Lecture 17: Hereditary Cancer and Oncoviruses

Question 1

how many hereditary cancers are known?

Answer 1

50 forms

about 1-2%

Question 2

Ras proto-oncogene

Answer 2

• Ras gene family include some of the most frequently mutated genes in human tumors
• encode signal transduction molecules associated with cell membrane
• regulate cell growth and division

Question 3

kinases

Answer 3

enzymes that are responsible for phosphorylation

Question 4

how many exons does the RET proto-oncogene?

Answer 4

21

Question 5

what happens when RET behaves like other receptor tyrosine kinases?

Answer 5

-then binding to ligand causes dimerization and activation of the receptor

Question 6

what does it mean by saying RET is a proto-oncogene?

Answer 6

a single activating mutation on only one allele should be sufficient to cause neoplastic transformation

Question 7

what happens when there is a mutation of codon 634?

Answer 7

-constitutively (always on) activate the tyrosine kinase receptor by causing receptor monomers to dimerize, mimicking the effect caused by binding of a ligand to a receptor

Question 8

what processes is RET signaling involved in?

Answer 8

• proliferation
• migration survival
• differentiation

Question 9

what can happen if constant signaling by RET is in the wrong place at the wrong time?

Answer 9

cell proliferation

Question 10

neoplasia

Answer 10

the formation of a cell mass (benign or malignant)

Question 11

oncoviruses

Answer 11

viruses that contribute to the formation of cancer

Question 12

what percentage of global cancer incidence is linked to an infectious agent?

Answer 12

18%

Question 13

what percentage of Epstein-Barr virus accounts for what percentage of all virus associated cancer?

Answer 13

1%

Question 14

what viruses cause most cancer?

Answer 14

RNA retoviruses

Question 15

how do pathogens infect cells?

Answer 15

when they gain access to the cell’s interior

-pathogens target certain cell types and not others

Question 16

what makes once cell type different from another?

Answer 16

• heterochromatin v euchromatin
• TF collection in nucleus
• cell surface markers
• cytoplasmic proteins

Question 17

about 18% of human cancers are caused by infections, what are viruses that account for 12% of that?

Answer 17

EBV, HPV, HepB, HepC, HTLV-1, KSHV, and MCV

Question 18

what are the DNA cancer causing viruses?

Answer 18

EBV, HPV, HCV, PHV16, KSHV

Question 19

what are the RNA cancer causing viruses?

Answer 19

HTLV-1, HIV-1

Question 20

Retroviruses

Answer 20

• RNA viruses
• animal viruses that cause cancer
• reverse transcriptase copies RNA to DNA
• DNA copy enters into the nucleus
• retroviruses integrate into host genome as a provirus

Question 21

provirus

Answer 21

replicated with host’s DNA during normal cell cycle

Question 22

acute transforming retroviruses

Answer 22

• carry cell-derived oncogenes

- infect and transform cells into cancer cells

Question 23

what are the three ways retroviruses can cause cancer?

Answer 23

1. ) proviral DNA may integrate near protooncogenes, which stimulates high rates of transcription
2. ) acute transforming retroviruses
3. ) normal retrovirus with normal viral gene products can stimulate inappropriate cell growth