Downregulation of CD166 inhibits invasion, migration, and EMT in the radio-resistant human nasopharyngeal carcinoma cell line CNE-2R

Objective: CD166 is known as a tumor stem cell specific marker, associating with tumor metastasis. The purpose of this study was to further discuss CD166 gene on cell proliferation, invasion, metastasis, and the epithelial-mesenchymal transition (EMT) in CNE-2R cell line of nasopharyngeal carcinoma (NPC). Materials and methods: CNE-2R cells were transfected with lentivirus CD166-shRNA, and quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Western blotting were used to confirm the silencing effects. The wound healing test and transwell test were carried out to assess cell invasive and migratory abilities in vitro. With the establishment of xenograft nude mouse model, Western blotting and immunohistochemistry were undertaken to detect the expression level of E-cadherin, N-cadherin, and vimentin. In vivo metastasis detection was carried out by injecting tumor cells into nude mice via the tail vein. Results: The invasive and migratory abilities of CNE-2R cells were significantly reduced after CD166 was downregulated. In addition, silencing of CD166 of CNE-2R cells increased the expression of E-cadherin, while down-regulated the expression of N-cadherin and vimentin. Immunohistochemistry of tumors showed consistent results with in-situ tumor formation experiment. Additionally, the growth of transplanted tumor was inhibited. In addition, in vivo metastasis test proved that knockdown of CD166 suppressed pulmonary metastasis and liver metastasis according to hematoxylin and eosin (H&E) staining. Expression of E-cadherin increased, while expression of N-cadherin and vimentin decreased, as revealed by Western blotting of metastatic lung tumors. Conclusion: Silencing of CD166 in CNE-2R cells evidently inhibited proliferation, invasion, metastasis, and EMT process in vivo and in vitro.