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BPM1 Exam 2 - Foundations to Medicine 2 > FTM 65-66 - Cancer Genetics 1 & 2 > Flashcards

FTM 65-66 - Cancer Genetics 1 & 2 Flashcards

1
Q

Does non-mendelian inheritance of cancer follow the threshold model? Why or why not?

A

It does not because cancer is usually just caused by an accumulation of genetic alterations. And while environment can cause genetic alterations it usually isn’t thought to have a huge impact

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2
Q

What is unique about cell progression in cancer vs other diseases?

A

Tumor cells become progressively more aggressive which usually isn’t seen in other diseases. It is selected for in cancer

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3
Q

What are the stages of tumor progression and what causes them?

A

Normal - Hyperplastic - Dysplastic - Neoplastic - Metastatic

Tumor progression results from waves of mutation followed by clonal expansion

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4
Q

What are the essential alterations in malignant transformation?

A
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5
Q

Define monoclonal and polyclonal tumors.

A

Monoclonal Tumors - tumors that arose from a single cell

Polyclonal Tumors - tumors that arose from several cells

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6
Q

What are the ways to determine if a tumor is monoclonal?

A
  1. Examine the X-inactivation pattern, if all the cells have the same copy of X inactivated then this strongly suggests monoclonal
  2. Examine for chromosomal abnormalities, if all the cells have the same abnormality then this strongly suggests monoclonal
  3. Multiple myeloma cells produce an Ig antibody. If all the antibodies produced are the same then this suggests monoclonal
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7
Q

What are the three primary cancer causing genes and what do they do?

A
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8
Q

What is a proto-oncogene and how can its mutation cause cancer?

A
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9
Q

What are tumor suppressor genes and how can their mutation cause cancer?

A
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10
Q

What is the MAP kinase pathway?

A

It is the signaling pathway by which external growth factors can trigger a cell to grow by activating gene expression within that cell.

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11
Q

List the primary components of teh MAP kinase pathway and describe their function. What can occur is any of these components are mutated

A
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12
Q

What are oncogenes?

A

Mutant or misregulated proto-oncogenes

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13
Q

What type of receptor is the GF receptor of the MAP kinase pathway? How is it activated?

A
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14
Q

How can a GF receptor be oncogenicly activated?

A
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15
Q

What causes Burkitt Lymphoma?

A

A reciprocal translocation event causing the myc proto-oncogene (chromosome 8) to fuse to the IgH locus (chromosome 14). This turns myc into an oncogene because it is now placed under the regulation of the active IgH promoter. This leads to increased myc production causing B-lymphocytes to undergo rapid cell divisions resulting in a malignant phenotype

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16
Q

What causes Chronic Myeloid Leukemia?

A

The Philadelphia Chromosome translocation which is a translocation event between chromosomes 9 and 22 leading to the fusion of the BCR and ABL genes to form a hybrid BCR-ABL fusion protein that acts as an unregulated cytosolic tyrosine kinase. This will result in the cell signal for proliferation and survival being constitutively active.

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17
Q

What is used to treat Chronic Myeloid Leukemia and how does it work?

A

Imatinib mesylate (Gleevec) is a powerful tyrosine kinase inhibitor specific to only a few tyrosine kinases including BCR-ABL. It will bind to the active site of the fusion protein and prevent its activity

18
Q

What makes Ras a proto-oncogene? How can it be oncogenicly activated?

A

It is a GTPase that when activated initiates the phosphorylation cascade in the MAPKinase pathway for cell proliferation. Its overactivity would cause unregulated cell proliferation.

Single point mutations on this protein can eliminate Ras’s intrinsic GTPase activity causing it to be constitutively active.

19
Q

What is a double minute chromosome? Where are they usually found? How can they be visualized?

A

Extrachromosomal fragments of DNA containing an amplified oncogene. Usually seen in aggressive tumors. Usually seen with FISH

20
Q

What is an HSRS and what does it indicate?

A

An abnormal homogeneously staining region of chromosome. It indicates the presence of gene amplificatoin. If this gene is an oncogene it will lead to cancer formation

21
Q

Differentiate a double minute chromosome from a HSRS.

A
22
Q

What causes Wilms Tumor?

A
23
Q

What is a tumor suppressor gene?

A
24
Q

Differentiate between familial and non-familial (sporadic) cancer.

A
  • Sporadic is 10,000 times more likely
  • Familial often has multiple bilateral tumors
  • Familial is present at an earlier age
  • In both forms, only a small portion of cells become cancer
25
Q

What type of gene requires both alleles to be knocked out for cancer to develop?

A

A tumor suppressor gene

26
Q

What are the common mechanisms that could produce the “2nd hit” in a tumor suppressor gene?

A

Non-disjunction

Mitotic Recombination

Gene Deletion

Point mutation

Aberrant methylation

27
Q

How does the Rb protein regulate the G1/S checkpoint?

A
28
Q

Virtually all cancers show _____________________________________ as a result of mutation in one of these genes _________________________________.

A

Dyregulation of the G1-S checkpoint

RB, CDK4, Cyclin D gene, CDKN2A

29
Q

What causes retinoblastoma? How does the presentation of retinoblastoma differ between its familial and sporadic forms?

A

A mutation of the Rb gene on chromosome 13.

The familial form presents with multiple bilateral tumors early on

The sporadic for presents with a single tumor later on

30
Q

List P53s many functions

A
  1. Slows cell cycle (g1 arrest) to allow time for DNA repairs
  2. Increases DNA repair capabilities
  3. If DNA damage is too great it will initiate apoptosis
31
Q

How can p53 activate apoptosis?

A
32
Q

What is Li-Fraumeni syndrome? What causes it?

A

L

33
Q

What is the APC pathway? How does it work?

A

A pathway that controls the expression of growth promoting genes.

When no WNT signal is not present, APC interacts with and phosphorylates ß-catenin causing it to become ubiquitinated and degraded.

When WNT signal is present, APC does not bind ß-catenin and it translocates into the nucleus where it forms a complex with TCF-4 to activate growth promoting genes.

34
Q

What is FAP? What causes it? How does it inherit? What are its symptoms?

A

Familial adenomatous polyposis is a type of colon cancer caused by an autosomal dominant mutation (there are many different mutations) in the APC gene on chromosome 5. Mutant APC cannot bind ß-catenin which means the APC pathway is constitutively on. It presents with >100 adenomatous polyps throughout the distal colon

35
Q

What is Lynch Syndrome? What causes it? What are its symptoms?

A

Lynch Syndrome, or HNPCC, is a hereditary non-poluposis colon cancer caused by a mutation of DNA mismatch repair genes. At least five gene can be responsible but MSH2 on chromosome 2 accounts for ~60% of mutations and MLH1 on chromosome 3 accounts for ~30% of mutations. These cells accumulate mutations at rates up to 1000 times higher than normal. Presents with many colon polyps that progress slowly and exhibit microsatellite instability (short repetitive sequences of DNA)

36
Q

What are mutator genes?

A

Genes/proteins that arent’ directly involved in control of cell division but cause cancer by increase the rate of mutation accumulation (ie - dna repair genes)

37
Q

What disease does each picture show

A

Left - FAP

Right - HNPCC

38
Q

What are the BRCA genes responsible for?

A

DNA repair and apoptosis when DNA can’t be repaired

39
Q

Do cancers caused by the BRCA genes have allelic or locus heterogeneity?

A

Both

Locus heterogeneity because there are two different genes that can cause the cancers, BRCA1 and BRCA2

Allelic heterogeneity because many different muations in the BRCA1 gene can increase the risk of developing cancer

40
Q

Discuss HER-2 and its involvement with cancer and its treatment.

A

HER-2 is the human epidermal growth factor receptor 2 and it binds to EGF to start a signaling pathway that ends with cell growth and proliferation. 30% of breast cancers have HER-2 amplified as double minutes or hsrs. For tumors that are Her2+, Herceptin (an inhibitor of HER-2) is very effective in decreasing tumor cell proliferation

BPM1 Exam 2 - Foundations to Medicine 2 (29 decks)

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