Biology of Cancer

Biology of Cancer

• Two major dysfunctions in the process of cancer development:
  • Defective cell proliferation (growth)
    • Stem cells
      • Undifferentiated cells
      • Ultimately differentiate and become mature, functioning cells of only that tissue
    • All cells are controlled by an intracellular mechanism that determines proliferation
      • Orderly process progressing from a state of immaturity to a state of maturity
      • Stable and will not change
    • Cancer cells grown in culture are characterized by loss of contact inhibition
      • Grow on top of one another and on top of or between normal cells
    • Cancer cells respond differently than normal cells to intracellular signals regulating equilibrium
      • Divide indiscriminately and continuously
        • Pyramid effect
  • Defective cell differentiation
    • Two types of genes that can be affected by mutation are
      • Protooncogenes
        • Regulate normal cellular processes such as promoting growth
        • Genetic locks that keep cells functioning normally
        • Mutations that alter their expression can activate them to function as oncogenes
      • Tumor suppressor genes
        • Suppress growth
        • Function to regulate cell growth
          • Prevent cells from going through the cell cycle
        • Mutations make them inactive
          • Result in loss of suppression of tumor growth