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Results for “virtual protein profiling”

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PubMed2005

The global transcriptional effects of the human papillomavirus E6 protein in cervical carcinoma cell lines are mediated by the E6AP ubiquitin ligase.

The function of the human papillomavirus (HPV) E6 protein that is most clearly linked to carcinogenesis is the targeted degradation of p53, which is dependent on the E6AP ubiquitin ligase. Additional functions have been attributed to E6, including the stimulation of telomerase activity and the targeted degradation of other cellular proteins, but in most cases it is unclear whether these activities are also E6AP dependent. While E6 clearly influences the transcriptional program of HPV-positive cell lines through the inactivation of p53, it has been shown that at least a subset of its p53-independent functions are also reflected in the transcriptional program. For this study, we have determined the extent to which E6AP is involved in mediating the set of E6 functions that impact on the global transcriptional program of HPV-positive cell lines. The transcriptional profiles of approximately 31,000 genes were characterized for three cell lines (HeLa, Caski, and SiHa cells) after small interfering RNA (siRNA)-mediated silencing of E6 or E6AP. We found that E6 and E6AP siRNAs elicited nearly identical alterations in the transcriptional profile of each cell line. Some of the expression alterations were apparent secondary effects of p53 stabilization, while the basis of most other changes was not reconcilable with previously proposed E6 functions. While expression changes of the TERT gene (telomerase catalytic subunit) were not revealed by the array, telomerase repeat amplification protocol assays showed that both E6 and E6AP knockouts resulted in a suppression of telomerase activity. Together, these results suggest that E6AP mediates a broad spectrum of E6 functions, including virtually all functions that impact on the transcriptional program of HPV-positive cell lines.

Cell Line, Tumor↗

PubMed2003

Biosensor profiling of molecular interactions in pharmacology.

Techniques employed to profile the pharmacological properties of a molecule in vitro normally require some type of radio-, enzymatic- or fluorescent-labeling of the ligand and/or the receptor. In contrast, biosensor techniques do not require labeling, and they allow virtually any complex to be screened with minimal assay development. Scientists in both academia and industry are now using biosensors in areas that encompass almost all sectors of drug discovery, diagnostics and the life sciences. Assays have been developed for the analysis of small molecules, proteins, oligonucleotides, bacteriophage, viruses, bacteria and cells. In addition, novel biosensor applications are being developed for the predictive profiling of key pharmacokinetic parameters of a molecule (adsorption, distribution, metabolism, excretion and toxicity).

Animals↗

PubMed1991

Use of polymeric reversed-phase columns for the characterization of polypeptides extracted from human pancreata. II. Effect of the stationary phase.

The potential value of eight commercial available polymer-based reversed-phase (RP) columns for peptide and protein separations was evaluated using crude acetic acid extracts of normal and diabetic human pancreata and mixtures of pure polypeptides as samples. All columns were characterized with acetic acid gradients in water as mobile phase, and different chromatographic profiles were obtained depending on the type of polymer column (bare or derivatized) and the type of ligand. Some of the columns were virtually free from effects related to the polymer skeleton whereas in others the separation was influenced by both the ligand and the polymeric backbone. Two selected polymeric RP columns were, together with a silica-based C4 column, further characterized with acetonitrile gradients in trifluoroacetic acid (TFA), and the separation temperature was found to have a drastic effect on the separation efficiency for proteins with mol. wt. greater than 6000 dalton. No such effect was seen for polypeptides with mol. wt. less than 6000 dalton. Mixtures of pure peptides and proteins were separated using acetic acid gradients in water, acetonitrile or isopropanol, and normally the highest efficiency was found with the use of acetonitrile as mobile phase modifier. Isopropanol was less suitable as an organic modifier. The separation of the beta-lactoglobulin A- and B-chains may be used to give a rapid estimate of the chromatographic usability of polymer-based RP-columns for peptide and protein separations in acetic acid gradients in water and in acetonitrile gradients. Recoveries for insulin, proinsulin, growth hormone, ovalbumin and human serum albumin were measured for several polymer-based RP columns eluted with acetic acid gradients in water and with acetonitrile-based mobile phases. The highest recoveries of serum albumin and ovalbumin were found after elution with acetic acid gradients in water.

Acetates↗

PubMed1999

Bacterial growth state distinguished by single-cell protein profiling: does chlorination kill coliforms in municipal effluent?

Municipal effluent is the largest reservoir of human enteric bacteria. Its public health significance, however, depends upon the physiological status of the wastewater bacterial community. A novel immunofluorescence assay was developed and used to examine the bacterial growth state during wastewater disinfection. Quantitative levels of three highly conserved cytosolic proteins (DnaK, Dps, and Fis) were determined by using enterobacterium-specific antibody fluorochrome-coupled probes. Enterobacterial Fis homologs were abundant in growing cells and nearly undetectable in stationary-phase cells. In contrast, enterobacterial Dps homologs were abundant in stationary-phase cells but virtually undetectable in growing cells. The range of variation in the abundance of both proteins was at least 100-fold as determined by Western blotting and immunofluorescence analysis. Enterobacterial DnaK homologs were nearly invariant with growth state, enabling their use as permeabilization controls. The cellular growth states of individual enterobacteria in wastewater samples were determined by measurement of Fis, Dps, and DnaK abundance (protein profiling). Intermediate levels of Fis and Dps were evident and occurred in response to physiological transitions. The results indicate that chlorination failed to kill coliforms but rather elicited nutrient starvation and a reversible nonculturable state. These studies suggest that the current standard procedures for wastewater analysis which rely on detection of culturable cells likely underestimate fecal coliform content.

Antibodies, Bacterial↗

PubMed1985

The thermotropic properties of human plasma fibronectin.

Thermal denaturation profiles for human plasma fibronectin under a variety of conditions have been determined. Although a single melting curve for this protein, with a thermal transition midpoint of 58.4 +/- 1.0 degree C and a calorimetric enthalpy change (delta Hc) of 1040 +/- 100 kcal/mol, is obtained in dilute neutral salt solutions, it is estimated that a total of seven to eight independent two-state thermal transitions are present in this endotherm. These values are not significantly altered by the presence of Ca2+, up to levels of at least 20 mM. Upon variation of the pH, no distinct thermal transitions are noted at values below pH 5.0 and above pH 10.0. Between pH 7.0 and 10.0, virtually no alterations in the thermotropic properties of fibronectin are observed, indicating that the individual domains of this protein, which contribute to the thermogram, are preserved in this pH range. Upon alteration of the ionic strength of the buffer, from 0.05 to 0.4 M KCl, small changes are observed in the thermal transition profiles of fibronectin, indicative of conformational changes in the protein resulting in a larger number of cooperative units undergoing the temperature-induced unfolding reaction.

Calcium↗

PubMed1995

Glial environment in the developing superior colliculus of hamsters in relation to the timing of retinal axon ingrowth.

We have examined the developmental changes of glial cell organization in the superior colliculus of embryonic and neonatal hamsters in reference to the known sequence of retinal axon ingrowth and arborization in the midbrain. Immunolocalization of vimentin, a marker for neuronal and glial cell precursors, reveals a uniform distribution of radially oriented cells, with perikarya located at the ventricular surface and thin, elongated processes fanning out toward the pia. These vimentin-positive cells, referred to as the lateral radial cells, are present in the tectum from embryonic day (E) 10 (earliest day examined) until approximately postnatal day (P) 5. Vimentin expression in the lateral radial cells decreases markedly during the second week of postnatal life: application of DiI to the ventricular surface reveals that the pial attachment of the lateral radial cells is withdrawn and that the radial processes are gradually pulled back toward the ventricular zone. By P14, virtually no vimentin-positive radial cells are detectable in the superior colliculus. At no time during development are the lateral radial cells immunopositive for the glial fibrillary acidic protein (GFAP); however, shorter, vimentin-positive astrocytic profiles can be seen in the tectum around the time the radial fibers have been withdrawn, suggesting that at least some radial cells are transformed into astrocytes that will colonize the mature colliculus. At approximately E12, a second group of cells, referred to as the midline radial glia, is detected at the tectal midline. These cells are tightly bundled, forming a raphe in the tectum. They are intensely vimentin positive from E13 until at least P14. From the time of birth, the midline radial cells also exhibit intense immunoreactivity for GFAP. The lateral radial cells are present in the superior colliculus prior to and during the period of neurogenesis but remain well past the time when collicular neuronal migration is completed. Pial processes of the lateral radial cells are present within the superficial tectal layers during the time retinal axons are entering this target; they may be involved in directing the growth and initial collateralization of retinotectal axons. Their withdrawal from retinorecipient collicular zones begins at about the time arbors are being elaborated on retinal axons. In contrast, the midline glia become distinct just prior to the time retinal axons enter the superior colliculus and persist during the time retinotectal projections are being fully established. These raphe glia may be involved in maintaining the laterality of the retinotectal projection.

Animals↗

PubMed2000

Rab3B regulates ZO-1 targeting and actin organization in PC12 neuroendocrine cells.

Rab3B is a monomeric GTPase that modulates norepinephrine secretion when expressed in PC12 neuroendocrine cells. In the present study we determined whether rab3B also regulates the organization of intercellular junctions, since this GTPase localizes to regions of cell contact in multiple cell types. The stable expression of rab3B, but not the closely related rab3A, led to two morphological phenotypes in PC12 cells: (i) reorganization of F-actin into long filopodia and (ii) redistribution of the junction-associated protein ZO-1. ZO-1 localization was not appreciably affected by the expression of a GTP binding mutant of rab3B (N135I) that stimulates norepinephrine secretion by PC12 cells. The apparent diversity of these rab3B phenotypes implies that this GTPase is capable of influencing cell signaling pathways that in turn modulate the cytoskeleton and junction organization. In support of this hypothesis we observed that rab3B expression also altered the profile of proteins that interact with the signaling molecule, phosphatidylinositol 3-kinase (PI3-kinase). The effect of rab3B on protein interactions with PI3-kinase was reversed by inhibitors of this kinase. Furthermore, PI3-kinase inhibitors virtually abolished ZO-1 localization at the surfaces of cells that express rab3B, but not rab3A, whereas these inhibitors had no effect on rab3B-dependent norepinephrine secretion. Our results indicate that rab3B can influence junctional protein targeting and secretion by distinct mechanisms.

Actins↗

PubMed1994

Use of model cell lines to study the biosynthesis and biological role of cancer-associated sialosyl-Tn antigen.

Sialosyl-Tn (STn) is a mucin-associated carbohydrate antigen that is not expressed by most normal epithelial cells but becomes expressed in several types of adenocarcinomas, where it is often associated with a poor prognosis. Little is known about the regulation of the STn phenotype in tumor cells and the immune response to STn antigen. In the present study, we established clonal cell lines in which virtually all of the cells were STn positive (designated LS-C) or STn negative (designated LS-B). These two cell lines, derived from a single parental cell line, LS174T, have the same total protein electrophoretic profiles but carry markedly different oligosaccharide structures on their mucin; the mucin from LS-C cells has only the Tn and STn structures, whereas LS-B cell mucin lacks these simple structures but carries more complex oligosaccharides. These results indicate that lack of STn expression by cells can be due to the lack of STn synthesis rather than inaccessibility of antibodies to bind to STn by steric hindrance. Both clones were similar in their growth rates, response to gamma-interferon, and sensitivity to lysis by lymphokine-activated killer cells. These cells may be important models for understanding the regulation of glycosylation at the cellular level and for further studies of tumor biology and immune response to STn antigen.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed2003

Towards determining the differentiation program of antigen-presenting dendritic cells by transcriptional profiling.

Dendritic cells (DC) represent professional antigen-presenting cells that develop from hematopoietic progenitors through successive steps of differentiation. Employing DNA microarray technology, we analysed the specific changes in gene expression that occur when human progenitor cells differentiate into DC. CD34 progenitor cells were first amplified in vitro with stem cell factor (SCF), Flt3 ligand (FL), thrombopoietin and IL-6/soluble IL-6 receptor fusion protein, and cells were then induced to differentiate into DC with IL-4 and GM-CSF. DC maturation was induced by TNFalpha. Progenitor cells and DC were subjected to transcriptional profiling by DNA microarrays that represent 13000 human genes. Our analysis revealed specific changes in the expression of a large number of cell surface antigens including molecules involved in antigen uptake and processing, cell migration and antigen presentation. Genes encoding such molecules were upregulated during DC differentiation as were genes encoding cytokines, cytokine receptors, chemokines and chemokine receptors. Stem cell genes and genes related to the multilineage differentiation potential and proliferative state of progenitor cells were downregulated. Our analysis also provides information on the expression profiles of transcriptional regulators such as the NF-kappaB/rel and STAT transcription factors. Interestingly, NF-kappaB/rel factors were found to be expressed in both progenitor cells and DC at similar levels and were induced by TNFalpha. In contrast, expression of STAT factors increased during DC differentiation and their expression was virtually unaffected by TNFalpha.

Antigens, CD↗

PubMed2003

The construction and use of bacterial DNA microarrays based on an optimized two-stage PCR strategy.

BACKGROUND: DNA microarrays are a powerful tool with important applications such as global gene expression profiling. Construction of bacterial DNA microarrays from genomic sequence data using a two-stage PCR amplification approach for the production of arrayed DNA is attractive because it allows, in principal, the continued re-amplification of DNA fragments and facilitates further utilization of the DNA fragments for additional uses (e.g. over-expression of protein). We describe the successful construction and use of DNA microarrays by the two-stage amplification approach and discuss the technical challenges that were met and resolved during the project. RESULTS: Chimeric primers that contained both gene-specific and shared, universal sequence allowed the two-stage amplification of the 3,168 genes identified on the genome of Synechocystis sp. PCC6803, an important prokaryotic model organism for the study of oxygenic photosynthesis. The gene-specific component of the primer was of variable length to maintain uniform annealing temperatures during the 1st round of PCR synthesis, and situated to preserve full-length ORFs. Genes were truncated at 2 kb for efficient amplification, so that about 92% of the PCR fragments were full-length genes. The two-stage amplification had the additional advantage of normalizing the yield of PCR products and this improved the uniformity of DNA features robotically deposited onto the microarray surface. We also describe the techniques utilized to optimize hybridization conditions and signal-to-noise ratio of the transcription profile. The inter-lab transportability was demonstrated by the virtual error-free amplification of the entire genome complement of 3,168 genes using the universal primers in partner labs. The printed slides have been successfully used to identify differentially expressed genes in response to a number of environmental conditions, including salt stress. CONCLUSIONS: The technique detailed here minimizes the cost and effort to replicate a PCR-generated DNA gene fragment library and facilitates several downstream processes (e.g. directional cloning of fragments and gene expression as affinity-tagged fusion proteins) beyond the primary objective of producing DNA microarrays for global gene expression profiling.

Cyanobacteria↗

PubMed2004

Tracking repeats using significance and transitivity.

MOTIVATION: Internal repeats in coding sequences correspond to structural and functional units of proteins. Moreover, duplication of fragments of coding sequences is known to be a mechanism to facilitate evolution. Identification of repeats is crucial to shed light on the function and structure of proteins, and explain their evolutionary past. The task is difficult because during the course of evolution many repeats diverged beyond recognition. RESULTS: We introduce a new method TRUST, for ab initio determination of internal repeats in proteins. It provides an improvement in prediction quality as compared to alternative state-of-the-art methods. The increased sensitivity and accuracy of the method is achieved by exploiting the concept of transitivity of alignments. Starting from significant local suboptimal alignments, the application of transitivity allows us to (1) identify distant repeat homologues for which no alignments were found; (2) gain confidence about consistently well-aligned regions; and (3) recognize and reduce the contribution of non-homologous repeats. This re-assessment step enables us to derive a virtually noise-free profile representing a generalized repeat with high fidelity. We also obtained superior specificity by employing rigid statistical testing for self-sequence and profile-sequence alignments. Assessment was done using a database of repeat annotations based on structural superpositioning. The results show that TRUST is a useful and reliable tool for mining tandem and non-tandem repeats in protein sequence databases, capable of predicting multiple repeat types with varying intervening segments within a single sequence. AVAILABILITY: The TRUST server (together with the source code) is available at http://ibivu.cs.vu.nl/programs/trustwww

Algorithms↗

PubMed1984

Structural comparison of lactate dehydrogenase homologs differing in sensitivity to hydrostatic pressure.

The muscle-type (M4) lactate dehydrogenases (L-lactate: NAD+ oxidoreductase EC 1.1.1.27) of two teleost fishes, Sebastolobus alascanus and Sebastolobus altivelis , differ in the susceptibility of ligand binding to perturbation by moderate hydrostatic pressures. The enzyme homologs were purified by affinity chromatography. The amino-acid compositions of these enzymes are virtually identical. The proteins were digested with trypsin and the peptide mixtures mapped using reverse-phase HPLC. Although there was variation in elution times of some peaks, the amino-acid compositions of the fractions from the two profiles were highly similar. Only one clear difference in amino-acid composition was found and this peptide was sequenced using the manual dansyl-Edman method. The enzyme of S. alascanus , which is susceptible to pressure-perturbation, had a histidine at position 115; the S. altivelis enzyme had an asparagine. Ionization of histidine is affected by pressure and may be involved in the differences between the two lactate dehydrogenase homologs. There is no covalently bound phosphate associated with either enzyme, and thus phosphorylation cannot account for the differences between the enzyme homologs. Acquisition of pressure-tolerance appears to involve only minor changes in primary structure.

Amino Acid Sequence↗

PubMed1994

Consecutive mutations leading to the emergence in vivo of imipenem resistance in a clinical strain of Enterobacter aerogenes.

Three consecutive isolates of Enterobacter aerogenes were obtained from the blood cultures of a hospitalised patient who was receiving antibiotic therapy. The initial isolate possessed an inducible cephalosporinase and was susceptible to third-generation cephalosporins. After ceftazidime treatment, a second isolate resistant to this antibiotic and characterised by stable overproduction of the chromosomal beta-lactamase was obtained, and therapy was altered to a new combination which included imipenem. During this course of treatment, a strain of E. aerogenes was isolated that was resistant to virtually all beta-lactam agents including imipenem. Comparison of biotypes and ribotyping profiles indicated that the three isolates were probably derived from a single strain which had undergone several mutations during antibiotic exposure. Examination of outer-membrane protein (OMP) preparations and lipopolysaccharide (LPS) profiles showed that the imipenem-resistant isolate lacked a major OMP and high molecular mass LPS. Furthermore, this isolate displayed reduced permeability to cephaloridine compared with the initial isolate. The introduction of a plasmid carrying a wild-type ampD allele prevented cephalosporinase production and restored beta-lactam susceptibility in the imipenem-resistant isolate. It was concluded that stable derepression of class-I beta-lactamase production and reduced permeability are both required for expression of imipenem resistance in E. aerogenes, and that previous exposure to cephalosporins may encourage the emergence of such strains.

Aged↗

PubMed2001

Altered outward-rectifying K(+) current reveals microglial activation induced by HIV-1 Tat protein.

Microglial cells are believed to be one of the key elements in the development of the HIV-related neuropathology. Not only can microglial cells be productively infected by the virus, but they are also sensitive to viral proteins. Among them, the HIV-1 regulatory protein Tat, which was shown to have neurotoxic activity, is able to promote some proinflammatory functions of microglia. Considering that microglial activation goes along with a change of ion channel profile, we aimed to study whether Tat could influence microglial electrophysiology. When microglial cultures obtained from neonatal rats were treated with Tat (> or = 100 ng/ml), whole-cell recording showed the appearance of a large outwardly rectifying current (OR) virtually absent in untreated control cells. According to voltage dependence of the kinetic variables, K(+) permeability, and pharmacological sensitivity, the Tat-induced current was due to the presence of functional Kv1.3 channels. The effect of Tat was abolished by specific anti-Tat polyclonal antibody and by heat denaturation of Tat protein, confirming that the OR enhancement was due to the viral protein. Interestingly, the OR current induced by Tat was largely prevented by two inhibitors of the transcription factor NF-kappaB, TPCK and SN50, which suggests an involvement of NF-kappaB in the effect of the viral protein. The relatively high dose of Tat needed to observe an effect (> or = 100 ng/ml) might indicate that the action of Tat required entrance of the protein into the cell, rather than being mediated by a membrane receptor. In conclusion, the HIV-1 protein Tat is able to enhance OR K(+) current in rat microglia through a mechanism involving the activation of NF-kappaB. We propose that such effect of Tat could be part of the process of microglial activation known to take place in the brain of persons with neuro-AIDS.

Animals↗

PubMed1988

Immunochemical analysis of acetaminophen covalent binding to proteins. Partial characterization of the major acetaminophen-binding liver proteins.

A sensitive immunoassay for detecting acetaminophen (APAP) bound to proteins was developed using an affinity purified antibody directed against the N-acetylated end of the APAP molecule. Western blots of electrophoretically resolved liver proteins taken from mice given an hepatotoxic dose of APAP demonstrated that nearly 85% of the total detectable protein-bound APAP was covalently associated with proteins of 44 and 58 kD. Pretreatment of liver extracts with the sulfhydryl-specific reagent, N-ethylmaleimide (NEM), prior to derivatization with the reactive metabolite of APAP, N-acetyl-p-benzoquinone imine (NAPQI), greatly reduced immunochemically detectable APAP-protein adducts and indicated that the antibody detects protein-thiol conjugates of APAP. To investigate the basis of the binding selectivity in vivo, a variety of systems which yielded APAP-protein adducts were analyzed. Systems which activate APAP enzymatically, as in hepatocyte suspensions or in post-mitochondrial (S9) fractions fortified with an NADPH-regenerating system, resulted in a protein binding profile similar to that produced in vivo. Conversely, when extracts or cells were treated with chemically synthesized NAPQI, an alternative protein binding profile was obtained. Two-dimensional electrophoretic analysis of the reduced protein thiol (PSH) content of liver proteins using [3H]NEM labeling revealed that the 58 kD APAP-binding proteins were rich in PSH, whereas the major 44 kD binding protein had virtually no detectable PSH. Many PSH-rich proteins that were not arylated in vivo did bind NAPQI in vitro. However, the 44 kD proteins were not arylated when chemically synthesized NAPQI was added to homogenates or cell suspensions. The present data further suggest that, in addition to the amount and reactivity of free protein sulfhydryls, the cellular localization with respect to the cytochrome P-450 activation site may influence the susceptibility of proteins to NAPQI binding. These findings signal the need for caution in interpreting studies of APAP mechanisms that rely solely on NAPQI addition.

Acetaminophen↗

PubMed1976

A procedure for the quantitative recovery of homogeneous populations of undegraded free and bound polysomes from rat liver.

A procedure is described for the preparation of free and bound polysomes from whole homogenates of rat liver tissue. Liver is homogenized in a conventional medium containing glutathione; then after a 12-min centrifugation at 131000g, the free polysomes in the supernatant are saved, while the membrane-bound polysomes in the pellet are suspended in a mixture of ribonuclease inhibitors (cell sap, 250 mM KCl, and glutathione), homogenized in the presence of detergent (Triton X-100), centirfuged for 5 min at 1470g, decanted, and treated with deoxycholate; the polysomes in the two supernatants are harvested by centrifugation through sucrose gradients containing 250 mM KCl and cell sap. Free and bound polysomes prepared in this manner are undegraded, equally active in cell-free protein synthesis, and virtually free of ribonuclease, membranous material, glycogen, deoxycholate, completed protein, and cross-contamination. The recovery of polysomes is approximately 95% and the distribution between the free and membrane-bound state is 25 and 75%, respectively. The molecular weight profiles after sodium dodecyl sulfate-acrylamide gel electrophoresis of the polypeptides completed and released by free and bound polysomes in vitro are different, indicating that there are quantitative differences in the synthesis of various size polypeptides between the two polysome classes. The differential centrifugation procedure is rapid and reproducible, requires much less ultracentrifugation than the isopycnic technique, and provides a nearly quantitative means of separating free and bound polysomes.

Animals↗

PubMed1991

[Angioedema due to acquired complement-C1-inhibitor deficiency in a female patient with non-Hodgkin lymphoma and autoimmune hemolytic anemia].

A case of angioedema due to acquired deficiency of the regulatory protein C1-esterase-inhibitor (C1-INH) is reported. The edematous attack occurred 3 1/2 weeks after initiation of successful therapy for autoimmune-hemolytic anemia in the course of long-standing non-Hodgkin's lymphoma. At the time of acute edema the complement profile was typical: virtual absence of C1-INH function was associated with diminished concentrations of the components of the classical pathway of complement (C1q, C1r, C1s, C2, C4) and reduced complement hemolytic activity (CH50). Anti-C1-INH-autoantibodies were not detected. The angioedema lasted for about one week, and no further attacks occurred during the five-months follow-up period. Although there was only a minor adjustment to the therapy, the C1q, C2, C4 and CH50 values gradually increased to levels close to the lower limit of the normal range, while C1r and C1s showed normal values. In contrast to most other reports, this case was characterized by angioedema which was precipitated only after initiation of appropriate treatment for the underlying disease rather than before therapy or even diagnosis of the underlying disease.

Aged↗

PubMed2004

Loss of cyclin E requirement in cell growth of an oral squamous cell carcinoma cell line implies deregulation of its downstream pathway.

Cyclin E and Cdk2 have been shown to play an important role in G1/S transition of the cell cycle. Two E-type cyclins (E1 and E2) have been identified to date and share functionally similarities. Upregulation of these cyclins has been observed frequently in human cancers. We examined the expression profile of cyclin E1 and E2 in cell lines derived from human oral squamous cell carcinoma (SCC), and found that the expression of cyclin E1 protein was hardly detected in HSC-2 cells. Although cyclin E2 was abundantly expressed, histone H1 kinase activities of both E-type cyclins were virtually undetectable in this cell line. Inhibition of cyclin E1, but not that of E2, by using vectors expressing antisense-oriented their cDNAs induced drastic growth suppression on HOC313 cells that express both E-type cyclins. Inhibition of neither cyclin E1 nor E2 suppressed the growth of HSC-2 cells, and compensatory elevation of cyclin E1 was not evident in cyclin E2-inhibited HSC-2 cells. In contrast, HSC-2 cells expressed cyclin D1 and hyperphosphorylated forms of Rb family proteins, and were arrested in G1 by overexpression of p16(INK4), a specific inhibitor against D-type cyclin activity. These results indicate that HSC-2 cells lost proper growth control specifically mediated by cyclin E and suggest that deregulation of its downstream pathway may contribute to tumorigenesis of oral SCC.

Cell Division↗