Microbiology Lecture 4.

Question 1

What are the 6 main differences between malignant cells and normal cells?

Answer 1

tumorigenicity, lack of differentiation, immortality, lack of contact inhibition, resistance to apoptosis, chromosome abnormalities

Question 2

What are the cancers caused by a virus that have a vaccine?

Answer 2

cervical cancer (HPV vaccine) and hepatocellular cancer (hep B vaccine)

Question 3

oncogene

Answer 3

surface receptors for growth factors in normal cells

Question 4

How is growth and differentiation of cells regulated?

Answer 4

by numerous surface receptors and internal signaling pathways

Question 5

myc

Answer 5

proto-oncogene transcription factor that controls growth of cell

Question 6

sis

Answer 6

proto-oncogene that controls growth of cell - platelet-derived growth factor

Question 7

erb B

Answer 7

proto-oncogene growth factor receptor

Question 8

scr

Answer 8

proto-oncogene membrane signaling of growth factor binding

Question 9

ras

Answer 9

porto-oncogene signal transduction from surface receptors

Question 10

fms

Answer 10

proto-oncogene growth factor receptor

Question 11

CMO2

Answer 11

proto-oncogene hematopoiesis

Question 12

p53

Answer 12

proto-oncogene that controls cell cycle; stimulated by DNA damage to stop cell cycle

Question 13

pRB

Answer 13

proto-oncogene that controls cell cycle; blocks E2F (which controls cell cycle regulation

Question 14

Large T antigen

Answer 14

allows cell to proliferate without control by blocking p53 and RB

Question 15

What is damage to DNA normally managed by?

Answer 15

pause in cell cycle, attempted repair of DNA, resumption of the cycle or apoptosis

Question 16

oncogene specific to chronic myelogenous leukemia

Answer 16

abl

Question 17

oncogene specific to breast cancer

Answer 17

her2/neu

Question 18

What mechanisms do retroviruses cause cancer?

Answer 18

1. contain oncogenes and express them in infected cells 2. insert their promoter into a chromosome and cause expression of regional oncogenes

Question 19

What mechanism do DNA viruses use to be oncogenic?

Answer 19

encode proteins that disturb the cell cycle and prevent apoptosis (esp p53 and pRB)

Question 20

SV40 virus

Answer 20

primate virus (species specific!!!) causes cell transformation and cancer in rodents - transforms human cells to malignant state by expressing T antigen - contaminant of early polio vaccines

Question 21

adenoviruses

Answer 21

a group of human viruses, some of which cause cell transformation and cancer in rodents, but only cause colds and sore throats in people

Question 22

E1A and E1B

Answer 22

analogous to T antigen

Question 23

Which cancers are caused by a virus? What is the associated virus?

Answer 23

1. cervical cancer: human papillomaviruses 2. Burkitt’s lymphoma: Epstein Barr virus 3. hepatocellular carcinoma: HBV 4. leukemia and lymphoma: HTLV-1 and HTLV-2 5. Kaposi’s sarcoma: KSHV, HHV8

Question 24

What do low risk types of HPV cause?

Answer 24

warts

Question 25

What do high risk HPVs cause?

Answer 25

squamous cell carcinomas of the cervix, penis, oropharynx

Question 26

What are the E6 and E7 genes?

Answer 26

function the same way as T antigen of SV40 virus: E6 binds P53 (leads to degradation of ubiquitan pathway) and E7 binds Rb (prevents interaction with E2F)

Question 27

Where are E6 and E7 genes present?

Answer 27

both low and high risk HPV - but have low affinity binding in low risk HPVs

Question 28

What type of vaccine is the HPV vaccine?

Answer 28

empty virus capsid

Question 29

Epstein Barr virus

Answer 29

herpes virus that causes mononucleosis in western world, childhood lymphoma (burkitt’s) in parts of Africa and AIDS patients, nasopharyngeal cancer in Asia

Question 30

What is the translated oncogene present in Epstein Barr virus?

Answer 30

myc (which is overexpressed): translocated from chromosome 8 to 14 - becomes active, activating expression of other genes

Question 31

Which virus can have tumors and recurrences predicted? How?

Answer 31

EBV by IgA antibodies

Question 32

Hepatitis viruses (HBV and HCV)

Answer 32

cause chronic hepatitis that predisposes you to cirrhosis and liver cancer - prevalent in africa and asia

Question 33

Human T-cell lymphotropic virus (HTLV-1 and HTLV-2)

Answer 33

RNA virus but with no oncogene - tax gene causes overexpression of IL-2 and IL-2 receptor - causes leukemia and lymphoma

Question 34

Where is HTLV-1 and HTLV-2 prevalent?

Answer 34

caribbean countries

Question 35

Kaposi Sarcoma Herpes Virus (KSHV, HHV8)

Answer 35

associated with Kaposi’s sarcoma in patients with HIV but uncertain mechanism