Browsing by Subject "Nicotine"

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Open Access
Application of a customized pathway-focused microarray for gene expression profiling of cellular homeostasis upon exposure to nicotine in PC12 cells
(2004) Konu Ö.; Xu X.; Ma J.Z.; Kane J.; Wang J.; Shi, S.J.; Li, M.D.
Maintenance of cellular homeostasis is integral to appropriate regulation of cellular signaling and cell growth and division. In this study, we report the development and quality assessment of a pathway-focused microarray comprising genes involved in cellular homeostasis. Since nicotine is known to have highly modulatory effects on the intracellular calcium homeostasis, we therefore tested the applicability of the homeostatic pathway-focused microarray on the gene expression in PC-12 cells treated with 1 mM nicotine for 48 h relative to the untreated control cells. We first provided a detailed description of the focused array with respect to its gene and pathway content and then assessed the array quality using a robust regression procedure that allows for the exclusion of unreliable measurements while decreasing the number of false positives. As a result, the mean correlation coefficient between duplicate measurements of the arrays used in this study (control vs. nicotine treatment, three samples each) has increased from 0.974±0.017 to 0.995±0.002. Furthermore, we found that nicotine affected various structural and signaling components of the AKT/PKB signaling pathway and protein synthesis and degradation processes in PC-12 cells. Since modulation of intracellular calcium concentrations ([Ca2+]i) and phosphatidylinositol signaling are important in various biological processes such as neurotransmitter release and tissue pathogenesis including tumor formation, we expect that the homeostatic pathway-focused microarray potentially can be used for the identification of unique gene expression profiles in comparative studies of drugs of abuse and diverse environmental stimuli, such as starvation and oxidative stress. © 2003 Elsevier B.V. All rights reserved.
Open Access
Investigation of the effects of nicotine on the expression profile of SW620 colon adenocarcinoma cells using a functional genomics approach
(2009) Kaya, Onur
Colon cancer is the third most common form of cancer with approximately 655,000 deaths worldwide annually and the second principal cause of cancer-related death in the Western world. Studies focusing on genomic instability and cell culture in recent years have shown that there is a statistically significant link between tobacco smoking and colorectal cancer. Although nicotine is one of the most potent chemical in tobacco, it was not studied extensively in colorectal cancers. Nicotine works as an agonist of nicotinic acetylcholine receptors and modulates the intracellular calcium concentrations hence deregulating multiple signal transduction pathways (e.g., PI3K/AKT, MAPK, mTOR). It has been shown that nicotine accelerates cell proliferation while it increases cell migration, metastasis and angiogenesis, and inhibits apoptosis in lung and gastric cancers. The aim of this study was to give more insight into the association between nicotine and colon cancer by investigating the gene expression profiles of SW620 colon adenocarcinoma cells under 48h 1µM nicotine treatment at different serum levels to reflect molecular response to growth factor-induced and –depleted conditions (10% FBS or 0.1% FBS). We used multiple approaches including cell culture techniques, microarray technology, and gene-network analysis to assess the effects of nicotine on cell proliferation and transcriptome profile. Furthermore, the selected genes that are involved in cell cycle and apoptosis were used to confirm and evaluate the transcriptome analysis results with real time qRT-PCR and Western Blot techniques. In this project, our findings indicated that serum starvation of SW620 colon adenocarcinoma cell line resulted in decreased cell proliferation, which could be rescued by 1µM nicotine via deregulation of multiple pathways including cell cycle, apoptosis, Ca2+ signaling, and ribosomal protein expression. This study implicated that nicotine-, thus acetylcholine-mediated signaling may have an important role in tumor development and metastasis.
Open Access
Nicotine coregulates multiple pathways involved in protein modification/degradation in rat brain
(Elsevier, 2004) Kane, J. K.; Konu, Özlem; Ma, J. Z.; Li, M. D.
Previously, we used cDNA microarrays to demonstrate that the phosphatidylinositol and MAP kinase signaling pathways are regulated by nicotine in different rat brain regions. In the present report, we show that, after exposure to nicotine for 14 days, ubiquitin, ubiquitin-conjugating enzymes, 20S and 19S proteasomal subunits, and chaperonin-containing TCP-1 protein (CCT) complex members are upregulated in rat prefrontal cortex (PFC) while being downregulated in the medial basal hypothalamus (MBH). In particular, relative to saline controls, ubiquitins B and C were upregulated by 33% and 47% (P<0.01), respectively, in the PFC. The proteasome beta subunit 1 (PSMB1) and 26S ATPase 3 (PSMC3) genes were upregulated in the PFC by 95% and 119% (P<0.001), respectively. In addition to the protein degradation pathway of the ubiquitin-proteasome complexes, we observed in the PFC an increase in the expression of small, ubiquitin-related modifiers (SUMO) 1 and 2 by 80% and 33%, respectively (P<0.001), and in 3 of 6 CCT subunits by up to 150% (P<0.0001). To a lesser extent, a change in the opposite direction was obtained in the expression of the same gene families in the MBH. Quantitative real-time RT-PCR was used to validate the microarray results obtained with some representative genes involved in these pathways. Taken together, our results suggest that, in response to systemic nicotine administration, the ubiquitin-proteasome, SUMO, and chaperonin complexes provide an intricate control mechanism to maintain cellular homeostasis, possibly by regulating the composition and signaling of target neurons in a region-specific manner.
Open Access
Regulation of Homer and group I metabotropic glutamate receptors by nicotine
(Wiley-Blackwell Publishing Ltd., 2005) Kane, J. K.; Hwang, Y.; Konu, O.; Loughlin, S. E.; Leslie, F. M.; Li, M. D.
The present study focuses on the nicotine-induced modulation of mRNA and protein expression of a number of genes involved in glutamatergic synaptic transmission in rat brain over different time periods of exposure. A subchronic (3 days) but not the chronic (7 or 14 days) administration of nicotine resulted in the up-regulation of Homer2a/b mRNA in the amygdala while in the ventral tegmental area (VTA) no change in expression of either Homer2a/b or Homer1b/c was observed. Although the increase in Homer2a/b mRNA was not translated into the protein level in the amygdala, a slight but significant up-regulation of Homer1b/c protein was observed in the same region at day 3. Both Homer forms were up-regulated at the protein level in the VTA at day 3. In the nucleus accumbens, 14 days of nicotine treatment up-regulated mRNA of Homer2b/c by 68.2% (P < 0.05), while the short form Homer1a gene was down-regulated by 65.0% at day 3 (P < 0.05). In regard to other components of the glutamatergic signalling, we identified an acute and intermittent increase in the mRNA and protein levels of mGluR1 and mGluR5 in the amygdala. In the VTA, however, the effects of nicotine on mGluR mRNA expression were long-lasting but rather specific to mGluR1. Nevertheless, mGluR1 protein levels in the VTA area were up-regulated only at day 3, as in the amygdala. These data provide further evidence for the involvement of nicotine in the glutamatergic neuronal synaptic activity in vivo, suggesting a role for the newly identified Homer proteins in this paradigm.
Open Access
Smoking and nicotine alter UGT1A expression
(2011) Ölmezer, Gizem
The expression and activity of enzymes taking role in drug metabolism are important as in the case of phase II glucuronidation enzymes; namely UDPglucuronosyltransferases (UGTs). Previously, it has been identified that smoking upregulates the expression of UGT enzymes in oral mucosa. We asked whether smoking induces UGT1A expression in other tissues and re-analyzed publically available datasets run with samples from smokers and non-smokers. It was observed that UGT1A enzymes were overexpressed in several types of epithelial cells of smokers. 30% of nicotine metabolism is performed by UGT enzymes; however, whether UGT1A expression is modulated by nicotine, the addictive component of tobacco smoke, is not known. For this purpose, the expression levels of UGT1A isoforms were measured using Real-Time PCR in nicotine treated SW620 colorectal cancer cells. Our findings showed that nicotine’s effect on UGT1A expression was isoform specific; and the magnitude of modulation differed among isoforms. Furthermore, the upregulation of UGT1A enzymes could only be observed in serum-deprived SW620 cells. In summary, nicotine metabolism enzymes are regulated by both smoking in vivo and nicotine in vitro. Nevertheless, enhanced xenobiotic metabolism may result in chemoresistance, which is undesirable for cancer patients. Therefore, before drug therapy cancer patients might be analyzed in terms of their smoking status and UGT1A expression patterns.
Open Access
Strain-and region-specific gene expression profiles in mouse brain in response to chronic nicotine treatment
(Wiley-Blackwell Publishing, 2008) Wang, J.; Gutala, R.; Hwang, Y. Y.; Kim J. -M.; Konu, O.; Ma, J. Z.; Li, M. D.
A pathway-focused complementary DNA microarray and gene ontology analysis were used to investigate gene expression profiles in the amygdala, hippocampus, nucleus accumbens, prefrontal cortex (PFC) and ventral tegmental area of C3H/HeJ and C57BL/6J mice receiving nicotine in drinking water (100 μg/ml in 2% saccharin for 2 weeks). A balanced experimental design and rigorous statistical analysis have led to the identification of 3.5-22.1% and 4.1-14.3% of the 638 sequence-verified genes as significantly modulated in the aforementioned brain regions of the C3H/HeJ and C57BL/6J strains, respectively. Comparisons of differential expression among brain tissues showed that only a small number of genes were altered in multiple brain regions, suggesting presence of a brain region-specific transcriptional response to nicotine. Subsequent principal component analysis and Expression Analysis Systematic Explorer analysis showed significant enrichment of biological processes both in C3H/HeJ and C57BL/6J mice, i.e. cell cycle/proliferation, organogenesis and transmission of nerve impulse. Finally, we verified the observed changes in expression using real-time reverse transcriptase polymerase chain reaction for six representative genes in the PFC region, providing an independent replication of our microarray results. Together, this report represents the first comprehensive gene expression profiling investigation of the changes caused by nicotine in brain tissues of the two mouse strains known to exhibit differential behavioral and physiological responses to nicotine.