Inhibition by vitamin C of apoptosis induced by N-nitrosamines in HepG2 and HL-60 cells.

Abstract

The aim of this study was to evaluate the effect of vitamin C towards N-nitrosopyrrolidine (NPYR)- and N-nitrosodimethylamine (NDMA)-induced apoptosis in human hepatoma (HepG2) and leukemia (HL-60) cell lines using flow cytometry analysis and the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay (TUNEL). None of the vitamin C concentrations tested (1-100 microM) caused cytotoxicity in HepG2 cells. However, there were significant losses of HL-60 cells viability, measured by MTT assay, 72 h after treatment with 50 and 100 microM vitamin C (29 and 46%, respectively). Moreover, an increase of lactate dehydrogenase release was significant with 50 microM at 72 h (28%) and with 100 microM of vitamin C at 48 and 72 h (27 and 36%, respectively). Also, the percentage of apoptotic HL-60 cells found in TUNEL assay increased to 21% when they were treated with 100 microM vitamin C for 72 h. Thus, in subsequent simultaneous treatments with NPYR (30 and 50 mM) or NDMA (27 and 68 mM) and vitamin C, concentrations of 5-50 microM vitamin C were used. Our results revealed that vitamin C, at all concentrations and times tested, reduced the apoptosis induced by NPYR and NDMA in both cell lines, showing a similar effect in HepG2 and HL-60 cells towards NPYR (50 mM)--65 and 63% of reduction, respectively--whereas towards NDMA (27 mM) the inhibition was higher in HL-60 than in HepG2 cells--75 and 57%, respectively. Therefore, our findings suggest that inhibition of apoptosis may be one of the mechanisms by which vitamin C exerts its protective effect.

• Authors: Nuria Arranz, Ana I Haza, Almudena García, Ma Eugenia Delgado, Joseph Rafter, Paloma Morales
• Journal: Journal of applied toxicology : JAT (J Appl Toxicol) Vol. 28 Issue 6 Pg. 788-96 (Aug 2008) ISSN: 0260-437X [Print] England
• PMID: 18344201 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright 2008 John Wiley & Sons, Ltd.

Chemical References

• Antioxidants
• Carcinogens
• Excitatory Amino Acid Agonists
• Nitrosamines
• Tetrazolium Salts
• Thiazoles
• N-Methylaspartate
• Cytochrome P-450 Enzyme System
• L-Lactate Dehydrogenase
• thiazolyl blue
• Ascorbic Acid
• N-Nitrosopyrrolidine

Topics

• Antioxidants (pharmacology)
• Apoptosis (drug effects)
• Ascorbic Acid (pharmacology)
• Carcinogens (toxicity)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Cytochrome P-450 Enzyme System (metabolism)
• Excitatory Amino Acid Agonists (toxicity)
• HL-60 Cells
• Humans
• In Situ Nick-End Labeling
• L-Lactate Dehydrogenase (metabolism)
• Liver Neoplasms (pathology)
• N-Methylaspartate (antagonists & inhibitors, toxicity)
• N-Nitrosopyrrolidine (toxicity)
• Nitrosamines (antagonists & inhibitors, toxicity)
• Tetrazolium Salts
• Thiazoles