The Study Of NLK Promotes Tumor Invasion And Metastasis Via ?-catenin Signaling In Oral Squamous Cell Carcinoma

Objective: Abnormal expression of NLK has been confirmed in the development of human carcinogenesis,invasion,migration,and stem cell differentiation.Nevertheless,expression of NLK and the role it may played in OSCC remain uncovered.The study aimed to ascertain NLK expression in OSCC,then to explore the potential mechanisms of NLK for modulating OSCC EMT.Materials and methods: 1.A total of 124 patients with OSCC were treated with radical resection and cervical lymphadenectomy from January 2006 to October 2010 in the Department of Maxillofacial Surgery,Affiliated Tumor Hospital,Tianjin Medical University.Another 43 cases of OSCC adjacent tissues were used as control.Relevant clinical medical records are complete.The survival data of the 124 OSCC patients were obtained by telephone follow-up.The immunohistochemistry assay was performed to detect the expression of NLK,?-catenin,EMT related proteins and MMP-2/9.The relevances of NLK to clinico-pathological trait,prognosis,?-catenin,EMT related proteins and MMP-2/9 were analyzed.2.Using lipofectamine 2000 to mediate transfection by NLK si RNA to knock down NLK expression in oral squamous cell carcinoma cells.?-catenin,EMT related proteins and MMP-2/9 were measured by western blot.The wound healing and transwell assay were performed to determine cell migration and invasion.Results: 1.NLK was overexpressed in 82 of all OSCC samples(66.1%),significantly higher than that in the para-neoplastic samples.OSCC samples with lymphnode metastasis showed a higher NLK expression compared with those without lymphnode metastasis.Apart from lymphnode metastasis,NLK expression was also higher in modertately or poorly differentiated OSCC tumors than in well differentiated OSCC tumors.Vimentin,E-cadherin,MMP-9,MMP-2,?-catenin and N-cadherin were relevant with the lymphnode metastasis.What's more,NLK was positively correlated with ?-catenin,N-cadherin,Vimentin,MMP-2 and MMP-9,negatively correlated with E-cadherin.After all variables were analyzed separately with survival status,we found NLK,pathological classification,lymphnode status,?-catenin,Vimentin,MMP-2 and MMP-9 significantly influenced survival.The Kaplan-Meier survival curves showed that high NLK expression was significantly associated with a poor survival time among the OSCC patients.Cox multivariate analysis indicated that high NLK expression,lymphnode metastasis and moderate or poor differentiation were negatively relevant to postoperative survival of these patients,indicating that NLK is an independent risk factor and has an adverse impact on prognosis.2.Knockdown of NLK expression in human squamous cell carcinoma SCC25 and UM1 cell lines,expression of ?-catenin and p-?-catenin were reduced.Meanwhile,knockdown of NLK expression decreased ?-catenin expression both in cytoplasm and in nucleus,especially in nucleus.3.NLK expression was knocked down in human squamous cell carcinoma SCC25 and UM1 cell lines,expression of EMT related proteins(N-cadherin,Vimentin),and invasion targets(MMP-2,MMP-9)were reduced,but E-cadherin was increased.Furthermore,migration and invasion of the tumor cells were inhibited while NLK was knocked down.Conclusion: NLK is overexpressed in oral squamous cell carcinoma,and is associated with tumor pathology,EMT,lymph node metastasis,and prognosis.And NLK promotes invasion and metastasis by regulating ?-catenin signaling pathway in oral squamous cell carcinoma.