OBJECTIVETo study the effects of monocyte-macrophages (THP-1) in malignant transformation of human bronchial epithelial cells (BEAS-2B) cells induced by coal tar pitch (CTP) and the expression of TNF-α in the process of the cell malignant transformation.

METHODSBEAS-2B cells and THP-1 Cells were divided into four groups: coal tar pitch (CTP) group, benzo(a)pyrene [B(a)P] group, dimethyl sulfoxide (DMSO) group, BEAS-2B and THP-1 co-culture (co-culture group) group. Carcinogenesis model was established. The soft agar colony formation, chromosome aberrations and cell cycle tests were used to detect the cellular malignant transformation. The ELISA assay was utilized to measure the levels of TNF-α in the supernatant of CTP group and co-culture group.

RESULTSThe chromosome number abnormalities could be observed in early stage of the experiment (the 10th generation cells), which showed the increased ratio of aneuploid to polyploid, and the decreased number of diploid. The colony formation rate of co-culture group (the 20th generation cells) was 17.63‰ ± 0.97‰, which was significantly higher than that (13.94‰ ± 0.84‰) of CTP group and that (12.96‰ ± 1.62‰) of B(a)P group (P < 0.05). The proportion of S phase cells in the co-culture group was 44.49% ± 0.68%, which was significantly higher than that (38.19% ± 1.26%) of CTP group and that (36.41% ± 1.19%) of B(a)P group (P < 0.05). The TNF-α level in the co-culture group was significantly higher than that in CTP group (P = 0.001).

CONCLUSIONMonocyte-Macrophages can accelerate the malignant transformation of BEAS-2B cells induced by CTP and increase the expression level of TNF-α.