Proteome characterization of a human urothelial cell line resistant to the bladder carcinogen 4-aminobiphenyl

BACKGROUND: The aromatic amine 4-aminobiphenyl (4-ABP) is an environmental and occupational contaminant known to be a major etiological agent of human bladder cancer. 4-ABP metabolites are able to form DNA adducts that may induce mutations and initiate bladder carcinogenesis. Cells exposed to 4-ABP may develop resistance to the carcinogen. The aim of the present study was to detect and identify proteins whose expression is altered in the bladder carcinoma RT112 sub-lines selected for acquired resistance to 4-ABP, in order to disentangle the mechanisms. RESULTS: Differential proteome analysis of cell lysates showed an overall perturbation in cell metabolism and energy pathways in the 4-ABP-resistant human urothelial clones, with over-expression of membrane trafficking proteins such as annexin 2. The resistant clones had altered expression of many proteins linked directly (i.e. lamin A/C, programmed cell death 6 interacting protein) or indirectly (i.e. 94 kDa glucose-regulated protein, fatty acid-binding protein) to decreased apoptosis, suggesting that resistance to 4-ABP might be associated with low apoptotic activity. CONCLUSION: Our data provide evidence that deregulation of apoptosis and membrane trafficking proteins might be strongly implicated in the selection of carcinogen resistant cells. Some of these proteins might have potential as biomarkers of resistance and cancer risk. We thank Dr. Monica Ganzinelli, Istituto di Ricerche Farmacologiche Mario Negri, for technical assistance in Western Blot analysis and antibodies gift. We thank Prof. Alberto Bardelli for providing RT112 bladder cancer cell line. This work was supported by Compagnia di San Paolo (Torino), The Italian Association for Cancer Research (AIRC), the Italian Technology and Research Ministry Regione Piemonte and partly by ECNIS (Environmental Cancer Risk, Nutrition and Individual Susceptibility), a network of excellence operating within the European Union 6th Framework Program, Priority 5: "Food Quality and Safety" (Contract No 513943).