[Effect of tumor-associated macrophages in promoting epithelial-mesenchymal transition of Hep3B hepatoma cells and related mechanisms].

Objective: To investigate the possible mechanisms of tumor-associated macrophages (TAMs) in regulating epithelia-mesenchymal transition (EMT) of Hep3B hepatoma cells, since EMT is closely associated with the malignancy of hepatoma cells and tumor microenvironment plays an important role in regulating EMT of hepatoma cells, and to provide new regimens for the clinical studies and treatment of liver cancer. Methods: Human monocytic leukemia THP-1 cells were successfully induced to TAMs. With TAMs as target cells, they were co-cultured with the supernatant of Hep3B hepatoma cells or Hep3B hepatoma cells, and Western blot and RT-PCR were used to measure the change in the expression of Toll-like receptor 4 (TLR4) in TAMs. The expression of TLR4 in TAMs was downregulated by transient plasmid transfection with shRNA. With Hep3B hepatoma cells as target cells, the supernatants of TAMs and TAMs transfected with shRNA TLR4 plasmid were used for intervention, and Western blot was used to measure the protein expression of E-cadherin, N-cadherin, and vimentin. The two-sided t-test was used for comparison of the means of two independent samples. Results: THP-1 cells were successfully induced to TAMs. According to the results of Western blot, compared with the control-CM group, the TAM-CM group had a significant reduction in the protein expression of E-cadherin and significant increases in the protein expression of N-cadherin and vimentin in Hep3B cells. After the expression of TLR4 in TAMs was downregulated, the culture solution of TAMs was used for the intervention of Hep3B cells (shRNA group), and compared with the TAM-CM group, the shRNA group had a significant increase in the expression of E-cadherin and significant reductions in the protein expression of N-cadherin and vimentin in Hep3B cells. Western blot and RT-PCR showed that the expression of TLR4 in TAMs was influenced by Hep3B cells. Conclusion: TAMs can promote EMT of Hep3B hepatoma cells, and downregulation of the expression of TLR4 in TAMs may reduce EMT of Hep3B hepatoma cells, suggesting that TLR4 on the surface of TAMs may be a key molecule involved in the interaction between TAMs and Hep3B hepatoma cells.