Effects of menadione on 1,2-dimethylhydrazine-induced mouse colon adenocarcinoma

The effects of menadione (Vit K3) administered at 20 or 40 mg.kg-1 ig 3 times a week for both 24 and 28 wk on 1,2-dimethylhydrazine (DMH)-induced mouse colon adenocarcinomas were investigated. At the 24th wk, the number of colon tumors in Vit K3 20 or 40 mg.kg-1 group (0.3 +/- 0.5 and 0.5 +/- 0.8, respectively) was less than that of DMH controls (2.1 +/- 2.5, P < 0.05), but the difference in incidence of colon tumors in these 3 groups was not significant (P > 0.05). After 28 wk, the tumor incidence of both Vit K3 groups (each 8 of 13) was lower than that of DMH controls (13 of 13, P < 0.05); the number of colon tumors of Vit K3 40 mg.kg-1 group (1.3 +/- 1.3, P < 0.05) was decreased, whereas the Vit K3 20 mg.kg-1 group (3.0 +/- 5.1, P > 0.05) was not different from the DMH controls (7.3 +/- 9.3). Determination of the nuclear DNA content of cells from DMH-induced mouse colon mucosa (24 wk) indicated that Vit K3 20 or 40 mg.kg-1 group showed lower DNA content (1.92 +/- 0.12 C and 1.91 +/- 0.10 C, respectively) decreased values of percent-over-3C and -4C and narrow distribution range. Besides, the colon mucosa of DMH-treated mice (28 wk) showed higher superoxide dismutase (SOD) activity (70 +/- 28 U/mg protein, P < 0.05) than the normal controls (30 +/- 20 U/mg protein). Vit K3 40 mg.kg-1 reduced the elevated SOD activity markedly (44 +/- 23 U/mg protein, P < 0.05).