Can vitamin C induce nucleotide excision repair? Support from in vitro evidence.

Intracellular vitamin C acts to protect cells against oxidative stress by intercepting reactive oxygen species (ROS) and minimising DNA damage. However, rapid increases in intracellular vitamin C may induce ROS with subsequent DNA damage priming DNA repair processes. Herein, we examine the potential of vitamin C and the derivative ascorbate-2-phosphate (2-AP) to induce a nucleotide excision repair (NER) response to DNA damage in a model of peripheral blood mononuclear cells.

In vivo vitamin C supplementation increases phosphoinositol transfer protein expression in peripheral blood mononuclear cells from healthy individuals.

Ascorbate can act as both a reducing and oxidising agent in vitro depending on its environment. It can modulate the intracellular redox environment of cells and therefore is predicted to modulate thiol-dependent cell signalling and gene expression pathways. Using proteomic analysis of vitamin C-treated T cells in vitro, we have previously reported changes in expression of five functional protein groups associated with signalling, carbohydrate metabolism, apoptosis, transcription and immune function.

Antiserum detection of reactive carbonyl species-modified DNA in human colonocytes.

Polyunsaturated fats have been linked to occurrences of sporadic colon cancer. One possible cause may be degradation of polyunsaturated fats during cooking, resulting in multiple reactive carbonyl species (RCS) that can damage nuclear DNA and proteins, particularly in rapidly dividing colon crypt cells. This study describes a novel antiserum against RCS-modified DNA, with apparent order of reactivity to DNA modified with 4-hydroxy-trans-2-nonenal > glyoxal > acrolein > crotonaldehyde > malondialdehyde; some reactivity was also observed against conjugated Schiff base-type structures.

Evidence of oligonucleotides containing 8-hydroxy-2'-deoxyguanosine in human urine.

The product of oxidative damage to DNA, 8-hydroxy-2'-deoxyguanosine (8-OHdG), when detected in urine, is considered to be a global, noninvasive biomarker of in vivo oxidative DNA damage. In this paper we describe a novel approach to confirm the presence of oligonucleotides containing 8-OHdG in human urine. Fractions of urine were prepared by gel-filtration chromatography, and the presence of oligonucleotides was confirmed by ELISA using a monoclonal anti-(single-stranded DNA) antibody.

A comparison of the gene expression profiles of CRL-1807 colonocytes exposed to endogenous AAPH-generated peroxides and exogenous peroxides from heated oil.

Oxidation of PUFAs in the diet has the potential to be genotoxic and hence carcinogenic. Such carcinogenic processes originate within stem cells of the colon. These cells appear to be predisposed to the carcinogenic process.

Dose-dependent modulation of the T cell proteome by ascorbic acid.

To investigate the hypothesis that the micronutrient ascorbic acid can modulate the functional genome, T cells (CCRF-HSB2) were treated with ascorbic acid (up to 150 microM) for up to 24 h. Protein expression changes were assessed by two-dimensional electrophoresis. Forty-one protein spots which showed greater than two-fold expression changes were subject to identification by matrix-assisted laser desorption ionisation time of flight MS.

Effect of vitamin E on gene expression changes in diet-related carcinogenesis.

Colorectal cancer (CRC) is responsible for the second highest associated mortality in Western Europe and the United States. Approximately 95% of CRC is sporadic and believed to involve environmental agents and chronic inflammation as causal elements. Several recent studies have suggested a link with diet, in particular, red meat, dietary fats, and low consumption of vegetables.

Immunochemical detection of UV-induced DNA damage and repair.

The application of an antiserum to ultraviolet radiation (UVR)-damaged DNA is presented. A novel experimental system was employed to ascertain the limits of detection for this antiserum. Using a DNA standard containing a known amount of dimer, the limits of detection were found to be 0.

Novel monoclonal antibody recognition of oxidative DNA damage adduct, deoxycytidine-glyoxal.

Glyoxal, a reactive aldehyde, is a decomposition product of lipid hydroperoxides, oxidative deoxyribose breakdown, or autoxidation of sugars, such as glucose. It readily forms DNA adducts, generating potential carcinogens such as glyoxalated deoxycytidine (gdC). A major drawback in assessing gdC formation in cellular DNA has been methodologic sensitivity.

Deoxycytidine glyoxal: lesion induction and evidence of repair following vitamin C supplementation in vivo.

Oxidative DNA damage is postulated to be involved in carcinogenesis, and as a consequence, dietary antioxidants have received much interest. A recent report indicates that vitamin C facilitates the decomposition of hydroperoxides in vitro, generating reactive aldehydes. We present evidence for the in vivo generation of glyoxal, an established product of lipid peroxidation, glucose/ascorbate autoxidation, or free radical attack of deoxyribose, following supplementation of volunteers with 400 mg/d vitamin C.