Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1522282 (EMT)
 2,868 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Structural modifications to the photoinactive benzophenoxazine Nile blue A have led to three novel derivatives which include 5-ethylamino-9-diethylaminobenzo[a]phenoxazinium (EtNBA), 5-ethylamino-9-diethylaminobenzo[a]phenothiazinium (EtNBS), and 5-ethylamino-9-diethylaminobenzo[a]phenoselenazinium (EtNBSe) chlorides. The incorporation of sulfur and selenium into the benzophenoxazine moiety results in lipophilic, red-absorbing (650-660 nm) chromophores which possess significantly increased singlet oxygen yields (0.025 and 0.65, respectively, compared to 0.005 for EtNBA). This study examines the photosensitizing efficacies and pharmacokinetics in vitro in the EMT-6 murine mammary sarcoma cell line as well as the physicochemical, photochemical, and redox properties of these new analogues. Comparisons with Photofrin II, the only photosensitizer available clinically, were made in an attempt to high-light their different pharmacological characteristics. The photodynamic activity of the benzophenoxazine dyes correlates with their ability to generate the phototoxin singlet oxygen and increases in the following order: EtNBA < EtNBS << EtNBSe. At an extracellular dye concentration of 0.5 microM, the light dose required to kill approximately 50% of the cells was 2.0 and < 0.5 J/cm2 for the sulfur and selenium dyes, respectively. The light dose required to kill approximately 50% of the cells for both EtNBA and Photofrin II could not be determined because of their weak phototoxic effect under these conditions. At a light dose of 3.3 J/cm2, EtNBSe is approximately 1000 times more phototoxic than Photofrin II. All three benzophenoxazine derivatives are characterized by a similar uptake/efflux pattern in vitro consisting of a rapid and extensive cellular accumulation followed by a slow efflux rate. Contrary to their rapid uptake, 50% of the accumulated EtNBS and EtNBSe is retained intracellularly after a 6-h period in dye-free medium. Video-enhanced fluorescence microscopy corroborates the rapid uptake measurements as well as indicating the intracellular localization of the dyes in both living and thermally inactivated cells. Low extracellular dye concentrations (0.05 microM) result in a punctate fluorescence pattern in the perinuclear region, while higher dye concentrations (> 0.1 microM) lead to additional fluorescence in the cytoplasm, cytomembranes, and other organelles but apparently not the nucleus. Absorption spectrometry revealed that living cells rapidly reduce the dyes to their colorless leuko form (photoinactive) if oxygen is not readily available in the environment. It is shown that the cellular reduction is an enzymatic process and that an oxygen-free and cell-free medium containing both the coenzyme NADH and the hydride transfer enzyme diaphorase is capable of reducing the dyes to the colorless leuko form.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Phototoxicity, redox behavior, and pharmacokinetics of benzophenoxazine analogues in EMT-6 murine sarcoma cells. 849 21

Drug resistance is a major obstacle in the successful treatment of cancer. Thus, elucidation of the mechanisms responsible is a critical first step in trying to prevent or delay such manifestations of resistance. In this regard, three-dimensional multicellular tumor cell spheroids are intrinsically more resistant to virtually all anticancer cytotoxic drugs than conventional monolayer cultures. We have employed the EMT-6 subline PC5T, which forms highly compact spheroids, and differential display to identify candidate genes whose expression differs between monolayer and spheroids. Approximately 5,000 bands were analyzed, revealing 26 to be differentially expressed. Analysis of EMT-6 tumor variants selected in vivo for acquired resistance to alkylating agents identified eight genes whose expression correlated with drug resistance in tumor spheroids. Four genes (encoding Nop56, the NADH SDAP subunit, and two novel sequences) were found to be down-regulated in EMT-6 spheroids and four (encoding 2-oxoglutarate carrier protein, JTV-1, and two novel sequences) were up-regulated. Analysis of the DNA mismatch repair-associated PMS2 gene, which overlaps at the genomic level with the JTV-1 gene, revealed PMS2 mRNA to be down-regulated in tumor spheroids, which was confirmed at the protein level. Analysis of PMS2(-/-) mouse embryo fibroblasts confirmed a role for PMS2 in sensitivity to cisplatin, and DNA mismatch repair activity was found to be reduced in EMT-6 spheroids compared to monolayers. Dominant negative PMS2 transfection caused increased resistance to cisplatin in EMT-6 and CHO cells. Our results implicate reduced DNA mismatch repair as a determinant factor of reversible multicellular resistance of tumor cells to alkylating agents.
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PMID:Gene expression analysis of tumor spheroids reveals a role for suppressed DNA mismatch repair in multicellular resistance to alkylating agents. 1525 49

Despite advances in basic and clinical research, metastasis remains the leading cause of death in breast cancer patients. Genetic abnormalities in mitochondria, including mutations affecting complex I and oxidative phosphorylation, are found in breast cancers and might facilitate metastasis. Genes encoding complex I components have significant breast cancer prognostic value. In this study, we used quantitative proteomic analyses to compare a highly metastatic cancer cell line and a parental breast cancer cell line; and observed that NDUFB9, an accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (complex I), was down-regulated in highly metastatic breast cancer cells. Furthermore, we demonstrated that loss of NDUFB9 promotes MDA-MB-231 cells proliferation, migration, and invasion because of elevated levels of mtROS, disturbance of the NAD+/NADH balance, and depletion of mtDNA. We also showed that, the Akt/mTOR/p70S6K signaling pathway and EMT might be involved in this mechanism. Thus, our findings contribute novel data to support the hypothesis that misregulation of mitochondrial complex I NADH dehydrogenase activity can profoundly enhance the aggressiveness of human breast cancer cells, suggesting that complex I deficiency is a potential and important biomarker for further basic research or clinical application.
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PMID:Down-Regulation of NDUFB9 Promotes Breast Cancer Cell Proliferation, Metastasis by Mediating Mitochondrial Metabolism. 2664 58

BACKGROUND Recent studies have illustrated that the transcription co-repressor, C-terminal binding protein 1 (CtBP1), links the metabolic alterations to transcription controls in proliferation, EMT, genome stability, metabolism, and lifespan, but whether CtBP1 affects the cellular redox homeostasis is unexplored. This study was designed to investigate the mechanism of CtBP1-mediated transcription repression that contributes to the metabolic reprogramming. MATERIAL AND METHODS Knockdown of CtBP1 in both mouse MEF cells and human melanoma cells changed cell redox homeostasis. Further, chromatin immunoprecipitation (ChIP) and luciferase reporter assay were performed for identification of CtBP1 downstream targets, pyruvate carrier 1 and 2 genes (MPC1 and MPC2), which contribute to redox homeostasis and are transcriptionally regulated by CtBP1. Moreover, blockage of the cellular NADH level with the glycolysis inhibitor 2-Deoxy-D-Glucose (2-DG) rescued MPC1 and MPC2 expression. MTT assay and scratch assay were performed to investigate the effect of MPC1 and MPC2 expression on malignant properties of melanoma cells. RESULTS The data demonstrated that CtBP1 directly bound to the promoters of MPC1 and MPC2 and transcriptionally repressed them, leading to increased levels of free NADH in the cytosol and nucleus, thus positively feeding back CtBP1's functions. Consequently, restoring MPC1 and MPC2 in human tumor cells decreases free NADH and inhibits melanoma cell proliferation and migration. CONCLUSIONS Our data indicate that MPC1 and MPC2 are principal mediators that link CtBP1-mediated transcription regulation to NADH production. The discovery of CtBP1 as an NADH regulator in addition to being an NADH sensor shows that CtBP1 is at the center of tumor metabolism and transcription control.
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PMID:C-Terminal Binding Protein 1 Modulates Cellular Redox via Feedback Regulation of MPC1 and MPC2 in Melanoma Cells. 3035 33