mouse, contains a truncating mutation in the Apc gene and spontaneously develops numerous adenomas in the small intestine but few in the large bowel. Our study investigated whether dextran sodium sulfate (DSS) treatment promotes the development of colonic neoplasms in Apc Min/1 mice. Apc Min/1 and Apc 1/1 mice of both sexes were exposed to 2% dextran sodium sulfate in drinking water for 7 days, followed by no further treatment for 4 weeks. Immunohistochemistry for cyclooxygenase-2, inducible nitric oxide synthase, b-catenin, p53, and nitrotyrosine, and mutations of b-catenin and K-ras and loss of wild-type allele of the Apc gene in the colonic lesions were examined. Sequential observation of female ApcMin/1 mice that received DSS was also performed up to week 5. At week 5, numerous colonic neoplasms developed in male and female Apc Min/1 mice but did not develop in Apc 1/1 mice. Adenocarcinomas developed in Apc Min/1 mice that received DSS showed loss of heterozygosity of Apc and no mutations in the b-catenin and K-ras genes. The treatment also significantly increased the number of small intestinal polyps. Sequential observation revealed increase in the incidences of colonic neoplasms and dysplastic crypts in female Apc Min/1 mice given DSS. DSS treatment increased inflammation scores, associated with high intensity staining of b-catenin, cyclooxygenase-2, inducible nitric oxide synthase and nitrotyrosine. Interestingly, strong nuclear staining of p53 was specifically observed in colonic lesions of Apc Min/1 mice treated with DSS. Our results suggest a strong promotion effect of DSS in the intestinal carcinogenesis of Apc Min/1 mice. The findings also suggest that strong oxidative/nitrosative stress caused by DSS-induced inflammation may contribute to the colonic neoplasms development. ' 2005 Wiley-Liss, Inc.

Hydroxyurea is a chemotherapeutic agent used for the treatment of myeloproliferative disorders (MPD) and solid tumors. The mutagenic and carcinogenic potential of hydroxyurea has not been established, although hydroxyurea has been associated with an increased risk of leukemia in MPD patients. To clarify whether hydroxyurea has potential carcinogenicity, we examined site-specific DNA damage induced by hydroxyurea using Hydroxyurea is an effective chemotherapeutic agent for neoplastic diseases. It is commonly used for patients with clonal myeloproliferative disorders (MPD), including chronic myelogenous leukemia, as well as for malignant solid tumors.1-3) Recently, hydroxyurea has been investigated for use in the treatment of human immunodeficiency virus (HIV) disease. 4,5) Hydroxyurea inhibits ribonucleoside diphosphate reductase, 6, 7) thereby blocking DNA synthesis and repair.Larger studies have documented an increased risk of leukemia for patients with MPD on hydroxyurea therapy. [8][9][10] De Simone et al. described the occurrence of multiple squamous cell skin carcinomas in a patient treated with hydroxyurea for chronic myelogenous leukemia. 11)Hydroxyurea has been experimentally shown to have clastogenic, 12) teratogenic, 13) and, in some settings, mutagenic effects.14) Recently, it has been reported that hydroxyurea increases DNA mutations in young patients with sickle cell disease.15) Hydroxyurea produces chromosome damage and mutation in cultured cells, 16,17) whereas it is an inactive mutagen in bacteria.18) Although hydroxyurea does not bind to DNA, 18) it has been reported that nitric oxide (NO) is generated from it.19-21) Therefore, there remains a possibility that hydroxyurea induces DNA damage via the formation of reactive nitrogen and oxygen species.In this study, we have examined whether hydroxyurea causes DNA damage in the presence of metal ion using 32 P-5′-end-labeled DNA fragments obtained from the human p16 and p53 tumor suppressor genes and the c-Ha-3 To whom correspondence should be addressed. E-mail: kawanisi@doc.medic.mie-u.ac.jp Abbreviations: 8-OHdG, 8-hydroxy-2′-deoxyguanosine (also known as 8-oxo-7,8-dihydro-2′-deoxyguanosine); HPLC-ECD, an electrochemical detector coupled to a high-pressure liquid chro-

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A methanol extract from Pueraria lobata showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from P. lobata was re-extracted with hexane, dichloromethane, ethyl acetate, butanol, and water, respectively. A suppressive compound in the dichloromethane and ethyl acetate extract fractions was isolated by SiO(2) column chromatography and identified as tectorigenin (1) by EI-MS and (1)H and (13)C NMR spectroscopy. Compound 1 and its methylated derivative [7,4'-di-O-methyltectorigenin (2)] had the suppressive effects on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against furylfuramide, 4-nitroquinoline-1-oxide, N-methyl-N'-nitrosoguanidine, and activated Trp-P-1, which do not require live metabolic activation by S9. These compounds also showed suppression of SOS-inducing activity against Trp-P-1 and AfB(1), which requires liver metabolizing enzymes. In addition to the antimutagenic activities of these compounds against furylfuramide, Trp-P-1 and activated Trp-P-1 were also assayed by an Ames test using S. typhimurium TA100.