Cancer and Stem Cells

Question 1

How does the body function and how does cancer break rules?

Answer 1

Body functions as ecosystem where Cells are usually committed to apoptosis if damaged, also committed to collaboration and cancer hurts this system by hurting rest, growth division, differentiation, and apoptosis

Question 2

What are the types of cancer?

Answer 2

Carcinomas (epithelial tissues), sarcomas (connective and muscle tissues), leukemias and lymphomas - blood cells

Question 3

What are the properties of cancer cells?

Answer 3

cells reproduce despite restraint on cell growth and division, cells invade local tissue and can colonize foreign locations

Question 4

Describe benign vs malignant tumors

Answer 4

benign - non invasive

malignant - invasive

Question 5

How do tumors progress and convert a healthy cell to a cancer cell?

Answer 5

multiple mutations are required to convert a healthy cell to a cancer cell, mutations can be present due to inheritance, chemical carcinogens, radiation, errors in dna replication, and defects in dna repair

Question 6

Why is PET used to detect cancer cells?

Answer 6

Cancer cells have increased glucose uptake and metabolism, since tumor cells do more glycolysis making it possible to visualize them with radioactively labeled glucose in PET scan

Question 7

What is cell senescence and how do cancer cells get around it?

Answer 7

cell division counting mechanism, depends on shortening of telomeres, provides a built in limit to number of times a cell divides
cancer cells get around this by keeping telomeres active, preventing them from shortening over time, checkpoints are disabled, so cell cycle proceeds

Question 8

Describe cancer cell properties

Answer 8

decreased sensitivity to anti proliferative signals, less likely to undergo apoptosis, defective in cell cycle mechanisms, induce angiogenesis (formation of new blood vessels), use stromal cells for support, stabilize telomere length

Question 9

How does cell division and apoptosis impact cells

Answer 9

Increased cell division and/or decreased apoptosis can cause a cell to be a tumor

Question 10

Why do cancer cells accumulate mutations?

Answer 10

• Mutations are accumulated at a higher rate in cancer cells
than in normal cells in part due to inability to repair DNA
damage or undergo proper chromosome segregation.

Question 11

Describe cancers that arise from a single cell

Answer 11

cells within the tumor share common chromosomal abnormalities (translocations), genetic mutations (point mutations), or epigenetic changes

Question 12

Describe cancer critical genes that cause an overactivity or underactivity mutation

Answer 12

Myc, Ras - overactivity mutation (gain of function), activating mutation enables oncogene to promote cell transformation
Rb, p53 - underactivity mutation (loss of function), tumor suppressor gene is eliminated through 2 mutation events

Question 13

How can an oncogene be made?

Answer 13

Gene amplification, deletion or point mutation in coding sequence, regulatory mutation, chromosome rearrangement (produces hyperactive fusion protein)

Question 14

What is dna from tumor cells tested for

Answer 14

DNA from tumor cells can be tested to see if it causes abnormal cell proliferation. Results in ID of Ras.

Question 15

What is the difference between hereditary and nonhereditary retinoblastoma

Answer 15

Individuals with inherited Retinoblastoma have a greater chance of developing a tumor

Question 16

What are the mechanisms of gene inactivation?

Answer 16

Genetic - accidental change in nucleotide sequence, epigenetic - accident causes dna packaging into heterochromatin or methylation of C nucleotides

Question 17

What are tumor suppressors and protooncogenes?

Answer 17

Tumor Suppressors: Rb, p16
• Proto-oncogene: Cyclin-Cdk
• E2F can inhibit and promote the cell cycle depending on which one is active

Question 18

What is the role of p53?

Answer 18

P53 - tumor suppressor, components of p53 pathway mutated in almost all cancers
Stable, active p53 leads to cell cycle arrest, apoptosis

Question 19

What are the stages of tumor progression?

Answer 19

Stages of tumor progression -
- Normal Epithelium
- Low grade intraepithelial Neoplasia - cell proliferation
- High grade intraepithelial neoplasia - more cell proliferation, basal lamina not invaded yet .
Invasive Carcinoma - cancerous tumor

Question 20

Describe the progression of colorectal cancer

Answer 20

Loss of Apc (not anaphase promoting complex, helps keep Wnt signaling pathway off), activation of K-Ras, loss of smad4 and other tumor suppressors, loss of p53, other unknown alternations

Question 21

What does metastasis require?

Answer 21

requires disruptions in cell cell and cell-matrix adhesion

Question 22

What are the difficult and easy steps in metastasis?

Answer 22

escape from parent tissue and colonization of remote site is difficult, travel through circulation is easy

Question 23

What does the tumor microenvironment look like?

Answer 23

includes cancer cells, includes stroma, Stromal cells evolve to support the cancer cells.

Question 24

What do tumors induce in order to survive?

Answer 24

Tumor induce angiogenesis, secrete signals that attract endothelial cells for the growth of blood vessels to the tumor. • Tumors require blood vessels to supply nutrients and oxygen to survive

Question 25

Describe the role of viruses in tumor progression

Answer 25

viral gene integrates into dna, causing viral proteins to be produced in high amounts, resulting in a malignant tumor

Question 26

What occurs as a result of virus infection?

Answer 26

viral protein E7 interferes with Rb to allow E2f to be active, p6 interferes with p53, inactivating it
cell proliferation is activated by dna virus