C-Myb Targeting C-fos Promotes The Development And Metastasis Of Colorectal Cancer

Objective Colorectal cancer(CRC)is one of the most common human malignancies in the world,while this tumor early diagnosis rate is low.The current mainly treatment plan is surgery,and depending the specific situation,combining with comprehensive treatment such as chemical drug treatment,radiation therapy,or traditional chinese medicine treatment.Although the current treatment methods have made a great progress than before,the clinical prognosis of CRC is still not ideal.Therefore,in-depth study of the possible pathogenesis of CRC,and searching new diagnostic markers and therapeutic targets can provide a new direction for the clinical diagnosis and treatment of CRC.Recent studies have found that c-Myb is a key transcription factor involved in various biological functions,and plays a key role in varieties of human tumors,but its mechanism of action in CRC has not been well studied.This study intends to demonstrate that the target of cMyb is c-fos in vitro and in vivo,and it can affect the proliferation,apoptosis,metastasis and invasion of colorectal cancer by regulating c-fos.Methods In this research,the expression level of c-Myb in 132 patients which enrolled in the study and the clinical significance were firstly examined and analyzed.Then,selected two CRC cell lines with high expression of c-Myb gene(SW620 and HCT116),using clustered regular interspersed short palindromic repeats/ CRISPR-associated9(CRISPR/Cas9)system to knockout(KO)c-Myb gene,and then the effect of c-myb KO on CRC cells was evaluated by cell function experiments in vitro and in vivo.Finally,RNA sequencing(RNA-seq)analysis investigated the potential carcinogenic mechanism of c-Myb in CRC progression.Chromatin immunoprecipitation assay(ChIP)was used to validate the downstream gene of c-Myb.Bying overexpression of the downstream target gene,we could found the corresponding phenotypic changes in the cell,therefore,the mechanism of action of c-Myb in the development of CRC was further verified.Results First,the abundance of c-Myb in CRC tissues and matched adjacent normal tissues of 132 patients which included in this experiment were examined.We found that the c-Myb expression in CRC tissues was significantly higher than in matched adjacent normal tissues.Moreover,the High expression of c-Myb in tumor tissues is significantly associated with distant lymph node metastasis in CRC patients.Secondly,patients with high c-Myb expression have lower overall survival(OS)and disease-free durvival(DFS)than those with low c-Myb expression,and the c-Myb abundance can be used as a significant independent prognostic factor for OS and DFS in patients with CRC.Through subgroup analysis,we found that c-Myb also has significant clinical prognostic significance in stage ? CRC patients and stage ? CRC patients,and c-Myb can be used as a significant independent prognostic factor for OS and DFS in patients with stage ? and ? CRC.Second,c-Myb KO inhibits CRC cell proliferation,anti-apoptosis,invasion,metastasis,colony formation and tumorigenesis in vivo.Third,RNA-seq analysis indicated that c-Myb may promote the progress of CRC by regulating c-fos.ChIP further verified that the transcription factor c-Myb binds to the the promoter region of c-fos,which is near the Transcription Start Sites(TSS)region.Finally,c-fos overexpression can rescue c-Myb KO from inhibiting the malignant features of CRC cells.Western blot(WB)analysis showed that overexpression of c-fos rescued the inhibition of c-Myb KO in the epithelial-mesenchymal transition(EMT)phenotype.Conclusion c-Myb can promote the development and metastasis of colorectal cancer.The c-Myb promotes the proliferation,anti-apoptosis,migration and invasion of CRC cells by regulating c-fos,and promotes invasion and metastasis of CRC through EMT.c-Myb abundance is a significant independent prognostic factor for postoperative OS and DFS in patients with CRC,and can be used as a clinical prognostic biomarker and therapeutic target.