The Stubborn Cells: Cancer Cells

The Stubborn Cells

Cancer is caused by a mutation (change) in a gene. During the past few years, scientists have made immense progress in understanding how certain changes in a person’s DNA can cause cells of the body to become cancerous. DNA carries the instructions for nearly everything our cells do. We usually resemble our parents because they are the source of our DNA. However, DNA affects more than our outward appearance. It influences our risks for developing certain diseases, including some kinds of cancer. When children are born with mutated DNA that was inherited from parents, the mutations are present in every cell of the child’s body. That means the mutations can be detected by testing DNA of blood cells.

The great majority of cancers, however, are not caused by inherited DNA mutations. They are the result of mutations acquired early in the child’s lifetime. Every time a cell prepares to divide into 2 new cells, it must copy its DNA. This process is not perfect, and errors sometimes occur. Fortunately, cells have repair enzymes that “proofread” DNA. Some errors can still slip past, particularly when the cells are growing rapidly. This kind of gene mutation can happen at any time in life. Acquired mutations start in one cell of the body, and that cell passes the mutation on to all the cells that spring from it. These acquired mutations are present only in the patient’s cancer cells and will not be passed on to their children. Although the causes of mutations responsible for certain adult cancers are known (for example, cancer-causing chemicals in cigarette smoke), the reasons for DNA changes that cause childhood cancers are not known. Some of these can occur in developing fetuses and are already present at birth.

Reference:

http://www.cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_and_causes_of_childhood_cancer_7.asp

Image:

http://en.wikipedia.org/wiki/Image:Cancer_requires_multiple_mutations_from_NIH.png