1 / 10

Cancer

Cancer. Lecture 42 BSCI 420,421,620 Dec 11, 2002 “Cancer cells break most of the basic rules of behavior by which multicellular organisms are built and maintained.” - Bruce Alberts Cancer as a microevolutionary process Principles of Oncogenesis Oncogenes (lecture 43).

paco
Download Presentation

Cancer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cancer • Lecture 42 BSCI 420,421,620 Dec 11, 2002 • “Cancer cells break most of the basic rules of behavior • by which multicellular organisms are built and maintained.” • - Bruce Alberts • Cancer as a microevolutionary process • Principles of Oncogenesis • Oncogenes (lecture 43)

  2. Cancer as a microevolutionary process • Because our bodies are complex societies of billions of cells, • some rules are necessary for the good of the entire organism. • “Cancer cells break most of the basic rules of behavior • by which multicellular organisms are built and maintained.” • What are those rules? • You shall behave like the other cells of your type, • e.g. only divide when told to do so by a mitogenic factor. • You shall maintain contacts or junctions with your neighbors • if you are in an epithelium. • You shall not go wandering off into other parts of the body • without permission. • If you are virus infected or your DNA is severely damaged, • you shall undergo apoptosis for the good of the whole.

  3. Cancer is a disease (or group of diseases) in which individual • mutant clones of cells proliferate, spread, and can destroy the • entire organism. • Some terminology: • A tumor is an abnormally growing clone of cells. • A tumor is benign if it remains together as a single mass • (surgury or local irradiation highly successful). • A tumor is malignant (or a cancer) if it invades other tissues. • Cancers of epithelial cell are called carcinomas. • Cancers of connective tissue or muscles are sarcomas. • Cancers of the blood cells are called leukemias.

  4. Principles of Oncogenesis (Formation of a cancer): • Cancers arise from a single cell. • Cancers are initiated by somatic mutation. • Carcinogens cause mutations in DNA • a. Chemical – many synthetic or natural chemicals • b. Physical – UV radiation -> skin cancer • c. Biological – tumor viruses • 4. Carcinogens can cause mutations in different ways. • a. Point mutations (eg. That activates an oncogene) • b. Deletions (e.g. of a tumor suppressor gene) • c. Gene amplification (to increase expression of an oncogene) • d. Virus insertion • e. DNA rearrangement or translocation (fig 23-5)

  5. 3 ways a proto-oncogene can be made overactive to convert It to an oncogene:

  6. Two ways of amplifying an oncogene (myc) • Multiple minute chromosomes containing the myc gene. • Multiple copies of myc on the same chromosome • Myc yellow fluor • cDNA hybridized • in situ • DNA - red

  7. Translocation between human chromosomes 9 & 22 puts the myc gene next to an active promoter of an Immunoglobulin gene in a pre-B lymphocyte and induces a leukemia. Creates a “Philadelphia” chromosome.

  8. A mutation may inactivate a tumor suppressor gene, • e.g. p53 or pRB. An inherited heterozygous mutant RB gene • may predispose a person to developing cancer, even at an early • age (Retinoblastoma in children)

  9. Six ways of losing the remaining RB gene

  10. Oncogenesis is a multi-step process: eg. Colon cancer

More Related