RESUMEN
To elucidate the role of vitamin D in the histopathological alterations process and K-ras gene mutation exon 1 of tissues including lung, stomach, esophagus, and testis, by the administration of urethane. An experimental study in inbred balb/c mice aged 9-11 weeks was designed. This investigation was performed from 2003 to 2005 in the Department of Medical Genetics, Medical Sciences/University of Tehran, Tehran, Iran. The samples were classified into 3 groups: the urethane group was characterized by intraperitoneal injection of 3 times urethane 600 mg/kg/day at 48 hour intervals. The second group U+D was given 3.5 mg/kg 6.3 mg/1000 ml vitamin D in the drinking water for 4 weeks following the same intake of urethane as the first group, and the third one was the control group. All mice were sacrificed after 20 weeks, tissues were removed and examined for histopathological changes and mutations in the exon 1 of the K-ras gene. Thirty mice were studied. The formation of lung tumor was, significantly, increased in the urethane group as compared with the control group p<0.005, however, such a difference was not found in the U+D and control groups. In addition, there was no significant difference between all groups in other examined tissues. There was no mutation in the exon 1 of K-ras gene of the lung adenomas, adenocarcinomas, and stomach metaplasia. Our results showed the anti-tumorigenic effect of vitamin D3 in lung tumors induced by urethane. Vitamin D may reduce the risks of a tumorigenic diet that includes high fermented foods and beverages that produce urethane in their process