DIFFERENTIAL-EFFECTS OF FERRITIN, CALCIUM, ZINC, AND GALLIC ACID ON IN-VITRO PROLIFERATION OF HUMAN GLIOBLASTOMA CELLS AND NORMAL ASTROCYTES

In vitro, when using low concentrations of ferritin (ng/ml) or CaCl2 ( mu g/ml), multiplication of a human, 1,3-bis-(2-chloroethyl)-1-nitroso urea (BCNU)-resistant glioblastoma cell line (U251) is enhanced 1.5 to 2 times more actively than multiplication of a normal astrocyte line (CRL 1656). Ferritin and Ca2+ ions exhibit a marked effect on DNA isol ated from these cells: glioblastoma DNA relaxation is strongly increas ed (as evidenced by increased 260 nm ultraviolet absorbance), being fr om 5 to 6 times that of astrocyte DNA, which remains only slightly aff ected. Under identical experimental conditions, Zn2+ and gallium ions selectively inhibit glioblastoma cell multiplication but at the same c oncentrations do not inhibit astrocyte multiplication. Ultraviolet abs orbance measurements demonstrate that both of these agents condense re laxed glioblastoma DNA in vitro. Zn2+ or gallium ions added to culture medium containing stimulatory concentrations of ferritin or Ca2+ ions selectively and strongly inhibit enhancement of glioblastoma cell mul tiplication by these mitogens while not affecting normal multiplicatio n of astrocytes.