Abstract: Objective To investigate the role of Rho GTPase-activating protein 21 (ARHGAP21) in regulating the migration and metastasis of non-small cell lung cancer (NSCLC) cells. Methods TCGA, CPTAC database were used to analyze the correlation of ARHGAP21 expression level in NSCLC and the patients' prognosis. The expression of ARHGAP21 in clinical specimens of NSCLC tissues was examined using Western blotting and immunohistochemistry. The effect of ARHGAP21 knockdown on migration ability of lung cancer cell lines was examined using Transwell assay and wound healing assay. A nude mouse model with injection of lung cancer H1299 cells via the tail vein was used to examine the effect of ARHGAP21 knockdown on the metastatic ability of the tumor cells. The possible mechanism of ARHGAP21 was predicted by bioinformatics analysis and verified using Western blotting. Results A low ARHGAP21 expression was associated with poor prognosis of patients with NSCLC (P<0.05). ARHGAP21 expression was significantly downregulated in lung cancer tissues as compared with the adjacent tissues (P<0.001). In cultured lung cancer cells, ARHGAP21 knockdown obviously promoted the migration ability of the cells (P<0.001). In the nude mouse models, injection of H1299 cells with ARHGAP21 knockdown, as compared with the negative control cells, resulted in a greater number of metastatic lung cancer nodules (P<0.05), which expressed higher levels of N-cadherin and vimentin. Bioinformatic analysis showed a close correlation of ARHGAP21 with APC, GSK3β, and Axin (P<0.001). Western blotting showed that ARHGAP21 knockdown significantly decreased ubiquitination of β-catenin, upregulated N-cadherin and activated the WNT signaling pathway in the lung cancer cells. Conclusion ARHGAP21 downregulation can significantly promote the migration and metastatic ability of NSCLC possibly as a result of WNT signaling pathway activation, which reduces the ubiquitination of β-catenin by affecting the expressions of APC, GSK3β, and Axin.

Key words: Rho GTPase-activating protein 21; epithelial-mesenchymal transition; WNT signaling pathway; non-small cell lung cancer