Biomedical subjects

Lawrence M Gelbert

Publications and source records attributed to Lawrence M Gelbert.

4 recordsLinked to original sources

PubMed2005

Transcriptional profiling of keratinocytes reveals a vitamin D-regulated epidermal differentiation network.

1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] regulates mineral homeostasis and exhibits potent anti-proliferative, prodifferentiative, and immunomodulatory activities. It mediates these effects by binding to the vitamin D receptor (VDR), which belongs to the superfamily of steroid/thyroid hormone nuclear receptors. As a result of keratinocyte differentiation and anti-proliferation activities, 1,25(OH)(2)D(3) and its synthetic analogs are therapeutically effective in psoriasis and show promise for the treatment of actinic keratosis and squamous cell carcinoma. To elucidate the VDR signaling pathway in keratinocytes, we examined the gene expression profile with 1,25(OH)(2)D(3) treatment using oligonucleotide microarrays. Out of the 12,600 genes investigated, 82 were upregulated and 16 were downregulated and many of these were involved in differentiation, proliferation, and immune response. We have identified three vitamin D-responsive chromosomal loci (1p36, 19q13, and 6p25) and show the induction of various class II tumor suppressor/growth-regulatory genes in response to 1,25(OH)(2)D(3). Finally, quantitative differences in gene expression revealed a vitamin D-regulated differentiation network and identified peptidylarginine deiminases, kallikreins, serine proteinase inhibitor family members, Kruppel-like factor 4, and c-fos as vitamin D-responsive genes, whose protein products may play an important role in epidermal differentiation in normal and diseased state.

Calcitriol↗

PubMed2004

An increase in the expression of ribonucleotide reductase large subunit 1 is associated with gemcitabine resistance in non-small cell lung cancer cell lines.

The mechanisms of resistance to the antimetabolite gemcitabine in non-small cell lung cancer have not been extensively evaluated. In this study, we report the generation of two gemcitabine-selected non-small cell lung cancer cell lines, H358-G200 and H460-G400. Expression profiling results indicated that there was evidence for changes in the expression of 134 genes in H358-G200 cells compared with its parental line, whereas H460-G400 cells exhibited 233 genes that appeared to be under- or overexpressed compared with H460 cells. However, only the increased expression of ribonucleotide reductase subunit 1 (RRM1), which appeared in both resistant cell lines, met predefined analysis criteria for genes to investigate further. Quantitative PCR analysis demonstrated H358-G200 cells had a greater than 125-fold increase in RRM1 RNA expression. Western blot analysis confirmed high levels of RRM1 protein in this line compared with the gemcitabine-sensitive parent. No significant change in the expression of RRM2 was observed in either cell line, although both gemcitabine-resistant cell lines had an approximate 3-fold increase in p53R2 protein. A partial revertant of H358-G200 cells had reduced levels of RRM1 protein (compared with G200 cells), without observed changes in RRM2 or p53R2. In vitro analyses of ribonucleotide reductase activity demonstrated that despite high levels of RRM1 protein, ribonucleotide reductase activity was not increased in H358-G200 cells when compared with parental cells. The cDNA encoding RRM1 from H358-G200 cells was cloned and sequenced but did not reveal the presence of any mutations. The results from this study indicate that the level of RRM1 may affect gemcitabine response. Furthermore, RRM1 may serve as a biomarker for gemcitabine response.

Antimetabolites, Antineoplastic↗

PubMed2004

Phencyclidine-induced changes in rat cortical gene expression identified by microarray analysis: implications for schizophrenia.

Acute phencyclidine induces schizophrenia-like symptoms in healthy humans and psychotic episodes in schizophrenics. Although phencyclidine is known as a N-methyl d-aspartate receptor antagonist (NMDA-R), the molecular events underlying the behavioral symptoms remain largely unknown. Statistical analysis of oligonucleotide microarray data was used to identify phencyclidine-induced alterations in rat cortical gene expression. Acute phencyclidine produced a statistically significant change in 477 genes in rat prefrontal cortex (PFC), a brain area associated with cognitive dysfunction in schizophrenics. Real-time quantitative PCR (RTQ-PCR) confirmed a subset of these changes ranging from -59% to 255% (smallest confirmation: -19%). Subsequent time-course and dose-response studies using RTQ-PCR confirmed and extended the original microarray results. At the molecular level, genes altered by phencyclidine are related to diverse biological processes including stress, inflammatory response, growth and development, neural plasticity and signal transduction. Further analysis, aimed at assessing the relevance of our results to schizophrenia, revealed dysregulation of genes related to: (i) thalamocortical projections, (ii) neurotransmission and neuromodulation, (iii) thyroid hormone activity, (iv) oligodendrocyte linage, (v) brain lipid metabolism, (vi) sleep architecture and (viii) the velocardiofacial syndrome.

Animals↗

PubMedDate not supplied

Optimization and validation of small quantity RNA profiling for identifying TNF responses in cultured human vascular endothelial cells.

INTRODUCTION: Affymetrix oligonucleotide microarrays are widely used in basic and applied research (Lander, E.S., (1999). Array of hope. Nature Genetics 21, 3-4; Lockhart, D.J. & Winzeler, E.A. (2000) Genomics, gene expression and DNA arrays. Nature 405, 827-836.) The need for a significant amount of starting RNA has limited its use in applications where the amount of RNA is limiting, such as with Laser Captured Microdissection (LCM), small biopsies, or peripheral blood in rodent models. To overcome this limitation, various RNA amplification and labeling methods have been described, however, further optimization and validation of these methods are needed. METHODS: Here we reported using the Arcturus technology to optimize amplification and labeling of small amounts of RNA for Affymetrix microarray studies. We assessed the technical feasibility and variation introduced by differences in starting RNA quantity and differences in technical performance by microarray hybridization. RESULTS: We demonstrated that the current approach is reliable to amplify as little as 40 ng total RNA, and it is suitable for Affymetrix studies yielding satisfactory quantitative chip performance. We also showed that differences in labeling methods contribute more to variation than the differences in starting RNA quantity per se. As a model, we studied the well-documented TNF-induced inflammatory responses in cultured human vascular endothelial cells. We were able to recapitulate the TNF-induced responses using small RNA sample profiling.

Algorithms↗