Cancer occurs when cells from a person's body grow out of control.
Our bodies are made up of trillions of cells, each performing an important function, like lung cells helping us breathe and muscle cells helping us move our arms and legs. These cells wear out and need to be replaced, so copies are made through a process called cell division. Errors can occur during this copying process, errors in the DNA called mutations. DNA contains the blueprint for building a cell and even a whole person, so when there is a mutation it can cause serious problems. One type of problem is cancer.
Most cells in the body have an inbuilt STOP signal that tells them when to stop dividing. For example, skin cells divide approximately 20 times and then they stop. This is important as we need to replace our skin cells; we lose them all the time. Cancer cells, however, can divide 100’s to 1000’s of times, forming tumours that interfere with the normal functioning of the body.
Scientists have found that one of the ways in which cancer cells keep on dividing is for them to maintain the ends of their chromosomes, and these ends are called “telomeres”. Normally these telomeres are gradually lost until they become too short and the cells stop dividing.
Cancer cells counteract the loss of telomeres using:
Telomerase activity or
ALT (Alternative Lengthening of Telomeres) mechanism
Telomerase is an enzyme that is active in embryos and foetuses during development. It enables us to develop from a single one-celled embryo into an individual with trillions of cells. Abnormal telomerase activity in cancer cells enables adult cells to continue to divide and form tumours. It is estimated that around 85% of cancer cells have telomerase activity.
ALT is another way by which cancer cells maintain their telomeres. These cells can be identified by ALT-associated bodies seen in the nucleus of tumour cells and stained with a special dye. Approximately 15% of tumour cells use the ALT mechanism to become immortal.
These mechanisms of tumour growth and development are being studied by the Cancer Research Unit
, Cell Biology Unit
, Telomere Length Regulation Group
, and Genome Integrity Group
at Children’s Medical Research Institute. These groups of researchers are trying different approaches to understand the processes around telomeres, which will be important for the development of new treatments for cancer.
The Cell Cycle Unit
also studies cancer, but they look at how cells divide. They have found several genes important for this process and are currently developing drugs targeted against dynamin
as a new treatment for brain cancers.