Vincristine transport mechanism

The contractile proteins of the spindle apparatus must draw apart the replicated chromosomes before the cell can divide. This process is prevented by the so-called spindle poisons (see also colchicine, p. 316) that arrest mitosis at metaphase by disrupting the assembly of microtubules into spindle threads. The vinca alkaloids, vincristine and vinblastine (from the periwinkle plant. Vinca rosea) exert such a cell-cycle-specific effect. Damage to the nervous system is a predicted adverse effect arising from injury to microtubule-operated axonal transport mechanisms. 

The vinca alkaloids, vincristine and vinblastine (from the periwinkle plant, Vinca rosea), inhibit the polymerization of tubulin subunits into microtubuli. Damage to the nervous system is a predicted adverse effect arising from injury to microtubule-operated axonal transport mechanisms. 

Three classes of plant-derived drugs, the vinca alkaloids (vincristine, vinblastine, and vinorelbine), the epipodo-phyllotoxins (etoposide and teniposide and the tax-anes (paclitaxel and taxotere), are used in cancer chemotherapy. These classes differ in their structures and mechanisms of action but share the multidrug resistance mechanism, since they are all substrates for the multidrug transporter P-glycoprotein. 

Mechanisms Vinblastine and vincristine are spindle poisons which, by preventing the assembly of tubulin dimers into microtubules, block the formation of the mitotic spindle. They act primarily in the M phase of the cancer cell cycle. Resistance may occur from increased efflux of the drugs from tumor cells via the membrane drug transporter. 

Periwinkle (Mnca) Toxins are vincristine and vinblastine, which inhibit microtubule formation during mitosis and are associated with disrupted axoplasmic transport in neurons Hallucinations can occur, but possibly not as a result of this mechanism... 

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