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

✍ Scribed by Nuria Arranz; Ana I. Haza; Almudena García; Ma Eugenia Delgado; Joseph Rafter; Paloma Morales

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 221 KB
• Volume: 28
• Category: Article
• ISSN: 0260-437X
• DOI: 10.1002/jat.1340

✦ Synopsis

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 µm) 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 µm vitamin C (29 and 46%, respectively). Moreover, an increase of lactate dehydrogenase release was significant with 50 µm at 72 h (28%) and with 100 µm 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 µm 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 µm 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. Copyright © 2008 John Wiley & Sons, Ltd.