Oxidative DNA damage induced by a hydroperoxide derivative of cyclophosphamide.
Interstrand DNA cross-linking has been considered to be the primary action mechanism of cyclophosphamide (CP) and its hydroperoxide derivative, 4-hydroperoxycyclophosphamide (4-HC). To clarify the mechanism of anti-tumor effects by 4-HC, we investigated DNA damage in a human leukemia cell line, HL-60, and its H(2)O(2)-resistant clone HP100. Apoptosis DNA ladder formation was detected in HL-60 cells treated with 4-HC, whereas it was not observed in HP100 cells. 4-HC significantly increased 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, a marker of oxidative DNA damage, in HL-60 cells. On the other hand, CP did not significantly induce 8-oxodG formation and apoptosis in HL-60 cells under the same conditions as did 4-HC. Using (32)P-labeled DNA fragments from the human p53 tumor suppressor gene, 4-HC was found to cause Cu(II)-mediated oxidative DNA damage, but CP did not. Catalase inhibited 4-HC-induced DNA damage, including 8-oxodG formation, suggesting the involvement of H(2)O(2). The generation of H(2)O(2) during 4-HC degradation was ascertained by procedures using scopoletin and potassium iodide. We conclude that, in addition to DNA cross-linking, oxidative DNA damage through H(2)O(2) generation may participate in the anti-tumor effects of 4-HC.
Department of Environmental and Molecular Medicine, Mie University School of Medicine, Tsu, Mie 514-8507, Japan.
Mariko
M
Murata
Toshinari
T
Suzuki
Kaoru
K
Midorikawa
Shinji
S
Oikawa
Shosuke
S
Kawanishi
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis; D002417:Cattle; D003300:Copper / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000737:chemistry; D005609:Free Radicals; D018922:HL-60 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008956:Models, Chemical; D009243:NAD / Q000737:chemistry; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D018906:Antineoplastic Agents, Alkylating; D003432:Cross-Linking Reagents; D005609:Free Radicals; D016159:Tumor Suppressor Protein p53; D009243:NAD; D003300:Copper; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003520:Cyclophosphamide; D004247:DNA; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D003849:Deoxyguanosine; D010100:Oxygen; C011272:perfosfamide