Oncology 4

Question 1

What are the 6 hallmarks of cancer?

Answer 1

• self-sufficiency in growth signals
• insensitivity to anti-growth signals
• evasion of apoptosis
• sustained angiogenesis
• tissue invasion and metastasis
• limitless reproductive potential

Question 2

In normal cells, growth and division requires external ____s

Answer 2

growth factors

Question 3

Growth factors are produced by ______ and bind to ______

Answer 3

• other cells

- cell receptors

Question 4

What do growth factors trigger? What does this in turn trigger?

Answer 4

Growth factors trigger intracellular kinases

These trigger cell division

Question 5

What is an important characteristic of growth factors regarding chemical composition?

Answer 5

They are diffusible

Question 6

When does abnormality of growth occur with cancer cells?

Answer 6

• too many receptors and overstimulation of growth

- self-production and release of GFs (stimulate growth)

Question 7

What type of trigger causes abnormality of growth in cancer cells?

Answer 7

may be genetic or environmental

Question 8

What are oncogenes?

Answer 8

• small segments of DNA

- can transform normal cells into malignant ones

Question 9

Where do oncogenes come from?

Answer 9

Activated from “normal” proto-oncogenes by a mutation

Question 10

What signals a cell to stop reproduction?

Answer 10

anti-growth signals from other cells

Question 11

What are the anti-growth signals used by other cells to signal a stop in reproduction?

Answer 11

• soluble growth factors
• immobilized inhibitors embedded in the extracellular matrix
• immobilized inhibitors on the surfaces of nearby cells

Question 12

What causes cells to become insensitive to anti-growth signals?

Answer 12

• stop listening to normal cells

- keep dividing over normal cells that have stopped growing

Question 13

Anti-growth signals are associated with this point in the cell cycle?

Answer 13

G1 checkpoint

Question 14

How do nectins and nectin-like substances play a role in normal cells?

Answer 14

• contact inhibition

- limiting movement of cells

Question 15

What is contact inhibition?

Answer 15

Mitosis is prevented once cells of a tissue come in contact with one another

Question 16

How do nectins and nectin-like substances play a role in abnormal cancer cells?

Answer 16

• may be deficient
• lack of normal contact inhibition
• overgrowth of cancer cells

Question 17

What are the phases of the cell cycle?

Answer 17

G0
G1
S
G2
M
G1 checkpoint

Question 18

What is the G0 phase?

Answer 18

• resting phase

- cell has left the cycle and stopped dividing

Question 19

What is the G1 phase?

Answer 19

Cell growth in preparation for increased DNA synthesis

Question 20

What is the S phase?

Answer 20

DNA synthesis

Question 21

What is the G2 phase?

Answer 21

Cell growth preceding mitosis

Question 22

What is the M phase?

Answer 22

Mitosis

Question 23

What is the G1 checkpoint?

Answer 23

• regulatory step preventing the move into DNA synthesis phase
• prevents cell division

Question 24

What is another name for tumor suppressor genes?

Answer 24

anti-oncogenes

Question 25

What do anti-oncogenes decrease when active?

Answer 25

Decrease risk of a cell becoming metastatic (cancerous)

Question 26

What do anti-oncogenes code for?

Answer 26

proteins that:

• have a repressive effect on the progression through the cell cycle
• promote apoptosis
• do both

Question 27

Which gene is nicknamed “the guardian of the genome”?

Answer 27

P53 tumor suppressor gene

Question 28

What does the P53 protein do?

Answer 28

changes gene expression to halt proliferation and trigger apoptosis when DNA is damaged

Question 29

At what phase in the cell cycle does P53 halt cell division in response to DNA damage?

Answer 29

G1 phase

Question 30

How often is the P53 gene found to be mutated or disrupted?

Answer 30

in more than 50% of all cancers

Question 31

Why is P53 gene mutation so bad?

Answer 31

• suppresses normal apoptotic proteins

- cell continues to multiply