Interference with Tim-3 protein expression attenuates the invasion of clear cell renal cell carcinoma and aggravates anoikis

Abstract

Tumor cells resistant to anoikis are considered to be candidates for metastasis. In the present study, the role of Tim-3 in anoikis and its influence on the invasion of clear cell renal cell carcinoma (ccRCC) was investigated. Here, polyhydroxylethylmethacrylate (poly-HEMA) was applied to two ccRCC cell lines, 786-O and Caki-2, to induce detachment from the extracellular matrix (ECM). Tim-3 mRNA and protein expression levels were assayed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot, respectively. Anoikis was measured by Ho33342/PI double staining, acridine orange staining, and further determined using the CytoSelect™ 24-well Anoikis Assay kit. Apoptosis was measured using flow cytometry, E-cadherin and N-cadherin protein expression were determined using western blotting and a Chemicon cell invasion assay kit was used to quantify the invasive capacity of 786-O and Caki-2 cells. It was demonstrated that detachment from the ECM decreases transcription and the protein expression level of Tim-3 in 786-O and Caki-2 cells compared with control cells. Interference with Tim-3 expression using small interfering RNA exacerbated anoikis in 786-O and Caki-2 cells induced by poly-HEMA treatment. E-cadherin upregulation, N-cadherin downregulation, and ECM detachment-induced reduction in invasion ability were all exacerbated by knockdown of Tim-3. In conclusion, interference with Tim-3 expression may attenuate the invasion of renal cell carcinoma by aggravating anoikis, indicating Tim-3 as a potential therapeutic target for treating ccRCC.