Epigenetic Field Cancerization in Gastric Cancer: microRNAs as Promising Biomarkers.

The biological role of microRNAs (miRNAs) in field cancerization is unknown. To investigate the involvement of miRNAs in gastric field cancerization, we evaluated the expression profile of ten miRNAs and their diagnostic value. We used three groups of FFPE gastric samples: non-cancer (NC), cancer adjacent (ADJ) and gastric cancer (GC). The expression profiles of , , , , , , and were investigated using qRT-PCR. The results obtained by qRT-PCR were validated in Small RNA-Seq data from the TCGA database. The search for target genes of the studied miRNAs was performed in the miRTarBase public database and miRTargetLink tool, using experimentally validated interactions. In addition, we also performed the functional analysis of these genes using enrichment in KEGG pathways. The potential as biomarker was evaluated using a receiver operating characteristic (ROC) curve and the derived area under the curve (AUC>0.85) analysis. The miRNAs , , , , , , , and were up-regulated in ADJ and GC compared to NC (<0.03); and and were up-regulated in GC compared to ADJ (<0.01). , , , and were not differentially expressed between GC and ADJ, suggesting that both share similar changes (>0.1). The TS-miR was up-regulated in ADJ compared to NC and GC (<0.01); we did not observe a significant difference in the expression of this miRNA between NC and GC. This feature may be an antitumor mechanism used by cancer-adjacent tissue because this miRNA regulates the , and oncogenes. The expression level of was associated with infection status (<0.05) Functional analysis using the genes regulated by the studied miRNAs showed that they are involved in biological pathways and cellular processes that are critical for the establishment of infection and for the onset, development and progression of GC. , , , , , , and were able to discriminate NC from other tissues with great accuracy (AUC>0.85). The studied miRNAs are closely related to field cancerization, regulate genes important for gastric carcinogenesis and can be potentially useful as biomarkers in GC.