Immunoregulation related gene of CSMD2 and RNA activity as potential predicter of 2-year survival in pancreatic cancer: A DNA and RNA sequencing analysis.

Abstract

e16212 Background: The 5-year survival rate of pancreatic cancer remains as low as 3%-15%. One of the key approaches to enrich current treatment options or improve effectiveness is new biomarker probing. We conducted DNA and RNA sequencing analysis to reveal potential biomarkers related to overall survival. Methods: Whole-exome sequencing, RNA sequencing and clinical data for 209 patients with pancreatic cancer were downloaded from TCGA. Clinical factors and mutational landscape (insertion/ deletion/ single nucleotide variant) were compared between group of OS2+ (OS longer than 2 years) and OS2- (OS longer than 2 years) with T test and Chi-square Test. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted with RNA sequencing data to clarify the functional differences between the two groups. Results: The rates of OS2+ for patients in stage of I/II/III/IV was 43% (9/21), 17.8% (27/152), 0% (0/4), 0% (0/5), respectively. 152 patients in stage II were included for further analysis. No difference of sex and age were found between group of OS2+ and OS2-. Tumor mutation burden was comparable between the two groups. Mutation landscape showed the two groups had the accordance of 50% in top 10 genes. Mutations of CSMD2(18.5% vs. 5.0% , P = 0.026), CMYA5(14.8% vs, 2.5% , P = 0.019) and KCNA6(14.8% vs, 3.3%, P = 0.034) were more frequent in OS2+ group. CSMD2 is thought to be involved in the control of complement cascade of the immune system, and its low expression was significantly associated with differentiation, lymphatic invasion, and tumor size in colorectal cancer. CMYA5 was predicted as novel oncogene in breast cancer with the tool of Moonlight, it may also participate tumor activity in pancreatic cancer. The role of KCNA6 in cancer cell activity is barely known yet. Evaluation of differentially expressed genes between the two groups detected difference in leukocyte differentiation and T cell activation (GO analysis) and MAPK signal pathway (KEGG panalysis), these immunoregulation and MAPK pathways may play critical roles in tumor development and progression and affect the prognosis of pancreatic cancer. Conclusions: Pancreatic cancer with 2-year survival presented significant different DNA and RNA alterations, in which CSMD2 and pathway of leukocyte differentiation and T cell activation are closely associated with immunoregulation. These might provide guidance for prognose management and development of new therapeutic targets. Further mechanistic insights and prospective validation studies are warranted.