BIOL 3510 1st Edition Lecture 26 Outline of Last Lecture I. TissuesII. Tight JunctionsIII. Cell Junctions IV. Three Key Mechanisms V. Embryonic Stem CellsOutline of Current Lecture I. Properties of Cancer CellsII. Genetic Instability FactorsIII. Causes of CancerIV. Treating Cancer Current LectureCancer: when rouge cells start ignoring the rulesTwo properties of cancer cells:1. Divide when they are not supposed to2. Move to and proliferate in tissues where they do not belong (metastasize)Benign tumor cells only have the first property, while malignant have both.A variety of factors can contribute to genetic instability:- Defects in DNA replication- Defects in DNA repair- Defects in cell-cycle checkpoint mechanisms- Mistakes in mitosis- Abnormal chromosome numbersCauses of Cancer:1. Accumulation of mutationso Every gene in your body has been mutated more than 10^9 timeso Mutations lead to genetic instability which raises the mutation rateThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Environmental factors that promote cancer (carcinogens: tobacco smoke, ionizing radiation, UV light, etc)2. Viruseso Example: human papiloma virus causes cervical cancerCancer is a disease of old age.Mutation in cancer cells give them an advantage over normal cells.Cervical cancer: tumor progressionProperties of Cancer Cells1. Reduced dependence on signals from surrounding cells (i.e. abnormal Ras activity)2. Less prone to apoptosis (ie: loss of p53)3. Proliferate indefinitely (ie: telomerase reactivated)4. Genetically unstable (increased mutation rate, abnormal chromosome number)5. Abnormally invasive (ie: loss of cadherins)6. Abnormal metabolism7. Able to survive in foreign tissuesMutated genes involved in cancer are called oncogenes or tumor suppressor genes.Conversion of a proto-oncogene into an oncogene.Retinoblastoma: cancer of the retinaColorectal cancer arises from the epithelial lining of the colon and rectum.- Most cases – no hereditary component- Small % - hereditary component, cancer is foreshadowed by development of 100s of polyps.Colorectal cancer is linked to mutations in adenomaatous polyposis coli (ApC) and beta-catenin.Cells in polyps accumulate more mutations leading to cancer.Cancer is usually not detected until a tumor has 100s of millions of genetically diverse cells.Treating Cancer1. Surgery2. Radiation and DNA-damaging chemotherapyo Normal cells fix the damage or undergo apoptosiso Cancer cells continue dividing and pass along broken chromosomes leading to cell death3. Drugs that target specific cancerso Gleevec treats chronic myeloid leukemia4. Drugs that block blood vessel formation5. Using the immune systemGleevec treats chronic myeloid leukemia by blocking the action of the oncogenic kinase,
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