Lecture 22: Cancer File

Question 1

Cancer increases with…

Answer 1

age

Question 2

Susceptibility to some cancers is familial (genetic), true or false ?

Answer 2

True

Question 3

Explain germ line cells in terms of cancer

Answer 3

1 cell, mutations passed onto next generation

Differentiate into soma

Question 4

Explain somatic cells in terms of cancer

Answer 4

Genetic dead end (mutations not passed on)
Disposable to natural selection

Are needed for germline cells

Question 5

What cells are able to reproduce the organism

Answer 5

Germline cells = CAN reproduce the organism

SOmatic cells = CANNOT reproduce the organism

Question 6

What cells have the higher mutation rate ?

Answer 6

Somatic cells have higher mutation rate than germ-line cells

Question 7

A series of how many mutations is required for cancer to start ?

Answer 7

series of 5-6 mutations required

Question 8

What are proto-oncogenes ?

Answer 8

Genes that encode proteins that stimulate cell proliferation

only need one copy to be mutated

Gain-of-function (dominant)

Question 9

What are tumor suppressor genes ?

Answer 9

Genes that encode proteins that prevent cell proliferation

Need both copies to be mutated

Loss-of-function (recessive)

Question 10

Proto-oncogenes are mutated to activated forms called……?

Answer 10

Oncogenes

Question 11

Give an example of some oncogenes

Answer 11

RAS, Jun, Fos

Question 12

Give an example of some tumor suppressor genes

Answer 12

Rb (Retinoblastoma), BRCA1 and BRCA2

Question 13

What is the key step for developing a tumor of the retina (retinoblastoma) ?

Answer 13

Loss of a single gene (Rb)

Question 14

What does the G1/S checkpoint do ?

Answer 14

Makes the decision whether to proliferate or not

Question 15

What does Rb do to the G1/S checkpoint ?

Answer 15

It causes a break in it

Question 16

Explain retinoblastoma in sporadic form

Answer 16

Affects older adults

tumour in one eye

Question 17

Explain retinoblastoma in familial form

Answer 17

Affects children, ususally multiple tumors in both eyes

Question 18

How is retinoblastoma treated ?

Answer 18

Tumor can be killed or eyes removed (90% survival rate)

Question 19

Explain Kudson’s two hit hypothesis

Answer 19

In regards to a normal homozygous WT cell :

1. at some point, a mutation arises. This is passed onto all daughter cells in heterozygous state, causing WT phenotype
2. at another point, a secodn mutation occurs in the homologous gene in a daughter cel. This cell is homozygous mutant. This mutant cell has the mutant phenotype and proliferates more (one step towards cancer)

Question 20

Use Kudsons two hit hypothesis to explain sporadic cancer

Answer 20

Two random somatic mutations are required in each copy of a gene in a single cell (thats why they are so rare)

Question 21

Use Kudsons two hit hypothesis to explain hereditary cancer

Answer 21

One mutant germ line is inherited, so only one somatic mutation is needed to trigger cancer. Thats why it happens more in younger people and more often than once

Question 22

What is the breast cancer associated gene ?

Answer 22

BRCA1
Is a loss-of-function allele (tumor supressor)

Increases risk to 90%

Question 23

Give information on sporadic breast cancer

Answer 23

occurs in older women, one tumour, one breast

Question 24

Give information on familial breast cancer

Answer 24

Younger women, multiple tumors, often affects both breasts

Question 25

Are loss-of-functiion mutations or gain-of-function mutations easier to generate

Answer 25

loss-of-function mutations are easier to generate, but need two independant events in same cell

Gain-of-function mutations are rare, but only need one event