Photocarcinogenesis

Question 1

What skin cancer arises from lifelong cumulative UV exposure?

Answer 1

SCC

Question 2

What skin cancers arise from intermittent burning episodes of sun exposure?

Answer 2

Melanoma and BCC

Question 3

What types of UV radiation cause direct and indirect DNA damage?

Answer 3

UBA - indirect

UVB - direct

Question 4

What are the 2 things produced from DNA by UVB?

Answer 4

Cyclobutane pyrimidine dimers and 6-4 photoproducts (less common but more damaging)

Question 5

What are the signature mutations produced by UVB?

Answer 5

CT or CC-TT

Question 6

How is damage from UVB repaired?

Answer 6

Nucleotide excision repair.

Question 7

How does UVA indirectly damage DNA?

Answer 7

Oxidises DNA bases and oxidised bases can pair with the wrong bases.

Question 8

What are the signature mutations of UVA damage?

Answer 8

GC-AT

Question 9

How is UVA damage repaired?

Answer 9

Base excision repair

Question 10

What mutation causes gorlins syndrome and BCCs?

Answer 10

PTCH

Question 11

What signalling pathway is commonly mutated in melanoma and what can target this?

Answer 11

Ras/Raf/MAPK

Vemurafinib

Question 12

What mutations cause familial melanoma?

Answer 12

CDKN2A and CDK4