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20 Cards in this Set
- Front
- Back
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How does cancer come to be in most basic terms |
Previously a stochastic model "random chance" Many mutational events build up sequentially leading to a loss of normal cellular controls MULTI STEP |
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What are proto-oncogenes? |
Normal genes in the cell cycle that have a transforming potential when mutated Have cell growth and proliferative effects |
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Examples of proto oncogenes |
Growth factors Growth factor receptors Protein kinases Signal transducers Nuclear proteins Transcription factors |
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Wht is an oncogene? |
A proto ongogene that is transformed - dominant gain of function |
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How do we transform oncogenes? |
Chromosomal translocation Gene amplification Point mutations Viral insertions |
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What is a tumour supressor gene |
Inhibitory to cell cycle, recessive loss of function mutation leads to cancer step/pathway |
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Give examples of tumor supressor genes |
Retinoblastoma and p53 |
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What does retinoblastoma protein do |
Cell cycle progression regulation
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What does p53 do |
Known as the guardian of the genome Regulates gene expression and cell cycle progression as well as the cells responses to DNA damage |
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What are the characteristics of cancer |
Self sufficiency in growth signals Insensetivity to anti growth signals Ability to evade programmed cell death Limitless replicative potential Sustained agiogenesis |
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What is the new challenge to accepted model of carcinogenesis |
That the mutations are controlled by a small population of cancer stem cells that accumulate over the life of the cell rather than being passed from generation to generation Like an organ tissue heirachy - has progenitor type cells/stem cells Bi-directional exchange from stem cells to cancer cells |
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What are the main causes of cancer? |
Viral Chemical Physical agents |
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How do retroviruses cause cancer |
Important oncogenic viruses, integrate adjacent to cellular oncogenes e.g. FELV and myc (activated by viral promoter) |
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How do DNA viruses cause cancer? |
Coupling with the cell differentiation process (warts and papilloma) |
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Give examples of some carcinogens that cause cancer? |
Bracken fern - malignant transformation with papilloma viruses Aspergillus produces and alkaloid - aflatoxin - liver cancer in trout
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How do chemicals cause cancer |
Chronic inflammation |
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Give an example of a parasitic infection that leads to cancer |
Spirocerca lupi helminth Oesophagus contains fibroblastic nodules - malignant transformation - fibrosarcoma or osteosarcoma |
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What physical agents cause cancer? |
UV and other radiaition DNA damage - multiple hits |
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What hormones cause cancer/influence development? |
Oestrogen - benign vaginal fibromas and mammary carcinoma Unknown pathogenesis |
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How can an animal be predisposed to cancer |
Pre-existing mutation present - e.g. to p53 Less *hits* in the pathway |
