PubMed Health⌕ Search

Biomedical subjects

David Gold

Publications and source records attributed to David Gold.

9 recordsLinked to original sources
PubMed2004

Genes affecting the cell cycle, growth, maintenance, and drug sensitivity are preferentially regulated by anti-HER2 antibody through phosphatidylinositol 3-kinase-AKT signaling.

The molecular mechanisms by which the anti-HER2 antibodies trastuzumab and its murine equivalent 4D5 inhibit tumor growth and potentiate chemotherapy are not fully understood. Inhibition of signaling through the phosphatidylinositol 3-kinase (PI3K)-AKT pathway may be particularly important. Treatment of breast cancer cells that overexpress HER2 with trastuzumab inhibited HER2-HER3 association, decreased PDK1 activity, reduced Thr-308 and Ser-473 phosphorylation of AKT, and reduced AKT enzymatic activity. To place the role of PI3K-AKT in perspective, gene expression was studied by using Affymetrix microarrays and real time reverse transcription-PCR. Sixteen genes were consistently down-regulated 2.0-4.9-fold in two antibody-treated breast cancer cell lines. Fourteen of the 16 genes were involved in three major functional areas as follows: 7 in cell cycle regulation, particularly of the G(2)-M; 5 in DNA repair/replication; and 2 in modifying chromatin structure. Of the 16 antibody-regulated genes, 64% had roles in cell growth/maintenance and 52% contributed to the cell cycle. Direct inhibition of PI3K with an inhibitor markedly reduced expression of 14 genes that were also affected by the antibody. Constitutive activation of AKT1 blocked the effect of the anti-HER2 antibody on cell cycle arrest and on eight differentially expressed genes. The antibody enhanced docetaxel-induced growth inhibition but did not increase the fraction of apoptotic cells induced with docetaxel alone. In contrast, the antibody plus docetaxel markedly down-regulated two genes, HEC and DEEPEST, required for passage through G(2)-M. Thus, anti-HER2 antibody preferentially affects genes contributing to cell cycle progression and cell growth/maintenance, in part through the PI3K-AKT signaling. Transcriptional regulation by anti-HER2 antibody through PI3K-AKT pathway may potentiate the growth inhibitory activity of docetaxel by affecting cell cycle progression.

Antibodies, Monoclonal↗
PubMed2004

A comparative analysis of data generated using two different target preparation methods for hybridization to high-density oligonucleotide microarrays.

BACKGROUND: To generate specific transcript profiles, one must isolate homogenous cell populations using techniques that often yield small amounts of RNA, requiring researchers to employ RNA amplification methods. The data generated by using these methods must be extensively evaluated to determine any technique dependent distortion of the expression profiles. RESULTS: High-density oligonucleotide microarrays were used to perform experiments for comparing data generated by using two protocols, an in vitro transcription (IVT) protocol that requires 5 microg of total RNA and a double in vitro transcription (dIVT) protocol that requires 200 ng of total RNA for target preparation from RNA samples extracted from a normal and a cancer cell line. In both cell lines, about 10% more genes were detected with IVT than with dIVT. Genes were filtered to exclude those that were undetected on all arrays. Hierarchical clustering using the 9,482 genes that passed the filter showed that the variation attributable to biological differences between samples was greater than that introduced by differences in the protocols. We analyzed the behavior of these genes separately for each protocol by using a statistical model to estimate the posterior probability of various levels of fold change. At each level, more differentially expressed genes were detected with IVT than with dIVT. When we checked for genes that had a posterior probability greater than 99% of fold change greater than 2, in data generated by IVT but not dIVT, more than 60% of these genes had posterior probabilities greater than 90% in data generated by dIVT. Both protocols identified the same functional gene categories to be differentially expressed. Differential expression of selected genes was confirmed using quantitative real-time PCR. CONCLUSION: Using nanogram quantities on total RNA, the usage of dIVT protocol identified differentially expressed genes and functional categories consistent with those detected by the IVT protocol. There was a loss in sensitivity of about 10% when detecting differentially expressed genes using the dIVT protocol. However, the lower amount of RNA required for this protocol, as compared to the IVT protocol, renders this methodology a highly desirable one for biological systems where sample amounts are limiting.

Algorithms↗
PubMed2004

PXR and the regulation of apoA1 and HDL-cholesterol in rodents.

Orphan nuclear receptors (ONRs) have been implicated in the regulation of lipids. Several clinical studies conducted either prospectively or epidemiologically have pointed to a link between the regulation of hepatic CYP enzymes and HDL-cholesterol (HDL-C) and/or apolipoprotein A1 (apoA1). The treatment of rats with a series of imidazole inducers of CYP3A yielded correlations between in vitro CYP3A activity measured as erythromycin demethylase activity and plasma HDL-C and hepatic apoA1 mRNA. Similarly, a correlation was established between in vivo CYP3A activity, measured as ethosuximide clearance, and plasma HDL-C and hepatic apoA1 mRNA. The treatment of wild-type (WT) mice with PXR agonists elicited increases in serum HDL-C and serum apoA1 levels. On the other hand, the treatment of PXR-knockout mice (PXR-KOs) with the same PXR agonists failed to elicit increases in either serum HDL-C or serum apoA1 levels. Superposition of the structures of three imidazoles known to be active CYP3A inducers in rats with the human PXR pharmacophore demonstrated a partial fit and predicted EC(50) values typical of weak-moderate hPXR inducers in humans. These imidazoles have been shown to increase apoA1 and HDL-C in rats and mice. Taken together, these data suggest that PXR plays an important role in the regulation of apoA1 and HDL-C in rodents.

Animals↗
PubMed2004

Establishment and characterization of a new mantle cell lymphoma cell line M-1.

A new mantle cell lymphoma cell line, M-1, was established from peripheral blood mononuclear cells of a patient with a diagnosis of blastoid variant of mantle cell lymphoma in leukemic phase. This cell line showed cell surface antigens identical to the original tumor and demonstrated the profile of a mature B-cell phenotype typical of mantle cell lymphoma: positive for CD5, CD19, CD20, sIgM and FMC7, and negative for CD3, CD10 and CD23. Cytogenetically, the M-1 cell line showed chromosomal alterations similar to the initial clinical specimen, among which a translocation t(11;14) (q13;q32) resulting in the overexpression of cyclin D1 as well as additional abnormalities involving chromosomes 3, 9 and 10. This cell line was used as a model to investigate the activity of the three drugs doxorubicin, cyclophosphamide and vincristine, commonly used in the treatment of mantle cell lymphoma patients. The effect of the drugs was evaluated by a 24 h cytotoxicity test and a 7-days anti-proliferation test using a microculture tetrazolium-based assay (MTT). Both assays indicated a higher sensitivity of the cell line to vincristine when compared to doxorubicin and cyclophosphamide. The characterization of a new mantle cell lymphoma cell line is a unique tool for studying the biology of this subtype of lymphoma for which only a few cell lines have been established.

Antigens, Surface↗
PubMed2003

Activation of peroxisome proliferator-activated receptor gamma by a novel synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid induces growth arrest and apoptosis in breast cancer cells.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormonal receptor superfamily expressed in a large number of human cancers. Here, we demonstrate that PPARgamma is expressed and transcriptionally active in breast cancer cells independent of their p53, estrogen receptor, or human epidermal growth factor receptor 2 status. 2-Cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO), a novel synthetic triterpenoid, is a ligand for PPARgamma. We investigated the molecular mechanisms of CDDO on proliferation and apoptosis in breast cancer cells. In all breast cancer cell lines studied, CDDO transactivated PPARgamma, induced dose- and time-dependent cell growth inhibition, cell cycle arrest in G(1)-S and G(2)-M, and apoptosis. We then used differential cDNA array analysis to investigate the molecular changes induced by CDDO. After 16-h exposure of MCF-7 and MDA-MB-435 cells to CDDO, we found genes encoding the following proteins to be up-regulated in both cell lines: p21(Waf1/CIP1); GADD153; CAAT/enhancer binding protein transcription factor family members; and proteins involved in the ubiquitin-proteasome pathway. Among the down-regulated genes, we focused on the genes encoding cyclin D1, proliferating cell nuclear antigen, and the insulin receptor substrate 1. Using Western blot analysis and/or real-time PCR, we confirmed that CDDO regulated the expression of cyclin D1, p21(Waf1/CIP1), and Bcl-2. Cyclin D1 and p21(Waf1/CIP1) were additionally confirmed as important mediators of CDDO growth inhibition in genetically modified breast cancer cell lines. CDDO was able to significantly reduce the growth of MDA-MB-435 tumor cells in immunodeficient mice in vivo. The finding that CDDO can target genes critical for the regulation of cell cycle, apoptosis, and breast carcinogenesis suggests usage of CDDO as novel targeted therapy in breast cancer.

Animals↗
PubMed2003

A comprehensive approach to the analysis of matrix-assisted laser desorption/ionization-time of flight proteomics spectra from serum samples.

For our analysis of the data from the First Annual Proteomics Data Mining Conference, we attempted to discriminate between 24 disease spectra (group A) and 17 normal spectra (group B). First, we processed the raw spectra by (i) correcting for additive sinusoidal noise (periodic on the time scale) affecting most spectra, (ii) correcting for the overall baseline level, (iii) normalizing, (iv) recombining fractions, and (v) using variable-width windows for data reduction. Also, we identified a set of polymeric peaks (at multiples of 180.6 Da) that is present in several normal spectra (B1-B8). After data processing, we found the intensities at the following mass to charge (m/z) values to be useful discriminators: 3077, 12 886 and 74 263. Using these values, we were able to achieve an overall classification accuracy of 38/41 (92.6%). Perfect classification could be achieved by adding two additional peaks, at 2476 and 6955. We identified these values by applying a genetic algorithm to a filtered list of m/z values using Mahalanobis distance between the group means as a fitness function.

Blood Proteins↗
PubMed2003

Semantic category differences in cross-form priming.

Findings of category-specific impairments have suggested that human semantic memory may be organized around a living/nonliving dichotomy. In order to assess implicit memory performance for living and nonliving concepts, one group of neurologically intact individuals participated in a cross-form conceptual priming paradigm. In Block 1, pictures primed words while in Block 2 words were used to prime pictures. Across all phases of the experiment, subjects decided whether items represented something which was living or nonliving, and response times were recorded. Results revealed greater priming for living concepts across both blocks. Greater priming for living concepts may have occurred because of increased or prolonged conceptual activation of these concepts. Results are discussed in the context of theoretical accounts of the category-specific impairments observed in brain-damaged populations.

Adolescent↗
PubMed2003

Optimization of access-port placement for the lap-band system.

BACKGROUND: The technical aspects of access-port (AP) placement are not generally described in Lap-Band series. METHODS: From November 2000 to April 2002, we performed Lap-Band procedures laparoscopically on 180 patients. A retrospective review was conducted of 3 consecutive AP-placement techniques in nonselected and demographically identical groups. In Group A (n=48, Nov. 2000 to July 2001), the AP was placed at the left subcostal margin. In Group B (n=23, Aug. 2001 to Sept. 2001), the AP was tunneled over the subcostal fascia towards the subxiphoid area. In Group C (n=109, Oct. 2001 to Apr. 2002), the AP tubing was tunneled over the subcostal fascia and connected to the AP, which was inserted through a 3-cm subxiphoid incision. RESULTS: AP-related problems occurred within the first few months following surgery. In Group A, 24 of the APs (50%) were tilted, and 14 (29%) were completely flipped over. 11 APs (23%) were found to be broken. 19 patients (40%) underwent an additional AP-related procedure. In group B, 12 APs (52%) were tilted and 1 patient required surgery to turn the AP. In Group C, 8 APs (7%) were turned slightly. 1 AP was found to be broken and required surgery to replace it. In this group, all APs were accessible for adjustment in the office. CONCLUSIONS: Tunneling the AP along the left subcostal area is an important technique to protect the AP system from breakage, by changing AP-tube position from vertical to horizontal in relation to abdominal wall movement. This technique also keeps the AP-tube connection over the fascia and protects it from "wear and tear" forces. The addition of fixation at the subxiphoid location helps maintain a straight orientation of the AP for easier adjustments.

Adult↗