Objective: To characterize the role of tumor necrosis factor-α (TNF-α) and NF-κB play a role in macrophage-like THP-1 cells promoting coal tar pitch extract (CTPE)-induced tumorigenic transformation of human bronchial epithelial cells (BEAS-2B).
Methods: From passage 10, CTPE-induced BEAS-2B cells cocultured with THP-1 cells were treated with NF-κB inhibitor-Pyrrolidine dithiocarbamate (PDTC) every 3 passages and TNF-α antibody every passage. Alterations of cell cycle, karyotype and colony formation in soft agar of BEAS-2B cells at passages 20, indicative of tumorigenicity, were determined, respectively. In addition, mRNA and protein levels of TNF receptor associated factor2 (TRAF2) and Cyclin D1 in BEAS-2B cells were measured with Real Time-PCR and Western blot, respectively.
Results: The percentages of S-phase BEAS-2B cells at passage 20 in PDTC group and TNF-α antibody group were (33.97±2.16)% and (34.29±2.04)% respectively, which were less than that in Co-culture+CTPE group of 20th passage [(44.46±0.83)%], P < 0.05; The number of cells with aneuploidy in 100 cells in 20th passage PDTC group and TNF-α antibody group were 40 and 37, and there were significantly different when comparing to that of 20th passage Co-culture+CTPE group (75); The number of colony formation and the rate of colony formation of BEAS-2B cells in soft agar at passage 20 in PDTC group were (15.17±2.48) and (1.51‰±0.25‰), (13.33±2.58)and (1.33‰±0.26‰) in TNF-α antibody group, which were less that those in 20th passage Co-culture+CTPE group [(172.33±12.09) and (17.23‰±1.20‰)], P < 0.05; at the same time, the mRNA and protein levels of TRAF2 and Cyclin D1 in BEAS-2B cells were decreased after PDTC and TNF-α antibody treatment.
Conclusion: TNF-α and NF-κB could play an important role in THP-1 cells promoting coal tar pitch extract-induced tumorigenic transformation of BEAS-2B cells by influencing the expression of TRAF2 and Cyclin D1.