The Effect And Molecular Mechanism Of Transcription Factor TEAD1 In Colorectal Cancer

?Background?Colorectal cancer is the 3rd most common malignant cancer in China,and seriously threatens the health and survival of mankind.Therefore,the study of its mechanism is critical for prevention and treatment,as well as reducing the morbidity and mortality of colorectal cancer.Hippo pathway is an important regulator of cell proliferation,growth and apoptosis.In the development process,Hippo pathway controls tissue homeostasis,organ size,stem cell self-renew and tissue regeneration.It also plays an important role on the development of tumors.As results of Hippo dysregulation,the activation of YAP1 which promoting the development of colorectal cancer was always the focus of researches.YAP1 is a transcriptional coactivator and works with transcription factor TEADs family.It was unkown which TEAD mediate YAP1's effect on promoting development of colorectal caner,as well as the mechanism.?Objective?To investigate the correlation between transcription factor TEADs family and YAP1 in colorectal cancer,and confirm the main transcription factor binding to YAP1.To illuminate the role of TEAD1 on colorectal cancer cells,as well as its underlying molecular mechanisms which will be helped to provide new theoretical basis of therapeutic targets and prognostic markers for TEAD1.?Methods?The correlation between YAP1 and TEAD1 in colorectal cancer was analyzed by bioinformatics technique.RNA sequencing data of colorecatal cancer tissues was downloaded from TCGA database,and standardized by Log2 methods.The expression level and correlation of related genes were analyzed by Graphpad 5.0,which determine the major effector of Hippo pathway and its main transcription factor in colorectal cancer.The coexpression genes of YAP1 and TEAD1 in colorectal cancer was downloaded from cBioportal database.Then,the KEGG pathway and GO_BP analysis by DAVID Online tool was conducted to uncover the biological process mediated by YAP1-TEAD1.The expression profile and prognostic value of TEAD1 in colorectal cancer were analyzed.With colorectal cancer tissue and corresponding clinical pathological parameters of the patients,TEAD1 expression level was detected using immunohistochemistry method.The correlation between TEAD1 expression level and overall survival rate was also analyzed..The role of TEAD1 in colorectal cancer was investigated.Using lentivirus technology,strains with up-regulated and down-regulated expression of TEAD1 were set up.The impact of TEAD1 on cell proliferation and cell cycle was detected by BrdU labeling method,MTT assay and FACS.Meanwhile,the mechanism of TEAD1 in promoting cell proliferation in colorectal cancer was illuminated by double luciferase reporter system and chromatin immunoprecipitation(Ch IP).?Results?By analyzing gene sequencing data,we found the main effector of Hippo pathway is YAP1 in colorectal cancer.In four TEADs(TEAD1-4),which can bind to YAP1,the expression level of TEAD1 was higher than others(p<0.001).And the correlation between TEAD1 and YAP1 was the highest.The coexpression genes of YAP1 and TEAD1 was analyzed,and the result showed that the coexpression genes of YAP1 mainly involved in stem cell pluripotency regulatory signaling pathway,TGF-beta signal pathway,Hippo signaling pathway,pathway of cancer and Wnt signaling pathway.The related biological processes were DNA transcription and transcription regulation.The coexpression genes of TEAD1 mainly involved in local adhesion,PI3K-Akt signaling pathway,tumor-related signaling pathway,Ras signal pathway and Hippo signal pathway.The related biological processes were cell adhesion,angiogenesis,cell transfer,DNA transcription and transcription regulation.Intersecting the biological processes of YAP1 and TEAD1,results showed that these genes mostly participated in two common biological processes: DNA transcription and transcription regulation.Immunohistochemical results showed that TEAD1 was abnormally expressed in the nucleus of colorectal cancer cells.The expression of TEAD1 was related to tumor size(p<0.001),TNM stage(p<0.001)and CEA level(p<0.001),while had no relationship with age,gender or tumor location.Cox multivariate analysis showed that the expression of TEAD1 and TNM stage were independent risk factors(p<0.001).The Kaplan-Meier method was used to analyzed and showed five-year overall survival rate was higher in low expression group which indicated better prognosis(89.81% vs.82.22%,p<0.05).Up-regulated expression of TEAD1 significantly increased BrdU positive ratio in cells and it also leads to a rapid transition from Go/G1 phase to S phase and proliferation(p<0.05).However,down-regulated expression of TEAD1 showed the reverse(p<0.05).Meanwhile,TEAD1 was able to regulate the expression of CCND1,and the expression of CCND1 was up-regulated by TEAD1 overexpression(p<0.01).Down-regulated expression of TEAD1 could inhibit the expression of CCND1(p<0.05).TEAD1 can also regulate the expression of SP1(p<0.01).ChIP showed that the SP1 promoter region contains TEAD1 binding sequence element MCAT,and double luciferase reporter gene experiments further confirmed that TEAD1 can directly up-regulate the activation of SP1(p<0.01).In up-regulated expression of TEAD1 cells,downregulated expression of SP1 reduced the expression of CCND1 and inhibited the proliferation(p<0.01).?Conclusion?In colorectal cancer,the main effector of Hippo pathway is YAP1.The main transcription factor that bind to YAP1 is TEAD1 and the oncogenic role of YAP1 is depended on TEAD1.In colorectal cancer,TEAD1 regulates SP1 transcription directly,promoting the expression of CCND1 inderectly and therefore the proliferation of cells.TEAD1 predicts a poor prognosis in colorectal cancer.