Tumorigenesis

Question 1

What is an oncogene?

Answer 1

a mutated gene that can cause cancer by causing cells to grow and divide uncontrollably

Question 2

How does a proto-oncogene become an oncogene?

Answer 2

1) point mutation
2) gene amplification
3) chromosomal translocation
4) local DNA rearrangements
5) Insertional mutagensis

Question 3

How does self sufficiency help cancer cells?

Answer 3

-cancer cells generate their own growth signals, so they can proliferate uncontrollably without reliance on external signals

Question 4

What are some mechanics of self sufficiency in cancer cells?

Answer 4

1) they overexposes growth factors or have mutated versions of these receptors
2) may produce their own growth factors which bind to receptors on their own cell surface = autocrine signalling
3) they have mutations in parts of the signalling pathways (RAS, P13K) which keeps them in an on state = cell division
4) mutations in regulator proteins = unregulated proliferation

Question 5

How does the MYC protein affect cancer cells?

Answer 5

-is usually over expressed or hyperactivated causing uncontrolled cell growth and division
-upregulates CDKs and down regulates CDK inhibitors= ensures continuous cell cycle progression -> division
-can override checkpoints that control growth = allows cell to divide in unfavourable conditions
-works with other oncogenes that inhibit apoptosis

Question 6

What is terminal differentiation?

Answer 6

inhibits cell growth by inducing a permanent state in which cells exit the cell cycle and lose their ability to divide

Question 7

How does terminal differentiation link to oncogene expression?

Answer 7

-in some cases the proto-oncogene MYC can be down regulated
-oncogene activation can inhibit differentiation