p53 protein expression in breast cancer as related to histopathological characteristics and prognosis

Formalin-fixed, paraffin-embedded biopsies of 193 women with primary breast cancer followed-up for over 10 years were analysed immunohistochemically for the expression of p53 protein. Altogether, 58% (113/193) of the tumors were positive for p53 protein. Over-expression of p53 was associated with the ductal type, high-grade tumors, dense stromal inflammatory cell infiltrate, high S-phase fraction, high mitotic frequency and high values of the nuclear factors. In univariate analysis, intense p53 over-expression predicted a poor outcome, whereas a short recurrence-free survival (RFS) was related to p53 negativity. In axillary lymph-node-negative (ANN) tumors, p53 negativity was related to short RFS, and in axillary lymph-node-positive (ANP) tumors this inverse relationship was statistically significant. In Cox's analysis, p53 protein over-expression had no independent prognostic value comparable with the well-established prognostic factors. However, p53 protein accumulation was an independent indicator of long RFS in the entire cohort, in ANP tumors and in rapidly proliferating tumors. The results indicate a dual role for p53 protein over-expression in breast cancer prognosis. The low survival probability associated with intensively p53-positive tumors is probably related to rapid cancer-cell proliferation, whereas the long RFS of p53-positive tumors might be explained by the development of circulating antibodies to p53 protein. The role of p53 protein in breast cancer is incompletely understood, and the p53 gene should be subjected to detailed analysis of specific mutations.

Molecular cloning, sequencing and functional expression of an amphibian angiotensin II receptor

Xenopus laevis and mammalian angiotensin AT1 receptors couple to the phospholipase C signal transduction pathway. However, amphibian AII receptors (xAT), unlike mammalian AT1 receptors, do not recognize the non-peptide antagonist Dup 753. To investigate the basis of this distinction, we have isolated a 3.0 kb Xenopus myocardial xAT cDNA that encodes a 41,039 MW protein containing 362 amino acids. The xAT receptor has 60% amino acid identity and 65% nucleotide homology with the coding regions of known mammalian AT1 receptors. xAT receptors expressed in Xenopus oocytes mediate AII-induced Ca2+ mobilization and are pharmacologically distinct from mammalian AT1 receptors. xAT transcripts are present in Xenopus lung, liver, kidney, spleen, and heart, but not in adrenal, intestine, and smooth muscle. Comparative analysis of xAT and AT1 receptors should facilitate elucidation of the structural basis of their binding and activation properties.

Megakaryocytopoiesis and platelet production: does stem cell factor play a role?

Megakaryocytopoiesis, resulting in the production and release of platelets, is a multistage procession of cellular differentiation and maturation which is regulated by a constellation of cytokines. Since thrombocytopenia is a frequent dose-limiting toxicity of chemotherapy, newly-identified cytokines have been actively investigated for their potential megakaryocyte/platelet-promoting properties. Stem cell factor (SCF, also known as mast cell growth factor, Steel factor or Kit ligand) has been found to synergize with GM-CSF, IL-6, IL-3, IL-11 or Epo to increase the numbers of megakaryocyte-containing colonies (i.e., CFU-Meg, BFU-Meg, CFU-GMM, CFU-GEMM). On the other hand, SCF increased the number of megakaryocytes per colony in the presence of IL-3, GM-CSF or IL-6. SCF also stimulated the proliferation of specific megakaryocytic cell lines (i.e., CMK, M-07e). SCF did not, however, alter megakaryocyte markers or increase cell ploidy. Thus, SCF appears to expand the committed myeloid progenitor compartments, rather than increase the rate of megakaryocyte maturation or the number of platelets released. We describe studies in which SCF stimulated murine CFU-Meg alone and in the presence of IL-3. However, a decrease in cultured cell plating density resulted in ablation of this SCF-stimulation of CFU-Meg colonies. CFU-Meg colony stimulation by SCF was dose dependent, even under serum-free conditions. The effects of SCF in other in vitro and in vivo animal model systems are reviewed.

Epidermal growth factor induces serine phosphorylation of stathmin in a human colon carcinoma cell line (LIM 1215)

Changes in protein phosphorylation in the human colon carcinoma cell line LIM 1215 after stimulation with epidermal growth factor (EGF) have been analyzed by two-dimensional gel electrophoresis and phosphoamino acid analysis. In addition to a number of tyrosine-phosphorylated proteins, a family of small proteins (M(r) 19,000-20,000) is maximally phosphorylated on serine within 5 min of EGF stimulation. One member of the family has been purified by a combination of two-dimensional electrophoresis and reversed-phase high performance liquid chromatography and identified by amino acid sequence analysis as stathmin. Although phosphorylation of stathmin has been reported previously in leukemia cells and following stimulation of hemopoietic or lymphoid cells with several mitogenic agents, this is the first report of stathmin phosphorylation in response to EGF.

Hotspots for unselected Ty1 transposition events on yeast chromosome III are near tRNA genes and LTR sequences

A collection of yeast strains bearing single marked Ty1 insertions on chromosome III was generated. Over 100 such insertions were physically mapped by pulsed-field gel electrophoresis. These insertions are very nonrandomly distributed. Thirty-two such insertions were cloned by the inverted PCR technique, and the flanking DNA sequences were determined. The sequenced insertions all fell within a few very limited regions of chromosome III. Most of these regions contained tRNA coding regions and/or LTRs of preexisting transposable elements. Open reading frames were disrupted at a far lower frequency than expected for random transposition. The results suggest that the Ty1 integration machinery can detect regions of the genome that may represent "safe havens" for insertion. These regions of the genome do not contain any special DNA sequences, nor do they behave as particularly good targets for Ty1 integration in vitro, suggesting that the targeted regions have special properties allowing specific recognition in vivo.

Structure of synthetic peptide analogues of an eggshell protein of Schistosoma mansoni

The peptide (Gly-L-Tyr-L-Asp-L-Lys-L-Tyr)6, referred to as F4-6, was synthesized as a model for a schistosome eggshell protein in which the Gly-Tyr-Asp-Lys-Tyr consensus sequence is repeated over 40 times. Analysis by CD, Fourier transform infrared spectroscopy, potentiometric and spectrophotomertric titrations, NMR, and molecular modeling suggests that F4-6 forms some type of left-handed structure. A likely possibility appears to be a left-handed alpha-helix stabilized by Lysi-Aspi +4 salt bridges and possibly Aspi-Tyri +4 hydrogen bonding and Tyr-Tyr interactions. Spectroscopic studies of a number of F4-6 analogues support this conclusion. For example, substitution of D-Ala for Gly produces a peptide with enhanced left-handed helical spectral characteristics, whereas an L-Ala substitution results in a peptide with minimal structure. These studies suggest that the F4 protein from Schistosoma mansoni may be the first example of a naturally occurring protein devoid of proline and carbohydrate that forms a left-handed helix composed of L-amino acids, although alternative forms of other left-handed structures have yet to be rigorously excluded.

Megakaryocyte colony-stimulating factor (Meg-CSF) is a unique cytokine specific for the megakaryocyte lineage

The regulation of megakaryocytopoiesis and platelet production has not yet been clearly elucidated. Several cytokines have been shown to be capable of producing megakaryocyte colonies from bone marrow [i.e. Interleukin (IL)-3, granulocyte-macrophage (GM)-colony-stimulating factor (CSF), erythropoietin (Epo)]. In addition, other activities have been reported to stimulate megakaryocyte precursors, yet a megakaryocyte-CSF (Meg-CSF) has not been purified to homogeneity and IL-3, GM-CSF and/or Epo often contaminate purification attempts which could account for the activities. A Meg-CSF has been isolated from the urine of patients with aplastic anaemia and purified by sequential ultrafiltration, cation exchange, G-50 chromatography, preparative PAGE, chromatofocusing and cation exchange HPLC. The activity of this material is 2-4 x 10(4) CFU-Meg/mg as measured in a murine marrow, serum-containing assay. This activity also stimulates CFU-Meg in the absence of adherent accessory cells and in serum-free cultures, indicative of the direct stimulation on CFU-Meg. Immunoassays, colony forming assays, and proliferation assays demonstrate that purified Meg-CSF has no GM-CSF, IL-3, M-CSF, G-CSF or IL-1 alpha, -3, -6, -9 and -11. In confirmation of these results, neutralizing antibody to IL-6 also did not abrogate Meg-CSF activity. Therefore the previously-reported megakaryocyte colony-stimulating activity in purified aplastic anaemia patient urine is due to a unique cytokine: Meg-CSF.

Rapid purification of double-stranded DNA by triple-helix-mediated affinity capture

A simple and rapid method for the preparation of highly pure plasmid DNA has been developed. The DNA is directly captured from bacterial cell lysates by formation of a triple-helical structure between the plasmid dsDNA and a 20-base biotinylated oligonucleotide attached to streptavidin-coated magnetic beads and then eluted from the beads in pH 9 buffer solution. No phenol extraction, ethanol precipitation, RNase digestion, or CsCl gradient centrifugation is required. A general purpose cloning vector, pHJ19, was constructed for this application from pUC19 DNA by insertion of a 40-base sequence suitable for triple-helix formation. The approach was also found suitable for the purification of lambda bacteriophage DNA.

Effect of heat treatment on the microstructure of plasma-sprayed hydroxyapatite coating

One of the claimed benefits of plasma-sprayed hydroxyapatite coatings on metal prostheses is the generation of enhanced bone bonding. However, plasma-sprayed hydroxyapatite undergoes a range of transformations during spraying, and the final microstructures produced are complex, with a variety of phases present. The microstructures of plasma-sprayed hydroxyapatite coatings on titanium alloy substrate which have been subjected to post-heat treatment at 950 degrees C have been characterized using transmission electron microscopy. It was demonstrated that heat treatment can modify the coating microstructure and improve adhesion between coating and substrate. The results of chemical analysis revealed an increase in the Ca:P ratios, accompanied by the transformation of calcium phosphate phases from amorphous to crystalline. These transformations are related to phosphorus diffusion into the titanium alloy substrate, which results in the formation of a Ti3P phase.

Prognostic factors in invasive cervical carcinomas associated with human papillomavirus (HPV). Quantitative data and cytokeratin expression

As a part of a larger programme to search for the prognostic factors in cervical cancer, quantitative morphometry, demonstration of AgNORs and expression of different cytokeratin polypeptides (SK2-27, SK1, A 53-B/A2) were used to study a series of 85 cervical squamous cell carcinomas, previously analysed for the presence of human papillomavirus (HPV) DNA by in situ hybridization and polymerase chain reaction (PCR). The following nuclear profile parameters were calculated: nuclear area, perimeter, maximum diameter, ellipsoidity (form Ell), regularity (form Ar) and roundness (form Pe). In each case, the number of small (< 3 microns), large (> 3 microns), the total number and the ratio large/small AgNORs were registered. The cancer cell density and the lymphoid cell density were assessed. In the survival analysis, neither the expression of different cytokeratin polypeptides or the pattern of cytokeratin staining proved to be an independent variable. Similarly, none of the nuclear profile parameters analysed possessed an independent prognostic value in the survival analysis. The ratio of large/small AgNORs proved to be a significant independent prognostic predictor (p = 0.0104), second only to the lymphoid cell density. Also the total number of AgNORs was a prognostic indicator. This suggests that AgNOR size and ratio reflect tumor proliferation also in cervical squamous cell carcinoma, as shown in other human malignancies. Similarly, the density of cancer cell nuclei proved to be an independent prognostic predictor (p = 0.0601) in that the tumours in patients with longer survival showed lower density of the nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and expression of a novel angiotensin II receptor subtype

Angiotensin II (AII) is a major regulator of cardiovascular function and fluid homeostasis. Recently, the cDNA for an AII receptor (AT1) was cloned from rat smooth muscle and bovine adrenal. To search for AII receptor subtypes, we amplified rat adrenal cortex cDNA by PCR using primers based on the AT1 receptor. The product was distinct from the AT1 receptor as indicated by restriction enzyme analysis and DNA sequencing. A full-length cDNA clone (2.2 kilobase pairs) encoding a novel AII receptor (AT3) was obtained by screening an adrenal cortex library. The AT3 cDNA encodes a Mr 40,959 protein with 95% amino acid identity to the rat smooth muscle receptor, but the overall nucleotide similarity is 71% due to low homology in the 5'- (58%) and 3'- (62%) untranslated regions. Expressed AT3 receptors in Xenopus oocytes and COS-7 cells mediate agonist-induced Ca2+ mobilization but are pharmacologically distinct from the AT1 receptors. AT3 mRNA is most abundant in the adrenal cortex and pituitary and differs from AT1 mRNA in its tissue distribution. The structural features of the AT3 receptor, including two additional potential phosphorylation sites for protein kinase C, could be related to the distinctive binding properties of the adrenal and vascular receptors and to their differential regulation during altered sodium intake.

[Flow cytometric analysis of bone marrow cell cycles in patients with hematologic diseases]

Cell cycle phases of bone marrow cells from 8 patients with iron deficiency anemia (IDA), 8 aplastic anemia (AA), 30 myelodysplastic syndrome (MDS), 41 acute leukemia (AL) before treatment, 8 acute leukemia in relapse, 17 acute leukemia in complete remission (CR), 12 chronic myelogenous leukemia (CML) and 4 chronic lymphocytic leukemia (CLL) were analysed with flow cytometry. The proportions of phases of S. G2 M in patients with IDA, refractory anemia, and refractory anemia with ring sideroblast were similar to these in normal controls (P > 0.05). However, they were significantly lower in patients with AA, refractory anemia with excess of blast (RAEB) and transformed RAEB than those in normal controls (P < 0.01, respectively), and CML patients than in normal controls (P < 0.05). The S G2M% was apparently higher in patients with CML than that in CLL (P < 0.01). But, there was no difference between in ALL and ANLL (P > 0.05). It was higher in patients with AL in CR and in relapse than AL before treatment (both P < 0.01). It was still lower in the former than that in normal controls. (P < 0.05). The clinical significance of cell cycle status was also discussed in this paper.

Intercellular communication between follicular angiotensin receptors and Xenopus laevis oocytes: medication by an inositol 1,4,5-trisphosphate-dependent mechanism

In Xenopus laevis oocytes, activation of angiotensin II (AII) receptors on the surrounding follicular cells sends a signal through gap junctions to elevate cytoplasmic calcium concentration ([Ca2+]i) within the oocyte. The two major candidates for signal transfer through gap junctions into the oocyte during AII receptor stimulation are Ins(1,4,5)P3 and Ca2+. In [3H]inositol-injected follicular oocytes, AII stimulated two- to fourfold increases in phosphoinositide hydrolysis and production of inositol phosphates. Injection of the glycosaminoglycan, heparin, which selectively blocks Ins(1,4,5)P3 receptors, prevented both AII-stimulated and Ins(1,4,5)P3-induced Ca2+ mobilization in Xenopus follicular oocytes but did not affect mobilization of Ca2+ by ionomycin or GTP. These results indicate that the AII-regulated process of gap junction communication between follicular cells and the oocyte operates through an Ins(1,4,5)P3-dependent mechanism rather than through transfer of Ca2+ into the ooplasm and subsequent Ca(2+)-induced Ca2+ release.

Preparation and characterization of Al2O3 reinforced hydroxyapatite

The microstructure of Al2O3 reinforced hydroxyapatite (HA-Ca5(PO4)3OH) was studied. It was demonstrated that in this composite the Al2O3 particles are uniformly distributed in a matrix of spherical HA agglomerates formed by primary needlelike HA particles present before making green compact. In the HA + 20 wt% Al2O3 system, hydroxyapatite is partially decomposed into alpha-Ca3(PO4)2 and CaO with H2O vapour during sintering. Subsequently, the CaO is combined with Al2O3 to produce calcium aluminates (CaAl2O4 and CaAl4O7).

The structure of human acidic fibroblast growth factor and its interaction with heparin

The secondary and tertiary structure of recombinant human acidic fibroblast growth factor (aFGF) has been characterized by a variety of spectroscopic methods. Native aFGF consists of ca. 55% beta-sheet, 20% turn, 10% alpha-helix, and 15% disordered polypeptide as determined by laser Raman, circular dichroism, and Fourier transform infrared spectroscopy; the experimentally determined secondary structure content is in agreement with that calculated by the semi-empirical methods of Chou and Fasman (Chou, P. Y., and Fasman, G. C., 1974, Biochemistry 13, 222-244) and Garnier et al. (Garnier, J. O., et al., 1978, J. Mol. Biol. 120, 97-120). Using the Garnier et al. algorithm, the major secondary structure components of aFGF have been assigned to specific regions of the polypeptide chain. The fluorescence spectrum of native aFGF is unusual in that it is dominated by tyrosine fluorescence despite the presence of a tryptophan residue in the protein. However, tryptophan fluorescence is resolved upon excitation above 295 nm. The degree of tyrosine and tryptophan solvent exposure has been assessed by a combination of ultraviolet absorption, laser Raman, and fluorescence spectroscopy; the results suggest that seven of the eight tyrosine residues are solvent exposed while the single tryptophan is partially inaccessible to solvent in native aFGF, consistent with recent crystallographic data. Denaturation of aFGF by extremes of temperature or pH leads to spectroscopically distinct conformational states in which contributions of tyrosine and tryptophan to the fluorescence spectrum of the protein vary. The protein is unstable at physiological temperatures. Addition of heparin or other sulfated polysaccharides does not affect the spectroscopic characteristics of native aFGF. These polymers do, however, dramatically stabilize the native protein against thermal and acid denaturation as determined by differential scanning calorimetry, circular dichroism, and fluorescence spectroscopy. The interaction of aFGF with such polyanions may play a role in controlling the activity of this growth factor in vivo.