Lecture 13: Molecular biology of cancer Flashcards
What are the hallmarks of cancer?
- Proliferation of growth signals
- Insensitivity to growth inhibition signals
- Evasion of apoptosis
- Limitless replication potential
- Neo-angiogenesis
- Tissue invasion and metastasis
How are cancer cells able to proliferate growth signals?
1) Increased exposure to growth factors
2) increased growth factor receptor expression on the tumour cell
3) genetic change(s) in a growth factor response pathway resulting in “always on” signalling.
What makes cancer cells insensitive to growth inhibition signals?
Loss of function of a tumour suppressor gene e.g. P53 or RB
How are cancer cells able to evade apoptosis?
Caused either by gain of function of genes involved in the negative regulation of
apoptosis e.g., BCL2 or a loss of function of genes involved in the positive regulation of
apoptosis, e.g., BAX or P53
How do cancer cells develop the ability to undergo limitless replication?
Activation of telomerase- the enzyme responsible
for the maintenance of telomeres- allows for limitless replication.
Activation of telomerase prevents cells from reaching the point at which the cell can no longer divide.
What is neo-angiogenesis?
Process of new blood vessel production within and around a tumour to provide it with nutrients and oxygen.
How do cancer cells trigger neo-angiogenesis?
Release vascular
endothelial growth factor (VEGF).
How is tissue invasion and metastasis of cancer cells supported?
Supported and promoted by many different cellular events but neoangiogenesis certainly aids the process
of invasion and metastasis.
What are the enabling characteristics of cancer?
- Genome instability and mutation
* Tumour-promoting inflammation
What are 2 emerging hallmarks of cancer?
- Altered cellular energetics e.g. a switch to glycolysis for energy production
- Avoidance of immune cell recognition and destruction
