The Function And Mechanism Of FOXS1 In Invasion And Metastasis Of Colorectal Cancer

Most colorectal cancer patients die due to metastasis.Although systemic treatment of metastatic CRC has improved,the prognosis of patients with metastatic CRC remains poor.The 5-year survival rate is about 14%.A majority of studies have shown that tumor growth requires blood vessels to obtain nutrients,and that tumor cells require vessel intravasation and extravasation to complete metastasis.Accordingly,blood vessels accompany the entire process of metastasis.Tumor cells release many growth factors to promote neo-vessel formation.To this end,anti-angiogenesis therapy should effectively inhibit tumor growth and metastasis.However,patients with CRC will soon develop drug resistance after using anti-angiogenesis drugs such as Avastin.Therefore,it is necessary to find out new targets for inhibiting angiogenesis and to develop novel combinational therapeutic strategies.In our previous study,we have identified that FOXS1,which was involved in the formation of nerves and blood vessels during embryonic development,gene was significantly upregulated in CRC tissues.However,the role and mechanism of FOXS1 in angiogenesis and tumor growth as well as metastasis in CRC is unknown.This study aims to explore the role and mechanism of FOXS1 in tumor related angiogenesis and metastasis in CRC using in vitro and in vivo models.Methods:1.Bioinformatics analysis of FOXS1 expression was performed using TCGA and public CRC datasets.2.RT-PCR and IHC were performed to detect the expression of FOXS1 in CRC tissue samples.The correlation between FOXS1 expression and clinical parameters such as tumor differentiation,staging,metastasis and prognosis was analyzed using SPSS.3.MTT,Transwell and cecum orthotopic injection were performed to investigate the impact on proliferation and invasion in CRC cell lines with FOXS1 stable overexpression and knockdown4.GSEA gene enrichment method was performed to analyze the up-regulated signal pathway in FOXS1 high expression group in CRC on GEO and TCGA database5.Tubular formation experiments,chicken embryo allantoic membrane angiogenesis experiments and other experiments were performed to investigate the capability of angiogenesis in vitro and in vivo in CRC cell lines with FOXS1 stable overexpression and knockdown.6.Chromatin Immunoprecipitation(ChIP)was performed to detect and verify the binding site and transcriptional activation of CXCL8 promoter-specific sites by FOXS17.CXCL8 rescue experiments were performed to examine the angiogenesis capacity of CXCL8 regulated by FOXS1.Result:1.The expression level of FOXS1 protein is higher in CRC tissues than that of matched normal colorectal tissues.High FOXS1 expression is positively correlated with advanced T classification,M classification,and poor survival.2.Stable overexpression of FOXS1 promotes the proliferation and invasion of CRC cells both in vivo and in vitro;while knockdown of FOXS1 suppresses the proliferation and invasion of CRC cells.3.Stable overexpressing FOXS1 in CRC cells promotes angiogenesis both in vitro and in vivo.4.FOXS1 increased the expression of CXCL ELR+members.5.FOXS1 can directly bind to the promoter of CXCL8 and activates the transcription of CXCL8 gene.6.Suppression of CXCL8 reduces the capacity of angiogenesis induced by FOXS1.Conclusion:1.FOXS1 is upregulated in CRC.High FOXS1 expression is positively correlated with advanced T classification,M classification,and poor survival in CRC.2.FOXS1 promotes the proliferation,invasion and metastasis of CRC cells.3.FOXS1 overexpression promotes angiogenesis and upregulates of the pro-angiogenic CXCL ELR+members in CRC cells.4.FOXS1 directly interacts with the CXCL8 promoter and increases the transcription level of CXCL8.5.FOXS1/CXCL8 axis promotes angiogenesis and metastasis in CRC.