The Genetic Origins of Cancer

1
The Genetic Origins of Cancer

• Chapter 13

2
Definition of Cancer

• Cancer is a disease characterized by the
  uncontrolled proliferation of cells.
• The normal mechanisms that regulate cellular
  growth and division break down.
• This breakdown results from mutations that
  overcome the normal limits to the number of cell
  divisions that can take place before a cell dies.

3
Progression of Cancer

• Mutations usually occur in somatic cells.
• Progression of cancer comes through sequential
  accumulation of sets of mutations. (Aging)
• Genetically inherited mutant genes can predispose
  an individual to a more rapid progression of the
  disease.

4
Stages of Cancer Progression

• Primary cells
• Immortalization (Benign)
• Transformation
• Metastasis

5
Normal and Transformed Cells
6
Mutations Cause Transformations

• Proto-oncogenes are regular genes that, when
  mutated, uncouple the normal cell cycle control.

7
Proto-Oncogenes

• Many proto-oncogenes are the normal components of
  signaling pathways that regulate growth.
• Direct mutation or altered level of protein
  expression can disrupt signaling pathways.

8
What are the Sources of Somatic Cell Mutations?

• DNA Replication
• DNA Repair
• Some Viruses
• Transposons
• Retro-transposons
• Radiation
• UV-light
• Carcinogens

• Lack of active tumor suppressor genes.
• p53
• RB

9
Summary Questions

• What are the three stages of cancer?
• How does a person get cancer?