Notes on the Genetics of Cancer

Part 1 - Jan 22, 2007

What is Cancer?

What is Cancer?

• “The Disease caused by uncontrolled division of abnormal cells in a part of the body.”

Cancer Cells

• Undergo constant cell division (~ every 2 days) and never enter G0.

Cancer Cells

• Undergo constant cell division (~ every 2 days) and never enter G0.

• No adhesion dependence (don’t need to be attached to another cell)

Cancer Cells

• Undergo constant cell division (~ every 2 days) and never enter G0.

• No adhesion dependence (don’t need to be attached to another cell)

• No density dependence (continue to divide even when surrounded by other cells to form a 3D tumor)

Cancer Cells

• The are de-differentiated (your 200+ cell types all look the same when cancerous and lose their function)

Cancer Cells

• They invade other tissues (local or metastasis)

Cancer Cells

• They invade other tissues (local or metastasis)

• They are angiogenic (they cause the creation of new capillaries to bring blood to the tumor).

Cancer Treatment

• The best offense is a good _________

Prevention and Detection

• No smoking

• Avoid BBQ

• High fiber foods

• Fresh veggies

• Wear sunblock

• Mole watch

• Self-examination

• Colonoscopy

Treatments

• Excision: removal of tumor (lumpectomy) and surrounding tissues (radical), including lymph nodes

Treatments

• Chemotherapy: drugs that target rapidly dividing cells, such as a cancerous tumor, but unfortunately include hair follicles, dermal cells that create skin, and the lining of the digestive system.

Treatments

• Radiation: destroys DNA and stimulates apoptosis (intentional cell death) via activation of the p53 gene (tumor suppressor gene).

• Anti-angiogenesis drugs

• Anti-telomerase drugs

The Genetics of Cancer

• Mutation in cell cycle genes > loss of control of cell cycle

• 2 (colon) to 15 (lung) gene mutations are required for cancer to happen

Protooncogenes

• These genes stimulate cell division (repair and replacement of cells).

• Dominant alleles (only 1 needed), so only 1 mutation necessary

• Once mutated and stuck in “on” position, called “oncogenes” (onco=cancer)

• Protooncogene = gas pedal

Tumor supressor gene

• TSG’s arrest cell division.

• Recessive alleles, so two mutations needed for effect (cancer).

• TSG’s = brakes

POGs + TSGs

• So….if you have a mutation of a POG and both copies of the TSG, it is like gluing the gas pedal to the floor and disconnecting your brakes. Not good.