MicroRNAs in tumorigenesis, metastasis, diagnosis and prognosis of gastric cancer.

MicroRNAs (miRNAs), which are small single-stranded RNA molecules composed of 18-23 nucleotides, act as oncogenes or tumor suppressor genes playing important roles in tumor formation, infiltration and metastasis. Subsequently, miRNAs expression contributes to cancer diagnosis and prognosis. Gastric cancer currently has high morbidity and mortality among all malignant tumors, yet it lacks early specific diagnostic markers and effective treatments. In gastric cancer, many studies have detected abnormal expression forms of miRNAs and confirmed their involvement in its tumorigenesis, progression, invasion and metastasis. They may become valuable diagnostic markers and therapeutic targets for gastric cancer. Studying the role of miRNAs in gastric cancer and its relationship with diagnostic and prognostic parameters might help to improve the sensitivity of diagnosis as well as the efficacy of gastric cancer treatment. This review aims to highlight the advancements which might provide new methods for early clinical diagnosis and effective therapeutic options, along with predict response to treatment for gastric cancer.