Purpose: To explore the effect of overexpression of DCN（decorin） gene on the expression of epidermal growth factor receptor (EGFR), cellular-myelocytomatosis viral oncogene (C-Myc) and cyclin dependent kinase inhibitor (p21)in tumor-bearing nude mice with oral squamous cell carcinoma（OSCC）.
Methods: The expression of DCN gene in human oral squamous cell carcinoma(HSC-3) was up-regulated by liposome transfection. Nude mice were used as the carrier of OSCC. H-E staining was used to determine the pathological grade of tumor-bearing tissues in each group. Immunohistochemistry was used to detect the expression of EGFR, C-Myc and p21 protein in tumor-bearing tissues of each group after DCN overexpression. RT-qPCR and Western blot were used to quantitatively detect the expression of EGFR, C-Myc and p21 in tumor-bearing tissues of each group after DCN overexpression, and to determine the effects of DCN overexpression on the expression of EGFR, C-Myc and p21 in tumor-bearing tissues of OSCC nude mice. SPSS 20.0 software package was used for statistical analysis.
Results: H-E staining showed that the animal model of OSCC was successfully constructed. The tumor-bearing tissues of nude mice in the plasmid group were significantly lighter than those in the empty vector group and non-transfected group(P＜0.05). IHC results showed that DCN, EGFR, C-Myc and p21 proteins were expressed in the tumor-bearing tissues of nude mice in each group, the expression of DCN,EGFR and C-Myc proteins in the plasmid group was significantly different from the other groups(P＜0.05).There was no significant differece in p21 protein expression in each group(P＞0.05). RT-qPCR and Western blot results showed that DCN, EGFR, C-Myc and p21 were expressed in diffrent degrees in tumor-bearing tissues of nude mice（P＜0.05）.
Conclusions: DCN can inhibit the growth of tumor in OSCC nude mice. In tumor-bearing tissues of nude mice with OSCC, overexpression of DCN can down-regulate the expression of EGFR and C-Myc, and up-regulate the expression of p21.DCN may play an inhibitory role in the occurrence and development of OSCC.