Role of miR‑34 in gastric cancer: From bench to bedside (Review).

Gastric cancer (GC) is a prevalent digestive system malignancy that is associated with a poor prognosis specifically for advanced‑stage patients. MicroRNAs (miRNAs) are small, non‑coding RNAs that have been reported to play roles as oncogenes or tumour suppressors in all types of cancer, including GC, by post‑transcriptionally regulating cancer‑related genes. Recently, miR‑34a and miR‑34b/c, members of the microRNA‑34 (miR‑34) family, were identified to be direct transcriptional targets of the onco‑suppressor p53. In this review, we report that miR‑34 is epigenetically downregulated or silenced in GC tissues and cell lines, changes which may result from mutations in p53 or DNA methylation and histone modifications of the miR‑34 promoter regions. Moreover, miR‑34 has been identified as a tumour‑suppressor in GC. p53‑induced miR‑34 regulates several different target genes and signalling pathways, inducing apoptosis, senescence, and cell cycle arrest and repressing GC cell proliferation, migration and metastasis, thus contributing to the suppression of carcinogenesis and GC cancer progression. Furthermore, miR‑34 is a novel prognostic and predictive biomarker in GC, and restoring miR‑34 expression by delivering miR‑34 mimics may be a promising therapeutic strategy for the treatment of GC.