Modulation of regulatory proteins of G1/S by variations in the levels of H2O2 in tumor cells

IBAÑEZ, IRENE L.; POLICASTRO, LUCÍA L.; TROPPER, IVANNA; MOLINARI, BEATRIZ; DURÁN, HEBE A.

Montevideo

Congreso; V Annual Meeting of Society for Free Radical Biology and Medicine(SFRBM)- South American Group and V International Conference of Peroxynitrite and Reactive Nitrogen Species; 2007

SFRBM- South American Group - Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Uruguay

High levels of reactive oxygen species (ROS) induce cytotoxic effects, whereas at physiological concentrations, ROS are involved in the regulation of cellular functions, such as proliferation and apoptosis. In a previous report we demonstrated an endogenous imbalance of antioxidant enzymes coupled to a rise in H2O2 levels in cancer cells. Moreover, scavenging H2O2 with exogenous catalase (CAT) or by transfection with cDNA of CAT inhibited cell proliferation. The aim of the present study was to evaluate the mechanisms by which the modulation of the levels of ROS regulates cell proliferation in tumor cells, by analyzing cell cycle and regulatory proteins of G1/S in different types of tumor cell lines. The PIG1 (melanocytes), A375 (melanoma), PAJU (neuroblastoma), and LoVo (colon carcinoma) human cell lines and the CH72-T4 (spindle-cell carcinoma) murine cell line were used. Cell cycle analysis was performed by flow cytometry. Cyclins D1 and E, CDK4, CDK2 and p27 were determined by western blot. The levels of reactive oxygen species (ROS) were measured by flow cytometry using the DCFH assay and proliferation was evaluated by the MTT assay. The comparison between normal melanocytes (PIG1) and melanoma (A375) showed higher levels of endogenous ROS (p