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General Pathology > Neoplasia Carcinogenesis > Flashcards

Neoplasia Carcinogenesis Flashcards

1
Q

What are the 4 steps involved in carcinogenesis?

A
  1. Independence from normal control mechanisms
  2. Avoid apoptosis
  3. Immortality
  4. Metastatic capability
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2
Q

What phase is G1 known as in the cell cycle?

A

Resting phase

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3
Q

What phase is G2 known as in the cell cycle?

A

Gap phase

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4
Q

What occurs during S phase of the cell cycle?

A

DNA replication

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5
Q

What occurs during the M phase of the cell cycle?

A

Mitosis

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6
Q

What is a proto-oncogene?

A

Potential oncogene - normal genes that regulate cell growth and differentiation.

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7
Q

What is an oncogene?

A

Activated proto-oncogene - causes cell proliferation and does not recognise growth inhibitory signals = tumor formation.

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8
Q

What is the initiator in the ‘initiator/promoter’ theory?

A

A carcinogen that causes irreversible DNA change that does NOT induce full blown neoplasia in a cell

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9
Q

What is the promoter in the ‘initiator/promoter’ theory?

A

Increase the proliferation of neoplastic cells

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10
Q

Induced neoplasms take a long time due to a multi_____ process and ________ exposure to the agent

A

Induced neoplasms take a long time due to a multi-step process and prolonged exposure to the agent

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11
Q

Initiation results from DNA ______

A

Initiation results from DNA mutation

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12
Q

The promoter does not initiate DNA damage. True/False?

A

True

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13
Q

Name an example of a promoter

A

Hormones
Inflammation/healing
Epigenetic mechanisms

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14
Q

Promoters still have an effect on cells if applied before initiation. True/False?

A

False - they have no effect if applied before initiation

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15
Q

Name 2 things promotion of tumour development results in

A
  1. Permanency of the DNA error

2. Potential for additional errors to develop

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16
Q

Initiation of tumour development can lead to what 4 cell actions?

A
  1. Increased cell proliferation
  2. Decreased cell death
  3. Decreased DNA repair
  4. Increased cell lifespan
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17
Q

The DNA mutation that occurs during initiation must be passed onto daughter cells. True/False?

A

True - Permanent change

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18
Q

Increased mitosis/cell proliferation can occur in which phase of tumour development (initiation or promotion)?

A

Initiation

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19
Q

An increased repair of DNA can occur during initiation. True/False?

A

False - decreased repair of damaged DNA

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20
Q

A _______ in the rate of cell ____ or _____ occurs during initiation of tumour development

A

A decrease in the rate of cell death or apoptosis occurs during initiation of tumour development

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21
Q

What happens in the progression phase of tumour development?

A

stepwise transformation of a benign tumor to a neoplasm and to malignancy.

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22
Q

Progression can be caused by an increased mitotic division/cell replication. True/False?

A

True

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23
Q

Inhibition of ______ can cause progression of tumour development.

A

Inhibition of apoptosis can cause progression of tumour development.

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24
Q

The removal of cell _____ restriction via promoters can cause ______ of tumour development

A

The removal of cell growth restriction via promoter can cause progression of tumour development.

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25
Q

What is aneuploidy?

A

Altered karyotype

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26
Q

What is tumour heterogeneity?

A

Different tumour cells show distinct morphological and phenotypic profiles

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27
Q

Altered cell ____ by inactive gene expression is a factor in causing progression of tumour development

A

Altered cell phenotype by inactive gene expression is a factor in causing progression of tumour development

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28
Q

Name 2 forms of aneuploidy that lead to gene deletions or amplifications in tumour progression

A
  1. Change in chromosome number

2. Altered chromosomes via translocation or deletion

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29
Q

What carcinogenic agent can bring about neoplasia on its own without an initiator?

A

Oncogenic viruses

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30
Q

It requires only a single DNA error to make cells neoplastic, so time is not a factor. True/False?

A

False - multiple DNA errors are needed to make cells neoplastic and time IS a factor

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31
Q

Neoplasia is more common in younger animals. True/False?

A

False

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32
Q

Neoplasia can arise in-utero. True/False?

A

True

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33
Q

_ cell tumours are more common than __ cell tumours

A

B-cell tumours are more common than T-cell tumours

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34
Q

What type of tissue is the source of the greatest number of tumours?

A

Epithelium

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35
Q

Why is epithelial tissue the greatest source of tumour development?

A

Epithelium has the highest turnover rate of an tissue

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36
Q

If tissues have a high turnover rate, why are they more susceptible to cacinogenesis?

A

Higher turnover = more cell divisions = higher chance of replication errors

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37
Q

How does metastasis develop? (2 reasons)

A
  1. Loss of intracellular adhesion

2. Loss of apoptotic control

38
Q

Metastasis has the ability for ______ invasion

A

Metastasis has the ability for vascular invasion

39
Q

There are 3 main transmissible neoplasms. What are they?

A
  1. Transmissible venereal tumour of dogs
  2. Devil facial tumour disease
  3. Transmissible haemocyte neoplasia of molluscs
40
Q

How is devil facial tumour disease transmitted?

A

Biting (mouth, lips, nose)

41
Q

Name the 3 categories of carcinogens

A
  1. Viruses
  2. Radiation
  3. Chemicals
42
Q

What type of RNA virus is a causative agent in carcinogenesis?

A

Retroviruses

43
Q

What type of DNA viruses (2) can cause carcinogenesis?

A
  1. Papillomaviruses

2. Herpesviruses

44
Q

Name 2 types of radiation that can cause cancer?

A
  1. UV light

2. Ionising radiation (X-rays)

45
Q

What is a naturally occurring compound that can cause carcinogenesis?

A

Mycotoxin/aflatoxins

46
Q

What 3 types of chemicals can lead to carcinogenesis?

A
  1. Alkylating compounds
  2. Nitrosamines
  3. Aromatic amines
47
Q

What is the mechanism behind infectious causes of cancer?

A

Induction of chronic inflammation

48
Q

Chronic inflammation leads to the production of reactive _____ and ____ radicals

A

Chronic inflammation leads to the production of reactive oxygen and nitrogen radicals

49
Q

Toxic nitrogen and oxygen radicals cause repetitive cell ____ and _____

A

Toxic nitrogen and oxygen radicals cause repetitive cell damage and repair

50
Q

The repetitive damage and repair of cells caused by toxic oxygen and nitrogen radicals is known as……..

A

Hyperplasia

51
Q

Where are viral oncogenes inserted in the host?

A

Host genome

52
Q

Once inserted into the host genome, viral oncogenes lead to _____ host cell oncogene ________

A

Once inserted into the host genome, viral oncogenes lead to uncontrollable host cell oncogene production

53
Q

A reduction in tumour cell detection and elimination is caused by what in the host?

A

Viral-induced immunosuppression

54
Q

What are xenobiotics?

A

Exogenous chemicals

55
Q

What cells does papillomavirus infect in cattle?

A

Squamous epithelial cells

56
Q

What is the most common actinic tumour of any animal?

A

Squamous cell carcinoma

57
Q

What cell type are the most susceptible to sunlight?

A

Basal cells

58
Q

Why are basal cells more susceptible to sunlight and SCC?

A

Basal cells have a high turnover and are more superficial

59
Q

Name 3 triggers of apoptosis

A
  1. Irreparable DNA damage
  2. Hypoxia
  3. Unrestricted mitosis
60
Q

What is p53?

A

Transcription factor

61
Q

What does p53 mediate?

A

Induction of BAX

Temporary mitotic cycle arrest

62
Q

How does p53 temporarily stop mitosis cycle?

A

Via p21 blocking action of cyclin/CDK complexes

63
Q

___% of human tumours have a p53 gene mutation

A

50% of human tumours have a p53 gene mutation

64
Q

Cytochrome C leakage from mitochondria is an alternative pathway to………

A

Apoptosis

65
Q

Loss of cell anchorage to adjoining cells or intracellular matrix can cause what?

A

Apoptosis

66
Q

The overexpression of C-myc transcription factor can cause ……..?

A

Apoptosis

67
Q

What are telomeres?

A

DNA segments at the end of chromosomes

68
Q

What does telomerase do?

A

Prevents telomere shortening

69
Q

Neoplasms can express telomerase, leading to cell immortality. True/False?

A

True

70
Q

What is a proto-oncogene?

A

Normal gene that encodes proteins to promote mitosis

71
Q

What are oncogenes?

A

Altered proto-oncogenes lacking control mechanisms

72
Q

What are the 3 functions of proto-oncogenes?

A
  1. Codes for growth factors and their receptors
  2. Relay proteins in signal transduction pathways
  3. Transcription factors
73
Q

Oncogenes need a _____ copy to promote mitosis

A

Oncogenes need a single copy to promote mitosis

74
Q

What do tumour suppressor genes encode?

A

Regulatory proteins that inhibit mitosis

75
Q

What is the ‘two hit hypothesis’?

A

Function is lost when both alleles of a gene mutate

76
Q

What type of mutation is the first ‘hit’ in inherited cancers known as?

A

A germline mutation

77
Q

What type of mutation is the second ‘hit’ in inherited cancers known as?

A

Somatic mutation

78
Q

With a mutation, what acts as the promoter?

A

Altered genes

79
Q

Name the 3 genetic mechanisms of tumour suppressor genes? (i.e. how is function lost)

A
  1. Point mutations
  2. Deletions
  3. Recombination
80
Q

When function of mitosis is lost due to tumour suppressor genes, the change in an organism/cell is caused by the modification of gene ________ rather than the alteration of the genetic _____.

A

When function of mitosis is lost due to tumour suppressor genes, the change in an organism/cell is caused by the modification of gene expression rather than the alteration of the genetic code.

81
Q

What is known as the ‘master switch’ (example of tumour suppressor genes)

A

pRB

82
Q

What does pRB do?

A

Controls cells entering into mitosis

83
Q

What is the mechanism that allows pRB to control cells entering/exiting mitosis cycle?

A

Releases/inhibits E2F transcription factor, forcing the cell into the S phase.
Hyperphosphorylation by cyclin/CDK complexes

84
Q

What is p53 known as?

A

Master brake/genome guardian

85
Q

What does p53 do?

A

Causes cell cycle arrest and induces apoptosis after DNA damage

86
Q

What is angiogenesis?

A

New vessel growth

87
Q

Tumours require sufficient blood supply to proliferate. True/False?

A

True

88
Q

What happens when a tumour outgrows its blood supply?

A

Necrosis

89
Q

What growth factors do malignant tumours produce?

A

Vascular endothelial growth factor

Fibroblast growth factor

90
Q

What do the growth factors produced by malignant tumours induce?

A

Formation of capillaries

General Pathology (4 decks)

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