PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Chapter 24- CancerCancer is due to failure of the mechanisms that control growth of cells. Accumulation of mutations in DNA24.1. Tumor Cells and the Onset of CancerOncogenesisTerminologyCarcinomas:Sarcomas: Benign:Malignant:Metastasis:Cancer stem cells:Need mutations in specific genes to transform cells into tumor cellsMulti-hit model:Support for the multi-hit model:Successive mutations in colon cancer24.2. Cancer and Misregulation of Growth Regulatory PathwaysMutations occur in particular types of genes1. Oncogenes2. Tumor suppressor genesOncogenes are at several different cell signaling levels or stepsa) Oncogenes encoding cell-surface receptorsExample is human EGFR2 (Her2) geneb) Oncogenes in the middle of signaling pathwaysExampl e is rasGlycine #12Glutamine #61c) Oncogenes that encode transcription factorsExample is myc24.4 Cancer and Mutation of Cell Division and Checkpoint RegulatorsCalled tumor suppressor genes1) Retinoblastoma (Rb) gene2) p5324.5 Carcinogens in CancerLinks between occupations or chemicals and cancerDirect acting and indirect acting carcinogens1. Direct acting2. Indirect actingWhere do adducts form?Guanine is a common target and is attacked at the 2,3,6,7, 8 positions.DNA adducts may alter the ability to appropriately base pairCarcinogen example #1: benzo[a]pyreneLung cells, benzo[a]pyrene exposure, and tumorsCarcinogen example #2: aromatic