Sonic hedgehog signaling may promote invasion and metastasis of oral squamous cell carcinoma by activating MMP-9 and E-cadherin expression.

The aim of this study was to investigate sonic hedgehog (SHH) signaling pathway components (Shh and Gli-1), E-cadherin, and MMP-9 expression in human oral squamous cell carcinoma (OSCC) and to evaluate their role in prognosis. Expression of Shh, Gli-1, and MMP-9 was significantly upregulated in 74 OSCC samples compared with non-cancerous tissue samples (Shh IOD: 162.44 ± 29.35 and 608.82 ± 170.99; Gli-1 IOD: 203.50 ± 71.57 and 831.11 ± 242.352; MMP-9 IOD: 196.69 ± 64.48 and 721.64 ± 197.99 in non-cancerous and tumor tissues, respectively, P < 0.01), whereas E-cadherin expression was downregulated (E-cadherin IOD: 1,006.19 ± 230.42 and 442.20 ± 156.11; in non-cancerous and tumor tissues, respectively, P < 0.01). Highly expressed proteins were associated with lymph node metastasis; moreover, overexpression of Gli-1 was related to tumor recurrence and cancer clinical staging. Spearman's analysis indicated that the expression of Gli-1 and MMP-9 was positively correlated, whereas expression of Shh/Gli-1 and E-cadherin was negatively correlated. Kaplan-Meier results revealed that patients with low Shh, Gli-1, and MMP-9 expression survived longer than those with high expression. In contrast, low E-cadherin expression was associated with poor prognosis (P < 0.01). In conclusions, transcription factor Gli-1 of the SHH signaling pathway may be an important mediator of invasion and metastasis of OSCC through induced expression of MMP-9 and E-cadherin and may serve as a new prognostic marker.