Lecture 5: Mutation and Cancer Flashcards

1
Q

Gene Mutations Classification:

  • mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body
A

Inherited (germ line)

-These mutations are also called germline mutations because they are present in the parent’s egg or sperm cells, which are also called germ cells

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2
Q

Gene Mutations Classification:

  • mutations occur at some time during a person’s life
  • present only in certain cells, not in every cell in the body.
  • These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division.
A

Acquired (somatic/sporatic)

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3
Q

Can genetic mutations in somatic cells (cells other than sperm or egg cells) be passed on the next generation?

A

No

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4
Q

What are the types of mutations at the chromosomal level?

A
  • Deletions
  • Duplications
  • Inversions
  • Translocations t[#,#]
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5
Q

d9p

A

Acute Lymphoblastic Leukemia

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6
Q

d13q14

A

Retinoblastoma

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7
Q

Rare form of cancer that rapidly develops from the immature cells of a retina, the light-detecting tissue of the eye. It is the most common malignant cancer of the eye in children.

A

Retinoblastoma

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8
Q

Philadelphia Chromosome-
t(9:22)

A

Chronic Myelogenous Leukemia(CML)

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9
Q

most common variant: t(8;14)(q24;q32)

A

Burkitts Lymphoma

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10
Q

______ encodes a cytoplasmic tyrosine kinase

A

C-abl

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11
Q

____ promotes oligomerization

A

Bcr

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12
Q

________ fusion promotes activation of abl by oligomerization induced autophosphorylation.

A

Bcr-abl

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13
Q

Philadelphia chromosome –
translocation of chr ____ and ____

A

9, 22

-Translocation resulting in fusion of 2 genes with alters structure of normal c-abl protein

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14
Q

Burkitts Lymphoma-most Common Variant
T….

A

(8;14)(q24;q32)

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15
Q

Burkitts Lymphoma-most Common Variant
T(8;14)(q24;q32):

____ is brought under the
transcriptional control of the IG enhancer elements leading to its constitutive transcriptional deregulation.

A

MYC

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16
Q

Associated with the Epstein-Barr Virus (EBV) in nearly 100% of cases in endemic form in central Africa.

A

Burkitts Lymphoma

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17
Q

Burkitts Lymphoma:

In the sporadic forms (occur in Western countries), EBV is present in approximately ___% of cases and in ____% of immunodeficiency associated cases

A

30, 40

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18
Q

Type of mutation at the DNA level.

  • transition (purine for purine, pyrimidine for pyrimidine)
  • transversion (purine for pyrimidine)
A

Base substitutions (Point Mutation)

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19
Q

Mutation type at the DNA level leads to risk factor and/or risk marker in
disease

A

SNP

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20
Q

Type of mutations at the DNA level

A
  • Base substitutions (Point Mutation)
  • Frame shift mutation
  • Deletion
  • Insertion
  • SNP (when leads to risk factor and/or risk marker in
    disease)
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21
Q

Consequences Of Point Mutations

A

-Silent
-Missense*
-Nonsense-change to stop codon

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22
Q

Examples of Missense point mutation

A

hemaglobinopathies (sickle cell, T for A; glutamic acid to
valine)

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23
Q

Examples of nonsens-change to stop codon mutations

A
  • Alpha thalassemias

-decreased protein produced (alpha vs beta globin)
-Constant Spring: from stop codon to glutamine @ 142 (TAA to
CAA) in alpha-thalassemia

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24
Q

from stop codon to glutamine @ 142 (TAA to
CAA) in alpha-thalassemia

A

Constant Spring

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25
Q

Fragile X: FMR-1(fragile -X mental retardation protein:

Premutation alleles generally considered to be between ____ to ____ repeats in length.

A

55, 200

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26
Q

Fragile X: FMR-1(fragile -X mental retardation protein:

Excessive amplification of a base triplet normally repeated only a few to 50 times, most commonly in the _____________.

A

5’ untranslated region of FMR1

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27
Q

Fragile X: FMR-1(fragile -X mental retardation protein:

Fragile X: FMR-1(fragile -X mental retardation protein: > _____ repeats of CGG)

A

200

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28
Q

Huntingtons Disease
Caused by the length of a repeated section (____, codes for _____) of a gene exceeding a normal range.

A

CAG, Gin

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29
Q

Huntington’s Disease:

The HTT gene is located at ________.

A

4p16.3

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30
Q

> 40 trinucleotide repeats – full penetrance ie. the proportion of individuals carrying a particular variant of a gene (allele or genotype) that also expresses an associated trait (phenotype)

A

Huntington’s Disease

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31
Q

Epstein-Barr virus, one of the herpes viruses:

Burkitt’s Lymphoma-involves the fusion of

A

c-myc, IGH

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32
Q

Epstein-Barr virus:

Causes infectious mononucleosis and linked to what two cancers?

A

non-Hodgkin lymphomas and nasopharyngeal cancer.

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33
Q

The cancer is thought to be due to the pro-oncogenic effect of viral DNA
incorporated into host lymphocyte DNA

A

Human T-cell Leukemia (HTLV-1)

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34
Q

Long-standing infection with the hepatitis ___ or ____ viruses can lead to cancer of the liver

A

B, C

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35
Q

The Kaposi’s sarcoma-associated herpesvirus (KSHV), is associated with

A

non-Hodgkin lymphoma

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36
Q

Early genes of HPV:

E6 —>

A

transforming protein; causes p53 degradation

37
Q

Early genes of HPV:

E7 —->

A

transforming protein; interferes with Rb binding

38
Q

HPV:

E___ being largely responsible for driving cell proliferation and E__ for enhancing cell survival

A

7, 6

39
Q

HPV: the combination of E6 and E& is a very potent inducer of…

A

keratinocyte immortalization

40
Q

Cancer:

a gene which in certain circumstances can transform a cell into a tumor cell.

Usually a gain of _______

A

Oncogenes

usually a gain of function and dominant

41
Q

Cancer:

genes normally arrest cell
division.

Usually a loss of

A

Tumor suppressors

usually a loss of
function and recessive

42
Q

Proto-oncogenes and oncogenes have italicized three letter designations, such as ____.

A

ras

43
Q

An oncogene that occurs within a virus has the prefix “__”
* An oncogene that occurs within a cell has the prefix “__”

A

“v” v-ras

“c” c-ras

-Proto-oncogenes and oncogenes have italicized three letter designations, such as ras.

44
Q

A protein that a c-proto-oncogene or c-oncogene encodes has the same
three letter designation as the v-proto-oncogene or v-oncogene.
However, the term is not ________, and the first letter is capitalized. Ras

A

italicized

45
Q

Dominantly acting gene involved in up-regulated cell growth and
proliferation responsible for tumor development

Derived from normal cellular genes (by viral enhancement, mutation,
inappropriate overexpression) that function in cell growth and division

A

Oncogenes

46
Q

Human Oncogenes:

sis function?

A

growth factor, platelet-derived growth factor

(breast cancer)

47
Q

Human Oncogenes:

Her-2/neu (receptors) function?

A

protein kinase

(breast cancer)

48
Q

Human Oncogenes:

abl (intracellular signaling) function?

A

tyrosine kinase

(chronic myeloid leukemia)

49
Q

Human Oncogenes:

N-ras (intracellular signaling) function?

A

signal transduction

(many cancers)

50
Q

Human Oncogenes:

c-myc (nuclear protein) function?

A

nuclear protein, initiate cell cycle

(leukemia, Burkitt’s lymphoma)

51
Q

Locations of proto-oncogenes?

A

can be present in any chromosomes

52
Q

Code for proteins that regulate cell-cycle progression, and hold cells in quiescence or induce apoptosis if conditions are unfavorable for cell cycle progression

A

Tumor Suppresser Genes (Anti-oncogenes)

53
Q

mutation in P__ alteration is associated with almost all cancers

A

53

54
Q

Two tumor suppressor genes?

A

-Retinoblastoma (Rb)
-p53

55
Q

Knudson hypothesis is also know as….

A

two-hit hypothesis or multiple-hit hypothesis

56
Q

cancer is the result of accumulated mutations to a cell’s DNA

A

Knudson Hypothesis

57
Q

Knudson’s hypothesis refers specifically to the _______________ of tumor
suppressor genes. A mutation in both alleles is required, as a single
functional TSG is usually sufficient.

A

heterozygosity

58
Q

Carcinogenesis (the development of cancer) depended both on…

A

the activation of proto-oncogenes (genes that stimulate cell proliferation)
and on the deactivation of tumor suppressor genes (TSG), which are genes that keep proliferation in check

59
Q

Retinoblastoma (Rb) –> deletion in…

A

long arm (q) of chromosome
13 (d13q14)

60
Q

Retinoblastoma (Rb):

is a tumor suppresser that controls the cell cycle

A

Retinoblastoma protein (RB)

61
Q

Retinoblastoma is inherited how?

A

autosomal recessive inheritance

62
Q

What are the two forms of Retinoblastoma?

A

Inherited form:
* one chromosome has deletion
* second copy lost by somatic mutation

Sporadic form: both copies lost by individual somatic mutations

63
Q

Normal Functions Of TP53 Protein…

A

G1 growth arrest
Induces apoptosis following DNA damage
Inhibits tumor cell growth
Inhibits S phase
Represses transcription factors for growth and
replication
Cancer may involve deletion, mutation, or functional

64
Q

Cancer causes:

Point mutation within the proto-oncogene (RAS-____)

A

GTP

65
Q

Cancer causes:

Genetic rearrangements

within the coding sequence of the proto-oncogene (c-____ in CML)
Genetic rearrangements outside the coding sequence of the protooncogene
(c-____ Burkitt’s Lymphoma)

A

abl/bc

abl/bc

66
Q

Cancer causes:

Amplification and/or over expression of the proto-oncogene

 insertion of a strong viral ________
gene copy number variation

A

promotor

67
Q

Mutations outside of the structural gene may cause over expression
(high enhancer binding, decreased repressor binding)

A

Epigenetic overexpression of genes

68
Q

Other Causes Of Cancer:

The formation of new blood vessels
 . Tumors need blood vessels to grow and spread.
 The physiological process through which new blood vessels form from pre-existing vessels.
 Different from vasculogenesis, which is the de novo formation of endothelial cells from
mesoderm cell precursors

A

Angiogenesis

-VEGF, VEGF-R, angiopoietin-2, Tie1, Tie2 etc

69
Q

TSP-1, TSP-2 and
Angiostatin

A

Angiogenesis inhibitors for cell migration, proliferation, adhesion

70
Q

*BRCA1, BRCA2

A

Breast and ovarian cancer

71
Q

*bcr-abl

A

chronic myelogenous leukemia

72
Q

*bcl-2

A

B-cell lymphoma

73
Q

*HER2/neu (erbB-2)

A

breast cancer, ovarian cancer, others

74
Q

*N-mye

A

Neuroblastoma

75
Q

*EWS

A

Ewing tumor

76
Q

*C-myc

A

Burkitt lymphoma, others

77
Q

*p53

A

Brain tumors, skin cancers, lung cancer, head and neck cancers, others

78
Q

*MLH!, MSH2

A

colorectal cancers

79
Q

*APCC

A

colorectal cancers

80
Q

*RBI

A

Retinoblastoma (many different cancers)

81
Q

*P53

A

Li-Fraumeni Syndrome (sacromas, brain tumors, leukemia)

-many different cancers

82
Q

*INK4a

A

Melanoma (many different cancers)

83
Q

*APC

A

Colorectal cancer (due to familial polyposis)

-most colorectal cancers

84
Q

*MLH1, MSH2, or MSH6

A

Colorectal cancer (without polyposis)

-colorectal, gastric, endometrial cancers

85
Q

*BRCA1, BRCA2

A

Breast and/or ovarian

(only rare ovarian cancers)

86
Q

*WTI

A

Wilms Tumor

87
Q

*NF1, NF2

A

Nerve tumors, including brain

-small numbers of colon cancers, melanomas, neuroblastomas)

88
Q

*VHL

A

Kidney cancer

-certain types of kidney cancers)

89
Q

For the most part, cancer arises from a single cell, that is, cancer is a _________ disease. The average human being contains about 1014
cells (i.e., 100,000,000,000,000 cells), any one of which could, in
principle, become a cancer cell, if it acquired the right sort of mutations while it still had the potential to proliferate.

A

clonal

Therefore, the cancer cell arises and progresses once out of a
possible 10 14 cellular targets. That only happens in 1 in 3 people.
Even then it usually takes 60 or 70 years to occur.