PTEN and gastric cancer: A well-characterized circRNA, CDR1as (ciRS-7), is markedly up-regulated in GC and linked to poor survival in an independent validation cohort, and promotes GC cell migration and metastasis via antagonizing the miR-7-mediated expression of PTEN, which is broadly regarded as a negative regulator of the PI3K/AKT signaling pathway [57, 76].