Lecture 47

Question 1

What is the tumor progression pathway?

Answer 1

normal
hyperplastic
dysplastic
neoplastic 
metastatic

Question 2

what is the evidence of monoclonality?

Answer 2

1. examination of X-inactivation pattern in cancers
2. chromosomal abnormalities of cancers
3. multiple myeloma produce a monoclonal immunoglobulin

give evidence that cancers start from a single cell

Question 3

How do mutations take place?

Answer 3

1. environmental factors ( exogenous and endogenous)
2. germline inheritance
3. spontaneous mutations

Question 4

what gene mutations could lead to cancer development?

Answer 4

1. proto-oncogenes
2. DNA repair genes
3. apoptosis regulation genes
4. tumor suppressor genes

Question 5

what does a mutation in proto-oncogenes lead cause?

Answer 5

1. increase in one or more normal functions
2. new function is created

only a single allele is needed to be mutated

Question 6

What do mutations in tumor suppressor genes lead to?

Answer 6

result in a loss of function

both alleles must be impacted

Question 7

what do mutations in apoptosis regulation genes lead to?

Answer 7

gain or loss of function of the gene

either increase or decrease apoptosis

Question 8

What do mutations in DNA repair genes lead to?

Answer 8

impair the cell’s ability to recognize and repair nonlethal genetic damage

Question 9

describe the MAP kinase pathway?

Answer 9

major cellular proliferative pathway

1. growth factor presence outside the cell
2. binding of the growth factor to the receptor
3. receptor autophosphorylation
4. exchange of GTP to GDP on RAS
5. RAS binds to RAF and cascade begins
6. up or down regulation of cell survival and proliferation

Question 10

mutations of what 5 components of the MAP kinase pathway result in oncogene formation?

Answer 10

1. growth factors
2. receptors binding GF
3. tyrosine kinases
4. proteins with GTPase activity that are signal transducers
5. transcription factors

Question 11

How is a growth factor receptor mutation involved with breast cancer development?

Answer 11

ERBB2 gene is amplified in approximately 30% of breast carcinomas leading to overexpression of the HER2 receptor and that in turn will lead to a constitutively active tyrosine kinase.

Question 12

what are the two ways oncogenes are activated by gene amplification?

Answer 12

1. double minutes- extrachromosomal fragments

2. homogeneously staining regions- amplified oncogenes attached to the chromosome

Question 13

What is herceptin (trastuzumab)?

Answer 13

a monocolonal antibody against the HER2 receptor, thus blocking activity

this drug will lead to the regression of the cancer

Question 14

How can double minutes and homogeneously staining regions detected?

Answer 14

karyotyping or by FISH

Question 15

What is ERBB1 and what happens if it is mutated?

Answer 15

a gene that encodes for the epidermal growth factors

point mutations in ERBB1 results in a constitutive activation of the EGFR tyrosine kinase

this mutation can be seen in lung cancer

Question 16

Imatinib mesylate (Gleevec) does what?

Answer 16

a BCR-ABL tyrosine kinase inhibitor that is highly effective in CML as it suppresses the tumor proliferation