Cancer

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Cancer

• Ch 22 443-459
• Metastasis
• Types of cancer
• Causes of cancer
• Symptoms
• Treatment

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Some facts

• 500,000 deaths per year (more males)
• Older age group stricken more often
• More than 100 types of cancer, many due to
  mutations triggered by environmental factors
• Highest cancer incidence male - prostate
  female - breast
• Highest cancer deaths lung

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What is Cancer?

• Genetic disease
• Mutations lead to uncontrolled cell division
• triggering of Oncogenes starting point of
  mutations
• do not respond to inhibitory Transforming Growth
  Factor-? (TGF- ?) from neighbors
• Result in tumor progression of which leads to
  Cancer

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Tumors

• Multiplying cells Tumors
• Benign (disorganized and encapsulated)
• Malignant (invasive)
• When malignant cells invade surrounding tissues
  Metastasis

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Characteristics of Cancer cells

• Non-specialized Divide and divide innumerably,
  like immortals (unlike normal)
• No apoptosis Normal cells with distorted nuclei
  die, while mutated cancer cells dont
• No contact Inhibition dont mind piling on each
  other
• Induce Angiogenesis Produce new blood vessels to
  enable blood supply to the Overgrown cells
• Metastasize Affect other tissues

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Cancer cells

• Dysplasia
• Abnormal changes in sizes, shapes, and
  organization of cells in a tissue
• Anaplasia
• Disorganized condition
• Neoplasia
• Disorganized growth of cells

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Normal cells in culture

• Organized structure
• Limited cell growth
• Contact inhibition
• No overlapping

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Cancer cells in culture

• Disorganized
• Overlapping structure
• Uncontrolled cell growth
• Lack contact inhibition

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Carcinogenesis

• Development of Cancer

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Carcinogenesis

• Requires series of mutations
• Begins with a localized tumor (in-situ) and
  mutates to become malignant
• Invades the lymph nodes
• Ability to metastasize and affect surrounding
  cells
• Moves further to distant cells (ex-situ)
• In each successive step, the most genetically
  altered and aggressive cell becomes the dominant
  type of tumor

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Prognosis

• Probable outcome depends on
• Degree of progression of cancer
• Whether tumor has invaded surrounding tissues
• If so, are lymph nodes involved?
• Has the tumor metastasized?

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What causes a normal cell to become a cancer cell?
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Oncogenes

• Cancer-causing genes
• There are 2 ways that oncogenes can cause cancer
• 1. Oncogenes can be present in all cells but
  cause cancer when activated by some external
  trigger
• 2. A harmless gene for normal cell
  replacement may mutate into an oncogene

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Oncogene activity

• May code for faulty receptor in stimulatory
  pathway
• Produces abnormal protein product or abnormally
  high levels of normal product that meddles with
  cell cycle regulation
• Nearly 100 oncogenes identified

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Origin Development

• 4 classes of genes
• Mutations in genes that proof-read new DNA
• Mutations in genes that code for proteins which
  regulate the structure of chromatin
• Proto-Oncogenes that stimulate the cell cycle
• Tumor-Suppressor genes that inhibit the cell
  cycle
• Constant telomeres in cancerous chromosomes

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Regulation of Cell Cycle

• G phase organelles double in number (so that
  the 2 daughter cells will have all the
  organelles)
• S phase replication of DNA (one cells DNA
  doubles in amount to facilitate formation of 2
  new cells)
• M phase Cell division (Mitosis)

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How the drama begins?

• Stimulatory pathway that extends from Plasma
  membrane to nucleus
• Growth factor from next cell is welcomed by
  receptor proteins (host welcomes guest)
• Signals all inmates to receive the growth factors
  properly (cascade of enzymatic reactions)
• Inmates enter stage (nucleus) to introduce guests
  which triggers of cell division (good hosting)
• Drama begins (oncogenes turned on and cell begins
  to divide uncontrollably)

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Drama Staged!!!

• Proto-oncogenes mutate become oncogenes
• Codes for faulty receptor in stimulatory pathway
• So now, no more director (growth factor)
  required, the guest actors (faulty receptors)
  themselves do the needful (begin inducing more
  and more cell divisions)
• Tumor-suppressor genes (RB, p53) lose their
  jobs!, no more can they inhibit the
  uncontrollable cell division.

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Types of Cancer

• Leukemia cancer in the blood tissue (blood
  cancer)
• Lymphoma Cancer in the lymphoid tissue
• Melanoma Skin cancer
• Osteosarcoma Bone cancer
• Myeloma Cancer in the bone marrow
• Sarcoma Cancer in any of the soft tissues of
  the body

Endless list