[Application of NGF/PC12 cell system for the screening of tubulin inhibitors]

Microtubules are stiff polymers that extend throughout the cytoplasm of eukaryotic cells and regulate the location of intracellular compartments. Microtubules are formed by the polymerization of tubulin molecules, each of which is a heterodimer consisting of 2 closely related globular polypeptides: alpha-tubulin and beta-tubulin. Many of the microtubule arrays are labile and turn over rapidly; they depolymerize and repolymerize continually in living cells. One of the most striking examples is the mitotic spindle, which forms after the cytoplasmic microtubules disassemble at the onset of mitosis. The mitotic spindle is the target of a variety of agents that act by interfering with the exchange of tubulin subunits between the microtubules and the free tubulin pool. Some of these agents can be used as anticancer drugs. We have recently developed a simple and sensitive screening method for tubulin inhibitors, to which we have successfully applied the nerve growth factor/PC 12 cell system. In this report, we describe the details of our screening method for tubulin inhibitors, by which we have analyzed several well-known and new compounds as model experiments.