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Prevention of mouse lung tumors and modulation of DNA methylation by combined treatment with budesonide and R115777 (Zarnestra MT).

Alyaqoub FS, Tao L, Kramer PM, Steele VE, Lubet RA, Gunning WT, Pereira MA

Medical University of Ohio, Toledo, OH 43614, USA.

Budesonide (an anti-inflammatory glucocorticoid), R115777 (a farnesyl transferase inhibitor, Zarnestra, Tipifarnib) or combinations of them were evaluated for prevention of lung tumors and for modulation of DNA methylation in tumors. Lung tumors were induced by vinyl carbamate in female strain A mice. One week later, mice received 60 or 100 mg/kg R115777 by oral gavage and 5 days/week, 0.8 or 1.6 mg/kg of budesonide in their diet, or their combined treatment until killed at 20, 28 and 36 weeks after administering the vinyl carbamate. Other mice were administered the drugs for 2 weeks before killing at Week 20. At Week 20, the rank order for prevention of lung tumors was the combined treatment > budesonide > R115777. At later killings, R115777 was no longer effective, whereas budesonide and the combinations continued to prevent tumors, albeit at a reduced efficacy. DNA hypomethylation in lung tumors was prevented by treatment with R115777, budesonide and the combinations. When administered starting at Week 18 to tumor-bearing mice, the drugs reversed DNA hypomethylation in the tumors. In summary, combined treatment with budesonide and R115777 produced the following results: (i) it was more efficacious in preventing lung tumors than the individual drugs; and (ii) it prevented and reversed DNA hypomethylation in lung tumors. These results support the combined use of budesonide and R115777 in prevention of lung tumors and suggest that reversal of DNA hypomethylation in lung tumors would be useful as a surrogate end-point biomarker for prevention.

Published 14 December 2006 in Carcinogenesis, 28(1): 124-9.
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