Upregulated microRNA miR-21 promotes the progression of lung adenocarcinoma through inhibition of KIBRA and the Hippo signaling pathway.

Purpose: In this study, we aimed to identify the key pathways and hub genes in lung adenocarcinoma (LAD) through bioinformatics analysis and to identify the miRNAs that targeted the selected hub gene. The present study was conducted to explore the effect of the hub gene KIBRA, the Hippo signaling pathway and miR-21 on LAD progression.

Methods: Through gene set enrichment analysis (GSEA), the enriched KEGG pathways involved in LAD were identified. Weighted correlation network analysis (WGCNA) was employed to screen out hub genes. The differentially expressed miRNAs related to the hub gene were then screened by the network analysis. The mRNA expression levels of miR-21 and KIBRA were detected by qRT-PCR. The protein expression levels of KIBRA and the pathway related proteins LATS2 and YAP were determined by Western blot assay. The target relationship between miR-21 and KIBRA was confirmed by the dual luciferase reporter assay. Through colony formation assay, the viability of the LAD cells was determined. In addition, the mobility of LAD cells was detected by wound healing assays, and flow cytometry was employed to detect apoptotic cancer cells.

Results: The hub gene identified in the black module was KIBRA, and suppression of the Hippo signaling pathway was detected in LAD. KIBRA was downregulated and miR-21 was upregulated in LAD tissues and cells; moreover, miR-21 was found to target KIBRA. KIBRA reduced the proliferative and invasive ability of LAD cells and induced apoptosis. KIBRA also activated the Hippo signaling pathway in LAD. The role of MiR-21 was opposite that of KIBRA in LAD.

Conclusion: MiR-21 suppressed the Hippo signaling pathway and promoted the progression of LAD through targeting KIBRA.