L14- Cancer

Question 1

What is cancer?

Answer 1

A malignant tumour resulting from uncontrolled cell proliferation

Question 2

What is a benign tumour?

Answer 2

Tumour that doesn’t spread

Question 3

What is a malignant tumour?

Answer 3

Tumour that invades neighbouring tissues. Spreads to other parts of the body (matastasis)

Question 4

What are the cancer cell properties?

Answer 4

Can survive high levels of stress, to avoid apoptosis
Are genetically unstable
Abnormally invasive, intravasate, extravasate (enter and exit the blood vessels)
Can proliferate indefinately.

Question 5

What causes uncontrolled cell proliferation?

Answer 5

Mutations caused by: 
Dna-damaging substances/radiation
Inherited mutations
Introduced by viruses (cervical cancer)
Spontaneous mutations

Question 6

What must be mutated to cause cancer?

Answer 6

(The accelerator and the brakes)

Oncogenes (drive forward) and Tumour suppressor genes must both be mutated

Question 7

How many times will every gene in a person mutate in their lifetime?

Answer 7

10^9 separate occasions

Question 8

What do oncogenes do?

Answer 8

Over-expression/activation by mutation causes excessive cell proliferation

Question 9

What’s a proto-oncogene?

Answer 9

Unmutated (normal) gene that if mutated, turns into an oncogene

Question 10

How many oncogenes have to be mutated to cause problems?

Answer 10

Only one copy of the gene can be enough

Question 11

What are the 3 ways of converting a proto-oncogene into an oncogene?

Answer 11

1. Mutation in coding squence (Ras)
2. Gene amplification (Ras)
3. Chromosome rearrangement (BCr-Abl)

Question 12

Which 3 regulatory pathways are perturbed in almost all human cancers?

Answer 12

1. Alterations in cell proliferation
2. Alterations in DNA damage response
3. Alterations in cell growth

Question 13

What happens to the signal sequence in oncogenes that causes cancer cell proliferation?

Answer 13

The growth factor leaves the receptor, so the signalling should stop, but the signalling protein inside the cell is abnormally activated so the cell keeps on dividing in absence of growth factor.

Question 14

How many copies of the tumour suppressor gene must be mutated to allow excessive proliferation?

Answer 14

Usually both copies of the gene. (whereas oncogenes only one)

Question 15

What are 2 important examples of tumour suppressor genes?

Answer 15

Rb and p53

Question 16

What happens if p53 is inactive?

Answer 16

Cells proliferate even with damaged DNA. (usually stops it going into s phase if DNA damaged)

Question 17

How do cancer cells escape through the basal lamina better?

Answer 17

They can secrete more matric proteases to help them escape.

Question 18

What does chemotherapy do?

Answer 18

Blocks mitosis via depolymerising or stabilising microtubules.