Principles of Cancer - AB

Question 1

While many chemicals can cause cancer, what is the underlying etiology of cancer (i.e., what do chemicals that cause cancer actually do in the cell)?

Answer 1

Chemicals that cause cancer are actually causing mutations in our DNA, this results in uncontrolled cell proliferation.

Question 2

Describe the major difference between initiation of carcinogenesis and promotion.

Answer 2

Initiation leads to DNA damage, while promotion favors the growth of mutated cells over normal cells.

Question 3

What is the mechanism by which a loss-of-function mutation in Rb would promote progression through the cell cycle and possibly cancer?

Answer 3

The Rb protein is responsible for the restriction point (checkpoint) control. A loss-of-function mutation would stop the inhibition of the checkpoint, and allow the progression into the S phase.

Question 4

2 ultimate consequences of p53 activation

Answer 4

• halt the cell cycle to wait for DNA repair

- trigger apoptosis so the mutations are not propagated

Question 5

What is the primary reason why a dysfunctional mitotic checkpoint could result in cancer?

Answer 5

A dysfunctional mitotic checkpoint can cause missegregation of the chromosomes, creating a lack of (or excess of) growth-promoting DNA. Both of these could result in cancer.

Question 6

How does apoptosis differ from necrosis, and what is the function of Bcl-2 in apoptosis?

Answer 6

Apoptosis is a programmed cell-death, while necrosis is caused by external factors. Apoptosis is characterized by membrane blebbing, and fragmentation within a single cell. Necrosis is characterized by cellular swelling, then exploding, it’s contents are spread to the surrounding tissues.

Bcl-2 is an antiapoptotic protein. It prevents proapoptotic proteins from sequestering, and causing mitochondria to activate caspases (responsible for direct destruction of cytoskeletal proteins, and indirect destruction of DNA)

Question 7

What is angiogenesis and how is it relevant to tumors?

Answer 7

Angiogenesis is the growth of new blood vessels responsible for nourishment and growth. Activators and inhibitors (of angiogenesis) can control the growth and speed of the tumor.

Question 8

major target of antiangiogenic drug tx

Answer 8

VEGF

Question 9

How do metastatic cancer cells travel through the body?

Answer 9

blood stream or lymphatic system

Question 10

If metastatic cells are very rare, why is metastasis such a major problem clinically?

Answer 10

Drugs that work to stop metastasis are still being developed