cancer biology

Question 1

draw the pathway of cell growth

Answer 1

Ras is activated by GEF and activates both RAF and PI3K. RAF activates stranscription which makes MYC and D cyclins which cause cell growth. PI3K is inhibited by PTEN. PI3K activates AKT and mTOR which also cause cell growth

Question 2

what are the 8 fundamental changes in cell physiology

Answer 2

1. sustaining proliferative signalling
2. evading growth suppressors
3. avoiding immune destruction
4. enabling replicative immortality
5. inducing angiogensis
6. resisting cell death
7. deregulating cellular energetics
8. activating invasion and metastasis

Question 3

what is done at the following checkpoints:

• Restriction point
• G1 fase
• S fase
• G2 fase
• M fase

Answer 3

Restriction point: Rb needs to be phosphorylated if you want release of the restriction point
G1 fase: damaged DNA done by TP53
S fase: incompletely replicated DNA
G2: damaged or incompletely replicated DNA
M chromisome improperly attached

Question 4

what is the function of growth factors and growth inhibitors in the restriction point

Answer 4

growth inhibitors like TGF-B and INK4A –> hypophosphorylation of Rb –> block transcription
growth factors like Cyclind D and CDK4 –> hyperphosphorylation of Rb –> transcription

Question 5

what is a function of P53

Answer 5

cause apoptosis in the cell

Question 6

what is the mutation in the TP53 gene called and what kind of disease is this

Answer 6

this is the li fraumeni syndrome. people will develop multiple primary tumours of various kinds at young age. there is a dominant inheritance and heterozygous

Question 7

explain WNT and APC pathway and how a mutation affects them

Answer 7

WNT is a growth controlling factor. in resting cell APC will be bound to B catenin which cannot activate transcription then. If WNT is activated than APC will let B catenin go and cell proliferation can happen. in some mutations APC is affected and it can not bind to B catenin anymore –> cell growth

Question 8

what disease to people with a APC mutation develop

Answer 8

adenomatous polyposis coli cancer

Question 9

in which way can a tumor evade the immune response

Answer 9

• failure to produce tumor antigen
• mutations in MHC genes
• production of immunosuppressive porteins or expression of inhibitory cell surface proteins

Question 10

how can a tumorcell enable replicative immortality

Answer 10

somatic cells express telomerase in a situation in which they shouldnt. thus the cell will keep adding ends to their TTAGGG repeats and will not go into senescence.

Question 11

how does metastasis in tumors occur

Answer 11

E cadherin is inactivated which causes the tumor to loosen up. the ECM is degradated due to proteolytic enzymes. then the tumor can leave its place

Question 12

explain the cell death pathway

Answer 12

P53 will activate pro apoptotic factors like BAX/BAK. this will cause the mitochondria to produce cytochrome C which gets activated by APAF-1. this will activate Caspase 9 which activates caspase 3 which causes apoptosis. IAP inhibits Caspase 9. anti apoptopic facotrs like BCL2, MCL-1 will inhibit cytochrome c.

Question 13

Warburg effect

Answer 13

tumour cells like glycolysis even in aerobic environments

Question 14

what surpresses the warburg effect

Answer 14

TSG