miR-200b/c targets the expression of RhoE and inhibits the proliferation and invasion of non-small cell lung cancer cells.

Lung cancer is a major cause of mortality worldwide and non‑small cell lung cancer (NSCLC) accounts for ~80% of all cases of lung cancer. Increasing evidence indicates that Rho family GTPase 3 (RhoE) is important in the carcinogenesis and progression of NSCLC. In addition, several studies have indicated that microRNA (miR)‑200b/c is downregulated in NSCLC cells. However, the exact mechanism remains to be elucidated. In the present study, immunohistochemistry (IHC) assays were used to analyze the RhoE and epithelial‑mesenchymal transition (EMT)‑related proteins in NSCLC tissues. Putative target sequences of the RhoE 3' untranslated region (3'UTR) for miR‑200b/c were detected using bioinformatics analysis. The mRNA expression levels of RhoE and miR‑200b/c were determined by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis, and western blot analysis was used to detect the protein levels of RhoE in cells. The luciferase‑reporter activity of the RhoE 3'UTR was detected using a dual‑luciferase assay. A cell counting kit‑8 assay, flow cytometry and Transwell assay were used to detect cell proliferation, cell cycle, and invasion and migration ability, respectively. The IHC assays indicated that RhoE was overexpressed in NSCLC tissues. The bioinformatics analysis revealed that the RhoE 3'UTR contained a putative target site for miR‑200b/c, which was conserved across species. The results of RT‑qPCR analysis showed that the mRNA expression of RhoE was overexpressed and miR‑200b/200c was decreased in lung cancer tissues. The enhanced expression of miR‑200b or miR‑200c significantly downregulated the expression of RhoE at the mRNA and protein levels in A549 and NCI‑H1299 NSCLC cells. Furthermore, luciferase assays showed that miR‑200b and miR‑200c directly targeted the 3'UTR of RhoE. The forced expression of miR‑200b or miR‑200c markedly inhibited A549 cell and NCI‑H1299 cell proliferation, G0/G1 progression and cell invasion, which was consistent with the effects of RNA interference‑mediated RhoE knockdown in these cells. The suppression of RhoE regulated the expression of EMT‑related markers, which was consistent with the effect of miR‑200b/c in NSCLC cells, and the expression of EMT‑related proteins and RhoE were also correlated in the lung cancer tissues. Therefore, miR‑200b and miR‑200c targeted the expression of RhoE and inhibited the malignancy of NSCLC cells, and the downregulation of miR‑200b and miR‑200c may contribute to the high expression of RhoE in NSCLC.