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Biology 1002 Lectures 18 - 26 Outcomes

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Biology 1002B
Tom Haffie

Lecture 18 Outcomes 1 Four most common types of cancer in CanadaBreast cancerProstate cancerLung cancerColon cancer 2 Likely factors contributing to cancer incidence in Canada40 of women and 45 of men will develop cancer and rates among youth are rising 3 Role of cyclinCDK complexes in cell cycle regulation G1S checkpoint o Prevents cell from replicating their DNA if it is damaged o This checkpoint is monitored by CDK cyclindependent cynasea protein Enzyme that phosphorylates targets but CDKs are only active when they are bound to other proteins called cyclins o Cyclins are called cyclins because their production cycles with the cell cycleProduced early in the cell cycle binds onto and activates CDK and this cyclinCDK complex then phosphorylates a bunch of targets downstream which releases the G1 checkpoint o Post translational regulation of protein functionbinding together and binding CDK and phosphorylating downstream proteins to release the G1 checkpointAnother set of cyclinCDK complexes to release the next two checkpoints as well 4 Role of protooncogenes tumor suppressor genes and oncomirs in cancerCells need to be responsive to the environmentneed to know when to divide or notExpression of protooncogenes promotes cell cyclingEGFRepidermal growth factor receptor o Factor means proteino When there is EGF in the environment it binds to this receptor o It is perfectly normal and essential to embryonic development o Sometimes when a tumor is growing out of control it is because EGFR is on all the time and signalling all the time so it is dividing into a tumorCancer researchers say we found a cancer genefound the enemy o They call them oncogenes cancer genesstupid but they arent cancer genes just embryogenesthey are needed for embryonic development rapid cell division o If they become deregulated and overexpressed they can divide too much and promote tumor growthWhenever you hear people say oncogenes think in your mind embryogenes o When they are functioning normally they are called protooncogenes and once they start malfunctioning they are called oncogenesThis picture shows EGFR on topbiochemical telephone game 5 Role of p53 geneExpression of tumor suppressor genes slows cell cycling Another kind of sequence that seems to be relevant are genes that evolved to shut down the rapid cell growth during embryogenesis o Cells get large enough and need to stop growing o Genes have evolved to be embryo suppressorsCancer researchers find them and say they are tumor suppressorsThey didnt evolve to suppress tumors though
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