Paola Rojas

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Harry Cleaver

The University of Texas at Austin

Shabib H . Syed

University of the Punjab, Lahore, Pakistan

ELCHİN SULEYMANOV

Azerbaijan National Academy of Sciences

Gabriel Doménech-Pascual

University of Valencia

Alexis Cruz-Rodriguez

Instituto Tecnológico de Santo Domingo

Ariel M. Slipak

Universidad de Buenos Aires

Diego M. Papayannis

Universitat de Girona

Raul Letelier

Universidad de Chile

Daniel Barraez

Universidad Central de Venezuela

Rgo Araujo

UFBA - Federal University of Bahia

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Papers by Paola Rojas

Imbalance of antioxidant enzymes in tumor cells and inhibition of proliferation and malignant features by scavenging hydrogen peroxide

Molecular Carcinogenesis, 2004

The aim of this study was to evaluate the endogenous alterations of the antioxidant enzymes in tu... more The aim of this study was to evaluate the endogenous alterations of the antioxidant enzymes in tumor cells and to specifically compensate the resulting changes in the levels of reactive oxygen species (ROS) to control the malignant growth. We determined and compared the activities of antioxidant enzymes and the levels of superoxide anion () and hydrogen peroxide (H2O2) in tumor cell lines with different degrees of malignancy, paired with regard to their origin (PB/CH72T4, PDV/PDVC57, and HBL-100/MCF-7). An increase in superoxide dismutase activity and a decrease in the activities of H2O2-detoxifying enzymes, as a function of malignancy, coupled with a rise in H2O2 and a decrease in were demonstrated. Treatment of cells with exogenous catalase showed a dose-dependent inhibition of proliferation. This inhibition was also demonstrated in several cell lines of different tissue origin and species, suggesting a general role of H2O2 in cell proliferation. Moreover, stable expression of human catalase in MCF-7 cells inhibited proliferation and also reverted malignant features. We conclude that H2O2 played a crucial and general role in the regulation of proliferation and that an endogenous imbalance in antioxidant enzymes could be a relevant event in the carcinogenesis process. © 2004 Wiley-Liss, Inc.

H 2O 2 scavenging inhibits G1/S transition by increasing nuclear levels of p27 KIP1

Cancer Letters, 2011

The aim of the present study was to evaluate cell cycle regulation by scavenging H(2)O(2) in tumo... more The aim of the present study was to evaluate cell cycle regulation by scavenging H(2)O(2) in tumor cells. A significant arrest in the G1 phase of the cell cycle was demonstrated in CH72-T4 carcinoma cells exposed to catalase, associated with a decrease in cyclin D1 and an increase in the CDK inhibitory protein p27(KIP1). Moreover, we found a differential intracellular distribution of p27(KIP1), which remained in the nucleus after catalase treatment. In vivo experiments showed an increase in nuclear levels of p27(KIP1) associated with the inhibition of tumor growth by H(2)O(2) scavenging, confirming in vitro results. To conclude, H(2)O(2) scavenging may induce cell cycle arrest through the modulation of cyclin D1 and p27(KIP1) levels and nuclear localization of p27(KIP1). To our knowledge, this is the first report that demonstrates that the modulation of ROS alters the intracellular localization of a key regulatory protein of G1/S transition.

Moisés Villena Muñoz

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