Quantitative determination of water‐ and lipid‐soluble antioxidants in neoplastic and non‐neoplastic human breast tissue

Abstract

Ascorbic acid, cysteine, glutathione and uric acid were determined by reverse-phase high-pressure liquid chromatography (HPLC) in 46 breast tissue samples [neoplastic (C) and non-neoplastic (N) from the same patient]. Cholesterol, alpha-tocopherol and gamma-tocopherol were quantified in 64 similar samples by extraction into heptane followed by direct-phase HPLC. DNA was measured in all samples and the percentages of epithelium, fat and connective tissue were estimated in sections adjacent to the sample. Results confirm previous findings that ascorbic acid and glutathione, expressed as mumol/g DNA, were greatly increased in the epithelium of neoplastic tissue. Similar increases in cysteine could be accounted for by the presence of inflammatory cells. Although values of alpha- and gamma-tocopherol correlated with the percentage of fat in both types of tissue, these compounds were also present in the epithelium. Because of the varying amounts of fat in the samples, no significant difference could be found between N and C values. Cholesterol correlated with fat in N and epithelium in C. Consideration of 10 cases with equal amounts of fat in C and N tissue suggests that cholesterol is reduced in C in the epithelial cells.

Cytotoxicity of ascorbate, lipoic acid, and other antioxidants in hollow fibre in vitro tumours

“…2 lines of evidence suggest that tumour ascorbate levels may be higher than those in plasma. First, vitamin C concentrations in tumours are, on the average, 3 times higher than those in surrounding normal tissues (Langemann et al, 1989), presumably because tumour cells use membrane glucose transporters to internalize ascorbate (Agus et al, 1999). Secondly, tissue vitamin C concentrations in guinea pigs and humans exceed those in plasma by as much as 2 orders of magnitude (Hornig, 1975).…”

“…Tumour cells are often catalase deficient and therefore more sensitive than normal to hydrogen peroxide (Benade et al, 1969). Vitamin C accumulates in solid tumours at concentrations higher than those in surrounding normal tissue (Langemann et al, 1989;Agus et al, 1999). This has raised concerns that vitamin C may provide tumours with antioxidant protection from traditional therapeutic modalities (Raloff, 2000).…”

Visualizing metabolic changes in breast‐cancer tissue using 1H‐NMR spectroscopy and self‐organizing maps

“…In a small study of 10 cases with an identical content of fatty tissue in tumorous and nontumorous samples, the amount of cholesterol was found to decrease in neoplastic tissue. 41 The concentration of phosphatidylethanolamine (PtdEtn) was described as elevated in tumor tissue. 35,36,42 We have found this increase predominantly in grade 3 mammary carcinoma.…”

Comment re: Vitamin C Antagonizes the Cytotoxic Effects of Chemotherapy

“…In vivo, numerous reductive systems ensure plasma concentrations of dehydroascorbic acid do not exceed 1 μmol/L (3, 4). Although alluded to, the actual level of dehydroascorbic acid formed endogenously within the oxidative environments of tumors was not measured in either this (1) or the previous studies cited by this group (5,6). Most cells in vivo, including cancer cells, maintain a constant intracellular ascorbate concentration of 1 to 5 mmol/L, which never decreases to zero.…”