Objective  This work aims to study the DNA methylation and protein levels of the suppressor of cytokine signaling 3 (SOCS3) in oral squamous cell carcinoma (OSCC) tissue, and to explore its function in the development, invasion, and metastasis of OSCC.

  Methods  Atotal of 20 cases with normal oral mucosa were used as the case-control group. The expression of SOCS3 DNAmethyhtion and SOCS3 protein in 100 cases with OSCC is determined and analyzed using methylation pyrosequencing and Western blot to determine its correlation with clinico-pathological parameters.

  Results  The positive rate of SOCS3 DNA methylation is significantly higher in OSCC (85 %) than that in the normal oral mucosa tissues (20 %, P < 0.05); ii. The SOCS3 protein expression was also overtly lower in OSCC (1.76 ± 0.12) than in the normal oral mucosa (1.93 ± 0.25, P < 0.01). In OSCC, the SOCS3 expression was notably lower in the group with methylation (1.72 ± 0.21) than in the group without (1.92 ± 0.23, P < 0.01); iii. Tumor, Node and Metastasis classification revealed that the protein expression in the group with stage Ⅲ OSCC is lower than in the groups with both stage Ⅰ and Ⅱ lesions (P < 0.05), and lower in the group with lymph node metastasis compared with the group without metastasis (P < 0.05); iv. The expression of SOCS3 protein in OSCC is positively correlated with the differentiation degree (0.203 < r < 1, P < 0.05), but had a negative correlation with TNM staging and nodal metastasis (-1 < r < -0.203, P < 0.05).

  Conclusion  The high positive rate of SOCS3 DNAmethylation in OSCC leads to the down-regulation of the SOCS3 gene, which is closely related to the differentiation, invasion, and metastasis in OSCC.