9-hydroxystearic acid (9-HSA) belongs to the class of lipid peroxidation by-products, that greatly diminish in tumours, becoming unable to exert their normal controlling functions on cell division; its binding with the catalityc site of HDAC1 inhibits the activity of the enzyme and causes histone hyperacetylation as well as growth inhibition p21WAF1 mediated as well as differentiation. Recent work demontrates that cyclin D1 enhances recruitment of HDAC1 to target genes of differentiation. In particular cyclin D1 has been demonstrated to inhibit basal and ligand-induced PPARgamma activity through a direct interaction with HDAC1. In this work we investigated the effects of 9-HSA on cyclin D1 expression and localization and on its interaction with CDK4 and HDAC1, by using as a cellular model HT29 adenocarcinoma cell line. A flow cytometric cyclin D1 expression /DNA content analysis revealed that the percentage of cyclin D1 positive cells decreased of 25% in 9-HSA treated cells and that 9-HSA induced different patterns of cyclin D1 through the cell cycle phases. Modification of cyclin D1 expression as well as of its localization mediated by 9-HSA in tumour cells can have two effects: i) to substain an early inhibition of proliferation; ii) to promote a precise differentiation program by acting as a transcriptional factor or transcriptional co-factor. Immunofluorescence analysis in confocal microscopy has been used to monitor cyclin D1/CDK4 and cyclin D1/HDAC1 complexe formation when 9-HSA occupies the HDAC1 active site. The diminished expression of cyclin D1 is associated to a dimished presence of both CDK4/cyclin D1 and cyclin D1/HDAC1 complexe in treated cells. Moreover 9-HSA inhibition of HDAC1 removes the enzyme from chromatin binding proteins and results in a new clustering of PPARin nuclear membrane. This work presents preliminary data indicating that 9-HSA modulates cyclin D1 activity both as cell cycle and transcriptional regulator.
E. Pagnotta, N. Calonghi, C. Boga, G. Farruggia, L. Masotti (2005). HISTONE DEACETYLASE INHIBITOR 9-HSA DOWNREGULATES CYCLIN D1 EXPRESSION AND ALTERS ITS FUNCTIONS. SIENA : Tipografia Senese.
HISTONE DEACETYLASE INHIBITOR 9-HSA DOWNREGULATES CYCLIN D1 EXPRESSION AND ALTERS ITS FUNCTIONS
PAGNOTTA, ELEONORA;CALONGHI, NATALIA;BOGA, CARLA;FARRUGGIA, GIOVANNA;MASOTTI, LANFRANCO
2005
Abstract
9-hydroxystearic acid (9-HSA) belongs to the class of lipid peroxidation by-products, that greatly diminish in tumours, becoming unable to exert their normal controlling functions on cell division; its binding with the catalityc site of HDAC1 inhibits the activity of the enzyme and causes histone hyperacetylation as well as growth inhibition p21WAF1 mediated as well as differentiation. Recent work demontrates that cyclin D1 enhances recruitment of HDAC1 to target genes of differentiation. In particular cyclin D1 has been demonstrated to inhibit basal and ligand-induced PPARgamma activity through a direct interaction with HDAC1. In this work we investigated the effects of 9-HSA on cyclin D1 expression and localization and on its interaction with CDK4 and HDAC1, by using as a cellular model HT29 adenocarcinoma cell line. A flow cytometric cyclin D1 expression /DNA content analysis revealed that the percentage of cyclin D1 positive cells decreased of 25% in 9-HSA treated cells and that 9-HSA induced different patterns of cyclin D1 through the cell cycle phases. Modification of cyclin D1 expression as well as of its localization mediated by 9-HSA in tumour cells can have two effects: i) to substain an early inhibition of proliferation; ii) to promote a precise differentiation program by acting as a transcriptional factor or transcriptional co-factor. Immunofluorescence analysis in confocal microscopy has been used to monitor cyclin D1/CDK4 and cyclin D1/HDAC1 complexe formation when 9-HSA occupies the HDAC1 active site. The diminished expression of cyclin D1 is associated to a dimished presence of both CDK4/cyclin D1 and cyclin D1/HDAC1 complexe in treated cells. Moreover 9-HSA inhibition of HDAC1 removes the enzyme from chromatin binding proteins and results in a new clustering of PPARin nuclear membrane. This work presents preliminary data indicating that 9-HSA modulates cyclin D1 activity both as cell cycle and transcriptional regulator.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
