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Genetics of Cancer (PowerPoint download)

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					  Humongous Insurance


 Genetics of Cancer

Presented by Gina Reyes, Amie Fitzwater,
Brittany Anders-Larson, & Yoshie Tamura
     Chapter Contents
• Cancer is Genetic, But Usually Not
  Inherited.
• Characteristics of Cancer
• Origins of Cancer Cells
• Cancer Genes
• A Series of Genetic Changes Causes Some
  Cancers
• Environmental Causes of Cancer
• Evolving Cancer
• Key Concepts
                   2
   Cancer is Genetic, But
   Usually Not Inherited
• Whether cancer runs in your family or not,
  cancer is estimated to affect one out of
  every three people.

  The following
  chart is from the
  2008 Cancer
  Registry




                      3
     Cancer and Genes
• There are two types       • Somatic mutations
  of genetic changes        Are not passed on to the next generation
                            and it happens in the course of a person’s
  or mutations that         lifetime usually later on in life. Most
  cause cancer:             cancer mutations occur in this manner (as
                            referenced in the pie chart).


                            • Germline mutations
                            Are passed from generation to generation.
                            There is a 50/50 chance of
                            inheriting cancer if either parent has a
                            genetic change. This type of cancer can
                            develop if a environmental trigger
                            mutates a somatic cell or if somatic
                            mutation mixes with an inherited gene.



                        4
 Characteristics of Cancer

• Cell division –      Cancer cells no longer respond to stop
  signals and therefore can divide at a continuously fast rate
  if the cancer is a cancerous tumor.
• Look of a cancer cell -         Cancer cells look different
  when compared to normal cells. Cancer cells are rounder.
  This is also known as dedifferentiated.
• Growth of a cancer cell –           Cancers can take many
  years to grow (ei, lung cancer). Angiogenesis can make the
  cancer spread further by using the capillary extensions.




                            5
         Origins of Cancer cells
There are at least 4 situations that can lead to cancer at cellular level:
1.) Activation of stem cells:               2.) Dedifferentiation:
•   A cancer cell may descend               •   Cells lose their distinguishing
    from:                                       characteristics (their specializations)
     –   A stem cell that produces              due to a mutation occuring as the
         differentiated daughter cells          cells divide.
         (specialized cells) that retains
         the capacity to self-renew.        3.) Loss of balance at tissue
     –   Specialized cells that lose some      level:
         of their features but can still
                                            •   Normal cells favor differentiated cells (or
         divide.                                daughter cells).
•   Cancer stem cells produce               •   Tissues with abnormal balance will favor
    both cancer cells and                       cells that can divide continually
                                            •   Eventually that shift in balance will create
    abnormal specialized cells                  an excess amount of stem cells and
•   Cancer stem cells are found                 progenitors which causes a tumor.
    in cancers of the brain,
    blood, and epithelium (lining           4.) Faulty Tissue Repair:
                                            •   If too many cells divide to fill in the space
    tissues such in the breast,                 left by injured tissue, and those cells
    colon, and prostate).                       keep dividing, an abnormal growth may
                                                form.
            Cancer Genes
• When mutations activated oncogenes or inactivate tumor
  suppressor genes, cancer occurs.
• Proto-oncogene: A gene that normally triggers cell division
  when it is appropriate.
• When proto-oncogenes are turned on at the wrong time or
  place they function as “oncogenes”. This may be the result
  of either a mutation or a change in expression of the wild
  type gene.
• Also, a proto-oncogene that is moved near a gene that is
  highly expressed then it will also be rapidly transcribed.
       • Example: Proto-oncogenes are normally activated at the site of a
         wound. If it is activated at a site other than the wound (as an
         oncogene) it still stimulates mitosis and bumps up the growth
         factor production. These new, un-needed cells become a tumor.
                            Cancer Genes
 Activating an oncogene:                                          Tumor Suppressors
Increasing expression in a new location:                 •   Some cancer results from loss of a
• Placing proto-oncogene near a gene that                    gene that normally suppresses
    boosts its expression.                                   tumor formation by sending growth-
• Moving proto-oncogene next to a gene                       inhibiting signals.
    that is normally very active.                        •   Unlike activating an oncogene
     –   This can happen when a chromosome is
         inverted or translocated, placing the gene          (which usually gains a function) a
         in an new environment.                              tumor suppressor gene mutation
     –   When translocation or inversion places a            usually removes a function.
         proto-oncogene next to an antibody gene
         the immune system contributes to cancer.        •   Some of the best studied tumor
                                                             supressor genes are:
Fusion Proteins with New Functions:                           –   Retinoblastoma: a rare childhood
• When a proto-oncogene moves near                                eye tumor
    another gene and the gene pair is                         –   P53 gene: a single gene that causes
    transcribed and translated as if it were                      a variety of cancers when mutant
    one gene.                                                 –   BRCA1 (Breast cancer
     –   The double gene product, called a fusion                 predisposition gene 1): Familial
         protein, activates or lifts control of a cell            breast cancer
         division.                                                  •   Encodes a large protein that is
                                                                        normally in the nucleus, where it
Receiving a Too-Strong Division Signal                                  activates transcription of the genes
                                                                        that respond to p53 protein.
• When a proto-oncogene recieves too                                •   BRCA1: When functioning properly
    many signals to divide the gene will                                they are necessary for DNA repair
    replicate until it causes a tumor.
         Stages in the
     Development of Cancer
   One example of such a misfortunate event, is the rapid
             development of brain tumors:

• A protein called P53, with in the structure of our
  chromosomes, seizes to withhold the development
  of tumors.
• Followed by an interruption on chromosome 9,
  creating an error in the chromosomes immunity to
  cancer.
• As the genes cell cycle freezes growth develops on
  chromosome 7, putting mitosis to a halt.
• At the last stage of the tumors growth , the
  existence of chromosomes 10 mysteriously vanish.
     Cancer is commonly formed in
        the instability of genes
                   The cause of cancer is greatly impacted by genetics.

                                                •     A mutation is found when the inner
                                                      chromosomal alignment of a gene
                                                      becomes imbalanced .
                                                •     The whole genome risks instability at
                                                      the cost of the gene known as the
                                                      “gatekeeper” (who is in charge of
                                                      directing the correct balance of
                                                      somiotic cell division and the balance
                                                      of natural cell death).
                                                •     If the gate keeper does not delegate
                                                      the motions of the cells properly , a
                                                      mutation could occur leading to
                                                      cancer.
                                                •     Once a gene has mutated into a
                                                      cancerous condition. The affect and
                                                      stages of the mutation begin to
                                                      unfold, in the depths of our
                                                      chromosomal structures .


BUB1B (above) is an example of inherited cancerous
genes found commonly in young children.          10
         Preventing Cancer
                   By knowing your genetics

• Although preparation or prevention of a brain tumor may
  be impossible to achieve. Such inheritable cancers like
  colon cancers can be prevented . Thanks to the research
  of Doctor Eldon Gardener in 1947, who uncovered the
  link to the genetic inheritance of colon cancer.
• In a current day action towards the prevention of cancer.
  Doctors today can check the colon for polyps, a growth in
  the colon that can lead to cancer.
• The other preventive method is the ability to check stool
  samples for APC, a protein when found nonexistent in
  ones gene structure can lead to growth of colon cancer.
• The effect of such an inherited mutation causes the lining
  of the colon not to die off in its three day existence like it
  is supposed to.
                Preventing Cancer
                            By utilizing the environment
Although the fate of cancer can bestow among any •       The website http://www.therapeasecuisine.com
one, inheritance of the gene may eliminate the idea      gives information on how to personally prevent
of chance replacing it with fate. Yet, regardless of     cancer. Listing ideas like, “Eat more variety of
                                                         vegetables and do not use supplements that
chance or fate, luckily thanks to research and the       protect against breast cancer.”
ability to control some simple environmental
                                                     •   Even our text book list off suggestions of
factors we may be able to slow down or even              helpful choices to make in our diet such as,
delete the existence of cancer amongst our genes.        “Vitamins D and E, soy bean compounds, green
                                                         tea and certain anti- inflammatory drugs.”
                                                    •    Being aware of occupational hazardous such as
                                                         fumes, and chemicals, you may breath in at
                                                         work could potentially bring fourth the effect of
                                                         cancer.
                                                    •    Population studies, in which communities bear
                                                         recessive forms of cancer. Under go group
                                                         research have found environmental impacts
                                                         and genetic similarity.
                                                    •    Case- control studies have also been created to
                                                         watch over a persons life and the environment
                                                         of one that eats a diet high in vegetables and
                                                         exercises regularly and on that does not.
                                                         Usually the individual with the healthier
                                                         regimen, out lives of prolongs the occurrence of
                                                         cancer.
                                                    •    Though we can not yet fix our DNA or genetic
                                                         structure, we can make healthy choices in life.
                                                         The choice to live a life free from smoking, a
                                                         healthy diet and regular exercise, despite your
                                                         genetic inheritance could save your life.
    Evolving Cancer Diagnosis
          and Treatment
•   It is now possible to predict the likelihood of certain cancers.
•   A few cancer treatments include: surgery, radiation, and
    chemotherapy.
     – Surgery: Removes tumors
     – Radiation and Chemotherapy: non-selectively destroys rapidly dividing
       cells
         • If a patient does radiation and chemotherapy, they will need drugs to protect
           them from harmful side effects.
•   New drugs have been discovered to fight specific types of cancer.
•   Nowadays, we have more than fifty drugs that can stop the blood
    supply to tumor.
•   Using drugs and chemotherapy are useful ways to cure cancer but
    it means the patient will undergo a longer treatment.
•   There are several ways to find cancer but they don’t always
    pinpoint the cause requiring further examination.




                                      13
                 Key Concepts:
• Cancer is genetic, but not necessarily inherited.
• Cancer cells have different gene expression profiles
  compared to the cells from which they descended.
• Cancer is caused by loss of cell division control.
• 4 situations at cellular level lead to cancer:
        • Activation of stem cells that produce cancer cells,
          dedifferentiation, loss of balance at tissue level, and faulty tissue
          repair
• Single genes (oncogenes and tumor suppressor genes,
  when mutant, can cause cancer.
        • Proto-oncogenes normally control cell cycle and become
          oncogenes when they mutate, moved next to a highly expressed
          gene, or form a fusion protein.
        • Mutations in tumor suppressors removes a function
• A single mutant gene can destabilize chromosomes causing
  a predecessor of cancer.
• Treatments for cancer target the characteristics of cancer
  cells.

                                   14
                   References
Internet: Author Unknown 2008, 2008 Cancer Registry Report. Washington
Adventist Hospital, http://www.adventisthealthcare.com/WAH

Internet: Author Unknown, Mutation Types in Human Cancer. Nature,
http://www.Nature.com

Internet: Author Unknown, BUB1B human: BUB1 budding uninhibited by
benzimidazoles.http://www.cellmigration.org/resource/discovery/geiger/geiger
_rnai/images2/hr/thumbs/BUB1B_HR.jpg

Internet: CartoonStock.com, “Antioxidants”.
http://www.cartoonstock.com/directory/a/antioxidants.asp




                                    15

				
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posted:12/25/2011
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