Lentivirus-based RNA Silencing of Nemo-like Kinase (NLK) Inhibits the CAL 27 Human Adenosquamos Carcinoma Cells Proliferation and Blocks G0/G1 Phase to S Phase

Background: The Nemo-like kinase (NLK) is a serine/threonine-protein kinase that involved in a number of signaling pathways regulating cell fate. Variation of NLK has been shown to be associated with the risk of cancer. However, the function of NLK in oral adenosquamous carcinoma cells line CAL-27 is unknown. Methods: In this study, we evaluated the function of NLK in CAL-27 cells by using lentivirus-mediated RNA silence. The targeted gene expression, cell proliferation and cell cycle are investigated by RT-PCR, western-blot, MTT method, colony forming assay and flow cytometry analysis respectively. Results: After NLK silencing, the number of colonies was significantly reduced (54±5 colonies/well compared with 262±18 colonies/well in non-infected or 226±4 colonies/well in negative control group (sequence not related to NLK sequence with mismatched bases). Using crystal violet staining, we also found that the cell number per colony was dramatically reduced. The RNA silencing of NLK blocks the G0/G1 phase to S phase progression during the cell cycle. Conclusions: These results suggest that NLK silencing by lentivirus-mediated RNA interference would be a potential therapeutic method to control oral squamous carcinoma growth.