Inhibitory effects of gallium chloride and tris (8-quinolinolato) gallium III on A549 human malignant cell line

The effects of two gallium (Ga) compounds, Ga chloride (GaCl3) and tris(8-quinolinolato)Ga (III) on the viability of A549 human malignant lung adenocarcinoma cells were investigated. The results demonstrated that both drugs reduced the viability of A549 cells but to different extents. The inhibitory effects of tris(8-quinolinolato)Ga (III) were 10 times more profound than those produced by GaCl3. The IC50 was obtained with 2.5 microM of tris(8-quinolinolato)Ga (III) and 25 microM GaCl3 after an exposure time of 48 hours. Further, whereas the inhibitory effects of GaCl3 were both dose and time-dependent those of tris(8-quinolinolato)Ga (III) appeared to be only dose-dependent, indicating differences in their mechanism of action. Comparison with data drawn from the literature suggests that GaCl3 seems to be in the same range of activity as Ga nitrate or Ga-pyridoxal isocotinoyl hydrazone. Tris(8-quinolinolato)Ga (III) could be as effective as transferrin-Ga, but with the advantage of oral administration and a greater bioavailability of the tris(8-quinolinolato)Ga (III) compound.