Cancer treatment poses a great challenge since it involves developing drugs which could, in most instances, be toxic to some other cells of the body, apart from the targeted cancer cells. Vincristine is one such drug. Vincristine is FDA approved in the treatment of cancer, either singly or in combination with other anticancer drugs. It was initially approved for treatment of Acute leukemia (cancer of blood cells), but has since proved useful in combination with other drugs for treatment of other kinds of cancer.
Effects on Cancer Cell Division
Dividing cells go through two primary cycles. There is a relatively long resting phase (interphase), during which the cell matures and prepares for cell division. Then, it enters the stage of mitosis (metaphase) where it actually divides, first with synthesis of microtubules that form the spindles on which the DNA align and divide. These steps happen at highly increased rates in cancer cells. Vincristine binds to the microtubules, preventing the formation of spindles and freezing the cell in metaphase (metaphase arrest). The result is an inability of the cells to divide and actual death of the cells.
Effects on Cancer Cell Invasion
Cancer cells increase in bulk by rapid uncontrolled cell division. The spill over spill over of such cells out of their natural compartments into neighboring tissues account for direct invasion in cancer. Vincristine thus slows the growth of cancer cells by stopping the rapid cell division that accounts for increase in bulk of the cancer and its direct invasion of neighboring cells.
Effects on Cancer Metastasis
Cancer cells have abnormal intercellular binding that makes it easy for individual cells to breakaway and float off in tissue fluids. they can thus 'seed' other distant organs, in a process called metastasis. Vincristine prevents cancerous cells that have made their way to other tissues from multiplying and establishing a foothold, thus preventing metastasis.
Side Effects of Vincristine
Side effects and adverse reactions of Vincristine use are usually dose related and eventually clear up after discontinuation of the drug. These include hair loss, intestinal ulceration and even perforation, disturbances of nervous function and depressed white blood cell production. These have warranted its combination with other drugs to reduce the needed dose of Vincristine, like Cyclophosphamide, doxorubicin, vincristine and prednisolone in lymphoma.
