title: DNA cross-linking by in vivo treatment with 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea of sensitive and resistant human colon carcinoma xenograms in nude mice.
abstract: The DNA alkaline elution technique provides a sensitive assay for the effects of DNA-damaging drugs in mammalian cells. We have adapted this method to permit measurements of effects on DNA in solid tumors. Human colon carcinoma xenografts in nude mice were treated with a single i.p. injection of 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea, and the effects on the DNA were followed for 19 hr. Drug doses in the pharmacological range produced significant reductions in DNA alkaline elution rates in assays in which X-ray was used to introduce a standard frequency of single-strand breaks. These changes in alkaline elution rate were attribute to the production of both DNA interstrand and DNA-protein cross-links, which were distinguished from each other on the basis of the extent to which the effect on elution could be reversed by proteinase K. Crosslinking increased for about 8 hr after treatment with little change thereafter up to 19 hr. A drug-resistant tumor line exhibited substantially less cross-linking than did a drug-sensitive line at all time points examined.
mesh_terms: D000468:Alkalies; D000818:Animals; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000302:isolation & purification / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004351:Drug Resistance; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000378:metabolism; D009607:Nitrosourea Compounds / Q000494:pharmacology*; D012673:Semustine / Q000494:pharmacology*; D014183:Transplantation, Heterologous
chemical_list: D000468:Alkalies; D004273:DNA, Neoplasm; D004277:DNA, Single-Stranded; D009607:Nitrosourea Compounds; D012673:Semustine