Inhibition of surface immunoglobulin centeral capping of Daudi cells and cell spreading of HeLa-S3 cells by neocarzinostatin.

The effects of an antitumor antibiotic, neocarzinostatin (NCS), on the surface immunoglobulin central capping induced by anti-immunoglobulin M antibody on Daudi cells and on the cell spreading of trypsinized HeLa-S3 cells were examined. Pretreatment of Daudi cells and HeLa-S3 cells with NCS, 5 to 30 micrograms/ml, for 4 hr inhibited cap formation and cell spreading, respectively. It was shown that there is a direct relationship between the dose and the degree of inhibition. Inhibitors of DNA synthesis such as bleomycin, mitomycin C, and 1-beta-D-arabinofuranosylcytosine showed no inhibitory effect on cap formation or cell spreading. However, known microtubule-acting agents such as colchicine and vinblastine sulfate completely inhibited both capping and cell spreading at a dose of 10 micrograms/ml. In view of the fact that 10 micorograms NCS per ml also inhibit the formation of microtubular paracrystals induced by vinblastine sulfate in HeLa-S3 cells and that other agents known to influence microtubule function such as local anesthetics and calcium ionophores also inhibit both paracrystal formation and cap formation, these new observations add further support to our hypothesis that NCS affects microtubular proteins transmembranously in vivo.