The Cell Cycle & Mitosis Tutorial

Problem 9: Cancer

The sputum (fluid coughed up from the lungs) of many smokers contain cells with mutations (errors) in the genes for p53. The smoking induced mutations appear to be an early signal showing that cancer of the lungs will follow. What is the likely relationship between early p53 mutation and the development of lung cancer?

B.

Mutations in p53 would prevent abnormal cells from dying by apoptosis.

Correct. If the mechanism for eliminating abnormal cells is defective, then the cells will continue to divide and further damage their DNA. This process leads to cancer. Exposure to sun also causes apoptosis in damaged cells. This produces the familiar peeling and blistering associated with severe sunburn. Over many years, exposure to sun also leads to cancer. It is particularly interesting that smoke seems to cause a high frequency of p53 mutations.