PROMOTION OF CHEMICAL CARCINOGENESIS AND P53 EXPRESSION BY REDUCTION OF SUPEROXIDE DISMUTASE ACTIVITY IN THE LUNG OF RAT IN VIVO*

In the present experiment, an inhibitor of superoxide dismutase (SOD), diethyldithiocarbamate (DETC), was used to decrease SOD activity for the observation of the relation between SOD activity and carcinogenesis and the expression of P53 protein in vivo. 144 Wistar rats were used for the present study. The results showed that the SOD activity reduction by DETC resulted markedly in the promotion of the carcinogenesis and the expression of P53 protein in the lung tissues, but the increase of SOD activity by the addition of plus SOD inhibited the pathological changes significantly. The frequency of the pathological lesions and positive P53 expression are 36/42 and 8/42 in the animals without DETC and SOD; 16/52 and 4/52 in the animals with SOD and 46/50 and 26/50 in the animals with DETC respectively. The results reported in this paper suggest that: (1) the decrease of SOD activity enhanced the carcinogenesis induced by chemical carcinogen; (2) 1753 gene may be associated with the process of tumorigenesis; and (3) at the same time the abnormal expression of P53 protein may be associated with the transition from premalignant lesions to carcinoma.