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Cancer Cell Biology Flashcards

(44 cards)

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1
Q

What is a carcinogen?

A

A substance capable of causing cancer in living tissue

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2
Q

What are some way carcinogens react with DNA and cause mutations?

A

Chemically modify bases-point mutation

Strand breaks-deletion, chromosome translocation

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3
Q

What are some causes and risk factors of lung cancer?

A

Air pollution, asbestos, radon, smoking, second-hand smoking

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4
Q

What is a polyp?

A

An encapsulated abnormal outgrowth

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5
Q

What is Wnt and where is it produced?

A

Wnt (Wingless Integrated 1) is a secreted glycoprotein

Produced by the stromal cells at the bottom of the colonic crypts

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6
Q

What is the function of Wnt?

A

To drive proliferation

It is a growth stimulatory pathway

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7
Q

Explain the wnt signaling pathway?

A
  • Wnt binds to the frizzled receptor
  • This causes the phosphorylation of LRP, inducing the translocation of the destruction complex towards the receptor.
  • This releases Beta-catenin which translocates into the nucleus and acts as a transcription factor (increased cell prolideration)
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8
Q

Explain what happens in the absense of the wnt signaling pathway?

A
  • Wnt dosent bind
  • Destruction complex remains together and activates
  • GSK-3 phospharylates Beta-catenin
  • Beta-catenin undergoes ubiquitination and breaks down ( inhibition of proliferation)
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9
Q

What is the destruction complex in the wnt signalling pathway made up of?

A

GSK-3
Axin
Beta-catenin
APC

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10
Q

How does the mutation of APC in the destruction complex lead to cancer?

A
  • loss of function of APC prevents the ubiquination and degredation of the Beta-catenin
  • So can function as transcription factor and increase cell proliferation
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11
Q

What is meant by the multi-steps of cancer?

A

That it is a series of mutations and not just one

Starts off as a small adenoma, then leads to a large adenoma and then cancer

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12
Q

What is sporadic cancer?

A

Cancer due to a random chance/enviromental exposure

-accounts for around 70% of cancers

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13
Q

What is familial cancer?

A

Cancer that occurs in families
-from shared enivromental exposure
-similar genetic background
Accounts for around 20% of cancers

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14
Q

What is hereditary cancer?

A

Cancer due to a inherited genetic mutation
Increased risk of cancer development
-Accounts for around 10% of cancers

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15
Q

What are the 3 main categories of cancer?

A

Sporadic
Familial
Hereditary

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16
Q

What do the hallmarks of cancer represent?

A

They outline the possible biological capabilities that can be aquired during the multistep process of cancer development

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17
Q

What is clonal evolultion in cancer?

A

Where with each mutation the abnormal cell gains selective advantage (heterogeneity) over neighboring cells giving rise to a clonal population

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18
Q

What is tumour heterogeneity?

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A

The observation that different tumour cells can show different mutations and morphological profiles

19
Q

What are cancer critical genes?

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A

All genes whose mutation contributes to the causation of cancer

20
Q

What are the 2 main classes of cancer critical genes?

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A

Proto-oncogenes

Tumour suppressor genes

21
Q

What are proto-oncogenes?

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A

Normal genes within our cells that promtoes cellular proliferation
-the accelerator

22
Q

What occurs when a proto-oncogene mutates?

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A

Proto-oncogenes when mutated, become over activated or overexpressed

  • become an oncogene
  • leads to increased/uncontrolled proliferation
23
Q

What are the 3 mechanisms that produce oncogenes?

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A

Translocation -new promoter region
Gene amplification-multiple copies
Mutation- within control region or within the gene

24
Q

What is the Philadelphia chromosome?

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A

A changed chromosome 22, containing part of chromosome 9 (reciprocal translocation)

25
What is the other name for the Philadelphia chromosome?
The BCR-Abl fusion gene
26
What does the Philadelphia chromosome cause?
Produces increased levels of tyrosine kinase activity | -leads to increased cell proliferation
27
What cancers is the Philadelphia chromosome found in?
Found in Chronic Myeloid Leukaemia (CML) | And in Acute Lymphoblastic Leukaemia (ALL)
28
Are oncogenes dominant or recessive?
Dominant
29
What is the significance of oncogenes being dominant?
There only need to be a mutation in one of the alleles to produce the uncontrolled cell growth -higher chance of loss of function
30
What are tumour suppressor genes?
Normal genes that negatively regulate (supress) cell proliferation -the brakes
31
What occurs when a tumour supressor gene mutates?
Results in a loss of function of the corresponding protein | Cell proliferation not regulated- leads to uncontrollable cell proliferation
32
Is a tumour suppressor gene usually dominant or recessive?
Recessive
33
What is the significance of a tumour suppressor gene being recessive?
A mutation in one allele doesn't result in a loss of function Loss of function requires a mutation in both alleles -less chance of loss of function
34
What is retinoblastoma and how is it caused?
The most common eye cancer in children | -caused by the mutation of the retinoblastoma (Rb) gene
35
What theory did Knudson propose?
The 2 hit hypothesis ( the Knudson hypothesis)
36
What is the 2 hit hypothesis?
That most tumour supressor genes require both alleles to be inactivated, either through mutation or epigenetic silencing, to cause a phenotypic change
37
What are the different mechansims of how a tumour suppressor gene can be inactivated?
-Epigenetic silencing -deletion of both alleles- homozygous deletion -loss of function to both alleles -loss of function to one allele and deletion of another (loss of heterozygosity)
38
What is a germline mutation?
A germline mutation is mutations in germ cells (reproductive cell in the body). These mutations are the only mutations that can be passed to offspring
39
What is a germ cell?
A germ cell is a reproductive cell of the body. Found in egg cells of females and sperm cells of males
40
What are examples of a germline mutation?
``` Retinoblastoma (Rb gene) Breast/Ovary cancer ( BRAC1 and BRAC2 gene) Colorectal cancer (APC) ```
41
What are the different types of point mutation?
Silent Missense Nonsense
42
What is a silent point mutation?
Change in single base | - same amino acid coded for, dosen't affect the function of the protein
43
What is a missense point mutation?
Change in single base | -results in a codon that codes for a different amino acids therefore could or could not affect function of protein
44
What is a nonsense mutation?
Change in base that produces a stop codon | - stops transcription of protein therefore changes the fucntion of that protein

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