Lecture 3a: Skin Cancers, Defects in Skin Repair

Question 1

Intrinsic Risk Factors

Answer 1

Unmodifiable: Random errors in DNA replication

Question 2

Non-Intrinsic Risk Factors

Answer 2

Modifiable or Partially Modifiable

Question 3

Endogenous Risk Factors

Answer 3

Partially Modifiable
-Biological Aging
-Genetic susceptibility
-DNA repair machinery
-Hormones
-Growth factors
-Inflammation

Question 4

Exogenous Risk Factors

Answer 4

Modifiable
-Radiation
-Chemical carcinogens
-Tumor causing viruses
-Bad lifestyles such as smoking, lacking of exercise, nutrient imbalance

Question 5

Cancers are caused by DNA mutations and chromosomal rearrangements that may be:

Answer 5

-Inherited
-Indued by environmental factors
-Results from DNA replication errors

Question 6

Epigenetic changes

Answer 6

Silencing of tumor suppressors or activation of oncogenes that can lead to uncontrolled cell growth and division.

Question 7

Number of DNA replication errors that can cause damage per day

Answer 7

70,000 nucleotide lesions or modifications per day

Question 8

Evidence that random, unpredictable DNA copying “mistakes” account for nearly ______ or _______ of mutations that cause cancer.

Answer 8

66% or two-thirds

Question 9

Bad Luck Hypothesis

Answer 9

66% of cancer mutations result from DNA copying errors. 29% are attributed to environment. 5% are inheritance.

Question 10

Germline mutations

Answer 10

Hereditary cancers that account for 5% of all cancers.
-Occurs in precursor cells for the sperm or egg cell.
-Mutation expressed in ALL body cells.

Question 11

Li-Fraumeni Syndrome

Answer 11

Caused by mutations of TP53 gene in germinal cells. A type of cancer predisposition syndrome, inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to increase the risk of developing cancers.

Question 12

Acquired/Somatic Mutations

Answer 12

Most common type of mutation.
-Found in sporadic cancers, accounts for 95% of all cancers
-Expressed in some of the body cells “Soma”
-Not hereditary

Question 13

Factors that cause acquired mutations

Answer 13

-Age
-Chemicals
-Tobacco
-Viruses

Question 14

Philadelphia Chromosome

Answer 14

Abnormal version of chromosome 22 that contains a fusion of 2 genes, ABL gene and BCR gene.

Question 15

How is the Philadelphia Chromosome generated?

Answer 15

When proto-oncogene Abelson murine leukemia (ABL1) gene on band q34 on chromosome 9 translocated to band q11 on chromosome 22 where the breakpoint cluster gene (BCR) is. Fusion of ABL and BCR can cause immature WBCs to grow uncontrollably and build up in marrow and blood.

Question 16

Philadelphia chromosome (Ph+) abnormality is found in ___________ of chronic myeloid leukemia patients.

Answer 16

20-30%

Question 17

Function of the BCR-ABL gene

Answer 17

Production of an abnormal tyrosine kinase protein that is not properly regulated

Question 18

Tyrosine kinase

Answer 18

Common signaling molecule that when activated triggers cell division. Active for too long in patients with CML.

Question 19

Treatment for Chronic Myeloid Leukemia

Answer 19

BCR::ABL1 tyrosine kinase inhibitors

Question 20

Most common type of skin cancer in humans

Answer 20

Basal Cell Carcinoma

Question 21

UV-A