What do cells respond to?
Specific chemicals that signal them to divide
What do the pathways for cell signalling utilised by cells have in common?
They all display the same fundamental characteristics
What do all signalling pathways involve?
- Chemical messenger
- Cellular response
What is signal transduction?
Essentially, the transmission of a signal from the outside of a cell to the nucleus
What can the signal transduced from the outside of the cell to the inside result in?
Alterations in cell metabolism, gene transcription, and/or cell shape
What does alteration in gene transcription lead to?
Changes in protein expression
What are proto-oncogenes?
Genes coding for proteins that help regulate cell growth and differentiation
In what physiological process are proto-oncogenes fundamental?
What happens to proto-oncogenes in malignancy?
They become activated to an oncogene due to mutations, or increased expression
Where is oncogene activation an important mechanism?
In human cancers
What are the types of mutations that can cause cancer?
What can be deleted in mutations?
- Base pair(s)
What can be inserted in mutations?
- Repeats of base pair(s)
- Novel insertions
What can be substituted in mutations?
Base pairs .
What can be amplified in mutations?
What can be translocated in mutations?
What kind of proteins are encoded for by oncogenes?
- Growth factors
- Growth factor receptors
- Protein kinases/proteins that activate protein kinases
- Proteins that control the cell cycle
- Proteins that affect apoptosis
- Transcription factors
What do growth factors do?
Stimulate cells to divide
Give an example of a growth factor
What do growth factor receptors do?
Transduce signals from the outside of the cell to the inside
Give an example of a growth factor receptor
EGF receptor (erbB)
Give two examples of protein kinases
Give an example of a protein that activates protein kinases
Give an example of a protein that controls the cell cycle
Give an example of a protein that affects apoptosis
Give an example of a transcription factor
What is the significance of Myc in malignancy?
It is one of the most commonly altered oncogenes
What are the mechanisms of oncogene activation?
- Insertional mutagenesis
- Chromosomal translocation
- Chromosomal amplification
- Point mutation
- Ras signalling
What happens in insertional mutagenesis?
DNA viruses incorporate a viral oncogene, which is inserted into the host DNA
Give two examples of viruses capable of insertional mutagenesis
- Human papillomavirus 16/18
- Hepatitis B