MicroRNA-598 inhibits the growth and maintenance of gastric cancer stem-like cells by down-regulating RRS1.

Emerging evidence has identified the critical role of microRNAs in gastric cancer (GC). Herein, this study intends to characterize the tumor suppressive role of microRNA-598 (miR-598) in GC stem-like cells, with the involvement of RRS1. The CD133+ GC stem-like cells were sorted by flow cytometry, after which immunofluorescence assay was used to determine the co-localization of CD133 and CD44v8-10. The miR-598 expression was examined in the CD133+ and CD133- cells. Subsequently, the CD133+ cells were subjected to miR-598 mimics, miR-598 inhibitors or RRS1 siRNA to validate the effect of miR-598 on GC stem-like cell proliferation, colony formation, apoptosis, migration and invasion capacities. Besides, the effect of miR-598 on the expression of key factors (OCT4, SOX2 and NANOG) associated with stem cell characteristics was measured. The obtained results indicated that the sphere forming capacity was higher in CD133+ cells. CD133+ MKN-45 cells expressed CD133 and CD44v8-10, and were expressed on the cell membrane. MiR-598 was poorly expressed in CD133+ cells. Notably, miR-598 negatively regulated RRS1. In response to miR-598 mimics and RRS1 siRNA, the MKN-45 cells displayed inhibited proliferation, colony formation, migration and invasion, accompanied by elevated apoptosis. Besides, the miR-598 inhibitors reversed the situation. This study highlights that miR-598 a tumor suppressor in GC stem-like cells by inhibiting RRS1, whereby miR-598 represses MKN-45 cell growth and invasion by attenuating self-renewal of GC stem-like cells.