Ultrastructural changes of the palatal mucosa following application of 4-nitroquinoline-l-oxide (4NQO) in rats subjected to major salivary gland excision

Overexpression of Bcl-2, SOCS 1, 3 and Cdh 1, 2 are associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model

BACKGROUND

The objective was to assess histopathological changes and the expression of proliferating cell nuclear antigen (PCNA), Bcl-2, suppressor of cytokine signaling (SOCS) 1 and 3, Vimentin, TWIST1, and Cdh 1 and 2 in early stages of experimental oral carcinogenesis process using a shorter period of exposure to 4-nitroquinoline oxide (4-NQO) model.

METHODS

In this study, 20 rats were divided into control group (n = 10), sacrificed on the first day of the experiment, and experimental group (n = 10) treated with 50 ppm of 4-NQO solution dissolved in drinking water for 8 and 12 weeks. The histological sections were stained with H&E or subjected to immunohistochemistry for detecting PCNA, Bcl-2, SOCS 1 and 3, and STAT 3. Some specimens were used for verification of Vimentin expression, Cdh 1, Cdh 2, and TWIST1 by RT-qPCR.

RESULTS

At both 8 and 12 weeks, morphological changes occurred mainly in the posterior portion of the tongue and were limited to the epithelial tissue, including moderate to severe dysplasia at 8 weeks, and severe dysplasia with exacerbation of atypical cells at 12 weeks. Expression of SOCS 1 and 3 increased from 8 to 12 weeks (P < 0.05), whereas STAT 3 expression was reduced mainly at 12 weeks (P < 0.05) in comparison with the control group. The expression of all epithelial-mesenchymal transition markers (EMT) was increased after 12 weeks, reaching statistical significance (P < 0.05) for Cdh 1 and 2.

CONCLUSIONS

Together, the results suggested that overexpression of Bcl-2, SOCS 1 and 3, and Cdh 1 and 2 is associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model.