Cell cycle regulation is an internal process to control the rate of cell growth and division. Without cell cycle regulation, cells could grow in an uncontrolled manner, expending a great deal of energy and causing problems for the host organism. Breakdowns in this process can be seen in medical problems like cancer, where cells start to divide uncontrollably and form a tumor because they are no longer being regulated.
Different types of cells need to reproduce at varying rates. Some areas of the body, like the skin, have very high cell turnover. In other areas, the cells grow much more slowly. Within each cell, the same genes coding for cell differentiation also provide the framework for cell cycle regulation, ensuring that the cell divides and multiplies at an appropriate rate.
Proteins in the cell, such as cyclins and cyclin-dependent kinases, are responsible for cell cycle regulation. As their levels wax and wane, they control different aspects of cell replication and division. They bind to receptors inside the cell to regulate stages of the process, allowing cells to start duplicating and dividing. Each stage of the cell division process is carefully regulated to make sure it takes place at the right time and to reduce the risk of errors such as incomplete sets of chromosomes in the daughter cells.
In cancerous cells, this process is disrupted by changes to the cell structure. Instead of controlling the rate of replication, the proteins responsible for cell cycle regulation allow the cell to divide and keep dividing, over and over again. The new cells may be poorly differentiated, and could have other structural variations as a result of the rapid divisions, and they can start to spread through the body, crowding out healthy cells because they cannot grow quickly enough to combat the cancerous cells.
The process of cell cycle regulation is studied in a variety of settings, from labs where people can experiment with single celled organisms to medical research facilities where cancer cells are grown in culture to see where the cell cycle regulation went wrong. This research is applied in a number of ways. Drugs to stimulate more rapid growth and division could be useful for the treatment of some diseases, while figuring out how to identify and kill rogue cells is a critical part of cancer treatment. Advances in microbiology allowing people to break down all the components of cells to learn more about how they are put together have contributed significantly to the development of more aggressive treatments for disease.