Cancer Mutation Types (4- Bio)

Question 1

What are the different cancer mutation types?

Answer 1

1) Point mutation
2) Deletion
3) Amplification
4) Transolation

Question 2

What is a point mutation?

Answer 2

Change in a single nucleotide in DNA

Question 3

Point mutation examples

Answer 3

-p53 (tumour suppressor): most mutated gene
loss of function= decreased tumour suppressor activity
gain of function= increase in oncogenic activity

-RAS (oncogene)
mutations affect 12,13 or 61 codons
making it always active= increased proliferation
GTpase regulation pathway

Question 4

What is a deletion?

Answer 4

When a chunk of gene is removed, truncated proteins

Question 5

Deletions examples

Answer 5

-INK4 deletion
It acts as a tumour suppressor, inhibits cyclin-dependent kinase and Rb phosphorylation
Mutation= decrease in tumour suppressor activity

• EGFR deletion
  Always active; inhibits p53

Question 6

What is amplification?

Answer 6

Increase the no of copies of gene

Question 7

Examples of amplification

Answer 7

MDM2
- an increase=decrease in p53, as it ubiquitinates p53 for degradation

MYC, RAS, HER2 and EGFR (oncogenes) are commonly amplified

Question 8

What is translocation?

Answer 8

Rearrangment of chromosomes; fusion proteins

Question 9

Translocation examples

Answer 9

BCR/ABL; the philadelphia chromosome
Translocation of chromosomes 9 and 22
Fused BRC (serine threonine kinase) and ABL (GTPase) together, protein is no longer regulated

Associated with chronic myeloid leukemia

Question 10

What drugs target BCR/ABL?

Answer 10

Inatinib, Nilotinib and Dasatinib