Gene Profiling And The Expression Of DNAH17 And P53 In Colorectal Tubular Adenoma And Carcinoma And Their Significance

Background Colorectal carcinoma(CRC)is the third-most common cancer and a leading cause of cancer-related death world-wide.Most CRC cases develop slowly through the normal mucosa–adenoma–carcinoma sequence,tubular adenomas(TAs)is the most common type of traditional adenoma,with aprevalence rate of more than 80%.Although adenomas tissues are typically destroyed during malignant progression,residual adenomas often continue to exist with the carcinoma lesions and more than 30% of adenomas recur after complete removal.Multiple genes and signaling pathways have been shown to participate in the initiation and development of CRC.APC mutation was found to be driver event in conventional colorectal adenomas and the subsequent mutational events mainly affect the KRAS/NRAS.Mutations in the tumor suppressor genes FBXW7 and SOX9 play an important role in the adenoma–carcinoma sequence.Ma et al.found that the overexpression of DNMT1 protein could effectively predict early CRC and severe precancerous lesions,which may have potential clinical application value.Although genetic alterations in CRC are well characterized,there are still many unidentified mechanisms underlying different steps of such synchronous adenomas and carcinomas.Therefore,the temporal evolution of the mutational landscape during the adenoma-to-carcinoma progression in a given individual can be investigated by simultaneous genomic profiling of benign and malignant lesions from a single individual.Due to its ability to detect a large numbers of variants simultaneously,next generation sequencing(NGS)has been widely used in many studies.Whole-exome sequencing(WES)allows one to enhance sequencing power and cost-effectiveness ratio,providing a more complete investigation of the genomic landscape.Currently,WES is the most used NGS technique for the identification of rare genetic variants associated with disease.In this study,we investigated genetic changes implicated in colorectal TAs and CRC by whole exome sequencing and explored the relationship between protein levels of characteristic gene and clinicopathological characteristics of colorectal TAs or CRC patients,in order to provide neodoxy for the early screening of TAs and early discovery,personalized treatment and prognosis evaluation of CRC.Purpose1)To explore the genetic changes implicated in colorectal TAs and CRC samples by WES.2)To investigate the expression of significant gene mutants in colorectal TAs and CRC tissues and their relationship with clinicopathological characteristics of patients.3)To analyze the correlation of gene co-expression in CRC.4)To compare the accuracy of immunohistochemistry for detection of p53 mutations in CRC using NGS as the gold standard.Method1)We performed whole exome-based mutational analyses for 18 synchronous pairs of colorectal TAs and CRC and corresponding normal mucosa.2)Paraffin samples were expanded from 62 cases of synchronous colorectal TAs and CRC.The expression of significant gene mutants in paraffin samples was detected by immunohistochemistry,and the correlation of gene co-expression in CRC was analyzed.Result1)We obtained mutational landscapes for synchronous colorectal TAs and carcinomas and validated two possible evolution scenarios of synchronous colorectal TAs and carcinomas.2)We observed significant differences in the distribution frequency of mutations in DNAH17 and TP53 genes between TAs and carcinoma sample groups,TP53 was consistent with gene being an early driver of carcinogenesis,and DNAH17 is in line with a late driving event involved in tumor progression.3)The expression of DNAH17 and p53 were significantly increased during the colorectal normal–adenoma–carcinoma sequence(all p< 0.05).4)DNAH17 showed a trend of more frequent high expression in adenoma with the maximum diameter of the size >2cm and the mutation p53 was also significantly correlated with tumor size(p<0.05).In addition,the expression level of DNAH17 protein was positively correlated to a higher tumor stage and deeper tumor invasion,whereas the expression level of p53 protein was positively correlated to lymph node metastasis(p<0.05).5)In CRC,DNAH17 expression was positively correlated with p53 mutation(r=0.313,p<0.05).6)In the detection of TP53 mutations,immunohistochemistry and NGS results are in good agreement.ConclusionThe expression of DNAH17 and p53 may play an important role in the transformation from colorectal normal mucosa to carcinoma through TAs.Combined immunohistochemical detection of DNAH17 and p53 may be useful for evaluating the biological behavior of colorectal TAs and CRC.