Differential effects of gallium nitrate on proliferation of brain tumor cells in vitro

Gallium nitrate possesses antineoplastic activity against certain solid tumors; however, no studies exist regarding the effect of this metal on brain tumor cell proliferation. Several human brain tumor and rhabdomyosarcoma cell lines were incubated with increasing concentrations of gallium nitrate and cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The growth of medulloblastoma 324, rhabdomyosarcoma TE671, and RD cells was markedly inhibited by gallium nitrate, while glioblastoma cell growth was only moderately inhibited (U373 cells) or actually stimulated (U87 cells). Gallium inhibited the cellular uptake of 59Fe; however, this block in 59Fe uptake was variable and closely paralleled the inhibitory effects of gallium on cell growth. Intracellularly, gallium may interfere with DNA synthesis by inhibiting ribonucleotide reductase. Such effects may be of relevance in the treatment of brain tumors with this metal.