Loss of CDH1 promotes the metastasis of hypopharyngeal squamous cell carcinoma through the STAT3-MMP-9 signaling pathway

BACKGROUND: Distant metastasis is the major cause of death in patients with hypopharyngeal squamous cell carcinoma (HSCC). CDH1 is correlated with tumor invasion and metastasis; however, its function in HSCC remains unclear. METHODS: We used immunohistochemistry (IHC) staining to evaluate the expression of CDH1 in 31 and 78 specimens from primary HSCC patients with and without postoperative lung metastases respectively. Sulforhodamine B (SRB) and CCK-8 assays were used to test the proliferation of HSCC cells. Motility of HSCC cells was investigated by migration and invasion assays. Western blot analysis was used to measure the levels of CDH1 and other proteins. RESULTS: We found that the low expression of CDH1 was significantly associated with postoperative lung metastasis in HSCC (P<0.001). Moreover, CDH1 was reduced concomitantly with the upregulation of MMP-9 in the same HSCC sample. Further mechanistic investigation showed that silencing CDH1 elevated the level of MMP-9, which was coupled with the phosphorylation of STAT3. Subsequently, inhibiting STAT3 either by siRNA transfection or by pharmacological suppression with AG490 attenuated MMP-9 upregulation and prevented the enhanced proliferation and invasion caused by CDH1 loss in FaDu cells. CONCLUSIONS: CDH1 plays vital roles in HSCC metastasis and might serve as a potential therapeutic target for the clinical treatment of HSCC.