OBJECTIVETo observe the expression changes of VEGF, iNOS and the level of MVD and NO during the evolution of Golden hamster cheek pouch carcinogenesis. To study the effect of NO in carcinogenesis in the pouch of hamster, and to investigate the effect of NOS inhibitor L-NAME in interfering with carcinogenesis.

METHODS90 golden hamsters were divided into three groups: 40 in experiment group, 40 in control group and 10 in blank group. DMBA was painted on hamster's cheek pouch in experiment and control group, L-NAME was given to hamster in experiment group at the dose of 0.02 ml/g. Hamsters were killed at 6, 9, 12 and 16th weeks, respectively. The blank group was killed at the 16th week. SABC immunohistochemistry assay was used to detect the expression of iNOS, VEGF and factor VIII-related antigen. MVD was measured. The level of NO was measured by Spectrophotometry.

RESULTSThe difference between control group and experiment group at the 12th week and 16th week was observed. The difference of positive expression rate of iNOS in all group was significant and difference between blank group and control group was significant. The difference of positive expression rate of VEGF in all group was significant and difference between blank group and control group at the 12th and 16th week was significant; there was significant difference in every group MVD from the 6th week control group to the 16th week control. There were significant difference among the control group, except the 6th week of experiment and control group.

CONCLUSIONThere is an increased expression of iNOS and the level of NO, as well MVD during the evolution of Golden hamster cheek pouch carcinogenesis from slightly dysplasia to invasive carcinoma. NO plays an important role during the evolution of carcinogenesis, and iNOS inhibitor L-NAME can inhibit the carcinogenesis.