TLC - L5 - Cancer

Question 1

How does progesterone effect breast cancer?

Answer 1

It protects against it.

Question 2

What is tumour progression?

Answer 2

Multistep process, producing sequential clones of mutant cells selected for increasingly cancerous phenotypes.

Question 3

How many independant mutations are required for full-blown cancer?

Answer 3

3-10

Question 4

How do cancer cells survive?

Answer 4

• Develope independance from proliferating constraints.
• Escape signals that drive differentiation.
• Avoid apoptosis.
• Develope genetic instability.
• Overcome senescence.
• Become invasive and metastasize.

Question 5

What kind of cells enter the terminally differentiated G₀ state?

Answer 5

• Neurones.
• Skeletal muscle.

Question 6

What kind of cells withdraw from the cell cycle reversibly?

Answer 6

• Liver cells.
• Lymphocytes.
• Skin fibroblasts.

Question 7

Can cells be proliferative or non-proliferative?

Answer 7

Yes.

Question 8

What kind of cells never enter G₀ state?

Answer 8

• Epithelial.
• Bone Marrow stem cells.

Question 9

What 2 opposing groups of proteins control whether a cell is dividing or not?

Answer 9

• Antioncogenes.
• Proto-oncogenes.

Question 10

Out of antioncogenes and proto-oncogenes which is dominant?

Answer 10

Antioncogenes.

Question 11

What is an antioncogene?

Answer 11

Tumour supressor - gene that encodes a protein involved in controlling cellular growth.

Question 12

What is a proto-oncogene?

Answer 12

Genes that provide signals that lead to cell division or regulate programmed cell death - can become an oncogene.

Question 13

What is an oncogene?

Answer 13

A gene that causes the transformation of normal cells into cancerous tumor cells.

Question 14

What is Tp53?

Answer 14

An antioncogene.

Question 15

What percentage of human cancers are due to a loss of function in the p53?

Answer 15

50%

Question 16

When do p53 levels increase?

Answer 16

In response to DNA damage.

Question 17

What does p53 do?

Answer 17

• Halts cell cycle until repair occurs.
• Induces apoptosis.

Question 18

Is the number of replications during a cells life time unlimited?

Answer 18

No - imperfect DNA replication shortens telomers.

Question 19

How are gamete cells telomeres different?

Answer 19

Due to the action of telomerase (enzyme) embryos telomere length is re-extended this re-sets replication limit.

Question 20

How do cancer cells avoid replicative senescence?

Answer 20

By activating telomerase.

Question 21

What is replicative senesence?

Answer 21

Limitation in the number of times cells can divide.

Question 22

Briefly how does radiotherapy work?

Answer 22

Promotes apoptosis.