Silencing of lysyl oxidase-like 2 inhibits the migration, invasion and epithelial-to-mesenchymal transition of renal cell carcinoma cells through the Src/FAK signaling pathway

The aim of the present study was to investigate the effects of lysyl oxidase-like 2 (LOXL2) on the invasion, migration and epithelial-to-mesenchymal transition (EMT) of renal cell carcinoma (RCC) cells through the steroid receptor coactivator (Src)/focal adhesion kinase (FAK) signaling pathway. RCC tissues and adjacent normal tissues were collected from 80 patients with RCC. Immunohistochemistry was used to determine the positive expression rate of the LOXL2 protein. The expression levels of LOXL2 in the HK-2, 786-O, ACHN, Caki1 and A498 cell lines were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The high LOXL2-expressing 786-O cells were selected for gene silencing experiments, whereas Caki1 cells, which exhibited low LOXL2 expression, were used for overexpression experiments. RT-qPCR and western blot analysis were applied to determine the expression of LOXL2, FAK, Src, matrix metalloproteinase (MMP)-9, epithelial (E)-cadherin, neuronal (N)-cadherin and vimentin. A MTT assay, a Transwell assay, a wound healing assay and flow cytometry were performed to detect cell proliferation, invasion, migration, cell cycle distribution and apoptosis, respectively. The protein expression rate of LOXL2 in RCC tissues was higher compared with that in adjacent normal tissues. Compared with adjacent normal tissues, the mRNA and protein expression levels of LOXL2, FAK, Src, MMP-9, N-cadherin and vimentin and the levels of FAK and Src phosphorylation were increased, while the mRNA and protein expression levels of E-cadherin were decreased in RCC tissues. Following the transfection of 786-O cells with small interfering (si) RNA against LOXL2, the mRNA and protein expression levels of FAK, Src, MMP-9, N-cadherin and vimentin and the levels of phosphorylated FAK and Src were notably decreased in the si-LOXL2 and PP2 inhibitor treated groups, while that of E-cadherin was substantially increased. Additionally, cell proliferation, invasion, migration and the percentage of RCC cells in the G1 phase were reduced, and cell apoptosis was increased. Additionally, Caki1 cells transfected with LOXL2 exhibited an opposite trend. In summary, these results indicate that LOXL2 silencing inhibits the invasion, migration and EMT in RCC cells through inhibition of the Src/FAK signaling pathway.