Pituitary tumor-transforming gene 1 (PTTG1) is overexpressed in oral squamous cell carcinoma (OSCC) and promotes migration, invasion and epithelial-mesenchymal transition (EMT) in SCC15 cells

Pituitary tumor-transforming gene 1 (PTTG1) is an important oncogenic transcription factor implicated in various malignancies, including oral squamous cell carcinoma (OSCC), a common malignancy of head and neck. Although PTTG1 is reportedly overexpressed in OSCC tissues, its role in human OSCC remains elusive. Thus, this study was conducted to explore the correlation between PTTG1 expression and tumorigenesis of OSCC. We first examined PTTG1 mRNA and protein expression in 28 pairs of OSCC tissues and adjacent non-tumor tissues. PTTG1 protein levels in 98 OSCC specimens were also evaluated by using immunohistochemistry. Our data showed that both mRNA and protein expression levels of PTTG1 in OSCC tissue specimens were markedly higher than that in the corresponding non-tumor tissue samples. A high level of PTTG1 protein expression was found in 74 out of 98 cases (75.51 %) and it was correlated with lymph node metastasis (P = 0.002) and tumor-node-metastasis (TNM) stage (P = 0.007) of patients with OSCC. Moreover, forced overexpression of PTTG1 enhanced SCC15 cell migration and invasion, whereas knockdown of PTTG1 resulted in reverse phenomena. In addition, elevated PTTG1 also increased the activities and expressions of matrix metalloproteinase (MMP)-2, and enhanced epithelial-mesenchymal-transition (EMT) process in SCC15 cells. The EMT changes were accompanied by downregulation of epithelial cadherin (E-cadherin) protein expression and upregulation of snail and vimentin. In summary, our results illustrate that PTTG1 may contribute to the development and progression of human OSCC.