Overview of cancer and genetics Flashcards
What can cancer lead to?
Clonal evolution
What is clonal evolution?
- One cell ‘goes wrong’ (e.g mutation)
- Cancer growth, progression, treatment resistance, disease due to adaptation to changes in cancer environment
It is an expansion of a population of cancer cells
What does tumour progression involve?
Many, independent mutations occur
Triggers parallel clonal expansion
Cancer that is sporadic
Happens without a known cause (random)
70% of cancers
Random chance/environmental exposure
Familial cancer
20% of cancers
similar genetic background- presence of a genetic mutation?
shared environmental exposure
Hereditary cancer
10% cancers
inherited genetic mutation
increased risk of cancer development
How does cancer develop? (4 steps)
- A cell is mutated= abnormal cell
- Cancer develops from a single abnormal cell
- Further mutations of descendent cells of abnormal cell accumulate
- Muatted descendent cells gain certain capabilities to outgrow normal cells
What is hallmarks of cancer?
10 biological capabilities acquired by cells during multistep process of tumour development
Transform normal cell to cancerous cell
Done by mutations
What are the 10 hallmarks of cancer?
Resist cell death sustain proliferative signalling Induce angiogenesis tumour promoting inflammation activating invasion and metastasis genome instability and mutation evading growth suppressors avoiding immune destruction deregulating cellular energetics enabling replicative immortality
How do mutations allow cancer cells to evolve?
Cancer development and progression= repetition of mutations and proliferation
With each mutation= abnormal cells gain selective advantage over neighboring cells= large clonal population
this process= clonal evolution
as tumour progresses= genetic instability increases
What drives cancer in a cell?
Deregulation of cell homeostasis
How does deregulation of cell homeostasis drive cancer?
Loss of balance between cell proliferation and apoptosis= rise to cancer
Cancer= deregulation of cell proliferation and apoptosis pathways
Genes that cause disregulation= cancer critical genes
What does cancer depend on?
Set of mutations
epigenetic changes
What are cancer-critical genes?
Many genes that are altered in human cancers
Cancer risk can arise from too much/too little activity of gene product
What are the 2 types of cancer-critical genes?
Proto-oncogenes
Tumour suppressor genes
What are proto-oncogenes?
Genes have a gain of function-mutation that drives a cell towards a cancer
Their mutant/overexpressed form= oncogene
What are tumour suppressor genes?
Genes have a loss of function mutation
Contribute to cancer
What do mutations in oncogenes and tumour suppressor genes cause?
Enhancing cell proliferation, cell survival
Promote tumour development
What do oncogenes do?
Uncontrollable cell growth
Promote cell proliferation
Encode growth factors, GF receptors/nuclear proteins
Are oncogenes dominant or recessive?
Dominant
An example of a proto-oncogene?
Ras
When mutated= oncogene