Cell Cycle and Cancer Cancer is often referred to as a disorder of the cell cycl

Question

Cell Cycle and Cancer

Cancer is often referred to as a disorder of the cell cycle (see p 128 in your book).

Briefly describe the cell cycle and explain how it is regulated.

How might disruption of the cell cycle lead to cancer?

Find and describe the actions of a chemotherapeutic agent that directly targets the cell cycle. Be sure to explain specifically when during the cell cycle it works and what it interferes with.

Here is a good resource to get you started in finding a chemotherapeutic agent to discuss:

National Cancer Institute. 2012. Types of chemotherapy drugs

Explanation / Answer

A cell cycle may be defined as a series of events whch leads to the faithful division of a cell into two equal and identical daughter cells. In proyaryotes the cell division takes place by the process of binary fission. However, in eukaryotes the cell cycle can be divided into three phases: Interphase, Mitosis and Cytokinesis. Interphase is generally termed as the inert phase, but in reality it is the most active phase. The cell actively prepares to divide and synthesizes a lot of proteins, RNA and other molecules required for successful division. The Mitotic or M phase is the phase where division of the genetic material takes place. The last phase is cytokinesis where actual physical division of the cell takes place. Interphase is further divided into G1, S and G2 phase. In this whole cell division cycle their are certain timepoints where the cell cycle halts temporarily. During this time the cell the cell appraises the veracity of the whole cell division process and decides whether to go ahead of the cell division or not. These are called as cell cycle checlpoints. They serve as regulatory points. Currently there are three checkpoints that have been accepted by concensus; the G1 checkpoint, The G1/M checkpoint (before entry into Mitosis) and the Metaphae checkpoint ( another stage within mitosis).

Thus, failure of these regulatory checkpoints along with another factors such as mutations in genes such as p53 may lead to an uncontrolled cell division which ulimately forms a tumor. Thus, these multi factors leads to a perturbation of cell cycle which leads to cancer.

Their are a lot of chemotherapeutic agents that have been developed to target cell cycle/cell division proteins. For example: Inhibitors of Cdc25 have been developed which are useful for the arrest of cell cycle. Cdc proteins controls entry and progression into the cell cycle. It is a dual specificity phosphatase.Bortezomib is one of the first drugs which was a proteosome inhibitor and was tested for its role in treating multiple mlyeloma. It binds to the catalytic site of 26S proteasome and prevents degradation of pro-apoptotic factors and promotes apoptosis in cancerous cells.

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