Integrated analysis of mRNA and miRNA expression profiles in pancreatic ductal adenocarcinoma.

In the present study, to investigate the potential molecular mechanism of pancreatic ductal adenocarcinoma (PDAC), mRNA and miRNA expression profiles were integrated for systematic analysis. Results showed that a total of 76 common differentially expressed genes (DEGs) were identified from 2 mRNA expression profiles that contained 39 tumor and 15 normal samples. Notably, the tumor and normal samples were able to be clearly classified into 4 groups based on the DEGs. mRNA‑miRNA regulation network analysis indicated that 22 out of the 76 DEGs including MUC4, RRM2 and CCL2 are regulated by 5 reported miRNAs. Survival analysis using SurvExpress database demonstrated that the common DEGs were able to significantly differentiate low- and high-risk PDAC groups in 4 datasets. In summary, various biological processes are probably involved in the development and progression of PDAC. Firstly, activation of MUC4 induces nuclear translocation of β-catenin and promotes the process of angiogenesis that provides necessary nutrition or oxygen for cancer cells. Then, RRM2 induces the invasiveness of PDAC via NF-κB. Finally, the formation of an immunosuppressive tumor microenvironment by recruiting regulatory T cells with high expression of CCL2 further promotes cancer cell proliferation and vascularization. Identification of valuable biological processes and genes can be helpful for the understanding of the molecular mechanism of PDAC.