N-Nitrosopiperidine and N-Nitrosodibutylamine induce apoptosis in HepG2 cells via the caspase dependent pathway

Authors

  • Almudena García,

    1. Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
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  • Paloma Morales,

    1. Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
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  • Joseph Rafter,

    1. Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge University Hospital, NOVUM, S-141 86, Huddinge, Sweden
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  • Ana I. Haza

    Corresponding author
    1. Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Tel.: +34 91 394 37 47; fax: +34 91 394 37 43. E-mail addresses: hanais@vet.ucm.es

Abstract

The human hepatoma cell line (HepG2) exhibited a dose and time-dependent apoptotic response following treatment with N-Nitrosopiperidine (NPIP) and N-Nitrosodibutylamine (NDBA), two recognized human carcinogens. Our results showed a significant apoptotic cell death (95%) after 24 h treatment with NDBA (3.5 mM), whereas it was necessary to use high doses of NPIP (45 mM) to obtain a similar percentage of apoptotic cells (86%). In addition, both extrinsic (caspase-8) and intrinsic pathway (caspase-9) could be implicated in the N-Nitrosamines-induced apoptosis. This study also addresses the role of reactive oxygen species (ROS) as intermediates for apoptosis signaling. A significant increase in ROS levels was observed after NPIP treatment, whereas NDBA did not induce ROS. However, N-acetylcysteine (NAC) did not block NPIP-induced apoptosis. All these findings suggest that NPIP and NDBA induce apoptosis in HepG2 cells via a pathway that involves caspases but not ROS.

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