Abstract: Objective: To knock down the Toll-like receptor 2 (TLR2) gene in the colorectal cancer cells with lentiviral RNA interference technology, to explore its effect on the colorectal cancer cell proliferation, and to clarify its mechanism. Methods: The colorectal cancer HCT116 cells and HT29 cells in logarithmic phase were divided into non-infection control group, negative control group and gene knockdown group(TLR2-RNAi group); the cells were transfected with lentivirus-free, lentivirus-RNAi and lentivirus-TLR2-RNAi, respectively. The expression levels of TLR2 protein in the cells in various groups were detected by Western blotting method after stable transfection.The cell proliferation activities and the percentages of cells in different cell cycles were detected by CCK-8 method and flow cytometry. Western blotting method was used to detect the expression levels of PI3K/Akt and nuclear factor-κB(NF-κB) signaling pathway-related proteins and cell cycle-associated proteins cyclin D1 and cyclin D3 proteins in the cells in various groups. Results: Compared with non-infection control group and negative control group, the expression levels of TLR2 protein in the HCT116 cells and the HT29 cells in TLR2-RNAi group were decreased significantly (P<0.01). Compared with non-infection control group and negative control group,the cell proliferation activities in the HCT116 cells and the HT29 cells in TLR2-RNAi group were significantly decreased (P<0.05); the percentages of cells in S phase and G₂ phase were decreased significantly (P<0.05), and the percentages of cells in G₁ phase were increased significantly (P<0.05). Compared with non-infection control group and negative control group, the expression levels of PI3K, p-Akt, p-NF-κB, cyclin D1 and cyclin D3 proteins in the HCT116 cells and HT29 cells in TLR2-RNAi group were significantly decreased(P<0.01). Conclusion: Knockdown of TLR2 gene can inhibit the proliferation of colorectal cancer cells by regulating the expressions of PI3K/Akt and NF-κB cell signaling pathway proteins and cell cycle-associated proteins.

Key words: colorectal neoplasms, Toll-like receptor-2 gene, cell proliferation, cell cycle