The role of cellular trace elements in oral carcinogenesis induced by 4-nitroquinoline 1-oxide(4NQO).

The aim of this study was to define the changes of cellular trace element concentration during the carcinogenesis process of Wistar rat palatine mucosa squamous epithelial cell induced by 4-nitroquinoline-1-oxide (4NQO). 4NQO was painted three times weekly for nineteen weeks on the palatine mucosae of 28 Wistar rats. Histologically normal, precancerous and squamous epithelial cell carcinoma tissues were obtained, and were studied by electron probe X-ray microanalysis. The measured elements were copper (Cu), zinc (Zn), selenium (Se), and molybdenum (Mo). The results were that both copper and zinc in the cellular nucleus and cytoplasm of the squamous epithelial carcinoma cells were significantly decreased. The concentration of cytoplasmic molybdenum significantly decreased in precancerous cells and significantly increased in squamous epithelial carcinoma cells. Minor changes in the concentration of selenium were observed in the process of normal to precancerous and then to cancerous cells. Cu/Zn increased in squamous epithelial carcinoma cells and Cu/Se and Zn/Se decreased in squamous epithelial carcinoma cells. These results suggest that the changes in intracellular copper, zinc, molybdenum are distinctly related to experimental oral carcinogenesis.