Sex-determining region Y-related high mobility group box (SOX)-2 is overexpressed in cervical squamous cell carcinoma and contributes cervical cancer cell migration and invasion in vitro

Sex-determining region Y-related high mobility group box 2 (SOX-2) is a key pluripotency-associated transcription factor and may be implicated in the pathogenesis of cervical squamous cell carcinoma (SCC). The aim of this study was to explore SOX-2 expression in cervical SCC tissues and to examine whether and how SOX-2 regulates the malignant behaviors of cervical SCC cells in vitro. We here found that SOX-2 expression in the examined cervical SCC tissues was higher than that in the normal cervical and cervical intraepithelial neoplasia (CIN) tissues. Higher protein level of SOX-2 (nuclear positive staining cells ≥50 %) was detected in 34.9 % (29 out of 83 cases) of cervical SCC patients. We also noted that 100 % of well-differentiated and 66.7 % of moderately differentiated cervical SCCs showed lower SOX-2 expression (nuclear positive staining cells <50 %), while 58.8 % of poorly differentiated tumors had higher SOX-2 expression (P < 0.05). Furthermore, the migratory and invasive capabilities of SiHa cervical cancer cells were enhanced when SOX-2 was upregulated whereas suppressed when SOX-2 was downregulated. Also, the phosphorylation levels of protein kinase B (Akt) and extracellular regulated protein kinases (ERK) 1/2 were increased in SOX-2-overexpressed cancer cells but decreased in SOX-2-depleted cells. Additionally, LY294002 (Akt pathway inhibitor) or U0126 (ERK pathway inhibitor) significantly suppressed SOX-2-overexpression-induced migration and invasion in SiHa cells. Our results indicate that differentially expressed SOX-2 is associated with tumor differentiation (P < 0.05) and that SOX-2 contributes to the migratory and invasive behaviors of cervical SCC in vitro.