Scientific background

What is a cancer marker and why is this a hard problem to solve?

Markers are specific genes (DNA segments), RNAs or proteins with differential activity. These molecules may be found in blood or tissue samples, and specific combination of these markers may be involved in a given cancer.

Even under healthy conditions, these genes, RNAs and proteins are activated and deactivated to perform specific functions. Cancer is caused by alterations to these activities. The Mapping Cancer Markers project focuses on discovering abnormal marker combinations, which may relate to cancer initiation and progression. It does so by comparing and analyzing data from many cancer patients and healthy control patients.

Extensive data mining and statistical analysis is needed to discover the subtle combinations of activity related to a cancer, and differentiate such signals from normal variation. This is done by systematically testing whether any of these combinations of markers are significantly correlated with the presence of the cancer.

Because there are thousands of possible markers, the number of their combinations becomes astronomical. Testing every combination would be impossible, even with all of the resources of World Community Grid. Various mathematical methods will therefore be used to zero in on the most likely combinations to be examined on World Community Grid.

Are there any markers that are currently used?

There are several markers in clinical use. Two particular markers for breast and ovarian cancer, BRCA1 and BRCA2 recently received global attention after actress Angelina Jolie used them to assess her risk of developing the disease. In this particular case, only one marker BRCA1, in combination with family history was able to define her situation and to aid her in choosing her course of treatment.

What is the difference between DNA, RNA, a gene and a protein?

DNA (deoxyribonucleic acid) is a long, helix shaped molecule that forms a chromosome. It acts as the master blueprint in charge of encoding genetic instructions used to develop all cells for a given organism. Specific sections of the DNA are called genes. A gene usually encodes information about how to build a particular protein molecule. RNA (ribonucleic acid) molecules are similar to DNA molecules, but are constructed from DNA information, and are used more directly to regulate and direct the machinery (other molecules) which creates proteins. The range of functions performed by these molecules is very broad and complex, and is a major subject in molecular biology. Typically, genes on the DNA (master blueprint) are “transcribed” into RNA, a process which is explained in this video. Other machinery then reads the RNA instructions and makes proteins such as hemoglobin, which is used to transport oxygen and carbon dioxide in blood.

What are enzymes?

Enzymes are proteins that convert chemicals or act as catalysts. Certain enzymes in plants, for example, can assist in the absorption of carbon dioxide molecules and incorporate them into other cellular molecules.

Why are microorganisms important?

Microorganisms represent the great unseen and under appreciated majority of life on our planet. They are everywhere in the environment and in larger, more complex organisms. They are important for a huge variety of natural processes, including human health, agriculture and food production. For almost any kind of organic molecule, there will be a microorganism that has evolved the capacity to decompose, change, or construct it.