[Effect of superoxide dismutase and diethyldithiocarbamate on the induction of squamous cell carcinoma of lung with methylcholanthrene in rats].

The squamous cell carcinoma of lung was induced with methylcholanthrene (MCA) in iodized oil in Wistar rats. During the development of the cancer, the animals were given superoxide dismutase (SOD) or its inhibitor diethyldithiocarbamate (DDC). In DDC group, 3 out of 50 rats developed cancer and 4 developed atypical hyperplasia of bronchial epithelium within 35 to 40 days. In SOD group, no cancer developed in all of the 52 rats, and only one had atypical hyperplasia in the lungs. Only one of 42 control rats had cancer and 2 rats had atypical hyperplasia of bronchial epithelium. The difference in cancer frequency between groups DDC and SOD was significant (P < 0.05). The results suggest that there is a synergism between DDC and MAC in the induction of lung cancer, while SOD can inhibit MCA-induced lung cancer development. The mechanism of the effect of SOD and DDC was discussed.