p53 and TP53 during rat oral carcinogenesis induced by 4NQO

The medium-term tongue carcinogenesis assay is a useful model for studying oral squamous cell carcinomas phase by phase. Objective: the aim of the present study was to investigate the expressivity of p53, as well as mutations in exons 5-8 of TP53 gene during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide (4NQO) using immunohistochemistry and DNA sequencing, respectively. Methods: a total of 30 male Wistar rats were treated with 4-nitroquinoline 1-oxide in drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Results: statistically differences (p<0.05) were found in p53 expression 12 and 20 weeks after treatment,i.e., pre-neoplastic lesions and squamous cell carcinomas, respectively. A weak immunoexpression was observed in the negative control and in ‘normal' oral mucosa following 4 weeks after exposure to 4NQO. Regarding DNA sequencing, no mutation was found in all of the exons evaluated at all experimental periods. Conclusions: taken together, our results suggest that abnormal p53 expression was present in pre-neoplastic lesions and squamous cell carcinomas of the oral cavity. However, no mutations were detected during oral cancer progression.