Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.14.3 (luciferase)
 38,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In P388/VCR-10 cells, resistance to cytotoxic drugs is caused by the overexpression of the mdr3 gene, in absence of gene amplification. The gene is transcriptionally activated following integration of a full-length mouse mammary tumor virus (MMTV) within intron I, upstream of the coding region of the gene. This integration results in the production of MMTV/mdr3 fusion transcripts that originate from the antisense 5'LTR of the provirus. The mechanism of mdr3 activation in these cells remains unclear since it cannot be accounted for either by activation from the normal MMTV promoter or by activation of the mdr3 promoter by MMTV enhancer sequences. Subcloning and sequence analysis of the genomic region encompassing the 5' LTR of the provirus with adjacent mdr3 sequences up to exon 2 showed that the LTR had not undergone small rearrangements or deletions. Transfections of fusion plasmids containing this genomic fragment and the reporter gene luciferase showed the presence of transcriptionally active sequences in that region. Deletions of 5' and 3' sequences from this fragment have shown that the antisense LTR itself has little contribution to the activation of the luciferase gene, whereas the mdr3 derived sequences that include part of intron I and the beginning of exon 2 strongly activated luciferase expression when inserted in either orientations upstream of the reporter gene. These results suggest the presence of an activator element within intron I of mdr3 capable of activating transcription from a cryptic start site present in the antisense MMTV LTR. Derepression of this activator sequence within intron I by a mechanism involving integration of a transposable element may be a prerequisite to transcriptional activation of the gene which is silent in the parental P388 cells. Further support for a derepression mechanism of activation in P388 cells is provided by the identification of independent genomic rearrangements in the 5' region of mdr3 in additional MDR P388 derivatives analyzed in this study.
 ...
PMID:Activation of a MMTV/mdr3 fusion transcript from a cryptic viral promoter is stimulated by mdr-derived sequences located in intron I. 761 65

The transcription factor YB-1 is expressed in a wide range of cell types and has been implicated in the regulation of various genes involved in cell proliferation. Nuclear expression of YB-1 is correlated with MDR-1 gene expression in breast cancer and osteosarcoma. In this study, we asked whether YB-1 expression is enhanced in human colorectral carcinoma and if it is associated with the expression of target genes such as MDR-1, DNA topoisomerase II alpha and PCNA. YB-1, DNA topoisomerase II alpha, PCNA and MDR-1 expression were assessed by Western blotting, Northern blotting and immunohistochemistry in 26 human colorectal carcinomas. The involvement of YB-1 in DNA topoisomerase II alpha gene expression was examined by transient DNA transfection assays. YB-1 was overexpressed in almost all cancerous lesions in comparison with normal mucosa in surgically resected colorectal carcinomas of 26 patients. YB-1 expression correlated well with both DNA topoisomerase II alpha and PCNA expression. In contrast, no correlation was observed between YB-1 and MDR-1 expression. We also found that a transient co-transfection with a DNA topoisomerase II alpha promoter-luciferase plasmid and an antisense YB-1 expression construct resulted in a significant reduction of the promoter activity in KM12C human colon cancer cells. YB-1 may be an excellent proliferation-associated marker and may be a transcription factor regulating DNA topoisomerase II alpha gene expression in human colorectal carcinoma.
 ...
PMID:Enhanced coexpression of YB-1 and DNA topoisomerase II alpha genes in human colorectal carcinomas. 1059 87

The p53 homologue p73 efficiently activates p53-responsive genes. The well documented over-expression of p73 spliced forms in a wide variety of tumor types promoted us to elucidate the mechanisms underlying p73-mediated transcription. Using the luciferase reporter gene driven by Mdm2-minimal promoter in p53 null cells, we demonstrate that the weak transcriptional activity mediated by p73alpha was increased by the mutant form p73beta292, which by itself is transcriptionally inactive. Similarly, cooperation between p73beta and an inactive form of p73alpha increased p73beta-mediated transcriptional activities. Conversely, p73beta elicited a silencing effect on a gain of function mutant, p53(281), which by itself mediated efficient transactivation of the MDR promoter. Neither anisomycin nor actinomycin D altered p73-mediated transcriptional activities, whereas sorbitol profoundly inhibited them through a rapid proteasome-dependent degradation of p73. Our observations point to plausible scenarios in which p73, through cooperation between p73 spliced forms and suppression of gain of function mutant p53 may elicit changes in the transcription of p53 target genes that play key roles in cell growth and death.
 ...
PMID:p73 transcriptional activity increases upon cooperation between its spliced forms. 1069 2

The notion that wt p53 downregulates MDR-1 links p53 mutations to multidrug resistant phenotype. Alternatively, it has been envisioned that wt p53 protects cells against DNA damaging drugs by inducing MDR-1. Opposing conclusions on the relationship between MDR-1 and p53 have been predominantly based on the effects of p53 on MDR-1 promoter-constructs. We found that introduction of wt p53 slightly induced MDR-1 mRNA in three cell lines having endogenous mt p53. Wt p53-mediated induction of endogenous MDR-1 may represent a rudiment of cellular protection against toxic compounds earlier in evolution. Marked induction of p21WAF1/CIP1 (p21) mRNA was observed in all cell lines; and lower levels of wt p53 were required to induce p21 than MDR-1. Pgp was undetectable and wt p53 did not increase resistance to an MDR-1 substrate, suggesting the changes in MDR-1 mRNA may be functionally insignificant. Unlike endogenous MDR-1, the expression of an MDR-1 promoter (-434/+147 fragment) - luciferase construct was unchanged or even inhibited by wt p53 that may be secondary to wt p53-mediated cytotoxicity. Thus, partial promoter constructs may not accurately represent endogenous MDR-1.
 ...
PMID:Wild-type p53 marginally induces endogenous MDR-1 mRNA without causing a measurable drug resistance in human cancer cells. 1117 7

Retinoic acid is generated by a two-step mechanism. First, retinol is converted into retinal by a retinol dehydrogenase, and, subsequently, retinoic acid is formed by a retinal dehydrogenase. In vitro, several enzymes are suggested to act in this metabolic pathway. However, little is known regarding their capacity to contribute to retinoic acid biosynthesis in vivo. We have developed a versatile cell reporter system to analyze the role of several of these enzymes in 9-cis-retinoic acid biosynthesis in vivo. Using a Gal4-retinoid X receptor fusion protein-based luciferase reporter assay, the formation of 9-cis-retinoic acid from 9-cis-retinol was measured in cells transfected with expression plasmids encoding different combinations of retinol and retinal dehydrogenases. The results suggested that efficient formation of 9-cis-retinoic acid required co-expression of retinol and retinal dehydrogenases. Interestingly, the cytosolic alcohol dehydrogenase 4 failed to efficiently catalyze 9-cis-retinol oxidation. A structure-activity analysis showed that mutants of two retinol dehydrogenases, devoid of the carboxyl-terminal cytoplasmic tails, displayed greatly reduced enzymatic activities in vivo, but were active in vitro. The cytoplasmic tails mediate efficient endoplasmic reticulum localization of the enzymes, suggesting that the unique milieu in the endoplasmic reticulum compartment is necessary for in vivo activity of microsomal retinol dehydrogenases.
 ...
PMID:Biosynthesis of 9-cis-retinoic acid in vivo. The roles of different retinol dehydrogenases and a structure-activity analysis of microsomal retinol dehydrogenases. 1127 29

Retinoids have been shown to modulate inflammation and the immune response in many cell types including macrophages, endothelial cells, and vascular smooth muscle cells. However, present knowledge of whether inflammatory mediators modulate vitamin A status in these cells is limited. To identify the role of inflammation on retinoid metabolism in vascular smooth muscle cells, the cells were exposed to a combination of proinflammatory cytokines: interleukin-1beta, interferon-gamma, and lipopolysaccharides. Without stimulation with proinflammatory cytokines, vascular smooth muscle cells expressed retinol dehydrogenases-2 and 5 mRNA detected by RT-PCR. Stimulation with the combination of cytokines induced a substantial increase of retinol dehydrogenase-5 mRNA. This was associated with increased production of ligands for retinoic acid receptors, when assayed in a retinoic acid receptor-dependent luciferase reporter system. Our results demonstrate that inflammatory mediators activate the retinoid metabolic pathway in vascular smooth muscle cells, which potentially may modulate the inflammatory response in the vascular wall.
 ...
PMID:Increased retinoid signaling in vascular smooth muscle cells by proinflammatory cytokines. 1150 42

The microenvironment of rapidly growing tumors is associated with increased energy demand and diminished vascular supply, resulting in focal areas of prominent hypoxia. A number of hypoxia-responsive genes have been associated with growing tumors, and here we demonstrate that the multidrug resistance (MDR1) gene product P-glycoprotein, a Mr approximately 170,000 transmembrane protein associated with tumor resistance to chemotherapeutics, is induced by ambient hypoxia. Initial studies using quantitative microarray analysis of RNA revealed an approximately 7-fold increase in MDR in epithelial cells exposed to hypoxia (pO(2) 20 torr, 18 h). These findings were further confirmed at the mRNA and protein level. P-Glycoprotein function was studied by analysis of verapamil-inhibitable efflux of digoxin and rhodamine 123 in intact T84 cells and revealed that hypoxia enhances P-glycoprotein function by as much as 7 +/- 0.4-fold over normoxia. Subsequent studies confirmed hypoxia-elicited MDR1 gene induction and increased P-glycoprotein expression in nontransformed, primary cultures of human microvascular endothelial cells, and analysis of multicellular spheroids subjected to hypoxia revealed increased resistance to doxorubicin. Examination of the MDR1 gene identified a binding site for hypoxia inducible factor-1 (HIF-1), and inhibition of HIF-1 expression by antisense oligonucleotides resulted in significant inhibition of hypoxia-inducible MDR1 expression and a nearly complete loss of basal MDR1 expression. Studies using luciferase promoter constructs revealed a significant increase in activity in cells subjected to hypoxia, and such hypoxia inducibility was lost in truncated constructs lacking the HIF-1 site and in HIF-1 binding site mutants. Extensions of these studies also identified a role for Sp1 in this hypoxia response. Taken together, these data indicate that the MDR1 gene is hypoxia responsive, and such results may identify hypoxia-elicited P-glycoprotein expression as a pathway for resistance of some tumors to chemotherapeutics.
 ...
PMID:Hypoxia-inducible factor-1-dependent regulation of the multidrug resistance (MDR1) gene. 1206 80

Methoprene (isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate) is an insect juvenile hormone agonist that blocks metamorphosis in some insects. Recent evidence suggests that a metabolite, methoprene acid, activates vertebrate retinoid X receptors (RXRs), and may interfere with retinoic acid-regulated developmental processes. Methoprene, methoxy-methoprene acid, and two major breakdown products were tested for their ability to interfere with retinoid-regulated pathways when using transfected cells. The CV-1 cells were transiently transfected with genes encoding RXRs and response elements attached to luciferase reporters, and retinoic acid-sensitive F9 cells were stably transfected with retinoic acid receptor (RAR)/RXR response elements attached a lacZ reporter (Sil-REM/beta-gal-NEO). Experiments confirmed that methoxy-methoprene acid acted as a ligand for RXRs and was capable of activating transcription through RAR/RXR response elements. However, neither methoprene nor the breakdown products, 7-methoxycitronellal and 7-methoxycitronellic acid, activated transcription in transfected CV-1 or F9 cells. Methoprene and methoxy-methoprene acid may interfere with the conversion of all-trans-retinol and all-trans-retinaldehyde to all-trans-retinoic acid in the F9-derived cell line. Methoprene was as effective as the retinol dehydrogenase inhibitor citral in blocking the retinol-induced transcription of RAR/RXR-regulated reporter genes, whereas methoxy-methoprene acid blocked transcription stimulated by retinaldehyde.
 ...
PMID:Effects of methoprene, its metabolites, and breakdown products on retinoid-activated pathways in transfected cell lines. 1518 Mar 84

The Runx3 gene is a member of the runt domain family transcription factors, key regulators of development and differentiation in metazoan. Recently, Runx3 was identified as a tumor suppressor gene. Loss of Runx3 was found to be associated with genesis and progression of gastric cancer. In this study, we transfected the gastric cancer cell line SGC7901 with eukaryotic expression vector of Runx3. In vitro drug sensitivity assay suggested that SGC7901/Runx3 cells were more sensitive to various chemotherapeutic drugs. Blocking Runx3 expression in immortalized stomach mucosal cells (GES-1) or gastric cancer cells (SGC7901) by Runx3-specific small interfering RNA conferred the cells resistance to chemotherapeutic drugs. Flow cytometry examination suggested that expression of Runx3 in gastric cancer cells increased the intracellular accumulation and retention of adriamycin. Semiquantitative RT-PCR and Western blot suggested that Runx3 downregulated expression of Bcl-2, MDR-1 (P-gp) and MRP-1. Binding of Runx3 to promoter sequences of Bcl-2, MDR-1 and MRP-1 gene was detected by eletrophoretic mobility shift assay (EMSA) and supershift EMSA. We cloned the MDR-1 and MRP-1 gene promoters containing Runx binding sites and constructed the luciferase reporter vectors of these 2 promoters. Luciferase reporter assay suggested that Runx3 inhibited the promoter activity of the MDR-1 and MRP-1 promoter in SGC7901 cells. Taken together, our findings suggested that overexpression of Runx3 could sensitize gastric cancer cells to chemotherapeutic drugs by downregulating the Bcl-2, MDR-1 and MRP-1.
 ...
PMID:Tumor suppressor gene Runx3 sensitizes gastric cancer cells to chemotherapeutic drugs by downregulating Bcl-2, MDR-1 and MRP-1. 1575 76

Anti-tumor drug resistance and cancer metastasis are always clinically coincidental, which are conducted by different molecules such as P-glycoprotein (P-gp) and CD147, respectively. P-gp and CD147/CD98hc complex are both found highly expressed on cisplatin resistant ovarian cancer cell line SKOV3/DDP but only slightly expressed on its parent cell SKOV3. RNAi targeting CD98hc or CD147 both reduce their own and P-gp expression as well as cisplatin IC50 of drug-resistant tumor cells. CD147 interference only reduced membrane CD98hc rather than its intracellular forms. Stop of CD98hc also diminished CD147 translation. Cloned potential CD98hc promoter region showed promoter activity in luciferase assay under cisplatin pressure. Intracellular cisplatin accumulation was found increased in RNAi groups and the efflux ability of cisplatin resistant SKOV3 cells was disrupted as well. CD147 has been reported to play an important role in tumor metastasis. Taken together, CD98hc was for the first time revealed to be a bridge between MDR phenotype and tumor metastasis.
 ...
PMID:Bridge linkage role played by CD98hc of anti-tumor drug resistance and cancer metastasis on cisplatin-resistant ovarian cancer cells. 1761 93


1 2 3 Next >>