Figure 12'4 The cell cycle

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Figure 12.4 The cell cycle
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What causes cells to leave G1 and prepare for
Mitosis?

• Closeness of neighboring cells early vs. late
• Hormones HGF, Estrogens, Androgens
• Presence of enzymes called CYCLINS
• Physical stress/damage (exercise/injury)
• DNA (Genes) signal proteins to be made ? cell
  division

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Cancer Uncontrolled Cell Growth (Division)

• If cell division is not controlled, then crowding
  and even tissue damage may result rapid mitosis
  ? mistakes in cells
• Ex. Cancer body loses ability to control cell
  growth can crowd and even damage tissue in
  surrounding area forms tumor
• Cancer cells no longer function in interphase
  as supposed to
• Benign vs. malignant tumors
• benign - localized and not spreading
• malignancies - capable of breaking off and
  starting up in another location -- metastasis

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Cancer Cells
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Causes/Associations of Cancer

• Excess Hormones HGF, Estrogens, Androgens
• DNA Damage/Mutation toxins, UV radiation,
  nuclear radiation, viruses (HPV, sarcoma)
• Consistent Cell Damage ? faster mitosis
  mistakes in copies
• Natural Oncogenes genes that cause rapid cell
  division (cancer genes) (RAS gene) ? leads to S
  phase ? G2 ? M
• Mutated Tumor Suppressing Genes (ex p53) once
  cancerous cells present lack of these can make
  cancer worse! (cutting brakes of a car) stops S
  phase

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Steps in Cancer formation

• 1. Improper stimulus to divide (hormones, mutated
  oncogenes, carcinogens)
• 2. p53 (tumor supressing gene) mutation does not
  stop rapid mitosis ? form tumors
• 3. angiogenesis and metastasis tumors recruit
  blood vessels and branch off to new parts of the
  body
• 4. malignant cancer (spread) to other parts of
  body and disrupts functions of those parts of the
  body

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Figure 12.17 The growth and metastasis of a
malignant breast tumor
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Figure 12-17x2 Mammogram normal (left) and
cancerous (right)
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Cancer Treatments

• Surgery (old) remove the tumor
• Localized Radiation X-rays damages DNA of ALL
  cells in an area kills cells
• Chemotherapy chemicals aimed at destroying
  cells/stopping mitosis of cells
• Prevents DNA replicationwhat cycle stage is
  this?
• Prevents stages of mitosis
• Gene therapy (replace faulty tumor suppressing
  genes) Gene into virus, virus infect/inject DNA
• Immunotherapy initiate immune system cells
  (antibodies) to attack cancer cells
  (autoimmunity) alpha Interferon
• Anticyclins/Cytokines attack microtubulues/filam
  ents and prevent mitosis

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Transgenic Vectors

• Avigenics alpha interferon