Identification Of Genomic Alterations And Relevant Genes Of Perineural Invasion In Patients With Stage ? Colorectal Cancer

Background and PurposePerineural invasion(PNI)was associated with a poor outcome in many malignant tumors,such as colorectal cancer(CRC),pancreatic cancer,gastric cancer,breast cancer and prostate cancer.PNI was considered as an independent poor prognostic factor for them.Although the molecular mechanisms of PNI in pancreatic cancer was intensely and deeply studied in recent years,the molecular mechanisms underlying the association between PNI and stage ? CRC still remain unclear.By comparing the different genomic expression between the normal tissues and the stage ? CRC cancer with or without PNI,this study aims to initially explore the molecular events underlying the association between PNI and stage ? CRC.which has potential theoretical values for the screening of candidate biomarker and possible gene targeting treatment in CRC.Methods5 pairs of primary tumor tissues and paracancerous normal tissues of stage ? CRC with PNI and 5 pairs without PNI were collected and the genomic aberrations were detected by using array-based comparative genomic hybridization(array-CGH).Then we analyzed the data and identified genomic aberrations through relevant programs.In order to analyze the genomic aberrations between the normal tissues and the stage ? CRC cancer with or without PNI,in terms of biological process,cellular component,molecular function,biochemical metabolic pathways and signal transduction pathways,we performed GO analysis and Pathway analysis for these CGH data.We further collected 50 pairs of primary tumor tissues and paracancerous normal tissues of stage ?CRC with PNI and 50 pairs without PNI and performed the real-time PCR to further verify the expression of selected genomic aberrations identified by Array-based CGH.Results13 gains and 18 losses were frequently detected by Array-CGH in Stage ? CRC tissues compared with normal tissues.The most common gains were detected at 7q 11.21-q11.22(30%).8p11.21(30%),8p12-p11.23(30%),8q11.1-q11.22(30%),13q12.13-q12.2(30%),and 20q11.21-q11.23(30%),and the most frequent losses were found at 17p13.1-p12(60%),8p23.2(40%),and 18q11.2-q23(40%).High-level amplifications were discovered at 8p11.23-p 11.22,18q21.1,19q11-q12,and 20q11.21-q 13.32 and homozygous deletions were seen at 20p 12.1 in Stage ? CRC.Gains at 7q 11.21-q22.1,16p11.2,17q23.3-q25.3,19p13.3-p12,and 20p13-p11.1,and losses at 11q11-q12.1,1 1p15.5-p15.1,18p11.21,and 18q21.1-q23 were found more commonly in the PNI group.It is also observed that gains at 8q11.1-q24.3,9q13-q34.3,and 13q12.3-q13.1,and losses at 8p23.3-p12,17p13.3-p11.2 and 21q22.12 occurred more frequently in the NPNI group.GO analysis revealed that genes changed in stage ? CRC belonged to the classes of genes that participated in the following biological processes:organic substance biosynthesis,regulation of metabolic processes,regulation of macromolecule biosynthesis,DNA binding and organic cyclic compound binding.Pathway analysis revealed that the genes changed in stage ? CRC were mainly involved in the following pathways:signal transduction,gene expression,metabolism and immune system.GO analysis confirmed that the genes related to PNI mainly participated in sensory perception of smell,organic substance biosynthetic,DNA binding,olfactory receptor activity,odorant binding and heterocyclic compound binding.Meanwhile,the genes related to NPNI mainly belonged to homophilic cell adhesion via plasma membrane adhesion molecules,flavonoid glucuronidation,extracellular ligand-gated ion channel activity,peptidase regulator activity and peptidase inhibitor activity.The pathway analysis revealed that the genes related to PNI were mainly represented in the pathway of signal transduction,gene expression and metabolism,and the genes related to NPNI were mainly represented in the pathway of metabolism,signal transduction,immune system and metabolism of proteins.The validation for the candidate genes by real-time polymerase chain reaction(real-time PCR)showed that the gain of FLT1,FBXW7 and MACROD2 was more common in the NPNI group compared to the PNI group.ConclusionsOur results suggested that involved genomic changes may be the early events in the development of the PNI in stage ? CRC and it may promote the occurrence and procession of PNI in CRC through the pathway of signal transduction and gene expression.Olfactory receptor may play an important role in the occurrence of PNI in stage ? CRC.The gain of FLT1,FBXW7 and MACROD2 was more common in stage ?CRC without PNI.The involved genomic changes are valuable for the screening of candidate biomarker and possible gene targeting treatment in CRC.