Lecture 3b: Skin Cancer's and DNA Damage

Question 1

Xeroderma Pigmentosum

Answer 1

-Rare inherited disorder
-Autosomal recessive defect
-Nucleotide excision repair enzymes are mutated causing a reduction/elimination of NER
-Appear in infancy and early childhood
-Skin of people with XP does not protect itself from UV light
-1000 times the risk of developing skin cancer than the GP
-Increased risk for eye cancer and neurological problems

Question 2

Average patient with nonmelanoma skin cancer is about ________. The age of onset of nonmelanoma skin cancer is reduced by about _______ years earlier in XP patients.

Answer 2

-60 years old
-50 years —–> 10 YO

Question 3

Diagnostic techniques

Answer 3

-Hypersensitivity to sunlight during infancy
-Family history
-Assessment of post-UV DNA repair
-Sequence analysis

Question 4

Disorders of the cornea and eyelids

Answer 4

-Keratitis
-Corneal opacification
-Ectropion
-Hyperpigmentation of eyelids
-Loss of eye lashes

Question 5

UV radiation causes mainly what 2 main types of DNA damage

Answer 5

-Cyclobutane-pyrimidine Dimers
-Pyrimidine-Pyrimidome (6-4) photoproduct

Question 6

Inefficient DNA repair pathways

Answer 6

-Base excision repair
-Nucleotide excision repair
-Mismatch repair
-p53-Mediated DNA repair responses
-ATR-Chk1 DNA damage response

Question 7

Photoproducts

Answer 7

2 adjacent pyrimidine residues (Cytosine or Thymine) to form a dimer

Question 8

Risk of melanoma increases by _______ when tanning bed use starts before age 35

Answer 8

75%

Question 9

Melanosomes

Answer 9

Unique lysosome-related organelles found in cutaneous and ocular melanocytes, as well as retinal epithelial cells that synthesize and store melanin, the main mammalian pigment.

Question 10

Melanogenesis

Answer 10

The process of pigment formation that takes place in melanosomes which are present in specialized melanocytes.

Question 11

Melanocyte

Answer 11

Specialized cells that produce melanin pigments responsible for hair, skim, and eye pigment.

Question 11

Melanin

Answer 11

Black pigment synthesized nonenzymatically or enzymatically from dopamin, I-dopa, and l-tyrosine. Melanin containing cells in the brain and melanocytes of the hair and skin, pigment cells of inner ear, iris, and eye choroid originate in the neural crest.

Question 12

Melanoma incidence went up by more than ______ in men and _____ in women between the 1930s and 1960s

Answer 12

300% & 400%

Question 13

Melanosome transfer pathway

Answer 13

Melanosomes are packed globules enclosed by melanocyte plasma membrane, released into the extracellular space from various areas of melanocyte dendrites, phagocytosed by keratinocytes, and are then dispered in the perinuclear area.

Question 14

ABCD rule of melanoma diagnosis

Answer 14

A. Symmetry
B. Border is uneven, ragged, or notched
C. Coloring of different shades
D. Diameter