Study On CAFs-derived POSTN Regulates The Growth And Metastesis Of Oral Squamous Cell Carcinoma Via PTK7

Background and aim:Our previous study found that protein tyrosine kinase7（PTK7）was highly expressed in oral squamous cell carcinoma（OSCC）sphere-forming cells compared to adherent cells.The role of PTK7 in regulating the biological characteristics in OSCC is still unknown.The aim of this study is to detect the interaction between PTK7 and cancer associated fibroblasts（CAFs）in the tumor stroma,and to explore the influence and mechanism of periostin（POSTN）-PTK7 on biological characteristics of OSCC cells.Method:Real-time PCR,western blot and immunohistochemical analysis were performed to investigate the relative expression of PTK7 in OSCC tissues,to analyze the relationships between PTK7 and clinicopathologic features,or between PTK7 andβ-Catenin expression levels.A xenograft model was performed to observe the effects of PTK7 on tumor growth and lung metastasis.In addition,co-immunoprecipitation,MS and immunofluoresence analysis were used to detect the interaction between PTK7 and POSTN.Furthermore,PTK7 knockdown and overexpression lentivirus were constructed to affect the expression levels of PTK7.Then,the recombinant human POSTN was used to educated OSCC cells;the proliferation,colony and sphere-forming formation,as well as migration,invasion and wound-healing assay were measured to prove the influence of POSTN-PTK7 on the biological behaviors of OSCC cells.A OSCC cell xenograft model was used to assess the influence of POSTN-PTK7 on tumor growth.Finally,western blot analysis was performed to reveal the mechanism of POSTN-PTK7 in OSCCs.Results:Increased PTK7 expression was correlated with the Wnt/β-Catenin pathway and increased aggressive clinicopathologic features in OSCC.In addition,inhibition of PTK7 enhanced erlotinib efficacy and reducedβ-Catenin expression in vivo.In the lung metastasis experiments,PTK7antibody decreased lung metastasis rate compared to the control group.Furthermore,POSTN secreted by CAFs was found to be interact with PTK7.POSTN promoted the proliferation,migration,invasion and the CSCs-like phenotype in OSCC cells by interacting with PTK7.Knockdown of PTK7inhibited the influence of POSTN in promoting tumor growth and PTK7overexpression enhanced the function of POSTN in OSCC.In addition,PTK7 knockdown significantly increased the sensitivity of OSCC cells to erlotinib:the half growth inhibitory concentration(IC₅₀)of HN6 decreased from 6.022μM to 3.11μM and that of SCC-25 decreased from 4.732μM to1.729μM.However,PTK7 overexpression induced IC₅₀ increase from6.844μM to 17.92μM.The in vivo experiments also showed that POSTN-PTK7 promoted tumor progression in OSCC.Finally,we demonstrated that POSTN-PTK7 regulated Wnt/β-Catenin signaling in OSCC cells.Conclusion:This study identified that CAFs-derived POSTN interacted with PTK7 and promoted the proliferation,invasion and cancer stem cell-like phenotype by regulating the Wnt/β-Catenin pathway in OSCC.This further suggest that POSTN and PTK7 might be potential prognostic and diagnostic candidate genes for OSCC.