Class 4

Question 1

T/F
the viral origin of the majority of all malignant tumors … has now been documented beyond any reasonable doubt. It … would be rather difficult to assume a fundamentally different etiology for human tumors

Answer 1

False

Question 2

Viruses only isolated from 2 common types of cancer:

Answer 2

1. Cervical carcinomas: HPV

2. Hapatomas (liver carcinomas): HBV, HCV

Question 3

What did Yamagiwa show?

Answer 3

Coal tar condensates induced skin carcinoma in rabbits

Chemicals can directly induce cancer

Question 4

Can cancer be triggered by the activation of endogenous retroviruses in humans?

Answer 4

Most disease-inducing endogenous viruses have been eliminated from the gene pool by selection
Most endogenous proviruses are transcriptionally silent
Although evidence for role of endogenous virus reactivation in murine leukemia
So far, no good evidence for role of endogenous virus in human cancer

Question 5

Human DNA is around 98% _______

Answer 5

Non-coding or junk DNA

Question 6

8% of our DNA derives from ______

Answer 6

endogenous retroviral genomes

Question 7

T/F
Of the 40,000 retrovirus fragments, almost all are not intact, and are capable of forming infectious retroviral particles

Answer 7

False, Not capable

Question 8

How are Endogenous retroviruses (carcinogens) promoting cancer?

Answer 8

Non-viral mechanisms of mutation of DNA can also turn a cellular proto-oncogene into an oncogene during tumor formation

Question 9

Found strong associations between oncogenes from viral and non-viral mechanisms using ______

Answer 9

Southern blot procedure

Question 10

Results from Southern Blot Procedure?

Answer 10

Radiolabeled DNA probe made based on H-ras oncogene from a rat sarcoma VIRUS (Harvey virus)
Used to detect if mouse fibroblasts transformed by transfection with human bladder carcinoma (not VIRAL TUMOR) had the same oncogene?

But even the non-transformed cells had ras

Question 11

Can you remember an example of a tumor virus mechanism of carcinogenicity that deregulates expression?

Answer 11

Insertional Mutagenesis

Question 12

3 ways of activating c-myc proto-oncogene

Answer 12

Provirus integration

Gene amplification

Chromosomal translocation

Question 13

Can you remember an example of a tumor virus mechanism of carcinogenicity that involves a change in structure?

Answer 13

Single Point mutation

Question 14

How did H-ras proto-oncogene become converted to an oncogene in human bladder carcinoma?

Answer 14

Single point mutation

Question 15

Creation of fusion proteins

Answer 15

Chromosomal translocation

- can also change the structure/function of a protein

Question 16

Mechanism that causes activation of proto-oncogene change in structure/function

Answer 16

Ras Point mutations

Chromosomal translocations

Question 17

Mechanisms that cause deregulation of expression

Answer 17

Gene applification (myc)
chromosomal translocation
retroviral integration --> insertional mutagenisis