Lack of I-compounds in DNA from a spectrum of Morris hepatomas.
A partial, progressive loss of I-compounds (age-dependent, putative indigenous DNA modifications) has been observed recently during hepatocarcinogenesis induced in rats by 2,3,7,8-tetrachlorodibenzo-p-dioxin, choline-devoid diet or peroxisome proliferators. It was of interest, therefore, to investigate the status of I-compounds in hepatic neoplasms. I-compounds were measured by 32P-postlabeling in eight transplantable rat (Morris) hepatomas of different growth rates and in host liver. Most I-compounds seen in liver were not detected in any of the hepatomas, and those present exhibited low levels. Hepatomas displayed an overall level of one I-compound in 2 x 10(8) DNA nucleotides, which was 7-16 times lower than liver values. The extent of I-compound deficiency did not correlate with tumor growth rate. These results, taken together with previously documented pronounced tissue-, sex-, strain- and species-specificity of I-compound profiles, suggest that I-compounds are normal DNA modifications and that their deficiency may contribute to development and maintenance of neoplasia.
Randerath
K
K
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030.
Randerath
E
E
Danna
T F
TF
D000375:Aging; D000818:Animals; D002796:Choline Deficiency / Q000473:pathology; D004247:DNA / Q000302:isolation & purification*; D004273:DNA, Neoplasm / Q000302:isolation & purification*; D005260:Female; D008099:Liver / Q000032:analysis / Q000254:growth & development*; D008114:Liver Neoplasms, Experimental / Q000032:analysis* / Q000473:pathology; D000072317:Polychlorinated Dibenzodioxins; D051381:Rats; D011912:Rats, Inbred ACI; D011915:Rats, Inbred BUF; D011919:Rats, Inbred Strains
D004273:DNA, Neoplasm; D000072317:Polychlorinated Dibenzodioxins; D004247:DNA