title: NSAID-activated gene-1 as a molecular target for capsaicin-induced apoptosis through a novel molecular mechanism involving GSK3beta, C/EBPbeta and ATF3.
abstract: Capsaicin, a natural product of the Capsicum species of red peppers, is known to induce apoptosis and suppress growth. Non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) is a cytokine associated with pro-apoptotic and antitumorigenic property in colorectal and lung cancer. Our data demonstrate that capsaicin leads to induction of apoptosis and up-regulates NAG-1 gene expression at the transcriptional level. Overexpression of CCAAT/enhancer binding protein beta (C/EBPbeta) caused a significant increase of basal and capsaicin-induced NAG-1 promoter activity. We subsequently identified C/EBPbeta binding sites in the NAG-1 promoter responsible for capsaicin-induced NAG-1 transactivation. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed binding of C/EBPbeta to the NAG-1 promoter. Capsaicin treatment resulted in an increase of phosphorylated serine/threonine residues on C/EBPbeta, and the immunoprecipitation study showed that capsaicin enhanced binding of C/EBPbeta with glycogen synthase kinase 3beta (GSK3beta) and activating transcription factor 3 (ATF3). The phosphorylation and interaction of C/EBPbeta with GSK3beta and ATF3 are decreased by the inhibition of the GSK3beta and Protein Kinase C pathways. Knockdown of C/EBPbeta, GSK3beta or ATF3 ameliorates NAG-1 expression induced by capsaicin treatment. These data indicate that C/EBPbeta phosphorylation through GSK3beta may mediate capsaicin-induced expression of NAG-1 and apoptosis through cooperation with ATF3 in human colorectal cancer cells.
authors.affiliation: Laboratory of Environmental Carcinogenesis, Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Seong-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Chutwadee
authors.initials: C
authors.lastname: Krisanapun
authors.forename: Seung Joon
authors.initials: SJ
authors.lastname: Baek
mesh_terms: D051700:Activating Transcription Factor 3 / Q000502:physiology*; D017209:Apoptosis / Q000187:drug effects*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000502:physiology*; D002211:Capsaicin / Q000494:pharmacology*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D038362:Glycogen Synthase Kinase 3 / Q000502:physiology*; D000071679:Glycogen Synthase Kinase 3 beta; D055436:Growth Differentiation Factor 15 / Q000235:genetics* / Q000502:physiology; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000502:physiology; D018168:Receptors, Retinoic Acid / Q000502:physiology; D000072482:Retinoic Acid Receptor alpha; D015398:Signal Transduction
chemical_list: C490449:ATF3 protein, human; D051700:Activating Transcription Factor 3; D022782:CCAAT-Enhancer-Binding Protein-beta; C526140:GDF15 protein, human; D055436:Growth Differentiation Factor 15; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D011493:Protein Kinase C; D038362:Glycogen Synthase Kinase 3; D002211:Capsaicin