Bax is a transcriptional target and mediator of c-myc-induced apoptosis.

The c-Myc oncoprotein is a transcription factor involved in cellular transformation as well as apoptotic cell death. We show here that over-expression of c-Myc delivered by an adenovirus vector up-regulates endogenous proapoptotic bax mRNA and protein expression in human cells. In contrast, the cytotoxic tumor necrosis factor-related apoptosis-inducing ligand induces cell death without up-regulating bax expression. c-Myc/Max heterodimers bind to canonical E-box elements located in the bax promoter region as demonstrated by electrophoretic mobility shift analysis and DNaseI foot-printing assays. Analysis of bax regulatory region mutants suggests a model involving myc-dependent activation as well as relief of repression through distinct E-box elements. c-Myc-null cells are deficient in bax-promoter activation as compared with wild-type c-Myc-expressing cells. Overexpression of c-Myc in serum-starved human or mouse embryonic cells leads to apoptosis which is significantly reduced in the presence of growth factor-containing serum. c-Myc-induced apoptosis appears to be deficient in bax-null as compared with bax-wild-type mouse embryonic fibroblasts. The results suggest that the cell death-promoting gene bax is directly downstream of c-Myc in a pathway leading to apoptosis.

Novel strategies for therapeutic design in molecular oncology using gene expression profiles.

The sequence of the human genome is estimated to be available by the end of the year 2000 [1]. Pursuant to deciphering the genomic code, and the identification of the estimated 40,000 to 100,000 human genes, anticipated technological advances will make possible examination of global gene expression profiles. Despite the current inaccessibility to the entire genome, many fruitful gene expression profiling studies have been performed using less than 10% of the predicted suite of genes in human or mouse genomes. Even within the confines of this limited set of genes, many insights and discoveries have resulted and their applications to cancer research are particularly profound. This review will focus on recent applications of gene expression profiling that have benefited three major areas of research in molecular oncology: (i) discovery--applications which have found novel genes, families of genes, or pathways involved in cell growth deregulation and tumor development; (ii) diagnosis--applications that have refined, and in some cases, defined, diagnostic methodology; and (iii) therapeutic design--applications which hold potential for chemotherapeutic drug discovery.

ECC-1 human endometrial cells as a model system to study dioxin disruption of steroid hormone function.

ECC-1, an established epithelial cell line derived from an adenocarcinoma of human endometrial lining, was examined for growth optimization, steroid hormone receptor- and Ah receptor content, and dioxin modulation of estrogen receptor function. Proliferation of ECC-1 cells was accelerated by growth on a lethally irradiated feeder layer of murine 3T3 fibroblasts. Immunoblot analysis demonstrated the presence of Ah receptor an intracellular protein that binds and regulates the toxic action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The Ah receptor was functional in these cells as assessed by concentration and kinetic patterns of CYP1A1-mediated 7-ethoxycoumarin O-deethylase (ECOD) induction. The half-maximal effective concentration (EC50) for TCDD was 0.2 nM, and maximal activity appeared after 24-h exposure. A limited structure-activity examination of ECOD activity provided additional evidence for Ah receptor involvement. Competitive binding assays were performed to examine kinetic parameters for estrogen, progesterone, and glucocorticoid receptors. Binding parameters of dissociation constant (Kd) and number of binding sites (Bmax) derived from Scatchard analysis were: estrogen, Kd = 0.67 nM; Bmax = 321 fmol/mg cytosolic protein; progesterone, Kd = 1.31 nM; Bmax = 258 fmol/mg cytosolic protein; dexamethasone, Kd = 1.75 nM, Bmax = 128 fmol/mg cytosolic protein. Exposure of ECC-1 cells to TCDD reduced the estrogen receptor level by 40% without affecting the Kd value, and reduced estrogen receptor-mediated transcription by 50% assessed by transient transfection of an estrogen-responsive reporter plasmid. These data suggest that the ECC-1 cell line is a useful model system for examining the action of dioxin in human endometrial tissue. Both the estrogen receptor and Ah receptor have been implicated in diseases of the endometrium, and examining their interactions may elucidate mechanisms of uterine disease etiology, as well as potential targets for disease prevention.

Estrogen receptor reduces CYP1A1 induction in cultured human endometrial cells.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exerts its toxic action via the aryl hydrocarbon (Ah) receptor, which induces a battery of xenobiotic-metabolizing enzymes, including the cytochrome P450 isozyme, CYP1A1. TCDD-induced 7-ethoxycoumarin-O-deethylase activity was reduced 75% in cultured human endometrial ECC-1 cells exposed to various concentrations of 17beta-estradiol for up to 72 h, with a half-maximal effective concentration (EC50) of 0.9 nM. Reduced enzyme activity was correlated with decreased CYP1A1 mRNA levels, and transcription. Exposure to TCDD plus 17beta-estradiol also reduced CYP1A1 activity in MCF-7 breast cancer cells but not in Hep-3B human liver cells or HuE primary human keratinocytes, suggesting that the effect was specific to estrogen-regulated cells. Estrogen receptor antagonists 4-hydroxytamoxifen and 7alpha-[9-(4,4, 5,5,5-pentafluoro-pentylsulfinyl)nonyl]estra-1,3,5(10)-tr iene3, 17beta-diol restored TCDD-induced CYP1A1 transcription, steady-state mRNA levels, and enzymatic activity in ECC-1 cells. Gel mobility shift assay showed that 17beta-estradiol had little effect on Ah receptor binding to its DNA-responsive element. 17beta-Estradiol did not alter the induction of another Ah receptor-regulated gene, CYP1B1, suggesting that altered Ah receptor binding to DNA does not mediate reduced CYP1A1 transcription. Transfecting ECC-1 cells with a general transcription factor involved in CYP1A1 induction, nuclear factor-1, reversed 17beta-estradiol antagonism of dioxin induced-CYP1A1. The data suggest that 17beta-estradiol reduced CYP1A1 expression at the transcriptional level by squelching available nuclear factor-1, a transcription factor that interacts with both Ah and estrogen receptors.

Aloneness in tenuous self-states.

This article describes the inner world of severely impaired clients who operate within a behavioral mode of violence and manipulation. Clients who employ such tactics are attempting to exert control over an internal environment that threatens their sense of self-cohesion. While descriptive labels of "uncooperative" and "manipulative" may be apt, these terms are used pejoratively all too often. This article outlines nursing approaches that assist these clients to achieve greater self-cohesion.

[Preliminary considerations on blood lipid parameters and blood insulin after oral glucose tolerance test]. / Considerazioni preliminari su parametri lipidemici ed insulinemia dopo carico orale di glucosio.

The behaviour of total lipids, triglycerides and apolipoproteins A and B has been investigated in 41 subjects whose glucose and insulin levels have been evaluated after oral glucose tolerance test. Some of the patients showed a normal glycemic response, others a reduced glucose tolerance. Patients with a normal glycemic curve and a normal pattern of insulin values after loading had low mean total lipids and triglycerides and elevated Apolipo A values. Furthermore, subjects with altered glycemic curve and normal insulin levels presented high mean total lipids and triglycerides and low Apolipo A values. In conclusion we observed, in agreement with other authors, that a good blood insulin reaction is a favourable factor for the reduction of serum triglyceride levels, probably by activation of lipoproteinlipase, with a slight mean increase of apolipoproteins A.