[Interaction between malignant transformation of human pulmonary epithelial cells and activation of fibroblasts induced by Yunnan tin mine dust].

Objective: To study the interaction between transformation of human pulmonary epithelial cells and activation of fibroblasts induced by Yunnan tin mine dust.

Methods: (1) The immortalized human bronchial epithelial cell line BEAS-2B and human embryo lung fibroblast cell line WI-38 were grown in MEM medium containing 5% and 10% FBS, respectively, at 37 degrees C and 5% CO2 with saturated humidity. The cells were subcultured every 6 days. BEAS-2B cells and WI-38 cells were induced with Yunnan tin mine dust on every other generation at the concentration of 100 microg/ml. From the 11th generation, the cells were co-cultured. Epithelial cell transformation was tested using concanavalin A (ConA) agglutination and anchorage-independent growth assays. The cell cycles were analyzed through flow cytometry. The expressions of alpha-SMA in fibroblasts were determined with immunocytochemistry.

Results: (1) Cell morphology of mine dust-exposed epithelial cells began to transform at the 28th generation. Similar transformations were observed with mine dust-induced epithelial cells co-cultured with fibroblasts from the 20th generation and mine dust-induce epithelial cells co-cultured with mine dust-induced fibroblasts from the 16th generation. ConA agglutination assay and anchorage-independent growth assays were negative in normal BEAS-2B cells. At the 26 th generation, the agglutination test result of the mine dust-exposed epithelial cells was positive. Co-cultured with fibroblasts and mine dust-exposed fibroblasts, the agglutination time of the mine dust-exposed epithelial cells became short. Epithelial cell anchorage-independent growth assay was positive for mine dust-exposed epithelial cells co-cultured with fibroblasts at the 36th generations and for mine dust-exposed epithelial cells co-cultured with mine dust-exposed fibroblasts at the 26th generations. The clone formation rate of the 26th generation was 6.00 per thousand +/- 1.00 per thousand and 15.33 per thousand +/- 2.52 per thousand respectively, with the significant differences (P < 0.05). With generation adding, the portion of S phase increased for mine dust-exposed epithelial cells. (2) At the 26th generations, fibroblasts expressed alpha-SMA. Co-cultured with epithelial cell, the alpha-SMA expression of fibroblasts increased. Especially, positive cell numbers and intensity of staining dramatically increased with generation adding.

Conclusions: (1) The tin mine dust can induce malignant transformation of human pulmonary epithelial cells BEAS-2B and activation of fibroblasts WI-38. (2) The epithelial cells are major target in carcinogenesis induced by Yunnan tin mine dust. (3) Transformation of epithelia and activation of fibroblasts co-evolve in the developing process of induced lung cancer by Yunnan tin mine dust.