Cancer Biology (CH 24)

Question 1

proto-oncogene

Answer 1

produce proteins with normal cellular function; promote cell growth/apoptosis (i.e. Ras); Gain of function mutations cause to become oncogenes

Question 2

tumor supressor gene

Answer 2

produce proteins involved in negatively regulating cell growth/cell cycle progression (i.e. STATs & JAKs); loss of function mutations allow unregulated cell proliferation.

Question 3

proteins encoded by tumor supressor genes

Answer 3

intracellular proteins - regulate cell cycle progression; receptors/transducers that inhibit cell proliferation; checkpoint-control proteins; apoptosis promoting proteins;
DNA repair proteins

Question 4

hallmarks of cancer

Answer 4

self-sufficiency in growth signals, insensitivity to antigrowth signals, evasion of apoptosis, limitless replicative potential, tissue invasion and metastasis, sustained angiogenesis

Question 5

benign tumor

Answer 5

remain clustered (encapsulated) & can be removed

Question 6

malignant (metastatic) tumor

Answer 6

invade surrounding & distant tissue

Question 7

angiogenesis

Answer 7

the ability of a tumor to develop new blood vessels. needed for tumor >2mm to grow

Question 8

promotion of angiogenesis

Answer 8

Tumors secrete factors to induce angiogenesis: VEGF (vascular endothelial growth factor), FGF, TGFa. Tumors also induce surrounding cells to secrete these factors. Degradations of basal lamina of capillaries. Migration of endothelial cells toward tumor.
Endothelial cell proliferation.
Formation of new basement membrane and new elongated capillary.

Question 9

properties of transformed cells

Answer 9

these cells are immortalized (unlimited number of population doublings) and
display transformed phenotype:
morphology change, grow unattached to ECM, reduced requirement for growth factors, secrete plasminogen activator (degrade ECM), and loss of actin microfilaments

Question 10

“multi-hit” model

Answer 10

explains that the incidence of cancer increases with age because with an increase in the number of oncogenic mutations, there is an increased likelihood of tumor development & malignancy.

Question 11

proto-oncogene -> oncogene

Answer 11

Point mutation: constitutively active protein.
Chromosomal translocation: create fusion protein OR alter gene expression (turn on many copies of normal gene).
Gene amplification: multiple copies of growth promoting gene.

Question 12

Rous Sarcoma Virus (RSV)

Answer 12

first virus identified to cause cancer; retrovirus

Question 13

acutely transforming retrovirus

Answer 13

contain oncogenes; rapidly induce cancer

Question 14

slowly transforming retrovirus

Answer 14

lack oncogene; induce cancer by turning on expression of gene where they integrate - may be transforming over a long latency (i.e. Human T Cell Leukemia Virus)