Aluminum ions stimulate mitosis in murine cells in tissue culture

Addition of aluminum to the culture medium of Nakano mouse lens epithelial (NMLE) cells and Swiss 3T3K cells induced both 3 H‐thymidine incorporation and mitosis. This is in contrast to other metal ions such as vanadium, which, at concentrations high enough to increase 3 H‐thymidine incorporation, actually inhibits mitosis (Jones and Reid, J Cell Physiol 121:199, 1984 [1]). Aluminum concentrations between 20 μM and 50 μM were most effective. The 3T3 cells respond to aluminum with a 7.6‐fold increase, and NMLE cells respond with a 21‐fold increase in 3 H‐thymidine incorporation. DNA synthesis in NMLE cells was also found to be synergistically stimulated by aluminum and low concentrations of insulin (4.5 × 10 −8 M). A 3.25‐hr incubation with 50 μM aluminum was sufficient to induce 50% of maximum 3 H‐thymidine incorporation during the 40‐hr assay. Aluminum‐stimulated 3 H‐thymidine incorporation is inhibited by hydroxyurea, and aluminum causes an increase in cell number. Also, by sedimentation equilibrium analysis of the product of aluminum‐stimulated DNA synthesis it was found that a single copy of DNA was synthesized following addition of aluminum to quiescent cells. These facts indicate that aluminum induces both S‐phase DNA synthesis and mitosis. However, only 48% of the NMLE cells found to be labeled with DNA went on to divide. In contrast, although only a small percentage of 3T3 cells were found to be labeled after aluminum treatment, all of these cells appeared to go through mitosis.