Biology of Cancer (REVISE AND ADD A LOT - SECOND HALF) Flashcards
Key Feature of Cancer
The ability to spread
What is a cancer cell
Divides continuously & inappropriately
No longer maintains its original function
at least some of the cancer cells must be able to spread to other sites
Features of Cancer
Proliferation independently of signals (must also avoid signals that tell them to stop)
Immortality - avoiding senescence/telomere shortening
Avoiding apoptosis
Angiogenesis - must be fed
Metastasis and ability to proliferate in a new environment
How does cancer arise
Sporadic (95%) or Genetic Predisposition
REVISE?
What differentiates cancer from other genetic diseases
Mutations in a single cell can cause a life threatening disease
How many sporadic mutation diseases are there
One - Cancer
How long does sporadic cancer take to develop and why
Decades, because a series of mutations must accumulate in a cell for it to become a successful cancer
How does familial cancer grow
A mutation is already present, and has a selective advantage, dividing more and accumulating more mutations that lead to more selective advantages until a malignant tumour manages to develop
Driver and Passenger Mutations
Driver mutations - Mutatiosn that affect the function of genes which regulate proliferation, apoptosis, immortality etc. (cancer causing)
Passenger mutations - All other mutations that are not relevant to the promotion of cancer
Classes of genes that are targets for driver mutations
Oncogenes and Tumour Suppressor Genes
Oncogenes
Genes that promote cell proliferation
Gain of function mutations in cancer
Tumour Suppressor genes
Inhibit events leading to cancer
Loss of function mutations in cancer
Proto-oncogenes vs Oncogenes
Proto-oncogenes are the normal genes and oncogenes are those that are mutated
Checkpoints that are well characterised in the cell cycle
Restriction point in G1 phase (tells cells to either proliferate or not)
DNA Damage checkpoints in late G1 & G2
Metaphase checkpoint
Which regulatory checkpoint of the cell cycle is targeted by oncogenes
Restriction point in G1
Quiescence G0
A cell enters G0 and stops dividing, but this process is reversible
Immortality of a cancer
Two processes play a role in the intrinsic limit in the number of times a cell lineage may divide
Senescence - Cells in G0, don’t proliferate and this is irreversible
Apoptosis
Both processes severely restrict tumour growth and must be overcome to develop cancer
Sesescence
REVISE MINORLY
P53 Protein
A protein that detects telomeres getting too short and leads to senescence when they get to a certain shortness
All cancers must at some point overcome this protein and have a mutation in it
Cell in crisis
Damage accumulates in the telomeres that become too short
REVISE REST OF LECTURE, NOT LONG, ONLY LIKE 15 MINS
