Evaluation of circulating miR-21 and miR-222 as diagnostic biomarkers for gastric cancer

Introduction: Gastric cancer is responsible for a large number of death worldwide and its high death rate is associated with a lack of noninvasive tools in GC diagnosis. MicroRNAs (miRNAs), as gene regulators, were shown to dysregulate in different types of cancer. Moreover, it is proven that miRNAs are stable in serum/plasma, so they can be used as a potential noninvasive marker in GC diagnosis. The objective of this study is to investigate the plasma miRNA expression in GC samples compared to controls as a potential biomarker in cancer diagnosis. Materials and Methods: Expression levels of miR-21 and miR-222 were assessed using quantitative real-time polymerase chain reaction in plasma of 30 GC patients and 30 healthy controls. Diagnostic value of selected miRNAs was evaluated using receiver operating characteristic curve. Target prediction was done using bioinformatics tools to investigate the signaling pathways and function of the selected miRNAs. Results: Our results demonstrated that the expression levels of miR-21 and miR-222 were significantly higher in GC plasma than in the controls (P < 0.0001, P = 0.043). The sensitivity and specificity for miR-21 and in plasma were 86.7% and 72.2% and for miR-222 were 62.5% and 56.2%, respectively. Bioinformatics analysis revealed that most target genes of miR-21 and miR-222 are involved in cancer-related signaling pathway such as tumor initiation and progression. Conclusion: Our results indicated that miR-21 and miR-222 in plasma samples can be served as a potential noninvasive tool in GC detection. Furthermore, the miRNA target prediction manifested that miR-21 and miR-222 involve in key processes associated with GC initiation and development.