HMGA2 and gastric cancer: For example, in general, let-7 miRNAs act as a tumor suppressor by targeting oncogenes such as RAS and HMGA2 and let-7 miRNAs are downregulated in many cancers from solid organs [98], while they act as oncogenes since a metastatic gastric cancer cell line named AZ-P7a releases let-7 miRNAs into the extracellular environment to maintain their oncogenesis and invasiveness [21].