PCL477H1-Lecture 12 to post [Compatibility Mode]

PCL477H1-Lecture 12 to post [Compatibility Mode] - Lecture...

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ecture 12 overview Lecture 12 overview what is cancer cancer as a genetic disease sequential genetic changes on road to cancer relationship of DNA damage to cancer carcinogenesis DNA damage as an instigator of neoplastic transformation: -mutations leading to oncogene activation genomic instability as a cause of cancer susceptibility hromosomal instability and aneuploidy chromosomal instability and aneuploidy mutator phenotype and microsatellite instability
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Cancer: What is it? Cancer : applied to diseases with abnormal accumulation and inappropriate dissemination of cells Hyperplasia : increased capacity for proliferation Metastatic potential : ability of cells to invade, migrate and grow in an inappropriate region of the body Heterogeneity: from cell to cell within same cancer/tumour from tumour to tumour within the same cancer type Compared to normal cells, cancer cells display defects in regulatory circuits that govern proliferation and homeostasis
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he Hallmarks of Cancer The Hallmarks of Cancer 1. Self-sufficiency in growth signals (Hanahan and Weinberg, Cell 70: 57-70, 2000) Normal cells : require external stimulatory signals to proliferate: growth factors and receptors extracellular matrix components cell-to-cell adhesion/interaction molecules Cancer cells : reduced or loss of dependence on these external signals Insensitivity to growth hibitory signals 2. Insensitivity to growth-inhibitory signals -most cells in our tissues are instructed not to divide and remain in differentiated states (except stem cells) - any cancer cells display features of de- ifferentiation: ysplasia many cancer cells display features of de differentiation: dysplasia 3. Evasion of programmed cell death (apoptosis) Steady state cell numbers = cell proliferation + cell death ym p f Normal cells have a programmed lifespan Cancer cells nonresponsive to death signals, forgotten how to die
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The Hallmarks of Cancer limitless replication potential 4 . Normal cells typically have a limited ability to replicate themselves i.e. a cell population doubles so many times, then stops growing nters a state known as enescence (enters a state known as senescence ) The replication ability of most cancer cells is limitless –immortalization sustained angiogenesis he growth of new blood vessels) 5. sustained angiogenesis (the growth of new blood vessels) Normal cells need to be within 100 mm of a capillary blood vessel Advanced cancers acquire the ability to stimulate the growth of new blood vessels within the tumour 6. tissue invasion and metastasis Primary tumours spawn ‘pioneer’ cells -move out into adjacent tissues and into bloodstream or lymphatic system whereupon they continue growth in a new location -the major cause of cancer deaths benign tumour = no metastasis malignant tumour = evidence of metastasis
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ancer as a Genetic Disease Cancer as a Genetic Disease oncogenes: ‘over-activated’ versions of proto-oncogenes -originally discovered in viruses that cause cancer in animals (jun, fos, myc) Overactivity:
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PCL477H1-Lecture 12 to post [Compatibility Mode] - Lecture...

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