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Biomedical subjects

Shawn E Levy

Publications and source records attributed to Shawn E Levy.

7 recordsLinked to original sources
PubMed2006

Antiproliferative agents alter vascular plasminogen activator inhibitor-1 expression: a potential prothrombotic mechanism of drug-eluting stents.

OBJECTIVE: Drug eluting stents (DES) reduce the incidence of restenosis after coronary angioplasty. Enthusiasm has been tempered by a possible increased risk of in-stent thrombosis. We examined the effects of paclitaxel and rapamycin on the endothelial transcriptome to identify alterations in gene expression associated with thrombosis. METHODS AND RESULTS: Gene expression profiling was performed on human coronary artery endothelial cells treated with rapamycin or paclitaxel. Plasminogen activator inhibitor-1 (PAI-1) was the most consistently induced transcript in rapamycin-treated human coronary artery endothelial cells. RT-PCR and ELISA were performed to confirm positive findings. Transgenic mice engineered to express enhanced green fluorescent protein under control of the human PAI-1 promoter were also treated. Rapamycin and paclitaxel treated endothelial cells produced dose-dependent increases in PAI-1. There was a variable effect on endothelial tissue-type plasminogen activator (t-PA) expression. Enhanced expression of PAI-1 and enhanced green fluorescent protein were detected in coronary arteries, the aorta, and kidney of the mice. CONCLUSIONS: Antiproliferative agents stimulate the expression of prothrombotic genes. PAI-1 expression may also play a role in the prevention of restenosis through an antimigratory mechanism. The effects of antiproliferatives on vascular gene expression deserve further scrutiny in view of the increasing utilization of drug-eluting stents.

Animals↗
PubMed2006

Analysis of host- and tumor-derived proteinases using a custom dual species microarray reveals a protective role for stromal matrix metalloproteinase-12 in non-small cell lung cancer.

We used a customized Affymetrix protease microarray (Hu/Mu ProtIn chip) designed to distinguish human and mouse genes to analyze the expression of proteases and protease inhibitors in lung cancer. Using an orthotopic lung cancer model, we showed that murine matrix metalloproteinase (MMP)-12, MMP-13, and cathepsin K were up-regulated in tumor tissue compared with normal mouse lung. To determine the relevance of stromal proteases detected using this model system, we compared the results to an analysis of human lung adenocarcinoma specimens using the U133 Plus 2.0 Affymetrix microarray. MMP-12, MMP-13, and cathepsin K showed an increase in expression in human tumors compared with normal lung similar to that seen in the orthotopic model. Immunohistochemical analysis confirmed MMP-12 expression in the stroma of human lung tumor samples. To determine the biological relevance of stromal MMP-12, murine Lewis lung carcinoma cells were injected into the tail vein of syngeneic wild-type (WT) and MMP-12-null mice. MMP-12-null and WT mice developed equivalent numbers of lung tumors; however, there was a 2-fold increase in the number of tumors that reached >2 mm in diameter in MMP-12-null mice compared with WT controls. The increase in tumor size correlated with an increase in CD31-positive blood vessels and a decrease in circulating levels of the K1-K4 species of angiostatin. These results show a protective role for stromal MMP-12 in lung tumor growth. The use of the Hu/Mu ProtIn chip allows us to distinguish tumor- and host-derived proteases and guides the further analysis of the significance of these genes in tumor progression.

Animals↗
PubMed2005

Gene expression profile analysis of mouse colon embryonic development.

During late embryogenesis, the mouse colon develops from a pseudostratified, undifferentiated endoderm to a single-layered columnar epithelium with accompanying mesenchymal maturation. To identify regulatory genetic programs underlying these morphological changes, we profiled gene expression of the developing mouse colon by microarray from embryonic day (E)13.5 to E18.5. Unbiased cluster analysis of 13,484 cDNA elements revealed two distinct groups of genes whose expression changes reflect the dynamic morphological events of the epithelium and mesenchyme during this period. Additional analyses revealed two subsets of genes whose expression is either upregulated or downregulated over the same developmental period. Of those genes whose expression increases from E13.5 to E18.5 (n = 158), known functions include acquisition and/or maintenance of colonic differentiation. Genes whose transcription is downregulated over this period (n = 49) have demonstrated roles in nuclear organization, transcriptional regulation, and cell proliferation. These results provide the basis for a molecular portrait of colonic development during late embryogenesis and should be a valuable resource for investigators interested in colonic development and neoplasia, as well as comparative organogenesis.

Animals↗
PubMed2004

The ADP/ATP translocator is not essential for the mitochondrial permeability transition pore.

A sudden increase in permeability of the inner mitochondrial membrane, the so-called mitochondrial permeability transition, is a common feature of apoptosis and is mediated by the mitochondrial permeability transition pore (mtPTP). It is thought that the mtPTP is a protein complex formed by the voltage-dependent anion channel, members of the pro- and anti-apoptotic BAX-BCL2 protein family, cyclophilin D, and the adenine nucleotide (ADP/ATP) translocators (ANTs). The latter exchange mitochondrial ATP for cytosolic ADP and have been implicated in cell death. To investigate the role of the ANTs in the mtPTP, we genetically inactivated the two isoforms of ANT in mouse liver and analysed mtPTP activation in isolated mitochondria and the induction of cell death in hepatocytes. Mitochondria lacking ANT could still be induced to undergo permeability transition, resulting in release of cytochrome c. However, more Ca2+ than usual was required to activate the mtPTP, and the pore could no longer be regulated by ANT ligands. Moreover, hepatocytes without ANT remained competent to respond to various initiators of cell death. Therefore, ANTs are non-essential structural components of the mtPTP, although they do contribute to its regulation.

Adenine Nucleotide Translocator 1↗
PubMed2004

Proteome analysis of human colon cancer by two-dimensional difference gel electrophoresis and mass spectrometry.

Two-dimensional difference gel electrophoresis (2-D DIGE) coupled with mass spectrometry (MS) was used to investigate tumor-specific changes in the proteome of human colorectal cancers and adjacent normal mucosa. For each of six patients with different stages of colon cancer, Cy5-labeled proteins isolated from tumor tissue were combined with Cy3-labeled proteins isolated from neighboring normal mucosa and separated on the same 2-D gel along with a Cy2-labeled mixture of all 12 normal/tumor samples as an internal standard. Over 1500 protein spot-features were analyzed in each paired normal/tumor comparison, and using DIGE technology with the mixed-sample internal standard, statistically significant quantitative comparisons of each protein abundance change could be made across multiple samples simultaneously without interference due to gel-to-gel variation. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and tandem (TOF/TOF) MS provided sensitive and accurate mass spectral data for database interrogation, resulting in the identification of 52 unique proteins (including redundancies due to proteolysis and post-translationally modified isoforms) that were changing in abundance across the cohort. Without the benefit of the Cy2-labeled 12 sample mixture internal standard, 42 of these proteins would have been overlooked due to the large degree of variation inherent between normal and tumor samples.

Adult↗
PubMed2003

Microarray analysis in drug discovery: an uplifting view of depression.

Genomic profiling provides insights into drug evaluation for diseases without defined molecular mechanisms or cellular assays. Levy provides a brief background in the development of microarray analysis and discussion of the application of this technique to pharmacogenomics. Highlighted is the microarray analysis of primary human neurons treated with antidepressants, antipsychotics, or opioid receptor agonists, demonstrating that these classes of drugs can be properly categorized by using two different statistical analysis methods: classification tree and random forest. Not only is microarray analysis valuable for drug evaluation and leading candidate development, but the genes identified as markers for the various drug classifications point to new directions for research into the underlying pathways responsible for human diseases, such as depression and psychosis.

Animals↗