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Cancer Chromosome > DT: Cancer Genes > Flashcards

DT: Cancer Genes Flashcards

1
Q

What is a subsitution mutation?

A
  • Point mutation
  • Replacing DNA base pair with another
  • Where? -Coding and Non-coding regions
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2
Q

What does point mutations result in?

A
  • Amino acid changes > missense mutations
  • Premature stop codons> nonsense mutations
  • No change > silent mutation
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3
Q

Mutations in non-coding regions affect what?

A
  • Introns
  • Regulatory elements
  • > altering gene expression
  • > cancer contribution
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4
Q

Mutation in protein coding region result in?

A
  • Exons
  • Change in amino acid sequence
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5
Q

Insertion mutations

A
  • Additional nucleotide base added into DNA sequence
  • Disrupts reading frame in the coding region
  • Leads to frameshift mutations
  • Forming abnormal proteins
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6
Q

Deletion mutations

A
  • Removing nucliotide bases in the DNA sequence
  • Frameshift mutations
  • Results in dysfunctional proteins
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7
Q

Duplication mutations

A
  • DNA segment mistakenly repeated
  • Resulting from extra gene copy/ part of gene
  • Overexpression of affected gene
  • Contribute to cancer
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8
Q

Inversion mutations

A
  • DNA segment orientation is reversed within chromosome
  • Disrupts gene function and regulation
  • Lead to cancer
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9
Q

Translocation mutations

A
  • Exchange of genetic material between 2 different chromosomes
  • Or within chromosome
  • > fusion of genes
  • > fusion proteins
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10
Q

Give example of translocation mutation?

A
  • Philadelphia chromosome
  • translocation of chromosome 9 and chromosome 22
  • Resulting fusion gene= BCR-ABL
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11
Q

What is BCR-ABL gene associated with?

A
  • Chronic myeloid leukemia (CML)
  • Acute myloid leukemia (AML)
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12
Q

How does cancer arise?

A
  • ALL -mutations
  • This disrupts normal regulation
  • Affecting cell growth and division
  • Leads to uncontrolled cell division (characteristic of cancer)
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13
Q

Somatic Mutations

A

Acquired mutations
90-95%
Nor inherited, mutations during a persons lifetime, NOT passed down to offspring
> damage to genes

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14
Q

Inherited Mutations

A
  • Germline mutations
  • Genetic change-> any cells (incl.reproductive cells)
  • Passed directly from parent-> offspring
  • 5-10% of cancer cells inherited cancer
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15
Q

Factors for somatic mutations

A
  • Exposure to carcinogens- Tabacco smoke, UV
  • Aging
  • Random Errors in DNA replication
  • > > SPORADIC CANCER common type
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16
Q

What are 2 main groups of cancer genes?

A
  • Oncogenes
  • Tumor suppressor genes
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17
Q

What are oncogenes?

A
  • Mutated gene (spontaneous event) > cancer development
  • Gain of function
  • > acquire new function/overactive
  • > > cell proliferation> uncontrolled cell growth
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18
Q

What are non-mutated gene regions called?

A
  • Proto-oncogenes
  • > Role in normal cell function
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19
Q

Where are oncogenes primarily found?

A
  • Somatic tissues
20
Q

Why is it rare for oncogenes to be present in germline tissues?

A
  • Severely affect embryonic development
  • Lethal
21
Q

What is tumor supressor genes?

A
  • Mutated gene
  • Loses ability to restrain cell growth and division
  • ‘breaks’ cell division
22
Q

How are Tumor sup’ressive’ gene are activated

A
  • Recessive
  • Require 2 copes of allele
  • One copy of inherited
  • Second copy is ACQUIRED
  • > Cancer development
23
Q

What is familial cancer syndrome?

A
  • Allele inherited within families
24
Q

What is the function of tumor supressor gene?

A
  • Genome stability
  • Prevent uncontrolled growth in damaged and abnormal cells.
  • Via apoptosis
25
Q

What happens when tumor supressor genes are mutated?

A
  • Tumor supressor genes are no longer active ‘switched off’
  • Abnormal cell growth persist
  • Cell growth regulation is compromised (no longer functioning)
26
Q

If a copy is inherited what does this mean in terms of cancer development in an individual?

A
  • High susceptibility to cancer if second copy mutated later in life.
27
Q

What is retinoblastoma?

A
  • Rare eye cancer (children)
  • Mutation= RB1= Tumor supressor gene
28
Q
A
29
Q

What is familial adenomatous polyposis (FAP)-APC

A
  • Inherited
  • Polyps- colon and rectum
30
Q

Li-Fraumeni syndrome

A

Mutation- TP53 (tumor supressor gene)
* High risk -> breast cancer, sarcoma, brain tumour

31
Q

Mutated Oncogene act?

A

Dominantly

32
Q
A
33
Q

Family cancers linked to oncogenes

A
  • Multiple endocrine neoplasia Type 2 (MENS)
  • > multiple endocrine tumours
34
Q

What are the mechanisms that activate oncogenes?

A
  • Amplification
  • Translocation
  • Point mutation
    (PAT-O)
35
Q

What is amplification?

A
  • Oncogene amplified
  • > Multiple copies-> genome
36
Q

Can you give example of amplified oncogene?

A
  • Myc oncogene
  • > amplified in cancer cells
  • > increased expression and cell proliferation
37
Q

What is translocation?

A
  • Oncogene fusing with other genes
38
Q

Give example of translocation?

A
  • BCR-ABL fusion gene
  • > chronic myleoid leukemia
  • (chromosome 9 and chromosome 22)
39
Q

Give examples of point mutations that activate oncogenes?

A
  • Ras family of genes
  • > Krad
  • > Nras
  • > Hras

> > Colorectal and lung cancer contributions
(kinase pathway always on)

40
Q

What is Hras?

A

Oncogene

41
Q
A
42
Q

Where is Hras oncogene activated?

A

Bladder carcinoma
>promote uncontrollable cells growth
>cancer development

43
Q

H-Ras

What is the narrowed mutation region?

A
  • Relatively small DNA region
  • 350 BP
  • Activate H-Ras gene in bladder carcinoma
  • Indicated critical genetic changes occurs within soecifc region
44
Q

What did sequencing the H-Ras reveal?

A
  • Point mutation
  • Glycine to Valine amino acid change in the H-Ras protein
45
Q

H-Ras

How did this single point mutation changing glycine to valine affect the function of the H-Ras protein?

A

Promote uncontrolled cell growth
Contribute development in bladder carcinoma

46
Q
A

Cancer Chromosome (1 decks)

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