Intervention of nicotine on MNU-induced bladder cancer in rats.

This study examined the effect of nicotine on the expression of mutant p53 (mt-p53) in bladder cancer rats. The rat models of bladder cancer were established by infusing N-methyl-nitroso-urea (MNU, 10 mg/kg every 2 weeks for 8 weeks) into the bladder. Pathological examination on the bladder was conducted to confirm the establishment of the model. All the bladder cancer rats were randomly divided into an MNU group and 3 nicotine groups. In the nicotine groups, the rats were intragastrically administered nicotine at different concentrations (25, 15, 5 mg/kg respectively) 3 times per week for 8 weeks. The mt-p53 expression was detected by the immunohistochemical method. The results showed that rat bladder cancer models developed histopathological changes of bladder transitional cell carcinoma. The positive rate of mt-p53 expression in the 3 nicotine groups (25, 15, 5 mg/kg) was 75.00%, 58.33% and 41.67% by the 14th week, respectively, significantly higher than that in the MNU group (33.33%) (all P<0.05). The mt-p53 expression rate was positively correlated with the medication dose and time (P<0.05). It is concluded that nicotine may play an important role in the development of bladder cancer partially by increasing the expression of mt-p53.