[Studies on cell transformation and cell cycle in human embryo lungs induced by nickel compounds]

To elucidate the association between nickel compounds and occupational lung cancer.

Human embryo lung cells (MRC-9 and IMR-90) were transformed by water-insoluble nickel oxide and nickel subsulfide, and changes in cell cycle of these transformed cells were analyzed by flow cytometric technique.

Morphological transformation in MRC-9 and IMR-90 cells were induced after exposure to nickel compounds for 3 - 5 months, including formation of transforming foci, overlaying growth and epithelium-like changes in cells, etc. Some transformed cells could form colonies in soft agar media. Changes in cell cycle of the transformed cells were observed with flow cytometry. Proportions of cells at G(1) phase and G(2)/M phase were 62.61% and 16.37%, respectively, in the untreated MRC-9 cells and hyperploid cells were hardly seen in cell cycle plots. But, in the transformed MRC-9 cells, proportion of cells at G(1) phase reduced to about 50%, and that at G(2)/M phase increased to over 20% and that of hyperploid cells to over 10%. The same phenomenon was observed in the IMR-90 cells.

Water-insoluble nickel compounds can induce morphological transformation of human embryo lung cells and those transformed cells appeared certain biological characteristics of tumor cells.