SOX2 is a high mobility group box containing transcription factor that has been reported to be aberrantly overexpressed in various human malignancies, including laryngeal squamous cell carcinoma (LSCC). However, the potential role of SOX2 in LSCC migration and invasion remains to be elucidated. In the present study, we generated stable transformants of human LSCC cells constitutively overexpressing SOX2 and investigated the effects of SOX2 overexpression on migration and invasion in LSCC cells as well as the possible underlying mechanisms. We found that ectopic overexpression of SOX2 in LSCC cells enhanced their migratory and invasive ability in vitro, accompanied by increased expression and activity of matrix metalloproteinase (MMP)-2. Meanwhile, SOX2-induced cell migration and invasion were significantly abrogated by a neutralizing anti-MMP-2 antibody or small interfering RNA targeting MMP-2. Furthermore, overexpression of SOX2 induced phosphorylation of Akt and mammalian target of rapamycin (mTOR), which are downstream effectors of the PI3K pathway. Finally, LY294002, an inhibitor of PI3K, also markedly abolished SOX2-induced activation of the Akt/mTOR pathway and increased cell invasion and MMP-2 expression. Taken together, we conclude that SOX2 promotes migration and invasion of laryngeal cancer cells by inducing MMP-2 via the PI3K/Akt/mTOR pathway. Our findings suggest that SOX2 may serve as a potential therapeutic target for LSCC.

BackgroundMetastasis is the most common cause of disease failure and mortality for non-small cell lung cancer after surgical resection. Twist has been recently identified as a putative oncogene and a key regulator of carcinoma metastasis. N-cadherin is associated with a more aggressive behavior of cell lines and tumors. The aim of this study was to evaluate the clinical relevance of Twist and N-cadherin expression in NSCLC, and the effects of Twist1 knockdown on lung cancer cells.MethodsWe examined the expressions of Twist and N-cadherin by immunohistochemistry in 120 cases of non-small cell lung cancer (including 68 cases with follow-up records). We also analyzed Twist1 and N-cadherin mRNA expression in 30 non-small cell lung cancer tissues using quantitative reverse transcription polymerase chain reaction. The functional roles of Twist1 in lung cancer cell lines were evaluated by small interfering RNA-mediated depletion of the protein followed by analyses of cell apoptosis and invasion.ResultsIn lung cancer tissues, the overexpression rate of Twist was 38.3% in lung cancer tissues. Overexpression of N-cadherin was shown in 40.83% of primary tumors. Moreover, Twist1 mRNA expression levels correlated with N-cadherin mRNA levels. Furthermore, overexpression of Twist1 or N-cadherin in primary non-small cell lung cancers was associated with a shorter overall survival (P<0.01, P<0.01, respectively). Depleting Twist expression inhibited cell invasion and increased apoptosis in lung cancer cell lines.ConclusionsThe overexpression of Twist and N-cadherin could be considered as useful biomarkers for predicting the prognosis of NSCLC. Twist1 could inhibit apoptosis and promote the invasion of lung cancer cells, and depletion of Twist1 in lung cancer cells led to inhibition of N-cadherin expression.

SOX2 is a high-mobility group box containing transcription factor essential for the maintenance of embryonic stem cells. Recent evidence indicates that SOX2 overexpression correlates with metastasis and poor prognosis in patients with laryngeal squamous cell cancer. To investigate how SOX2 contributes to this aggressive phenotype, we introduced the human SOX2 gene into a low SOX2-expressing human laryngeal cancer cell line Hep-2. Cell migration and invasion were determined by the Transwell assay with or without Matrigel coating. The epithelial-mesenchymal transition (EMT)-related markers were assayed by Western blot analysis or immunofluorescence. Our results showed that exogenous expression of SOX2 in Hep-2 cells substantially promoted their migratory and invasive capabilities in culture. Moreover, Hep-2 cells stably overexpressing SOX2 underwent EMT phenotype, as evidenced by mesenchymal morphology, decreased expression of epithelial marker (E-cadherin), and increased expression of mesenchymal markers (N-cadherin, vimentin, fibronectin, and α-smooth muscle actin). Strikingly, Western blot analysis and immunofluorescence also showed that overexpression of SOX2 resulted in substantial increase and nuclear accumulation of β-catenin in Hep-2 cells. However, small interfering RNA targeting β-catenin significantly attenuated the reduced expression of E-cadherin and increased cell migration and invasion abilities in SOX2-overexpressing cells, suggesting that SOX2-induced EMT process, migration, and invasion are dependent on β-catenin activation. Taken together, our findings underscore a novel role for SOX2 in laryngeal cancer migration and invasion.