01-29 mcb135 senescence - Cellular Senescence What is it?...

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Unformatted text preview: Cellular Senescence What is it? What causes it? Why is it important (cancer and aging)? Cellular Senescence What is it? Response of normal cells to potentially cancer-causing events The senescence response is an anti-cancer mechanisms that prevents the proliferation (growth) of damaged or dysfunctional cells (potential cancer cells) First description: the Hayflick limit Proliferative capacity Number of cell divisions Finite Replicative Life Span "Mortal" Infinite Replicative Life Span "Immortal" EXCEPTIONS Germ line Early embryonic cells (stem cells) Many tumor cells What happens when cells exhaust their replicative life span? What happens when cells exhaust their replicative life span? REPLICATIVE SENESCENCE Irreversible arrest of cell proliferation (universal) Resistance to apoptosis (lecture on January 31) (certain cell types) Altered function (universal but cell type specific) THE SENESCENT PHENOTYPE Cellular Senescence What causes it? (what causes the senescent phenotype?) Cell proliferation (replicative senescence) = TELOMERE SHORTENING (lecture on February 26th) DNA damage Oncogene expression Supermitogenic/stress signals What do inducers of the senescent phenotype have in common? Inducers of cellular senescence Cell proliferation (short telomeres) DNA damage Oncogenes Strong mitogens/ stress Potential Cancer Causing Events Normal cells ('mortal') 'Immortal' cells (precancerous) Cell senescence Transformation Apoptosis Tumor suppressor mechanisms Cellular Senescence A crucial tumor suppressor mechanism Induced by potentially oncogenic events Most tumor cells are replicatively immortal...
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This note was uploaded on 04/02/2008 for the course MCB 135k taught by Professor Timiras during the Spring '08 term at University of California, Berkeley.

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01-29 mcb135 senescence - Cellular Senescence What is it?...

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