eBook Chapter 3 - Cell Signalling & Cancer

Question 1

Define intracellular signalling

Answer 1

a set of linked biochemical events that connect a specific biological stimulus with a specific cellular response §

Question 2

Cancer cells are capable of sustaining proliferative signally. In what 5 ways is this achieved?

Answer 2

1. cancer cells initiate production GFs resulting in autocrine signalling or in stimulation of the surrounding stroma cells enabling them to secrete appropriate growth factors
2. receptor activity can be deregulated by over expression or mutations
3. constitutive activity of the key proteins of downstream signalling pathways could be induced due to activating mutations
4. activation of additional downstream signalling pathways could be initiated by adding an input signals that is complementary but not usually present
5. disruption of negative feedback mechanisms could be sustained due to inactivating mutation

Question 3

What are the MAIM pathways and what are they important for in cancer?

Answer 3

M = mitogenesis, importnat for proliferation 
A = anti-apoptosis, important for survival 
I = invasion, important for motility
M = metastasis, importnat for motility

Question 4

How are signals transducer from one protein to another in a singularly pathway?

Answer 4

• intracellular signals are generated through protein-protein interactions or protein-lipid modifications (e.g. phosphorylation)
• there are also diffusible secondary messengers which are rapidly generated and related in high numbers, rapidly removed or degraded

Question 5

Give examples of secondary messenger

Answer 5

• sugars e.g. phosphorylated inositols IP3, and IP4
• metal ions e.g. Ca2+
• gases e.g. NO, and small molecules e.g. H2O2, nucleotides e.g. cAMP, ATP
• lipids e.g. phosphoinosiides PIP2 and PIP3

Question 6

Intracellular signals are generated by changing:
1.
2.
3.

Answer 6

1. localisation of a comment e.g. redistribution of a proteins through recruitment to another protein or membrane
2. enzyme activity of protein e.g. protein or lipid phosphorylation, lipid hydrolysis etc
3. concentration of an intracellular ligand e..g metal ions, lipids, nucleotides