What is Cancer? Flashcards
(54 cards)
How many different types of cancer is there?
> 200
What is carcinogenesis?
The change from a normal cell to a cancerous cell
Define cancer
An accumulation of abnormal cells which multiple through uncontrolled cell division and spread to other parts of the body through invasion and/ or distant metastasis via the blood and lymphatic system
Define clonal evolution
A series of mutations which accumulate in successive generations of the cell
Where do cancers originate from?
A single cell
What is the role of p53?
Monitor cells for signs of damage and cause this to be fixed
Why do tumour cells undergo clonal evolution?
To increase the cancer cells chances to avoid the hosts defence mechanisms
Why are blood tumours easier to treat than solid tumours?
They are monoclonal, solid tumours are polyclonal
Why are polyclonal tumours harder to tackle?
Each of the mutations will have a growth advantage and they will all be different
For chemotherapy, it is hard to find one which will target all of the different tumour cell types at once
How long can it take for CRC to turn from an adenoma to a full cancer?
5-15 years
What are the 6 main hallmarks?
Sustaining proliferative signalling Evading growth suppressors Activating invasion and metastasis Enabling Replicative Immortality Inducing Angiogenesis Resisting Cell Death
What are the 4 additional hallmarks?
Emerging hallmarks - Deregulating cellular energetics - Avoiding immune destruction Enabling characteristics - Genome instability and mutation - Tumour-promoting inflammation
Give 2 examples of tumour suppressors
p53
retinoblastoma (Rb)
How are tumour suppressors inactivated?
Mutations
Loss of heterozygosity
Give 3 examples of proto-oncogenes
cyclins
Myc
Ras
How do cancer cells increase cell growth?
- Production of their own extracellular growth factors
- Overexpression of growth factor receptors - cells become hyper-responsive to growth factors
- Alterations of the intracellular components of the signalling pathway
What is a truncated receptor?
A receptor which emits signals even in the absence of ligand binding
What is the function of Rb in normal cells?
Prevents inappropriate transition from the G1 phase of the cell cycle to the synthesis (S) phase
What are GAP phases?
Points where the cell cycle can be paused to fix any problems/ kill the cell if it is beyond repair by tumour suppressor genes in normal cells
How does phosphorylation of Rb effect the cell cycle?
Phosphorylation causes the release and activation of E2F family transcription factors and enables cell cycle progression
What factors cause p53 to induce a response?
- Lack of nucleotides
- UV radiation
- Ionising radiation
- Oncogene signalling
- Hypoxia
- Blockage of transcription
What does p53 induce when it is activated?
- Cell cycle arrest -> senescence OR return to proliferation
- DNA repair
- Block of angiogenesis
- Apoptosis
Where is p53 found?
in GAP phases of the cell cycle
What is Li-Fraumeni Syndrome?
A rare, autosomal dominant, hereditary cancer pre-disposition
