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Unit 7 - Chem 004 Spring 2007 Cancer Background CANCER...

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1 CANCER POISONS PARASITIC INFECTIONS Chem 004 - Spring 2007 Blackboard: http://blackboard.gwu.edu Office Hours: MW 3:10 – 3:55 PM, 1957 E street, room 213 or by appointment Cancer - Background - 1900 -- Less than 10% of people who developed invasive cancers survived. + 2000 -- Over 50% are cured. - 1970 -- 5 year survival rate of children with leukemia: less than 10%. + 2000 -- 60-70% alive after 5 years. Life and Death of Cells Human body: composed of ~100 trillion cells. In some cases these control mechanisms fail: • cells are produced at a faster rate than cells are dying. • cells are not dying as fast as they should. Tumors (from the Greek: swelling) and Cancer (from the Greek karkinos : crab) Cells are “programmed” Cells don’t just “get old” and die: after a certain time or certain number of cell divisions, a series of biochemical reactions causes the cell to die. Many cancers develop when this process of “cell suicide” ( apoptosis ) is faulty. Secrete large amounts of chemicals which interfere with other organs Parts may break away and begin growing in different regions of the body Grow and press on blood vessels and nerves Cell division: Control mechanisms Oncogenes Genes that, when expressed, make cells divide more rapidly Tumor Suppressor Genes (TSGs) Genes that suppress cell division A precise balance is required If TSG does not function correctly, oncogenes cause cells to grow and multiply beyond their normal numbers. If oncogenes do not function correctly, they will signal the cell to grow uncontrollably. Half of all cancers are due to a defect (mutation) in a TSG called p53 Causes cells to commit suicide if they have been damaged beyond easy repair If p53 is defective, cells do not kill themselves, but continue to grow and divide to form a cancer.
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