[Study on Lingual Mucosa Carcinogenesis of C57BL/6 Mice Induced by 4-nitroquinoline 1-oxide]

Objective: This study aimed to induce carcinogenesis of lingual mucosa in C57BL/6 mice by feeding them 4-nitroquinoline 1-oxide (4NQO) solution.

Methods: A total of 85 C57BL/6 mice were randomly divided into distilled water control group (DD group, n=5), 1,2-propylene glycol control group (PG group, n=5), and experimental group (EP group, n= 75). The mice in the experimental group were medially fed in 15 cages. By contrast, the mice in DD, EP, and PG groups were watered with distilled water, 50 mg.L-1 4NQO solution, and 1,2-propylene glycol solution. The mice in EP group were executed every two weeks from week 0, and the mice in the control groups were sacrificed at the 28th week. The mice were weighed. Mucosal lesions were measured by macroscopic observation and histopathologic detection.

Results: One mouse in EP group died of unknown reason. The weight of the mice in EP group presented weight loss compared with the mice in DD and PG groups after the 24th week. Seventy-nine macroscopic lesions were observed in the lingual mucosa, oral floor, and upper palatal and buccal mucosa. A total of 70 macroscopic lesions (88.6%) were located in the lingual mucosa. Mucosal lesions changed from simple hyperplasia to squamous cell carcinomas. Well-differentiated squamous cell carcinomas were observed in all mice of EP group by pathological section at the 28th week. No lesion was found in the mice of DD and PG groups.

Conclusion: The animal model of lingual squamous cell carcinomas was successfully established. The periods from 12th to 16th week and 20th to 28th week were the ideal times for the research on pathogenesis of early and medial-advanced stage during carcinogenesis of squamous cell carcinomas.