Home > Paclitaxel

Unfortunately, the Pacific Yew is one of the slowest growing trees in the world. Further, the treatment of just one patient requires the cutting down and processing of six 100-year old trees. This supply problem combined with the threat to a certain endangered owl species has prompted researchers to develop a bacterium ( Streptomyces coelicolor ) that fermentatively produces a paclitaxel-like compound.

Paclitaxel interferes with the normal function of microtubule growth. Whereas drugs like colchicine cause the depolymerization of microtubules in vivo, paclitaxel arrests their function by having the opposite effect; it hyper-stabilizes their structure. This destroys the cell's ability to use its cytoskeleton in a flexible manner. Specifically, paclitaxel binds to the tubulin protein of microtubules and locks them in place. The resulting microtubule/paclitaxel complex does not have the ability to disassemble. This adversely affects cell function because the shortening and lengthening of microtubules (termed dynamic instability) is necessary for their function as a transportation highway for the cell. Chromosomes, for example, rely upon this property of microtubules during mitosisIn biology, mitosis is the process of chromosome segregation and nuclear division that follows replication of the genetic material in eukaryotic cells. This process assures that each daughter nucleus receives a complete copy of the organism's genome.. Further research has indicated that paclitaxel induces programmed cell death ( apoptosisIn biology, Apoptosis (pronounced ap-a-tow'-sis is one of the main types of programmed cell death (PCD). As such, it is a process of deliberate suicide by an unwanted cell in a multicellular organism. In contrast to necrosis, which is a form of cell death) in cancer cells by binding to an apoptosis stopping protein called Bcl-2 (B-cell Leukemia 2) and thus arresting its function.

One common characteristic of most cancer cells is their rapid rate of cell division. In order to accommodate this, the cytoskeleton of a cell undergoes extensive restructuring. Paclitaxel is an effective treatment for aggressive cancers because it adversely affects the process of cell division by preventing this restructuring. Cancer cells are also destroyed by the aforementioned anti-Bcl-2 mechanism. Other cells are also affected adversely, but since cancer cells divide much faster than non-cancerous cells, they are far more susceptible to paclitaxel treatment.

The license to commercialize and market Taxol is held by the Bristol-Myers SquibbBristol-Myers Squibb is a pharmaceutical corporation, formed by a merger between two smaller pharmaceutical companies. Its Chairman and CEO are Peter R. Dolan, and it is headquartered in New York City. The company was involved in an accounting scandal in Co., which was selected for this role by the U.S. National Cancer InstituteThe National Cancer Institute (NCI is the United States Federal Government's principal agency for cancer research and training. The NCI is a component of the National Institutes of Health (NIH), one of eight agencies that compose the Public Health Service. Bristol-Myers holds an exclusive contract in the harvesting of yew trees from US government lands; it has been criticized for having a "cancer monopolyAlternate use: Monopoly (game In economics, a monopoly (from the Greek monos one + polein to sell) is defined as a market situation where there is only one provider of a product or service. Monopolies are characterized by a lack of economic competition fo". ( 1 - p.64The Best Democracy Money Can Buy (BooksEnthsiast.com, Penguin Plume USA) is a 2002 book written by Greg Palast. It is about corporate corruption, finance, globalization, political corruption, and the United States presidential election of 2000. External link)