L18: Tumors

Question 1

What is metastasis?

Answer 1

spreading of cancer cells through lymph of bloodstream to distant parts of the body

Question 2

What is malignant transformation?

Answer 2

when a cell has become able to form a cancer

Question 3

What are proto-oncogenes?

Answer 3

genest that normally contribute positively to the initiation and execution of cell division

Question 4

What are oncogenes?

Answer 4

mutant forms of proto-oncogenes that contribute to malignant transformation

Question 5

What are mutagens?

Answer 5

chemical or physical agents that increase mutation rate

Question 6

What are carcinogens?

Answer 6

a mutagen that increases the risk of cancer cell formation

Question 7

What are the two type of genes that if mutated, can lead to cancer?

Answer 7

1. proto-oncogenes

2. tumor suppressor genes

Question 8

About how many mutations does a cell have to to acquire to become a cancer cell?

Answer 8

5-6 usually but can be more or less

Question 9

What type of mutations do chemical carcinogens typically give rise to?

Answer 9

single base change mutations

Question 10

What type of mutations does radiation tend to induce?

Answer 10

more pronounced mutations (DNA breaks, cross-linked nucleotides, abnormal recombination, etc)

Question 11

What is an oncovirus?

Answer 11

pathogenic virus that infects cells and begins to exrpess virally encoded proteins that can over-ride the cell’s normal mechanisms for regulating cell division.
Can also prevent normal tumor suppression mechanisms

Question 12

What type of immune cells can easily recognize and kill tumor cells?

Answer 12

allogeneic CD8 T cells.

Allogeneic meaning from other individuals or antigen-distinct

Question 13

What are tumor antigens?

Answer 13

antigens found on tumor cells, but not on normal cells

Question 14

What are tumor-associated antigens?

Answer 14

antigens found on tumor cells and normal cells, but in smaller numbers on normal cells

Question 15

What are most tumor antigens recognized and what class MHC do they bind to?

Answer 15

most bind to MHC class I and are recognized by CD8 T cells.
They do however have the ability to be recognized by B cells

Question 16

Can a person be “vaccinated” against specific tumors?

Answer 16

Theoretically yes. as long as there is an antigen to be recognized

Question 17

How do tumor cells evade immune responses?

Answer 17

they are similar enough to appear as self molecules. almost half have mutations in MHC class I HLA, so they cannot be recognized by effector CTLs.
Some create an immunosuppression zone by producing cytokines to suppress immune responses

Question 18

Are tumor cells that do not express MHC class I susceptible to NK cell killing?

Answer 18

yes, but only if they are devoid of production of all the MHC class I alleles.

Question 19

What is the major downside of using monoclonal antibody treatments for tumor-specific treatments?

Answer 19

the foreign antibodies are recognized by the immune system and can only be used once without causing a severe immune reaction

Question 20

How can T cell responses be boosted to help fight cancer?

Answer 20

T cells specific for tumor antigens can be isolated from a patient and can be grown in vitro, then injected back into the patient.

Question 21

How is recombinant DNA being used to treat cancer?

Answer 21

Tumor cells are transfected with it to produce cytokines or chemokines that either stimulate or chemattract DCs to the tumor to facilitate uptake and presentation of tumor antigens to naive T cells.

Question 22

What are sarcomas?

Answer 22

cancer of cells other than epithelial cells

Question 23

What are carcinomas?

Answer 23

cancer of epithelial cells

Question 24

What are leukemias?

Answer 24

cancer of circulating cells

Question 25

What are lymphomas?

Answer 25

cancers involving solid lymphoid tumors

Question 26

What are myelomas?

Answer 26

cancers involving bone marrow

Question 27

What is an example of a cytokine that tumor cells can release to cause immunosuppression?

Answer 27

TGF-beta