Exploratory Analysis of MicroRNA (miRNA) as a Prognostic and Predictive Biomarker in Locally Advanced and Metastatic Gastric Cancer

Background and purpose Emerging evidence suggests that microRNAs (miRNAs) can function as oncogenes or tumor suppressors, playing an important role in pathogenesis, treatment response, and survival outcomes. This study aims to identify miRNAs as prognostic and predictive biomarkers in locally advanced and metastatic gastric cancer. Materials and methods This study was a prospective exploratory study of patients with gastric cancer from April 2018 to October 2022. Tissues of 50 paired locally advanced and metastatic gastric cancer patients were examined for the expression level of oncomiRs miR-21, miR-200b, miR-27a, miR-93, miR-18a, miR-25, miR-210, and miR-29c and tumor suppressor miR-204 using quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR), and the relevant association with clinical factors was analyzed. Results The expression of miR-29c, miR-27a, and miR-25 was differentially regulated into low and high based on the twofold change. Patients with low miR-29c expression demonstrated an increased propensity for metastasis (P = 0.03). Downregulation of miR-25 was significantly associated with the absence of peritoneal involvement (P < 0.0001) and liver metastasis (P < 0.005). High expression of miR-27a was associated with a better response to chemotherapy (P = 0.04). It was observed that the median follow-up duration was 7.98 months (range, 0.60-46.93 months). Notably, patients in the low miR-27a expression group had significantly better overall survival compared to the high expression group (12.03 (5.69-18.37) months vs 4.90 (3.47-6.33) months; P = 0.02). Conclusion The differentially regulated miRNAs, namely, miR-29c, miR-27a, and miR-25, may be used as predictive and prognostic biomarkers in advanced gastric cancer which require further validation.