The effect of different doses of cigarette smoke in a mouse lung tumor model

Abstract

Few studies have used Balb/c mice as an animal model for lung carcinogenesis. In this study, we investigated the effect of different doses of cigarette smoking in the urethane-induced Balb/c mouse lung cancer model. After injection of 3mg/kg urethane intraperitoneally, the mice were then exposed to tobacco smoke once or twice a day, five times a week, in a closed chamber. The animals were randomly divided into four groups. The control group (G0) received urethane only. The experimental groups (G1, G2 and G3) received urethane and exposure to the smoke of 3 cigarettes for 10 minutes once a day, 3 cigarettes for 10 minutes twice a day, and 6 cigarettes for 10 minutes twice a day, respectively. The mice were sacrificed after 16 weeks of exposure, and the number of nodules and hyperplasia in the lungs was counted. The results showed no statistically significant difference in the mean number of nodules and hyperplasia among the different groups, suggesting that the Balb/c mice are not suitable to study the pathogenesis of tobacco smoking-induced tumor progression in the lungs.

Keywords: Balb/c mice; experimental carcinogenesis; lung cancer; tobacco smoking; urethane.

Figure 1

Photograph (A) and graphic description (B) of the experimental system. The cigarettes were lightened in a glass and left to glow in the compartment; the produced smoke was drawn into the chamber where the mice were placed only for the exposure.

Figure 2

Photomicrograph of a representative lung nodule (A and B, H&E stain, 100× and 400×, respectively) and hyperplasia (C and D, H&E stain, 100× and 400×, respectively).

Figure 3

Boxplot presentation of lung nodules in each study group. The figure shows the most extreme values in the data set (maximum and minimum values), the lower and upper quartiles, the median and the outlier (*).