PubMed · 9616086
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
V S Pribluda, S J Green. 1998-05-15. A good estrogen.. https://doi.org/10.1126/science.280.5366.983g
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
2-Methoxyestradiol (2-ME) is a metabolite of 17beta-estradiol and a natural component of follicular fluid. Local concentrations of 2-ME may be increased by exposure to environmental pollutants that activate the expression of enzymes in the metabolic pathway from 17beta-estradiol to 2-ME. It has been suspected that this may have adverse effects on spindle formation in maturing oocytes, which would affect embryo quality. To study the dose-response patterns, we exposed denuded mouse oocytes to 2-ME during in vitro maturation. Meiotic progression, spindle morphology, centrosome integrity, and chromosome congression were examined by immunofluorescence and noninvasive polarizing microscopy (PolScope). Chromosomal constituents were assessed after spreading and C-banding. 2-ME sustained MAD2L1 expression at the centromeres and increased the number of meiosis I-blocked oocytes in a dose-dependent manner. 2-ME also caused dramatic dose-dependent increases in the hyperploidy of metaphase II oocytes. Some of these meiosis II oocytes contained anaphase I-like chromosomes, which suggests that high concentrations of the catecholestradiol interfere with the physical separation of chromosomes. Noninvasive PolScope analysis and tubulin immunofluorescence revealed that perturbations in spindle organization, which resulted in severe disturbances of the chromosome alignment at the spindle equator (congression failure), were caused by 2-ME at meiosis I and II. Pericentrin-positive centrosomes failed to align at the spindle poles, and multipolar spindles and prominent arrays of cytoplasmic microtubule asters were induced in 2-ME-exposed metaphase II oocytes. In conclusion, a micromolar level of 2-ME is aneugenic for mammalian oocytes. Therefore, exposure to 2-ME and conditions that increase the intrinsic local concentration of 2-ME in the ovary may affect fertility and increase risks for chromosomal aberrations in the oocyte and embryo.
UNLABELLED: We studied the involvement of interferon-regulated, PKR on 2-ME-mediated actions in human osteosarcoma cells. Our results show that PKR is activated by 2-ME treatment and is necessary for 2-ME-mediated induction of osteosarcoma cell death. INTRODUCTION: Osteosarcoma is the most common primary bone tumor and most frequently develops during adolescence. 2-Methoxyestradiol (2-ME), a metabolite of 17beta-estradiol, induces interferon gene expression and apoptosis in human osteosarcoma cells. In this report, we studied the role of interferon-regulated double-stranded (ds)RNA-dependent protein kinase (PKR) protein on 2-ME-mediated cell death in human osteosarcoma cells. MATERIALS AND METHODS: Western blot analyses were used to measure PKR protein and phosphorylation levels. Cell survival and apoptosis assays were measured using trypan blue exclusion and Hoechst dye methods, respectively. A transient transfection protocol was used to express the dominant negative PKR mutants. RESULTS AND CONCLUSIONS: PKR was increased in 2-ME-treated MG63 cells, whereas 17beta-estradiol, 4-hydroxyestradiol, and 16alpha-hydroxyestradiol, which do not induce cell death, had no effect on PKR protein levels. Also, 2-ME treatment induced PKR kinase activity as indicated by increased autophosphorylation and phosphorylation of the endogenous substrate, eukaryotic initiation factor (eIF)-2alpha. dsRNA poly (I).poly (C), an activator of PKR protein, increased cell death when osteosarcoma cells were treated with a submaximal concentration of 2-ME. In contrast, a serine-threonine kinase inhibitor SB203580 and a specific PKR inhibitor 2-aminopurine (2-AP) blocked the 2-ME-induced cell death in MG63 cells. A dominant negative PKR mutant protein conferred resistance to 2-ME-induced cell death to MG63 osteosarcoma and 2-ME-mediated PKR regulation did not require interferon gene expression. PKR protein is activated in cell free extracts by 2-ME treatment, resulting in autophosphorylation and in the phosphorylation of the substrate eIF-2alpha. We conclude from these results that PKR is regulated by 2-ME independently of interferon and is essential for 2-ME-mediated cell death in MG63 osteosarcoma cells.
Reactive oxygen species are known to be involved in several cellular processes, including cell signaling. SOD2 is a key enzyme in the conversion of reactive oxygen species and has been implicated in a host of disease states, including cancer. Using an integrated, whole-cell approach encompassing epigenetics, genomics, and proteomics, we have defined the role of SOD2 in multiple myeloma. We show that the SOD2 promoter is methylated in several cell lines and there is a correlative decrease in expression. Furthermore, myeloma patient samples have decreased SOD2 expression compared with healthy donors. Overexpression of SOD2 results in decreased proliferation and altered sensitivity to 2-methoxyestradiol-induced DNA damage and apoptosis. Genomic profiling revealed regulation of 65 genes, including genes involved in tumorigenesis, and proteomic analysis identified activation of the JAK/STAT pathway. Analysis of nearly 400 activated transcription factors identified 31 transcription factors with altered DNA binding activity, including XBP1, NFAT, forkhead, and GAS binding sites. Integration of data from our gestalt molecular analysis has defined a role for SOD2 in cellular proliferation, JAK/STAT signaling, and regulation of several transcription factors.