Cancer Basics
Cancer results from the uncontrolled division of somatic cells – the cells do not go through the
normal cell cycle.
Cancer can destroy the germline – organisms such as the drosophilia don’t divide so do not get
cancer.
We have 1014 cells and are estimated to undergo 1024 cell divisions in our life – there can be up to
20,000 breaks in DNA in each cell division – so why do we not get cancer more often?
- We have evolved to protect against cancer:
o Selection for tumour suppressor genes
o Multiple systems for DNA repair
o Immune control of transformed cells
Tumour Suppressors
Detect if a cell is growing uncontrollably and can induce apoptosis or senescence (halted). As you age
more and more cells are killed or halted. Moles tend to be senescent cells.
Unfortunately, tumour suppressors also accelerate ageing. As you age more and more cells are killed
or halted. Moles tend to be senescent cells.
It is believed that their action could be stronger up till reproductive age and then past this they
reduce their action in attempt to slow down ageing, increasing the risk of cancer. You also
accumulate more small mutations overtime which may result in a malignancy later in life. The
immune system also gets weaker and therefore is less likely to detect microtumours when they first
form.
The bigger the organism the more cells there are – this means there are more mutations every
second and so you need many more tumour suppressors – this is why the bigger the organism the
more likely they are to get cancer eg. a whale is almost guaranteed to get cancer.
Hallmarks of Cancer
Cancer is formed when there is damage to the DNA resulting in an uncontrollable growth.
Cancer cells have 6 hallmarks (according to Hanahan and Weinberg):
- Resisting cell death
- Sustaining proliferative signalling
- Evading growth suppressors
- Activating invasion and metastasis
- Inducing angiogenesis
4 more hallmarks have been added since then:
- Deregulation of cellular energetics
- Avoiding immune detection
- Genomic instability and mutations
- Pro-inflammatory secretions
Cancer results from the uncontrolled division of somatic cells – the cells do not go through the
normal cell cycle.
Cancer can destroy the germline – organisms such as the drosophilia don’t divide so do not get
cancer.
We have 1014 cells and are estimated to undergo 1024 cell divisions in our life – there can be up to
20,000 breaks in DNA in each cell division – so why do we not get cancer more often?
- We have evolved to protect against cancer:
o Selection for tumour suppressor genes
o Multiple systems for DNA repair
o Immune control of transformed cells
Tumour Suppressors
Detect if a cell is growing uncontrollably and can induce apoptosis or senescence (halted). As you age
more and more cells are killed or halted. Moles tend to be senescent cells.
Unfortunately, tumour suppressors also accelerate ageing. As you age more and more cells are killed
or halted. Moles tend to be senescent cells.
It is believed that their action could be stronger up till reproductive age and then past this they
reduce their action in attempt to slow down ageing, increasing the risk of cancer. You also
accumulate more small mutations overtime which may result in a malignancy later in life. The
immune system also gets weaker and therefore is less likely to detect microtumours when they first
form.
The bigger the organism the more cells there are – this means there are more mutations every
second and so you need many more tumour suppressors – this is why the bigger the organism the
more likely they are to get cancer eg. a whale is almost guaranteed to get cancer.
Hallmarks of Cancer
Cancer is formed when there is damage to the DNA resulting in an uncontrollable growth.
Cancer cells have 6 hallmarks (according to Hanahan and Weinberg):
- Resisting cell death
- Sustaining proliferative signalling
- Evading growth suppressors
- Activating invasion and metastasis
- Inducing angiogenesis
4 more hallmarks have been added since then:
- Deregulation of cellular energetics
- Avoiding immune detection
- Genomic instability and mutations
- Pro-inflammatory secretions
