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Vitamin C in Cultured Human (HeLa) Cells: Lack of Effect on DNA Protection and Repair
Department of Pharmacology and Toxicology, University of Navarra, C/Irunlarrea 1, 31009 Pamplona, Spain
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, PB 1046 Blindern, 0316 Oslo, Norway
Environmental Health Department, National Institute of Health, Rua Alexandre Herculano 321, 4000-055 Porto, Portugal
* Author to whom correspondence should be addressed.
Received: 19 February 2013; in revised form: 18 March 2013 / Accepted: 20 March 2013 / Published: 9 April 2013
Abstract: Aims: Dietary antioxidants, including vitamin C, may be in part responsible for the cancer-preventive effects of fruits and vegetables. Human intervention trials with clinical endpoints have failed to confirm their protective effects, and mechanistic studies have given inconsistent results. Our aim was to investigate antioxidant/ pro-oxidant effects of vitamin C at the cellular level. Experimental approach: We have used the comet assay to investigate effects of vitamin C on DNA damage, antioxidant status, and DNA repair, in HeLa (human tumor) cells, and HPLC to measure uptake of vitamin C into cells. Results: Even at concentrations in the medium as high as 200 μM, vitamin C did not increase the background level of strand breaks or of oxidized purines in nuclear DNA. Vitamin C is taken up by HeLa cells and accumulates to mM levels. Preincubation of cells with vitamin C did not render them resistant to strand breakage induced by H2O2 or to purine oxidation by photosensitizer plus light. Vitamin C had no effect on the rate of repair of strand breaks or oxidized bases by HeLa cells. However, vitamin C at a concentration of less than 1 μM, or extract from cells preincubated for 6 h with vitamin C, was able to induce damage (strand breaks) in lysed, histone-depleted nuclei (nucleoids). Conclusion: In these cultured human cells, vitamin C displays neither antioxidant nor pro-oxidant properties; nor does it affect DNA strand break or base excision repair.
Keywords: DNA damage; DNA protection; DNA repair; vitamin C
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Azqueta, A.; Costa, S.; Lorenzo, Y.; Bastani, N.E.; Collins, A.R. Vitamin C in Cultured Human (HeLa) Cells: Lack of Effect on DNA Protection and Repair. Nutrients 2013, 5, 1200-1217.
Azqueta A, Costa S, Lorenzo Y, Bastani NE, Collins AR. Vitamin C in Cultured Human (HeLa) Cells: Lack of Effect on DNA Protection and Repair. Nutrients. 2013; 5(4):1200-1217.
Azqueta, Amaya; Costa, Solange; Lorenzo, Yolanda; Bastani, Nasser E.; Collins, Andrew R. 2013. "Vitamin C in Cultured Human (HeLa) Cells: Lack of Effect on DNA Protection and Repair." Nutrients 5, no. 4: 1200-1217.