Effect of exogenous gangliosides on human neural cell division

Human neural cells in exponential growth phase were transferred to a serum-free medium and maintained for 72 hr without any detectable loss in viability. The two normal fetal cell lines (CHI and CHII) showed a serum-dependent cell proliferation, but the glioblastoma multiforme cells (12-18) were able to continue proliferating in this totally synthetic medium. The incorporation of [3H]thymidine into the acid-precipitable fraction of both normal and neoplastic human neural cells was assayed in the presence and the absence of exogenous gangliosides by a convenient new method. In serum-free medium, gangliosides (50 microM) inhibited the thymidine incorporation into the normal fetal cells within 24 hr and, in serum containing medium, reduced their proliferation within 48 hr. No such effects were detectable in the glioma cells. The inhibition of thymidine incorporation in the normal cells was reversible upon removal of the gangliosides. These results indicate a role of gangliosides in the postmitotic phase of normal human neural cells resulting in the regulation of cell proliferation.