Mechanisms Of Oncogenesis Flashcards
What is cancer the name for?
A group of diseases characterised by: Abnormal cell proliferation Tumour formation Invasion of neighbouring normal tissue Metastasis to form new tumours at distant sites
Where do carcinomas originate?
Epithelial cells
Where do sarcomas derive from?
Bone or muscle tissues
Where do adenosarcomas originate from?
Glandular tissue
What are the (many!) hallmarks of cancer?
Evading growth supressors Avoiding immune destruction Enabling replicative immortality Tumour-promoting inflammation Activating invasion and mutation Resisting cell death Deregulating cellular energetics Sustaining proliferative signalling
Why is cancer more prevelant the older you get?
Longer you live the more time there is for DNA to accumulate mutations that may lead to cancer
What do germline carcinogenic mutations cause?
An increased risk of developing cancer
What is cell proliferation caused by?
Growth factors
Cytokines
Hormones
What growth factors is cell proliferation caused by?
EGF, PDGF
What cytokines is cell proliferation caused by?
Growth hormones, interleukin
What are proto-onco genes?
Normal genes that can be activated to become oncogenes
What are oncogenes?
Proto-oncogenes that have been mutated in a way that leads to signals that cause uncontrolled growth
What do tumour supressor genes do?
Inhibit both growth and tumour formation
When do tumour supressor genes act?
In phase G1 of the cell cycle
What are the three assumptions that multistage carcinogenesis relies on?
Malignant transformation of a single cell is sufficient to give rise to a tumour
Any cell in a tissue is likely to be transformed as any other of the same type
Once a malignant cell is generated the mean time to tumour detection is generally constant
What are the names of the 5 models of carcinogenesis?
Chemical carcinogens Genome instability Non-genotoxic Darwinian Tissue organisation
What is the chemical carcinogen model of carcinogenesis?
Chemicals can alter initiation, promotion and progression to induce their carcinogenic effects
What is knudsons hypothesis for hereditary cancers based on?
Two-hit hypothesis
What is the two hit hypothesis?
At least two events are necessary for carcinogenesis and the cell with the first event must survive in the tissue long enough to sustain a second event
What are non-genotoxic modulators of risk?
Don’t seem to act through a structural change in DNA but rather through functional changes including epigenetic events
What is the mutation and selection model of clonal expansion?
Sequential accumulation of mutations due to carcinogen exposure
Tumour cells selected for ability to grow and invade
Selection includes resistance to therapy
What is the somatic mutation theory?
Cancer comes from a single somatic cell that has accumulated multiple DNA mutations