Transcriptomic effects of di-(2-ethylhexyl)-phthalate in Syrian hamster embryo cells: an important role of early cytoskeleton disturbances in carcinogenesis?

Yann Landkocz,Paule Vasseur,Franck Atienzar,Pascal Poupin

doi:10.1186/1471-2164-12-524

Yann Landkocz, Paule Vasseur + Show 2 more

Open Access

https://doi.org/10.1186/1471-2164-12-524

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Abstract

BackgroundDi-(2-ethylhexyl)-phthalate (DEHP) is a commonly used plasticizer in polyvinylchloride (PVC) formulations and a potentially non-genotoxic carcinogen. The aim of this study was to identify genes whose level of expression is altered by DEHP by using a global wide-genome approach in Syrian hamster embryo (SHE) cells, a model similar to human cells regarding their responses to this type of carcinogen. With mRNA Differential Display (DD), we analysed the transcriptional regulation of SHE cells exposed to 0, 12.5, 25 and 50 μM of DEHP for 24 hrs, conditions which induced neoplastic transformation of these cells. A real-time quantitative polymerase chain reaction (qPCR) was used to confirm differential expression of genes identified by DD.ResultsGene expression profiling showed 178 differentially-expressed fragments corresponding to 122 genes after tblastx comparisons, 79 up-regulated and 43 down-regulated. The genes of interest were involved in many biological pathways, including signal transduction, regulation of the cytoskeleton, xenobiotic metabolism, apoptosis, lipidogenesis, protein conformation, transport and cell cycle. We then focused particularly on genes involved in the regulation of the cytoskeleton, one of the processes occurring during carcinogenesis and in the early steps of neoplastic transformation. Twenty one cytoskeleton-related genes were studied by qPCR. The down-regulated genes were involved in focal adhesion or cell junction. The up-regulated genes were involved in the regulation of the actin cytoskeleton and this would suggest a role of cellular plasticity in the mechanism of chemical carcinogenesis. The gene expression changes identified in the present study were PPAR-independent.ConclusionThis study identified a set of genes whose expression is altered by DEHP exposure in mammalian embryo cells. This is the first study that elucidates the genomic changes of DEHP involved in the organization of the cytoskeleton. The latter genes may be candidates as biomarkers predictive of early events in the multistep carcinogenic process.

Highlights

Di-(2-ethylhexyl)-phthalate (DEHP) is a commonly used plasticizer in polyvinylchloride (PVC) formulations and a potentially non-genotoxic carcinogen
Identification of DEHP-responsive genes using Differential Display The Differential Display technique was used to identify genes differentially expressed in Syrian hamster embryo (SHE) cells, after 24 hrs of treatment with DEHP
An illustration of differentially-expressed fragments is given in Figure 1 which shows gels obtained after the Differential Display (DD) protocol and highlights fragments regulated more than 2-fold by DEHP

Summary

Introduction

Di-(2-ethylhexyl)-phthalate (DEHP) is a commonly used plasticizer in polyvinylchloride (PVC) formulations and a potentially non-genotoxic carcinogen. DEHP has been classified as a peroxisomal proliferator and as a non-genotoxic carcinogen in animals [9]. As a result of peroxisome proliferation, and DNA damage have been described in the human prostate adenocarcinoma cell line LNCaP [12,13] and the mouse Leydig tumor cell line MA-10 [14] exposed to high concentrations of DEHP (3 mM). Other studies have pointed out that peroxisome proliferation is not a necessarily pathway in the carcinogenicity of DEHP [18] and more liver tumors occurred in PPARa-null mice than in wild type animals [19]. An increased level of Bcl-2 and negative regulation of c-Myc expression has been related to inhibition of apoptosis in Syrian hamster embryo cells treated with 50 μM of DEHP [26]

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