Alterations to proteome and tissue recovery responses in fish liver caused by a short-term combination treatment with cadmium and benzo[a]pyrene P.M. Costa a, * , E. Chicano-Gálvez b , J. López Barea b , T.À. DelValls c , M.H. Costa a a IMAR-Instituto do Mar, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, 2829-516 Monte de Caparica, Portugal b Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 14071 Córdoba, Spain c UNESCO/UNITWIN/WiCop Chair-Departamento de Química Física, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Polígono río San Pedro s/n,11510 Puerto Real, Cádiz, Spain The interaction between cadmium and benzo[a]pyrene impairs specific responses to toxicity and tissue repair mechanisms. article info Article history: Received 2 February 2010 Received in revised form 18 July 2010 Accepted 21 July 2010 Keywords: Metal Polycyclic aromatic hydrocarbon Proteomics Apoptosis Hepatic parenchyma abstract The livers of soles (Solea senegalensis) injected with subacute doses of cadmium (Cd), benzo[a]pyrene (B[a]P), or their combination, were screened for alterations to cytosolic protein expression patterns, complemented by cytological and histological analyses. Cadmium and B[a]P, but not combined, induced hepatocyte apoptosis and Kupfer cell hyperplasia. Proteomics, however, suggested that apoptosis was triggered through distinct pathways. Cadmium and B[a]P caused upregulation of different anti-oxidative enzymes (peroxiredoxin and glutathione peroxidase, respectively) although co-exposure impaired induction. Similarly, apoptosis was inhibited by co-exposure, to which may have contributed a syner- gistic upregulation of tissue metalloproteinase inhibitor, b-actin and a lipid transport protein. The regulation factors of nine out of eleven identified proteins of different types revealed antagonistic or synergistic effects between Cd and B[a]P at the prospected doses after 24 h of exposure. The results indicate that co-exposure to Cd and B[a]P may enhance toxicity by impairing specific responses and not through cumulative damage. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The mechanisms underlying cellular detoxification and elimi- nation of xenobiotics are complex and are known to depend on multiple factors such as contaminant class, doses, biological species, affected tissue and cell types, and co-exposure to other contaminants. The complexity of these mechanisms in whole- tissue and organs has been an important constraint to many fields of xenobiotic research, such as environmental toxicology and human occupational health, especially when multiple contami- nants are involved. Most toxicological studies that focused on contaminant interactions aimed at the effects on common biomarkers, or potential biomarkers, such as metallothionein (MT), and cytochrome P4501A (CYP1A) induction, activity of antioxidant enzymes, etc. (e.g. Sandvik et al., 1997; Hurk et al., 1998; Orbea et al., 2002; Marigómez et al., 2005; Costa et al., 2009a; Roesijadi et al., 2009). Such studies revealed the existence of antagonistic (opposite effect) and synergistic (a combination that produces an outcome that is higher than the sum of each isolated xenobiotic) traits when an organism, organ or cell culture is exposed to multiple contaminants. Cadmium (Cd) and benzo[a]pyrene (B[a]P) are common contaminants in industrialized areas, especially affecting coastal water bodies, where organic enriched sediments or suspended particles function as a trap for metals such as Cd and hydrophobic organic xenobiotics like polycyclic aromatic hydrocarbons (PAHs), among which B[a]P is included. Airborne particle-bound Cd and B[a]P (e.g. fumes and ashes) are also of great concern to environmental and, especially, human health (Harris et al., 1985; Viaene et al., 2000). For such reasons, many studies have been carried out to evaluate Cd and B[a]P toxicity in aquatic and terrestrial environments (see Friesen et al., 2008 and Nordberg, 2009 for a review). Both xenobiotics have also been widely employed as model toxicants in in vivo and in Abbreviations: 1-cysPrx, 1-cys peroxiredoxin; 2-DE, 2-dimensional electropho- resis; ApoA-IV3, apolipoprotein A-IV3; B[a]P, benzo[a]pyrene; CatL, cathepsin L; Cd, cadmium; CDC48, cell division cycle 48; GPx, glutathione peroxidase; H4, histone H4; MS, mass spectrometry; MTI, metallothionein I; PAH, polycylic aromatic hydrocarbon; PCD, programmed cell death; PEPB, phosphatidylethanolamine- binding protein; TIMP2, tissue metalloproteinase inhibitor 2. * Corresponding author. E-mail address: pmcosta@fct.unl.pt (P.M. Costa). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2010.07.030 Environmental Pollution 158 (2010) 3338e3346