Horm Metab Res 2003; 35(11/12): 816-821
DOI: 10.1055/s-2004-814163
Original
© Georg Thieme Verlag Stuttgart · New York

Increased Activity of Catalase in Tumor Cells Overexpressing IGFBP-2

A.  Hoeflich1 , O.  Fettscher1 , G.  Preta2 , H.  Lahm1 , H.  J.  Kolb3 , E.  Wolf1 , M.  M.  Weber4
  • 1Lehrstuhl für Molekulare Tierzucht und Biotechnologie/Genzentrum, Ludwig-Maximilians-Universität, Munich, Germany
  • 2Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
  • 3Institut für Klinische Chemie, Städtisches Krankenhaus München-Harlaching, Munich, Germany
  • 4Schwerpunkt Endokrinologie und Stoffwechselerkrankungen, I. Medizinische Klinik und Poliklinik, Johannes-Gutenberg-Universität, Mainz, Germany
Further Information

Publication History

Received 20 August 2003

Accepted after Revision 23 September 2003

Publication Date:
07 January 2004 (online)

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Abstract

Elevated levels of IGFBP-2 are found in serum and tissues under various stressful conditions and in many malignancies. In previous studies, we have shown that overexpression of IGFBP-2 results in increased tumorigenic potential in Y-1 mouse adrenocortical tumor cells, and that these effects are presumably mediated through IGF-independent mechanisms. Here, we show that highly proliferative IGFBP-2-overexpressing Y-1 cells, but not control Y-1 cells, grow to very high cell densities. In order to evaluate whether the increased cell densities in IGFBP-2-transfected Y-1 cells were accompanied by alterations in the oxidative stress system, we analyzed the effect of IGFBP-2 overexpression on the activity of various antioxidative enzymes in two malignant cell lines. Among the tested antioxidative enzymes (catalase, superoxide-dismutase, glutathione peroxidase, glutathione S-transferase), only catalase enzyme activity was significantly higher in IGFBP-2-transfected Y-1 mouse adrenocortical tumor cells and in IGFBP-2-transfected human colon tumor cells (Caco-2) compared to control-transfected Y-1 and Caco-2 cells and non-tumor 293 human epithelial cells. However, overexpression of catalase in malignant cells did not result in increased resistance to oxidative stress as measured by cell viability and protein oxidation after treatment of the cells with hydrogen peroxide. This might be due to an upregulation of the GST enzyme activity after treatment with H2O2 that we observed selectively in the control-transfected Y-1 cells and which might compensate for the higher catalase activity in the IGFBP-2 overexpressing cells. In summary, we found a strong and selective upregulation of the catalase activity in IGFBP-2 overexpressing malignant Y-1 and Caco-2 cell lines that might contribute to the highly malignant phenotype of IGFBP-2 overexpressing tumors through as yet unknown mechanisms.