Inhibition of experimental colorectal cancer and reduction in renal and gastrointestinal toxicities by copper-indomethacin in rats.

PURPOSE: To evaluate, for the first time, the efficacy of copper-indomethacin in the inhibition of aberrant crypt foci formation using the azoxymethane-induced adenocarcinoma model, to examine cell viability in the HCT-116 colorectal cancer cell line, gastrointestinal permeability, mitochondrial oxidative damage, and renal toxicity in rat models.

METHODS: Azoxymethane-induced adenocarcinoma rats were dosed with indomethacin and copper-indomethacin for 28 days and aberrant crypt foci were evaluated. HCT-116 colorectal cancer cells were exposed to indomethacin and copper-indomethacin at 0-250 microg/mL (0-698 microM for indomethacin, and 0-147 microM for copper-indomethacin), and cell viability was measured. Acute gastrointestinal toxicity was measured using gastrointestinal permeability markers, gastrointestinal ulceration and bleeding, and measurement of an acute-phase protein haptoglobin. Effects of acute and chronic administration of indomethacin and copper-indomethacin on urinary electrolyte concentrations were examined.

RESULTS: Both indomethacin and copper-indomethacin resulted in a significant reduction in aberrant crypt foci in azoxymethane-treated rats. In parallel, high concentrations of indomethacin and copper-indomethacin also reduced cell viability in HCT-116 colorectal cancer cells. However, copper-indomethacin was considerably safer in all measures of gastrointestinal toxicity compared to indomethacin. In addition, indomethacin reduced urinary electrolytes at an ulcerogenic dose of 10 mg/kg acutely and chronically at 3.0 mg/kg for 28 days, whereas copper-indomethacin at equimolar doses of indomethacin affected urine electrolytes after acute dosing but not after chronic dosing for 28 days.

CONCLUSIONS: Copper-indomethacin has both gastrointestinal and renal sparing properties while maintaining efficacy in experimental adenocarcinoma.