Growth inhibition by sialosyl cholesterol of rat glioma cells.

Synthesized sialosyl cholesterol (?-sialosyl cholesterol) induced growth inhibition of rat astrocytoma cells (GA-1) or schwannoma cells (354-A) which was detected as a decline of cell growth curves and a suppression of DNA syntheses. The incubation time to initiate growth inhibition of GA-1 was as short as 10 min and that to complete the action was 2 h after the initiation of drug-stimulation, indicating an immediate incorporation of sialosyl cholesterol into glioma cells. The morphological alteration of 354-A, but not GA-1, from an epithelioid cell shape to a spindle-like shape was also detected by the stimulation and ascertained by fluorescence visualization of cytoskeletons: the reorganization of actin filaments distributing as a plasmalemmal undercoat to form stress actin fibers and no detectable change in distribution of tubulins. The results provide a possibility that sialosyl cholesterol incorporated into the plasma membrane may cause growth inhibition of both glioma cells and morphological differentiation of schwannoma cells mostly through alterations of membrane characteristics and/or cytoskeletal anchorage, and also suggest the therapeutic potential of sialosyl cholesterol for brain tumors.