The Noble Prize in Medicine or Physiology for 2009 Explains Cancer, Its Possible Treatment and the Process of Aging
The 2009 Nobel Prize in Medicine or Physiology was awarded to three researchers: Dr. Elizabeth H. Blackburn, Dr. Carol W. Greider and Dr. Jack W. Szostak. The three Nobel Laureates are responsible for explaining the role that telomeres and telomerase play in protecting chromosomes and DNA. Their discoveries have implications for cancer research and treatment and for research into the process of aging. This article aims to explain the study results and how those results affect you.
All life is composed of cells and every cell has a nucleus. The nucleus is the control center of a cell; it provides the cell with all the information and instruction the cell needs to do its job. The cells collectively run our bodies. The material in the nucleus that is fundamentally responsible for cell actions is called Deoxyribonucleic Acid (DNA). DNA is stored in structures called chromosomes which exist bunched up inside the nucleus. A specific section, or sequence, of DNA that is responsible for a specific action is called a gene.
The cells in our body constantly cycle. Our skin cells die and are replaced regularly. Our fingernails grow and are cut and grow again. Throughout our bodies cells are constantly wearing out and being replaced. Cell division (called Mitosis) is the method our body uses for growth and replacement. Our cells have the remarkable ability to split into equal halves, forming two cells where there previously was just one cell. The original cell, called a parent cell, divides into two identical cells called daughter cells.
Everything about the daughter cells, including the DNA and the chromosomes, is identical to the original parent cell. Just prior to cell division the instruction manuals (chromosomes) copy themselves, or replicate. Proper replication is the only way to ensure that the new cells will contain a complete set of DNA, or a full instruction manual. Any error in the DNA replication would cause the new cell to function improperly. The ends of every chromosome consist of telomeres and the prize winning research involves the role these telomeres play in ensuring that chromosomes copycorrectly.
The Research: Telomeres and Telomerase
Simply put telomeres and the enzyme telomerase work together to build a protective cap over the ends of each arm of a chromosome, preventing the ends from sticking together and from degrading. By protecting the ends of the chromosomes the telomeres ensure that the chromosomes, and their DNA, are copied correctly and so produce perfectly functional daughter cells. To use the instruction manual analogy, the telomeres would be the book binding that keeps the pages of the manual from coming loose or from sticking together. If thesetelomere end caps start to wear out or shorten they may not do their job correctly and some chromosomal damage could occur. Any daughter cells formed from damaged parent cells would themselves be damaged and this discovery goes a long way towards explaining how both cancer and aging operate.
The Process of Aging: Every time a cell divides the telomere gets just a tiny bit shorter. Eventually, the telomeres become so short that they no longer protect the chromosome adequately. The cell then can no longer replicate correctly and the cell dies without being replaced. This process may partially explain why our hair gets thinner and grows more slowly as we age and why our skin loses its youthful tightness and tone over time. The broad concept of human aging is very complex and is due to much more than worn out telomeres. However, this understanding of telomeres and their role in cell division helps explain one piece of the puzzle that is human aging. Active research into telomeres and aging continues.
Cancer:Doctors Blackburn, Greider and Szostak’s discovery about telomeres explains how cancer cells work.Cancer occurs whencell division goes haywire.Normally functioning single cells are not constantly in a state of division. Most of a cell’s life is spent attending to other matters and cell division occurs when needed. For example, when we get a cut, our skin cells hurry to divide and create new skin over the wound. Once the wound is healed the cells ramp down the rate of division and return to their normal daily activities.
Cancer cells, however, lack a shut off switch. Cancer cells also do not go through the aging process described above; their telomeres, instead of shortening with each copy, stay exactly the same length; a cancer cell doesn’t age or die on its own. The enzyme telomerase, which controls the rate of telomere degradation, is abnormally active in cancer cells. This heightened level of activity is what causes the telomeres of chromosomes in cancer cells to stay exactly the same length no matter how many daughter cells are made, thus ensuring that the cancer cells can replicate (and tumors grow) at will. Current research is focusing on drugs that can shut down the telomerase in cancer cells without impacting the functioning of normal cells.
The understanding of telomeres and telomerase brought about by the work of Blackburn, Greider and Szostak is critical to the understanding of both aging and cancer and offers hope that a truly effective cure for cancer can be found.