Alterações histológicas na língua de camundongos após indução da carcinogênese com 4-Nitroquinolina-1-Óxido

Abstract

INTRODUCTION: Squamous cell carcinoma (SCC) accounts for more than 90% of oropharyngeal cancers, with smoking being the main risk factor. 4NQO induces lesions in mice similar to those caused by smoking in humans, due to the similarity in the mechanism of action of the carcinogens and the tongue epithelium. OBJECTIVE: This study aimed to histologically analyze the lesions caused by 4NQO in the tongues of mice. METHODOLOGY: Twenty-four C57BL/6 mice were used: 12 animals received 4NQO (100 μg/ml) in drinking water, with 6 drinking for 14 weeks (G1A) and then euthanized, and the other 6 drinking for 14 weeks, observed for 9 weeks with autoclaved water (G1B), and then euthanized. The other 12 animals were divided into 2 control groups of 6 mice, observed for 14 weeks (G2A) and 23 weeks (G2B) with autoclaved drinking water. The tongues were immersed in 10% formaldehyde, embedded in paraffin, and stained with hematoxylin and eosin. RESULTS: In G1A, 2 animals developed mild dysplasia and 4 developed SCC. In G1B, all animals developed SCC. In G2A and G2B (control groups), no lesions occurred. CONCLUSION: It was concluded that 4NQO (100 μg/ml) induces epithelial dysplasia and SCC within 14 weeks (G1A) and SCC in 100% of animals within 23 weeks (G1B), with the observation period being necessary for the progression of epithelial alterations to cancer. It is concluded that for SCC development, both the carcinogen concentration and the induction and observation time are of paramount importance.