miR-135b-5p promotes gastric carcinogenesis by targeting CLIP4-mediated JAK2/STAT3 signal pathway

Background

Gastric cancer (GC) is a common cancer worldwide; however, its molecular and pathogenic mechanisms remain unclear. MicroRNAs (miRNAs), which target key genes in GC, are associated with tumor promotion or suppression. Therefore, identifying new miRNA mechanisms could improve the novel diagnostic and therapeutic strategies for patients with GC.

Methods

To explore the biological functions of miR-135b-5p in GC, bioinformatic analysis and in vitro functional assays, including colony formation, wound healing, Transwell, and EdU assays, were used to assess the proliferative, invasive, and migratory capacities of GC cells. Target genes were predicted using RNA-seq and online databases. Dual-luciferase reporter assay, fluorescence in situ hybridization and western blotting were used to confirm the regulatory relationship between miR-135b-5p and CLIP4. The role of CLIP4 in tumor progression was assessed using clinical samples and both in vitro and in vivo assays. The tumor-suppressive mechanism of CLIP4 in GC was elucidated using rescue assays.

Results

Our study identified that miR-135b-5p as one of the top three over-expressed miRNAs in GC tissues, with RT-qPCR confirming its upregulation. Functional analysis showed that upregulated miR-135b-5p promoted malignant phenotypes in GC cells. Mechanistic research indicated that miR-135b-5p acts as a cancer promoter by targeting CLIP4. Moreover, our study suggested that CLIP4 exerts its tumor-suppressive function by inhibiting the JAK2/STAT3 signaling pathway.

Conclusion

This study reveals a novel mechanism by which miR-135b-5p exerts its tumor-promoting functions by targeting CLIP4. The tumor-suppressive function of CLIP4 by inactivating the JAK2/STAT3 pathway is also elucidated. Regulatory mechanism of CLIP4 by miR-135b-5p provides a promising novel therapeutic strategy for GC patients.