New Cytoskeletal Proteins Are Induced in HeLa Cells by Vinca Alkaloids

The effects of Vinca alkaloids, vinblastine, vincristine, and vindesine, on protein synthesis were determined using HeLa cells. Vinblastine at the concentration of 1 microgram/ml induced new proteins, isoelectric points 4.8 and 7.0-7.5 and molecular weights 48 and 92 kd, in the HeLa cells, identified using two-dimensional gel electrophoresis. The 48-kd and the clustered (4-components) 92-kd proteins were also noted in HeLa cells treated with vincristine or vindesine. As most of the 48- and 92-kd proteins were Triton insoluble, they can be considered components of the cytoskeletal structure. Syntheses of these proteins were blocked by actinomycin D, therefore, new messenger RNA synthesis is required for induction. These proteins were not induced by an alkylating agent, antitumor antibiotics, or an antimetabolite. Our findings show that the 48- and the clustered 92-kd proteins are Vinca alkaloid reactive components and can be considered candidates for the elucidation of the antineoplastic effect of Vinca alkaloids.