Lecture 32 - Cancer II

Question 1

What are the two types of tumor suppressor genes?

L32 S6-7

Answer 1

Restrict cell growth and proliferation:

• inhibit progression through G1/S checkpoint
• ie. CKI and Rb

Maintain integrity of genome:

• detect DNA damage
• ie. ATM, ATR
• DNA repair enzymes

Question 2

What is retinoblastoma and what are the two types?

L32 S8-11

Answer 2

• loss of function of Rb protein which is a tumor suppressor
• results in eye cancer typically before the age of 2

Hereditary:

• occurs in both eyes (40% of cases)
• one inherited bad gene and other gene gets lost (loss of heterozygosity(

Sporadic:

• occurs in one eye (60% of cases)
• originally both genes are good but both end up losing functions

Question 3

What is p53 and what are its functions?

L32 S23

Answer 3

-tumor suppressor gene

Functions:

• arrests cell cycle (stimulates p21 (CKI) expression)
• role in DNA repair
• role in apoptosis
• blocks angiogenesis

Question 4

How does the papilloma virus stimulate tumor formation?

L32 S27-31

Answer 4

• viral DNA contains genes for proteins called E6 and E7
• E6 binds and inactivated p53
• E7 binds and Rb causing over expression of G1/S-Cdk and S-Cdk

Question 5

What is Bcl2 and what is its function?

L32 S35

Answer 5

• oncogene

- mutation prevents apoptosis

Question 6

What are the types of hereditary colorectal cancer and how do they occur?

L32 S46-49

Answer 6

Familial adenomatous polyposis coli (FAP):

• inherited defect in one copy of Apc (tumor suppressor gene)
• loss of heterozygosity results in no Apc transcription

Hereditary non-polyposis colorectal cancer (HPNCC):

• caused by defects in mismatch repair
• normal number of chromosomes unlike most colorectal cancers

Question 7

What is the function of Gleevec?

L32 S54

Answer 7

• binds in ATP binding site of Bcr-Abl preventing its function
• prevents development of leukemia