Regulation of UGT1A1 and HNF1 transcription factor gene expression by DNA methylation in colon cancer cells

Abstract

BackgroundUDP-glucuronosyltransferase 1A1 (UGT1A1) is a pivotal enzyme involved in metabolism of SN-38, the active metabolite of irinotecan commonly used to treat metastatic colorectal cancer. We previously demonstrated aberrant methylation of specific CpG dinucleotides in UGT1A1-negative cells, and revealed that methylation state of the UGT1A1 5'-flanking sequence is negatively correlated with gene transcription. Interestingly, one of these CpG dinucleotides (CpG -4) is found close to a HNF1 response element (HRE), known to be involved in activation of UGT1A1 gene expression, and within an upstream stimulating factor (USF) binding site.ResultsGel retardation assays revealed that methylation of CpG-4 directly affect the interaction of USF1/2 with its cognate sequence without altering the binding for HNF1-alpha. Luciferase assays sustained a role for USF1/2 and HNF1-alpha in UGT1A1 regulation in colon cancer cells. Based on the differential expression profiles of HNF1A gene in colon cell lines, we also assessed whether methylation affects its expression. In agreement with the presence of CpG islands in the HNF1A promoter, treatments of UGT1A1-negative HCT116 colon cancer cells with a DNA methyltransferase inhibitor restore HNF1A gene expression, as observed for UGT1A1.ConclusionsThis study reveals that basal UGT1A1 expression in colon cells is positively regulated by HNF1-alpha and USF, and negatively regulated by DNA methylation. Besides, DNA methylation of HNF1A could also play an important role in regulating additional cellular drug metabolism and transporter pathways. This process may contribute to determine local inactivation of drugs such as the anticancer agent SN-38 by glucuronidation and define tumoral response.

Genome-wide Discriminatory Information Patterns of Cytosine DNA Methylation

“…Our study was accomplished in a novel information-thermodynamics framework for methylome analysis where two magnitudes were used: (1) the amount of information gained/lost (I R ) with the CDM changes processed by the methylation machinery in a genomic region (GR) R (Equation (1), see material and method section) and (2) the uncertainty of not observing a SNP (LC R , Equation (3)). The physical basis of the amount of information I R has been described in the Introduction and is documented in a recent publication [11].…”

“…The numerical scale for each heatmap of I R is close to the range of values estimated from the experimental data according to Equation (1). The gradient of color scale is then constrained, in each case, to the maximum and minimum numerical values of I R .…”

“…The physics of information (expressed as difference in entropies) is expressed by Landauer's principle, according to which a molecular machine must dissipate a minimum energy of ε " k B T ln 2 (about 3ˆ10´2 1 Joules at room temperature) at each step in the (genetic) logic operations including proofreading [8,9]. Theoretically, Landauer's principle is a consequence of the second principle of thermodynamics [8].…”

“…Specifically, cytosine methylation is a widespread regulatory factor in living organisms, and changes introduced by DNA methylation can be inherited from one generation to the next. Some methylation changes can regulate gene expression and effect genomic imprinting [1,2]. Cytosine methylation arises from the addition of a methyl group to a cytosine's C5 carbon residue.…”

Utilização de Análise Bioinformática e Validação por PCR Quantitativa em Tempo Real na Identificação da Indução Transcricional dos Fatores de Transcrição E2F1 e E2F4 em Linhagens de Glioblastoma.

“…Discussão O HNF1, também conhecido por HNF1A (Hepatocyte Nuclear Factor 1 -Alpha) e TCF-1 (Transcription Factor 1) codifica um FT requerido para a expressão de diversos genes específicos do fígado. Esse gene tem sido relacionado a doenças (segundo uma extensa literatura) como diabetes, incluindo diabetes mellitus tipo I e II, diabetes gestacional e (Harries et al, 2006;Narayana et al, 2006;Rowley et al, 2006;Maraschin et al, 2008;Umeyama et al, 2009;Pal et al, 2010;Pinés Corrales et al, 2010), doenças renais (Malecki et al, 2005), adenoma (Bluteau et al, 2002;Laurent-Puig et al, 2003), câncer de mama, de endométrio e de ovário (Rebouissou et al, 2004), neoplasias colorretais (Jeannot et al, 2006;Bélanger et al, 2010) e neoplasias de esôfago (Piessen et al, 2007).…”