Human neutrophil immunodeficiency syndrome is associated with an inhibitory Rac2 mutation.

A 5-week-old male infant presented with severe bacterial infections and poor wound healing, suggesting a neutrophil defect. Neutrophils from this patient exhibited decreased chemotaxis, polarization, azurophilic granule secretion, and superoxide anion (O(2)(-)) production but had normal expression and up-regulation of CD11b. Rac2, which constitutes >96% of the Rac in neutrophils, is a member of the Rho family of GTPases that regulates the actin cytoskeleton and O(2)(-) production. Western blot analysis of lysates from patient neutrophils demonstrated decreased levels of Rac2 protein. Addition of recombinant Rac to extracts of the patient neutrophils reconstituted O(2)(-) production in an in vitro assay system. Molecular analysis identified a point mutation in one allele of the Rac2 gene resulting in the substitution of Asp57 by an Asn (Rac2(D57N)). Asp57 is invariant in all defined GTP-binding proteins. Rac2(D57N) binds GDP but not GTP and inhibits oxidase activation and O(2)(-) production in vitro. These data represent the description of an inhibitory mutation in a member of the Rho family of GTPases associated with a human immunodeficiency syndrome.

The effects of stem cell factor and granulocyte colony stimulating factor therapy on the activity of the neutrophil NADPH oxidase enzyme system.

BACKGROUND: To explore the effect of cytokine therapy on the NADPH oxidase in mature myeloid cells, we isolated neutrophils from patients receiving recombinant human granulocyte colony stimulating factor (G-CSF) and recombinant human stem cell factor (SCF) and evaluated oxidase activity. All patients had relapsed neoplastic disease and were at least 3 three weeks since the last course of chemotherapy or cytokine therapy. METHODS: Stimulus induced superoxide anion (O2-) production in response to PMA (200 ng/mL), fMLP (1 mumol/L), platelet activating factor (PAF, 2 mumol/L) priming of the fMLP induced response, and opsonized zymosan OZ (1 mg/mL) was measured. Polymorphonuclear leukocyte (PMN) subcellular components were prepared, after nitrogen cavitation, by separation on discontinuous sucrose gradients and NADPH oxidase activity was assessed in a SDS cell-free system. RESULTS: SCF had no effect on the activity of the neutrophil oxidase. Neutrophils isolated from patients treated with G-CSF and stimulated with PMA produced less (superoxide anion) O2- after therapy. PAF priming of the fMLP induced respiratory burst was also reduced after therapy with G-CSF. Subcellular NADPH oxidase activity was reduced before cytokine therapy commenced. This activity did not improve with cytokine treatment. CONCLUSIONS: It appears likely from this study that G-CSF therapy, with or without SCF, does not cause significant enhancement of neutrophil NADPH oxidase activity.

5'-Heterogeneity in human progesterone receptor transcripts predicts a new amino-terminal truncated "C"-receptor and unique A-receptor messages.

Human progesterone receptors (PR) are thought to comprise two naturally occurring hormone-binding proteins: 94-kDa A-receptors and 120-kDa B-receptors. In this paper we present evidence for a third human PR, an N-terminally truncated, 45- to 50-kDa species, termed the C-receptor. To determine the translational origin of B- and A-receptors we mapped the multiple messages that code for human PR by Northern blot analyses, using a series of oligonucleotides and cDNA fragment probes corresponding to different regions of the PR message. In addition to the six transcripts of 2.5, 3.2, 4.5, 5.2, 6.1, and 11.4 kilobases (kb) originally described, we found that the 11.4-kb species is a complex of four bands that we have termed I-IV. Analysis of poly(A)+ RNA derived from T47Dv human breast cancer cells using a variety of 5'-specific probes has identified three separate structural classes of human PR transcripts, indicating extensive 5'-termini heterogeneity. Class A messages, the 2.5- and 5.2-kb species, lack the sequences surrounding AUGB (codon 1), which is the translation initiation site for B-receptors, but contain AUGA (codon 165), the initiation site for A-receptors, and, therefore, potentially encode only the latter. Class B messages, consisting of the 3.2-, 4.5-, and 6.1-kb species as well as bands I and II of the 11.4-kb complex contain both AUGB and AUGA and could encode both receptor forms.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous measurement of progesterone receptors and DNA indices by flow cytometry: characterization of an assay in breast cancer cell lines.

Progesterone receptors (PR) are the strongest predictors of response to hormone therapy in metastatic breast cancer, while PR and the DNA indices of cell ploidy and percentage of S phase are useful prognostic indicators in early stage breast cancer. We have developed a flow cytometry method to measure PR and DNA indices simultaneously using two aneuploid breast cancer cell lines--PR-positive T47D cells and PR-negative MDA-231 cells. Cells were pretreated with the progestin 17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione, harvested, counted, fixed with paraformaldehyde, and permeabilized with Triton X-100. To measure total PR, cells were first exposed to a mixture of the mouse anti-PR monoclonal antibody AB-52, which binds both Protein A and Protein B of human PR, and to monoclonal antibody B-30 or B-64, which bind only Protein B. Then the cells were treated with fluorescein isothiocyanate-conjugated goat anti-mouse second antibody to produce a green fluorescence signal corresponding to PR. To measure nonspecific binding, cells were treated with mouse IgG1 as the first antibody in a parallel incubation. Specific immunoassayable PR is the difference between total and nonspecific binding. Following the antibodies, the cells were treated with RNase A and propidium iodide to give a red fluorescence signal corresponding to DNA content. Red and green fluorescence per cell was then quantified by flow cytometry. This method gives a strong specific signal for PR in several T47D cell sublines but no specific binding in MDA-231 cells. Progestin treatment led to apparent increases in PR. The proportion of cells in the G0-G1, S, and G2-M phases of the cell cycle was determined from DNA histograms and showed that both cell lines were hyperdiploid. The simultaneous flow cytometry method allowed assignment of relative PR levels in subsets of cells segregated by their DNA content. In T47D cells, PR were present throughout the cell cycle, and levels doubled in G2 and mitosis.

Progesterone metabolism in T47Dco human breast cancer cells--II. Intracellular metabolic path of progesterone and synthetic progestins.

We show here that progesterone added to the medium of proliferating T47Dco human breast cancer cells is metabolized with a half life of 2-4h. The final metabolic product, 5 alpha-pregnan-3 beta,6 alpha-diol-20-one, (P-metabolite) is released into the medium. This structure suggested that the intracellular metabolism of progesterone involves the enzymes 5 alpha-reductase, 3 beta-hydroxysteroid dehydrogenase, and 6 alpha-hydroxylase. To investigate this pathway, the cells were incubated with a variety of potential substrates. In addition to progesterone, only precursors with the 5 alpha-configuration served as substrates for the enzymes leading to P-metabolite formation. Some precursors with a 5 beta-configuration were also metabolized by T47Dco cells. This metabolism reflected activity by either 3 beta-hydroxysteroid dehydrogenase and/or 6 alpha-hydroxylase but, in contrast to progesterone metabolism, the rates were different and the products were often mixtures. In T47Dco and MCF-7 human breast tumor cells, the reduction at C-3 followed by 6 alpha-hydroxylation, appear to be the major, and possibly only, route of progesterone metabolism. In contrast, preliminary data suggest that in normal human breast epithelial cells, this is not an exclusive route. Androgens are partially subject to the same metabolic enzymes, but synthetic progestins are not metabolized by T47Dco during an 18 h incubation.

Progesterone metabolism in T47Dco human breast cancer cells--I. 5 alpha-pregnan-3 beta,6 alpha-diol-20-one is the secreted product.

Progesterone is a major hormone controlling normal breast development and function. In breast cancer, progesterone may be involved in tumor growth regulation, and the concentration of the intracellular receptor proteins for progesterone are used to distinguish hormone dependent from autonomous tumors. We have been studying the cytoplasmic and nuclear distribution of progesterone receptors after progesterone treatment of cultured T47Dco human breast cancer cells. Anomalous behavior of the receptors, when progesterone was compared to synthetic progestins, suggested that progesterone was being rapidly metabolized by the cells. We have now studied this metabolism in detail. When progesterone is added to medium of proliferating cells, it disappears with a half life of 2-4 h. A single metabolite (P-metabolite) is quantitatively released into the medium, but its release is delayed 10-14 h. The quantitative conversion of progesterone to P-metabolite was confirmed using two independent methods: gas chromatography with internal standards, and 14C-radioisotope measurements. We have used gas chromatography, gas chromatography/mass spectrometry, thin layer chromatography and nuclear magnetic resonance to identify the final metabolic product released into the medium as 5 alpha-pregnan-3 beta,6 alpha-diol-20-one.