Low colonic glutathione detoxification capacity in patients at risk for colon cancer.

BACKGROUND: Colon carcinogenesis is a multifactorial process influenced by hereditary as well as environmental factors. The glutathione/glutathione S-transferase detoxification system in the colon is important for protection against carcinogens. We investigated the levels of glutathione/glutathione S-transferase in normal colon mucosa of patients with colorectal cancer and in patients at high risk for colorectal cancer compared with those in healthy controls. MATERIALS AND METHODS: Glutathione content was analyzed by high-performance liquid chromatography, and glutathione S-transferase enzyme activity by spectrophotometric determination with 1-chloro 2,4-dinitrobenzene. Normal colon tissue of patients with colon adenoma (n = 64), colorectal cancer (n = 37), familial adenomatous polyposis (FAP; n = 19), hereditary non-polyposis colorectal cancer families with (HNPCC+Ad; n = 34) or without (HNPCC-Ad; n = 33) adenoma was investigated. RESULTS: Glutathione levels were significantly lower in the normal colon mucosa of patients with cancer, FAP, HNPCC-Ad or HNPCC+Ad compared with adenoma patients or healthy controls. Glutathione S-transferase enzyme activity in the distal colon was significantly lower in patients with cancer or FAP compared with the adenoma patients or healthy controls, whereas values in carcinoma patients were significantly lower compared with both the HNPCC-Ad and HNPCC+Ad groups. CONCLUSIONS: An association of low colonic glutathione/glutathione S-transferase activity levels and high clinical risk for the development of colorectal cancer was observed. This low glutathione detoxification capacity might contribute to the colon cancer risk.

Effect of resistant starch on potential biomarkers for colonic cancer risk in patients with colonic adenomas: a controlled trial.

Resistant starch decreases the concentration of secondary bile acids in the feces and the proliferation rate of colonic mucosal cells in healthy volunteers. This may reduce the risk of colon cancer. We investigated 23 patients with recently removed colonic adenoma(s) in a controlled parallel trial. They consumed 45 g of maltodextrin per day as placebo for four weeks and were randomly assigned to either 45 g of native amylomaize starch, containing 28 g of resistant starch type II or 45 g of maltodextrin for another four weeks. No effect on colorectal cell proliferation, fecal wet and dry weights, pH, and short-chain fatty acid excretion was seen. The bile acid concentration in fecal water decreased by 15% (P = 0.048) and the percentage secondary bile acids decreased by 14% (P = 0.002) on resistant starch relative to placebo. Whether this has a substantial role in colon cancer prevention in these patients remains to be established.

The effect of unfiltered coffee on potential biomarkers for colonic cancer risk in healthy volunteers: a randomized trial.

BACKGROUND: Epidemiologic studies suggest that coffee use might protect against colorectal cancer. Inconsistencies as to the effect of coffee use and colorectal cancer between epidemiologic studies might be related to the type of coffee brew. OBJECTIVE: We studied the effect of unfiltered coffee consumption on putative biomarkers for colonic cancer risk. DESIGN: A total of 64 healthy volunteers (31 men and 33 women), with a mean age of 43 +/- 11 years were randomly assigned to two groups in a crossover design, with two intervention periods of 2 weeks separated by a washout period of 8 weeks. Treatments were 1 L of cafetière (French press) coffee daily or no coffee. At the end of each intervention period, fasting blood samples, colorectal biopsies and 48 h faeces were collected. RESULTS: No effect of coffee on colorectal cell proliferation, assayed by estimating the Proliferating Cell Nuclear Antigen labelling index, was seen. Additionally, no effects were seen on the concentrations of faecal soluble bile acids and colorectal mucosal glutathione S-transferase activity. However, unfiltered coffee significantly increased the glutathione content in the colorectal mucosa by 8% and in plasma by 15%. Other aminothiols in plasma also increased on coffee. CONCLUSION: Unfiltered coffee does not influence the colorectal mucosal proliferation rate, but might increase the detoxification capacity and anti-mutagenic properties in the colorectal mucosa through an increase in glutathione concentration. Whether this effect indeed contributes to a lower colon cancer risk remains to be established.

Low levels of colonic glutathione S-transferase in patients with X-linked agammaglobulinaemia.

BACKGROUND: Patients with X-linked agammaglobulinaemia, a primary immunodeficiency disorder, suffer from recurrent infections of the respiratory and intestinal tract. Rapidly progressive colorectal cancer was diagnosed in three unrelated young adults with X-linked agammaglobulinaemia. This finding implies a 30-fold increase of risk for this cancer in this patient group. Glutathione S-transferases are a family of biotransformation enzymes involved in the detoxification of cytotoxic and carcinogenic compounds, that may function in the prevention of carcinogenesis. We investigated the possible role of the glutathione S-transferase enzyme system in the apparently increased colorectal cancer risk in X-linked agammaglobulinaemia patients. MATERIALS AND METHODS: We analysed the glutathione levels and the glutathione S-transferase enzyme activity and iso-enzyme composition in normal colonic biopsies of eight X-linked agammaglobulinaemia patients, 25 patients with a recent history of colonic adenomas and 10 healthy volunteers. RESULTS: X-linked agammaglobulinaemia patients had significantly lower glutathione S-transferase enzyme activities at all sites in the normal colonic mucosa as compared to adenoma patients. In X-linked agammaglobulinaemia patients the rectal glutathione S-transferase enzyme activity was lower than in the proximal colon and significantly lower as compared to controls. CONCLUSION: This lower glutathione S-transferase enzyme activity might play a role in the apparently increased colorectal cancer risk in X-linked agammaglobulinaemia patients, assuming that detoxification of carcinogenic compounds plays a role in the aetiology of colon cancer of these patients.