MiR-455-5p acts as a novel tumor suppressor in gastric cancer by down-regulating RAS18

Aim: To detect the potential regulation pathway of microRNA-455-5p (miR-455-5p) and RAB18, member RAS oncogene family (RAB18) in gastric cancer (GC) cells and tissues and discuss the clinical significance of miR-455-5p in GC genesis and progression. Methods: Real-time PCR was used to measure mRNA level of miR-455-5p in GC, TargetScan and dual luciferase assay were used to predict and demonstrate the candidate target gene of miR-455-5p, Western blot were utilized to detect the protein level of RAB18. Cell function assays were also performed to determine the function of miR-455-5p in GC. Results: miR-455-5p was reduced significantly in gastric cancer cells and tissues compared with the corresponding normal control, the lower expression of miR-455-5p was related to advanced clinical stage in gastric cancer, re-expression of miR-455-5p could inhibit human GC cell proliferation and invasion, overexpression of miR-4555p could also promote GC cell apoptosis. Furthermore, we found that RAB18 was a candidate target of miR-4555p. Re-expression of miR-455-5p could inhibit the protein level of RAB18. Conclusion: MiR-455-5p might serve as a novel biomarker in gastric cancer by targeting RAB18. (C) 2016 Elsevier B.V. All rights reserved.