Neoplasia II

Question 1

Name the 4 types of carcinogens

Answer 1

chemical, radiation-induced, viral, bacterial

Question 2

What occurs during the initiation step of chemical carcinogens? Promotion step?

Answer 2

irreversible mutations in the genome; tumor induction in previously initiated cells

Question 3

What is the #1 target of chemical carcinogens?

Answer 3

DNA - RAS, p53

Question 4

ionizing radiation induces DNA mutations and increases risk of ____ and ____ carcinomas

Answer 4

leukemia; thyroid

note: less likely to cause cancers of lung and breast

Question 5

In regards to viral carcinogens, name the RNA and DNA viruses

Answer 5

RNA viruses: HTLV, HCV

DNA viruses: HPV, EBV, HBV

Question 6

True or false? nonlethal genetic damage is at the heart of carcinogenesis

Answer 6

true

Question 7

There are four classes of normal regulatory genes that are principal targets of genetic damage. Name them

Answer 7

1. growth promoting proto-oncogenes
2. growth inhibiting tumor suppressor genes
3. genes that regulate apoptosis
4. genes involved in DNA repair

Question 8

Describe the sustained proliferative signal

Answer 8

proliferate without external signals. Usually a consequence of oncogene activation

Question 9

_____ promote autonomous cell growth; their un-mutated cellular counterparts are called ____-____ and participate in signaling pathways that drive proliferation

Answer 9

oncogenes; proto-oncogenes

Question 10

_____ are encoded by oncogenes and are able to promote cell growth in the absence of normal growth-promoting signals

Answer 10

oncoproteins

Question 11

Cancer cells don’t respond to molecules that inhibit growth of normal cells. This is usually due to inactivation of what type of genes?

Answer 11

tumor suppressor genes

Question 12

Tumor cells switch to aerobic glycolysis, this enables what?

Answer 12

rapid growth

Question 13

What is the prototypic anti-apoptotic protein that can be overexposed in tumor cells to extend survival?

Answer 13

bcl-2

Question 14

True or false? DNA repair genes are directly oncogenic

Answer 14

false; but permit mutations to occur in other genes that induce carcinogenesis

Question 15

A defect in this DNA repair pathway is evident in hereditary nonpolyposis colon cancer syndrome

Answer 15

mismatch repair

Question 16

A defect in this DNA repair pathway is evident in xeroderma pigmentosum

Answer 16

nucleotide excision repair

Question 17

A defect in this DNA repair pathway is evident in bloom syndrome, fanconi anemia, hereditary breast cancer syndromes

Answer 17

recombination repair

Question 18

Which of the following are possible mechanisms of evasion of the host response?

a. selective outgrowth of antigen-negative variants
b. loss or reduced expression of MHC molecules
c. activation of immunoregulatory pathways
d. secretion of immunosuppressive factors by tumor cells
e. induction of regulatory T cells
f. all of the above

Answer 18

f. all of the above

Question 19

Tumor clones compete with one another for survival and the “winners” tend to be more ____ over time

Answer 19

aggressive

note: cancer becoming resistant can be explained by selection of fittest cells