Multi-omics-based Pathological Mechanism Research And Prognostic Target Identification Of Rectal Adenocarcinoma

Colorectal cancer(CRC)has become the third most common cancer in the world.According to statistics,there were more than 130,000 new CRC patients in the United States,and more than 50,000 of them died in 2017.In China,new cases and fatal cases of CRC have shown an increasing trend in recent years.Although radiotherapy and chemotherapy combined with TME surgery have become the standard treatment for locally advanced rectal cancer(LARC)and significantly improve the local control rate of LARC,the risk of distant metastasis and the overall prognostic survival rate have not been significantly improved,and the recurrence of rectal cancer is still the leading cause of death in patients with rectal cancer.To this end,in this study,we select rectal adenocarcinoma(READ)with high recurrence and metastasis of colorectal cancer as the research object,then explore the key mechanisms of regulating the invasion and metastasis of rectal adenocarcinoma at the multi-omics level through modern biological techniques such as DNA methylation sequencing and transcriptome sequencing,and to discover prognostic markers of READ.Our study provide some new therapeutic targets and directions for the discovery and treatment of specific markers of READ.At the DNA methylation level,this study proposed a method for constructing a weighted methylation gene regulatory network based on canonical correlation analysis(CCA),combining with the mutilevel community discovery algorithm to perform gene module analysis on the methylation chip data of READ,and find that modules closely related to age and Event are mainly involved in biological processes such as cell metabolism,cell polarity and cell cycle regulation;modules closely related to the M feature are mainly involved in biological processes such as the chemotaxis of fibroblast growth factors and the activation and regulation of immune cells;The modules closely related to the N feature are mainly involved in the regulation of microtubule and flagella-based cytoskeleton formation,the regulation of synapses,and the regulation of cell mitosis;the modules closely related to the T feature are mainly involved in the regulation of the extracellular matrix and the formation of microfilaments Biological processes such as the regulation and migration of immune cells.And the methylation sites of seven genes of MAP4(cg04441191),KSR2(cg05658717),GRIN2A(cg09622330),YWHAG(cg10698404),SPAG9(cg17047993),CEP135(cg24504843),CEP250(cg24531267)are closely related to the prognosis of READ,which could be used as prognostic markers for the methylation level of READ.At the transcriptome level,this study proposed a bioinformatics analysis method based on gene co-expression network to analyze READ transcriptome data and found that module 11 significantly associated with clinical characteristic N,T,and event,mainly involved in two types of biological processes which were highly related to tumor metastasis,invasion and tumor microenvironment regulation: 1.cell development and differentiation;2.the development of vascular and nervous systems.Based on the results of survival analysis,seven key genes were found negatively correlated to the survival rate of rectal adenocarcinoma,such as MMP14,SDC2,LAMC1,ELN,ACTA2,ZNF532,and CYBRD1.At the level of copy number variation(CNV),this study proposed a genetic algorithm based on random forest to analyze the copy number variation data of READ,and found that genes related to clinical phenotype M are mainly involved in mitochondrial-related energy metabolism and cell-to-growth factors.Stimulus response and cell response to peptide hormone stimulation;clinical phenotype N-related genes are mainly involved in synaptic-related nerve signal transduction;clinical phenotype T-related genes are mainly involved in intercellular electrical signal transduction.According to the results of survival analysis,it was found that the copy number variation of 5 key genes(MLIP,GCM1,GFRAL,GSTA3,MIR586)was non-linearly correlated with the prognosis of READFinally,this study mapped the characteristic genes that affect the recurrence and metastasis of rectal adenocarcinoma at the DNA methylation level,transcriptome level,and copy number variation level to the chromosome.It was found that the 6p,13 q,and 19 p regions are the main area of DNA methylation and transcriptome,as well as copy number variation in READ.