Lecture 8

Question 1

Where do melanomas develop from?

Answer 1

Melanocytes

Question 2

If discovered early, melanomas can be excised and treated easily?

Answer 2

TRUE. Late stage melanomas have no treatment.

Question 3

What are the risk factors of melanoma?

Answer 3

Age - accumulate more mutations
Gender - high in males 
Skin colour - lighter = more risk 
Sunburn/UV exposure
Mutations e.g. XP, melanocortin, CDKN2A, TERT activation

Question 4

What are initiator mutations?

Answer 4

Begin formation of melanoma. Always activate MAPK signalling pathway. BRAFV600E and NRAS

Question 5

Which mutations are seen in progessive/late stage melanoma?

Answer 5

Prog - TERT, CDKN2A

Late - P53, PTEN

Question 6

TRUE OR FALSE

BRAFV600E is seen in more than 75% melanomas?

Answer 6

TRUE

Question 7

What model organism is good for studying cell cycle?

Answer 7

Yeast

Question 8

TRUE OR FALSE

Drosophila and C. Elegans are good for studying upstream controls of cell division/differentiation/death?

Answer 8

TRUE

Question 9

What are nude mice?

Answer 9

Mice with foxn1 mutation, have a defective immune system and so they can be injected with human melanoma cells and studied. They don’t have an immune system so they aren’t good for studying the role of immunity in cancer.

Question 10

What additional mutations are needed to study melanoma formation in mice with activated H- or N-RAS?

Answer 10

UV or CDKN2A KO

Question 11

Explain the tg line:

Tyr;Cre-ERT2;Braf(CA/+);PTEN(lox/lox)

Answer 11

Tyr - tyrosine promotor only found in melanocytes
Cre-ERT2 - Cre-recombinase only expressed in presence of tamoxifen
Braf(CA)- Cre-Activatable constitutively active form of Braf
PTEN - floxed allele of PTEN