Currently,exosomes rich in RNAs and proteins are regarded as vital mediators of intercellular communication.Here,we aimed to explore the effects of exosomal miR-1290 in gastric cancer (GC) and understand its mechanism of action on GC progression.We first isolated exosomes from serum samples of GC patients and healthy people and characterized them by transmission electron microscopy.Then,we examined the expression level of miR-1290 contained in the exosomes by quantitative reverse-transcription polymerase chain reaction and found that exosomal miR-1290 was overexpressed in GC patients and cell lines.Promotion of proliferation,migration,and invasiveness of GC cells was noted after they were incubated with the isolated miR-1290-rich exosomes compared with incubation with a negative control.Furthermore,we predicted that naked cuticle homolog 1 (NKD1) mRNA is a direct target of miR-1290 and confirmed their interaction by a dual luciferase reporter assay.NKD1 overexpression attenuated the stimulatory effects of miR-1290 on GC cells.Collectively,our results suggest that exosomal miR-1290 enhances GC cell proliferation and invasion by targeting NKD1 mRNA and downregulating NKD1 expression.A better understanding of this process may facilitate the development of novel therapeutic agents for GC.