An inverse dose response of 5-methyl cytidine on multiple primary spontaneous tumors and their regressions in mice.
Ten series mice of C3H/ST inbreds with spontaneous tumors have received 5-methyl cytidine (total 500 mice). Graded single doses of (1) 3.86, (2) 2.57, (3) 2.06, (4) 1.54, (5) 1.03, (6) 1.54, (7) 1.03, (8) 0.51, (9) 0.26, and (10) 0.13 mg/injection (three times weekly) were used. In series 1-5 the 5-methyl cytidine was dissolved in distilled water, and in series 6-10, the nucleoside was dissolved in physiological salt solution. In doses administered, series 4-5 overlapped with series 6-7. The number of mice that showed a regression of tumor increased in the successive series (48%-63% in series 1-5 and 25%-73% in series 6-10). As the number of mice with regressing tumors increased, the percentage of mice showing multiple primary tumors also increased. The administration of the nucleoside in physiological salt solution altered the inhibitory effect of 5-methyl cytidine on spontaneous tumors. For example, in physiological salt solution the 0.51 mg/injection gave as much inhibitory action as 1.03 mg/injection in distilled water. An inverse dose response is thus indicated between the amount of 5-methyl cytidine injected and the inhibition of spontaneous tumors in mice (percentage of regression and number of multiple primary spontaneous tumors are the criteria of inhibition considered).
D000818:Animals; D003562:Cytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D008809:Mice, Inbred C3H; D009378:Neoplasms, Multiple Primary / Q000188:drug therapy* / Q000473:pathology; D014677:Pharmaceutical Vehicles
D014677:Pharmaceutical Vehicles; D003562:Cytidine