Health Science-Module 2 Lecture 2

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Health Science-Module 2 Lecture 2
2014-03-15 23:32:14
Pathogenesis Cancer characteristics ofcancer cells

pathogenesis of cancer and characteristics of cancer cells
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  1. Cancer is the result of the interaction between a person's  __________ and three categories of external agents called ___________.
    • genetic factors
    • carcinogens
  2. what are carcinogens and what are the 3 categories of carcinogens?
    • cancer causing agents; capable of inducing neoplastic growth  
    • 3 categories: chemicals, radiation, some viruses or bacteria
  3. what are genes? what is it's function?
    • inherited instructions that reside within chromosomes
    • each gene instructs a cell how to build a specific product, a particular kind of gene.
  4. what is genetic instability?
    somatic cell mutation by carcinogenic agents
  5. what are some other factors of carcinogenesis? (3)
    • dietary habits
    • smoking
    • alcohol consumption
  6. Chemicals are commonly tested for carcinogenicity using what test?
    Ames test
  7. what are some typical chemical carcinogens? (4)
    • aflatoxin (mold)
    • arsenic
    • insecticides
    • polycyclic aromatic hydrocarbons
  8. what two viral carcinogens are responsible for about 80% virally-induced cancers?
    hepatitis B and HPV
  9. what is somatic mutations?
    acquisition of mutations that convert a normal cell to a cancer cell
  10. what is germline mutation?
    inheritance of an alteration or mutation that will cause or predispose cancer
  11. Types of DNA mutations: single base change. what is this mutation and what cancer can it cause?
    • point mutation
    • bladder cancer
  12. Types of DNA mutations: larger sections of DNA through amplifications (3)
    • deletions
    • insertions
    • translocations
  13. what is epigenetic changes? give an example.
    • type of DNA mutation; reversible heritable non-mutational changes that result in altered gene activity
    • BRCA1 activity in breast cancer
  14. what is miRNA?
    type of DNA mutation; small sequences of ssRNA that silence mRNA that can be silenced in cancer cells
  15. chromosomal changes such as changes in number is called?
  16. what chromosomal change created the Philadelphia chromosome and chronic myeloid leukemia (CML)?
    • translocation of Bcr-Abl genes
    • small piece of chromosome 9 and 22 break off and switch
  17. What happens to a gene when it's mutated?
    can produce dysfunctional proteins and cause a variety of effects
  18. Cancer mutations usually occur in 2 types of genes, name and briefly describe each function.
    • oncogenes: normal function is cell growth, gene transcription
    • tumor suppressor genes: normal function is cell cycle control, DNA repair, cell death (apoptosis)
  19. oncogenes are cancerous versions of __________________.
  20. what mutation does oncogenes undergo? (3)
    • "gain of function" mutations
    • they do even more of what they normally do
    • cause cells to divide more or die less
  21. _____________ genes can also act as oncogenes.
    growth factors
  22. what mutation does tumor suppressor genes undergo?
    • undergo "loss of function" (has to be both copies)
    • tumor suppressor genes usually act as inhibitors of cell replication
  23. what is the function of the tumor-suppressor mutation and oncogene?
    • tumor-suppressor mutation: lack of inhibition of the cell cycle
    • oncogene: overactive stimulation of the cell cycle
  24. _______________ are genes that correct errors in DNA replication
    Mutator genes
  25. what is the function of p53? (2)
    • apoptosis controllers
    • halts the cell cycle and initiates DNA repair
  26. what is the mutation gene that suppresses apoptosis?
    Bcl-2 an oncogene
  27. what is  classic example of carcinogenesis in action?
    colon cancer
  28. describe the 4 steps in carcinogenesis?
    • initiation: carcinogen produces a mutation in a cell
    • promotion: some other factor encourages proliferation of the cell
    • progression: transformed cells begin to grow autonomously
    • cancer: invasion and metastasis
  29. what is neoplasia?
    a new growth of cancerous cells
  30. what is anaplasia?
    cells of the tumor are undifferentiated and resemble embryonic cells
  31. define angiogenesis.
    growth and proliferation of endothelial cells that line the inner surface of existing blood vessels
  32. why is cancer potentially dangerous?
    their capacity to invade neighbouring tissues and colonize distant organs with their cells
  33. define invasion.
    direct migration and penetration of cancer cells into tissues
  34. define metastasis.
    refers to the ability of cancer cells to enter the vasculature and migrate to distant sites
  35. what are the 5 steps to the spread of malignant tumors?
    • invasion of connective tissue matrix(stroma)
    • invasion of blood and lymphatic vessels
    • circulation of tumor cells
    • invasion from blood vessels into tissues
    • angiogenesis
  36. Angiogenesis is ___________________.
    needed for tumor survival
  37. how do tumors destroys both the basement membrane and surrounding matrix which lies between the tumor and its path to metastasis?
    tumors secrete cytokinesis and enzymes called proteases
  38. what is metastatic cancer?
    • malignant spread of tumor cells away from the primary lesion
    • all malignant cells can metastasize
  39. what 3 ways can metastatic cancer occur through?
    • hematogenous spread (blood vessels)
    • lymphatic spread (lymphatic vessels)
    • direct seeding of body cavities/surfaces
  40. briefly explain metastasis via blood vessels. (4)
    • tumor embolus entering a vein is carried through larger and larger vessels to heart
    • enters pulmonary circulation
    • vessel size narrows in lungs, trapping embolus
    • embolus begins to grow
  41. why is the lung the most common site of secondary tumor growth?
    capillaries and veins have thin walls which is easy to penetrate
  42. what are the 2 organs that are common sites for secondary tumor growth?
    • lungs
    • liver
  43. how does a secondary tumor growth in the liver happen?
    • many veins pass through liver
    • liver sinusoids have small diameter which traps tumor emboli
  44. why are arterial metastasis less common than venous?
    arteries have thicker walls, so invasion's harder
  45. what are the 3 steps in metastasis via lymph nodes?
    • tumor cells get trapped in lymph node and start growing
    • alternate routes of flow carry tumor cells to new sites
    • lymph nodes also intersect with blood vessels
  46. how is another way metastasis spreads through body cavities?
    cells shed into the cavity and can establish masses in other regions of the cavity
  47. what is metastasis spread by implantation?
    spread/implantation facilitated by surgery
  48. Bloodstream carries cancer cells all over the body. Each type of cancer preferentially metastasizes to particular locations depending on what 4 things?
    • pattern of blood flow
    • organ specific factors
    • tumor progression
    • immune system
  49. how does organ specific factors factor into the decision of cancer cells to metastasize?
    some tissues secrete growth factors that stimulate proliferation of cancer cells
  50. Not all tumor cells that migrate via blood or lymph survive to set up new tumors, why is this?
    low survival may be due to combination of turbulence in blood causing mechanical damage, and host defenses
  51. what are the 5 Hallmarks of Cancer? briefly describe each.
    • 1. Growth without Go signals: do this by producing their own growth factors, over-express or change growth factors
    • 2. Failure to respond to STOP signals: cancer cells avoid the signals for anchorage dependent or density dependent growth
    • 3.Unlimited number of cell divisions: cancer cells have the ability to divide endlessly
    • 4. Avoidance of cell death: cancer cells that get past this have acquired the ability to avoid the cell death signals
    • 5. Angiogenesis: release signals that result in growth of blood vessels towards and into the tumor supplying it oxygen and nutrients  

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