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Test 2 FTM > Lecture 48 + DLA 32 > Flashcards

Lecture 48 + DLA 32 Flashcards

1
Q

What does a mutation in the RB lead to?

A

retinoblastoma and osteosarcoma

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2
Q

What does a mutation in the TP53 gene lead to?

A

Li-fraumenti syndrome

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3
Q

what does a mutation in the APC gene lead to?

A

familial adenomatous polyposis (colorectal cancer)

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4
Q

What does a mutation in the MSH2, MLH1, and PMS1/2 genes do?

A

Hereditary nonpolyposis colon cancer (HNPCC)

colorectal cancer

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5
Q

BRCA1/2 mutation?

A

familial breast or ovarian cancer

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6
Q

NF1 mutation?

A

Neurofibromatosis 1

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7
Q

WT1 mutation?

A

wilm’s tumor

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8
Q

how does wilms tumor occur?

A

it is an autosomal dominant inheritance pattern

loss of function of the WT1 gene (chromosome 11), thus incontrollable growth and differentiation

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9
Q

What is the two hit hypothesis for sporadic cancer?

A

mutations of both tumor suppressor genes must occur before cancer can develop

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10
Q

What is the two hit hypothesis for familial cancer?

A

The first mutation is inherited, thus the second mutation can occur in any cell.

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11
Q

What does the second mutation lead to?

A

loss of heterozygosity

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12
Q

What mechanisms can lead to the second mutation or second hit?

A
  1. loss through non-disjunction
  2. mitotic recombination
  3. gene deletion
  4. point mutation
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13
Q

What is the regulatory protein of the G1/S checkpoint?

A

Rb protein

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14
Q

what is the G1/S checkpoint pathway?

A
  1. growth factor presence leads to the creation of the cyclin/cdk complex
  2. cyclin/cdk phosphorylate Rb
  3. Rb then no longer represses E2F
  4. E2F then activates S-phase genes

no cyclin/cdk complex = no cell division

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15
Q

What does a mutation in the Rb protein do?

A

It does not bind to the E2F protein, thus their is an increase in s-phase genes and unregulated cell division

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16
Q

What does familial cancers look like on a pedigree?

A

seen in all generations

due to dominant traits

17
Q

What is the diff between familial and sporadic retinoblastoma?

A

familial:
multiple tumors
bilateral
early onset

sporadic:
single tumor
unilateral
later onset

18
Q

What are the three functions of the P53 protein?

A
  1. regulate the cell cycle (proliferation)
  2. scan the DNA for errors
  3. apoptosis
19
Q

What does p53 increase the expression of?

A

increases the expression of proteins that lead to apoptosis

20
Q

The normal APC pathway?

A

APC is a component of the WNT signaling pathway

  1. destruction of complex inactivated
  2. beta-catenin not degraded
  3. beta-catenin moves to the nucleus and forms with TCF-4
  4. activates growth promoting genes

when there is no Wnt signal beta-catenin is degraded

21
Q

what happens when APC is mutated?

A

Beta-catenin is never degraded even in the absence of the wnt signal.

thus growth is occuring without the wnt signal

22
Q

FAP vs HNPCC

A 
FAP:
APC mutation
accelerated 
numerous polyps
normal tumor progression 
gatekeeper 
HNPCC:
MSH2 / MLH1 mutation 
normal tumor initiation
fewer polyps 
accelerated tumor progression (microsatellite instability)
caretaker
23
Q

explain BRCA1 and BRCA2

A

involved in DNA repair and apoptosis

allelic heterogenicity is relevant here

usually leads to breast and or ovarian cancer when mutated

24
Q

what are the epigenetic chances in tumor cells?

A

tumor suppressor genes are methylated and deactivated

DNA methylation and histone modifications

25
Q

miRNA’s in cancer cells?

A

more miRNA’s that inhibit tumor suppressor RNA’s

reduction of miRNA’s that could inhibit oncogene RNA

26
Q

roles of epigenetics in tumorigenesis?

A

Silencing of tumor suppressor loci causing cell
overgrowth

Loss of imprinting causing activation of growth
associated genes or oncogenes

MicroRNAs

27
Q

What is an intrinsic pathway of apoptosis?

A
  1. BAX is produced due to DNA damage
  2. BAX goes to the mito
  3. BAX leads to the release of cytochrome C from the Mito and activates apaf-1
  4. Cleavage of procaspases to caspase proteases (activation via a cascade)
  5. apoptosis
28
Q

what does the BCL protein do?

A

inhibits the action of BAX, thus non-apoptotic

29
Q

what three things trigger apoptosis?

A
  1. lack of supply of growth factor (extrinsic pathway)
  2. response to genotoxic stress (intrinsic pathway)
  3. mediated by immune cells (perforin/granzyme pathway)
30
Q

extrinsic pathway of apoptosis?

A
  1. binding to death receptor
  2. adaptors
  3. disc formation
  4. caspase 8 activation
  5. execution pathway
31
Q

perforin/granzyme pathway?

A
  1. cytotoxic T cells go through perforin
  2. leads to granzyme A and B
  3. granzyme B = caspase 10 activation = execution pathway
  4. granzyme A = SET complex = DNA cleavage

Test 2 FTM (28 decks)

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