Minimal arecaidine concentrations showing a promotion effect during DMBA induced hamster cheek pouch carcinogenesis

The purpose of the present study was to determine the minimal arecaidine concentrations showing a synergistic effect on DMBA-induced hamster cheek pouch carcinogenesis. One hundred and twelve male adult Syrian golden hamsters were divided into 16 groups, each containing seven animals. After eight weeks of DMBA initiation and then four weeks of arecaidine promotion, 100% tumor incidence was found with arecaidine concentrations of 400 mu g/ml and 500 mu/ml; average tumor numbers were 1.86+/-0.63 and 1.86+/-0.93 respectively (P<0.05). After four weeks of DMBA and a subsequent eight weeks of arecaidine painting, all hamsters developed visible tumors with arecaidine concentrations of 900 mu g/ml and 1000 mu g/ml; average tumor numbers were 1.86+/-0.82 and 2.14+/-1.09 respectively (P<0.05). The tumor dimensions varied little and differences were not statistically significant. Without DMBA pretreatment, regardless of the high arecaidine concentrations (1000 mu g/ml, 2000 mu g/ml and 3000 mu g/ml) applied, no visible tumor growth was observed; only hyperkeratosis and inflammation could be discerned histologically. Thus, the minimal concentrations of arecaidine displaying a synergistic effect in the DMBA-induced hamster cheek pouch of carcinogenesis were found to be 400 mu g/ml applied for foul weeks after eight weeks of DMBA application, and 900 mu g/ml applied for eight weeks after four creeks of DMBA painting. These findings may be useful for other studies concerning the tumorgenicity of arecaidine.