored proportionately as a function of reactivated CAT enzyme activity following a 40-h repair/expression incubation period. The validity of the approach was indicated by the ability of the assay to discriminate xeroderma pigmentosum virus-transformed lymphocyte cell lines of both severe (complementation groups A and D) and moderate (complementation group C) excision repair deficiencies from repair-proficient cell lines. Similar results were observed when a mitogen-stimulated peripheral blood lymphocyte culture from an xeroderma pigmentosum A patient was assayed concurrently with mitogen-stimulated peripheral blood lymphocytes obtained from healthy individuals. Adaptation of this DNA repair assay as a field test in a pilot-tested select group of basal cell carcinoma patients and cancer-free controls led to the preliminary identification of a specific subset at risk for this disease as a consequence of significant reduction to the repair of photochemically (UV)-damaged plasmid DNA.
Cancer Res 1991 Nov 01
PMID:Development and field-test validation of an assay for DNA repair in circulating human lymphocytes. 193 49

Identification of cis-regulatory sequences is a first step in analyzing the regulation of the human multidrug-resistant 1 (MDR1) gene which encodes the 170-kilodalton membrane P-glycoprotein in normal tissues and tumor cells. We have studied several overlapping genomic clones containing the 5'-flanking region of the gene. These clones span about 30 kilobases (kb) of contiguous DNA containing 10 kb of the gene and 20 kb of the 5'-flanking sequence. The nucleotide sequence of the first exon and the 2 kb preceding the exon were determined. DNA sequences containing the 5'-flanking regions were linked to the chloramphenicol acetyltransferase (CAT) gene. For transient CAT assay, we have employed six cell lines, including human cancer KB, vincristine-resistant VJ-300 derived from KB, mouse adrenal tumor Y-1, African green monkey kidney CV-1, mouse fibroblast NIH3T3, and human adrenal carcinoma SW-13 cells. Promoter activity was very weak regardless of the length of the promoter region in mouse adrenal tumor Y-1 and monkey kidney CV-1 cells, in which endogenous P-glycoprotein was expressed. Introduction of a 700-base genomic DNA fragment from a site located at 10 kb far upstream of the initiation site increased the transcription of the CAT gene in Y-1, CV-1, and SW-13 cells. However, no significant increase in the CAT activity could be observed in NIH3T3, KB, and VJ-300 cells. This fragment markedly augmented the expression of the CAT gene regardless of orientation or position, and it acted in a cell type-specific manner even with heterogenous promoters. Our present study suggests that the 700-base pair fragment may carry a tissue-specific transcriptional enhancer that is active in at least some adrenal and kidney-derived cell lines.
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PMID:Tissue-specific enhancer of the human multidrug-resistance (MDR1) gene. 197 33

Cell lines derived from the major morphological types of human lung cancer were tested for their ability to utilize the SV40 enhancer/early promoter. These cell lines were transfected with a recombinant plasmid containing a reporter gene, coding for chloramphenicol acetyltransferase (CAT), under the control of the SV40 enhancer/early promoter. The transfected cells were then assayed for CAT activity. Non-small-cell carcinomas, especially squamous carcinomas, were found to be 2-3 orders of magnitude more efficient in utilizing the SV40 enhancer/early promoter than small-cell carcinomas. The presence of different SV40 enhancer/early promoter specific DNA-binding nuclear factors in squamous and small-cell carcinomas was demonstrated in gel mobility shift experiments. These observations seem to suggest that the set of transcriptional regulatory factors associated with squamous carcinomas may be distinct from that associated with small-cell carcinomas.
Int J Cancer 1990 May 15
PMID:Differential utilization of the SV40 enhancer and early promoter in various human lung carcinoma cell lines. 215 40

Glutathione S-transferase (GST) Ya subunit gene expression is induced in mammalian tissues by two types of chemical agents: (i) planar aromatic compounds (e.g., 3-methylcholanthrene, beta-naphthoflavone, and 2,3,7,8-tetrachlorodibenzo-p- dioxin) and (ii) electrophiles (e.g., trans-4-phenyl-3-buten-2-one and dimethyl fumarate) or compounds easily oxidized to electrophiles (e.g., tert-butylhydroquinone). To study the mechanism of this induction, we have introduced deletions in the 5' flanking region of a mouse GST Ya subunit gene, fused it to the coding sequence for chloramphenicol acetyltransferase (CAT) activity, and transfected the Ya-CAT genes for expression into hepatoma cells. We show that a single cis-regulatory element, between nucleotides -754 and -713 from the start of transcription, is responsible for the induction by both planar aromatic and electrophilic compounds. Using murine hepatoma cell mutants defective in either the Ah-encoded aryl hydrocarbon receptor (BPrc1 mutant) or in cytochrome P1-450 gene (c1 mutant), we show that induction by planar aromatic but not by electrophilic inducers requires a functional Ah receptor and cytochrome P1-450 activity. From this it is concluded that Ya gene activation by planar aromatic compounds involves metabolism of these inducers by the phase I xenobiotic-metabolizing cytochrome P1-450 system into electrophilic compounds, which is consistent with a recently proposed model [Prochaska, H. J. & Talalay, P. (1988) Cancer Res. 48, 4776-4782]. Therefore, the regulatory sequence of the Ya gene should be considered an electrophile-responsive element (EpRE) activated exclusively by inducers containing an electrophilic center. An EpRE-containing 41-bp oligonucleotide ligated at the -187 site of the Ya gene promoter confers upon it an increase in basal activity and xenobiotic inducibility. The basal activity augments with the number of EpRE copies. DNase I protection patterns show the protection of the EpRE domain by a nuclear factor(s) that becomes more abundant upon exposure of Hepa 1c1c7 cells to tert-butylhydroquinone.
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PMID:Xenobiotic-inducible expression of murine glutathione S-transferase Ya subunit gene is controlled by an electrophile-responsive element. 216 52

We have examined the effect of the protein kinase C (PKC) inhibitor, staurosporine, on tumor necrosis factor (TNF)-induced cytotoxic action and augmentation of human immunodeficiency virus (HIV) expression on the chronically HIV-infected T-cell line, MOLT-4/HIV (HTLV-IIIB strain). Staurosporine enhanced the decrease in the number of viable cells caused by TNF treatment for 3 days (1 ng/ml of TNF, 43% decrease; 1 ng/ml of TNF + 20 nM staurosporine, 94%), whereas the cytotoxic action on that cell line induced by 10 ng/ml of 12-O-tetradecanoylphorbol-13-acetate (TPA), which was known to be an activator of PKC, was partially inhibited by staurosporine. In addition, staurosporine augmented the TNF cytotoxic activity against other cell lines including HIV-uninfected U937 cells(100 ng/ml of TNF, 53% decrease in the number of viable cells; 100 ng/ml of TNF + 5 nM staurosporine, 86%). However, staurosporine did not change the sensitivity of cells to TNF; thus, those insensitive to TNF were not changed to TNF sensitive by staurosporine. Furthermore, staurosporine did not affect the augmentative effect of TNF on HIV expression evaluated by levels of p24 antigen. Moreover, HIV long terminal repeat (LTR)-directed chloramphenicol acetyltransferase assay showed that staurosporine strongly inhibited the TPA-induced activation of HIV LTR, while that caused by TNF was little affected (10 ng/ml of TPA, 98.4% conversion; 10 ng/ml of TPA + 40 nM staurosporine, 22.2%, 1 ng/ml of TNF, 98.5%; 10 ng/ml of TNF + 40 nM staurosporine, 93.9%). These results suggest that TPA and TNF facilitate HIV replication by different pathways and that staurosporine augments TNF cytotoxicity by possible suppression of PKC activity in both HIV-infected and uninfected cells.
Cancer Res 1990 Sep 01
PMID:Augmentation of cytotoxic effect of tumor necrosis factor on human immunodeficiency virus-infected cells by staurosporine, a potent protein kinase C inhibitor. 238 36


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