Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

EMS - MoD > 20. Carcinogenesis - causes of cancer > Flashcards

20. Carcinogenesis - causes of cancer Flashcards

(71 cards)

Start Studying
1
Q

Give some examples of occupational carcinogens

A
  • cadmium and nickel
  • radon (mining)
  • solvents and preservatives (painters and furniture makers)
  • tannins (leather footwear manufacture)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Give examples of chemical carcinogens

A
  • PAHs

- nitrosamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Give examples of infectious agents as carcinogens

A
  • HPV

- H. pylori

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give examples of radiation as a carcinogen

A
  • UV light

- radon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give examples of mineral carcinogens

A
  • asbestos

- heavy metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give examples of physiological carcinogens

A
  • oestrogen

- androgens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the carcinogens involved in chronic inflammation?

A
  • free radicals

- growth factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

There is a very wide variety of agents implicated in carcinogenesis. What do they all have in common?

A

Prolonged exposure to each of these agents can lead to the accumulation of genetic alterations in clonal populations of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which organ does aflatoxin target?

A

Liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which organs does alcohol target?

A

Pharynx, larynx, oesophagus, liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which organ does asbestos target?

A

Lung pleura

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which organ do X-rays target?

A

Bone marrow (leukaemia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which organ does UV light target?

A

The skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which organ does oestrogen target?

A

Breast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which organs does tobacco smoke target?

A

Mouth, lung, oesophagus, pancreas, kidney, bladder etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which organ does HBV (hepatitis B virus) target?

A

Liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which organ does HPV (human papilloma virus) target?

A

Cervix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Carcinogen can also by non-genotoxic. What does this mean?

A

Induce proliferation and DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is an INITIATOR?

A

A carcinogen that can modify or damage DNA (genotoxic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a PROMOTER

A

A carcinogen that can induce proliferation and DNA replication (non-genotoxic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a “complete” carcinogen?

A

A carcinogen that can both initiate and promote. eg. UV light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does mutation induction (initiation) require?

A
  • chemical modification of DNA

- replication of modified DNA and mis-incorporation by DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

DNA polymerases make mistakes at a very low but significant rate. What does this result in?

A

Accumulation of genetic variation or polymorphisms in coding and non-coding sequences in the genome. Some of these changes are deleterious (mutations)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How might chemical modification of the nucleotides involved in base-pairing occur?

A

Through environmental insult or through the action of endogenous reactive molecules such as free radicals produced by normal physiological processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Agents that are good promoters contribute to carcinogenesis in 2 important ways. What are they?
- stimulate the 2 rounds of DNA replication required for mutation fixation - stimulate clonal expansion of mutated cells, which enables the accumulation of further mutations
26
Give an example to explain the stages of initiation, promotion and progression
- mouse skin tumour model - genotoxic initiating agent damages DNA - promoting agents fixes damage as a mutation and converts normal cell into mutated initiated cell - promoting agent stimulates clonal expansion of initiated cell to produce papillomas - further rounds of mutations and clonal expansion allows papilloma to progress to carcinoma
27
What makes DNA replication a more error-prone process?
DNA damage DNA replication in the presence of DNA damage is an error-prone process that can result in permanent changes in DNA sequence
28
Repeated treatment with promoting agents/ exposure to exogenous or endogenous mutagens can result in what?
Gradual accumulation of mutations
29
Exogenous mutagens are environmental and endogenous mutagens occur naturally within cells. Give examples of the latter
- oxygen radicals | - lipid metabolism byproducts
30
Give some common genetic abnormalities
- base pair substitution - frameshift - deletion - gene amplification - chromosomal translocation - chromosomal inversion - aneuploidy
31
What is a base pair substitution also known as?
Point mutation
32
Explain base pair substitutions/point mutations
- smallest change in DNA sequence that can give rise to change in gene function - can result in amino acid substitution (missense) - or can introduce stop codon resulting in truncated protein product
33
What is a frameshift mutation?
Gain or loss of one to several base pairs that results in a shift in the reading frame of a gene transcript
34
What can gene amplification result in?
A cell having anything up to a hundred copies of a gene that it would normally only have two copies of
35
How can we illustrate that some chromosomes are present in appropriate numbers/exchange of material?
By chromosomal painting
36
Chr 9:22 exchange is a specific translocation. What is it known as and what is it associated with?
Philadelphia chromosome Associated with chronic myeloid leukaemia
37
Chromosomal translocations can result in what?
- genes being moved to a more transcriptionally active region of the chromosome - genes being recombined into new gene fusions
38
What is aneuploidy?
Any departure from the normal structure or number of chromosomes
39
How many cancer genes have been found with translocations?
about 300 of the 500 cancer genes
40
What causes epigenetic inactivation of TSGs? (most commonly)
Abherrent methylation of gene promoters (happens in in tumours)
41
Mutations found in oncogenes lead to what? | Mutations found in TSGs lead to what?
Mutations found in oncogenes lead to a gain in function Mutations found in TSGs lead to a loss of function
42
What are direct acting carcinogens?
Interact directly with DNA eg. oxygen radicals, nitrosamines, UV light, ionising radiation
43
What are procarcinogens?
Require enzymatic (metabolic) activation before they react with DNA eg. aromatic amines, polycyclic aromatic hydrocarbons (PAHs)
44
Are the majority of carcinogens that we ingest direct acting or procarcinogens?
The majority are pro carcinogens and require metabolic activation by enzymes that normally function in the detoxification and excretion of toxic chemicals
45
The majority of carcinogens that we ingest require metabolic activation by enzymes that normally detoxify and excrete toxic chemicals. In what way does thin introduce a genetic influence to our sensitivity to cancer?
People who activate a particular chemical more efficiently are more likely to get cancer But those who excrete the activated chemical less efficiently are also more likely to get cancer
46
What are the products in the metabolic activation of benzopyrene?
Benzo pyrene Benzo pyrene 7,8-epoxide Benzo pyrene 7,8-dihydrodiol Benzy pyrene 7,8-diol, 9,10-epoxide Ultimate carcinogen = BPDE
47
What are the enzymes involved int he activation of benzopyrene?
P450 mixed function oxidases Epoxide hydrolase P450 mixed function oxidases
48
Give a classic example of a pro carcinogen and state how it can be generated
Benzopyrene Can be generated through the combustion of most organic material such as meat, tobacco and fuel
49
BPDE causes mutation in which gene?
TP53 | seen in this gene in the lung tumours of smokers
50
What are the 4 general stages in DNA damage and repair?
1. Damaging agent 2. DNA lesions 3. Repair process 4. Disease syndrome
51
Give a pathway from carcinogen exposure to cancer
- carcinogen exposure - metabolic activation (eg. cytochrome P450s) - DNA damage (- DNA repair) - DNA replication - DNA mutation (eg. in proto-oncogene or tumour supressor gene) - progression - cancer
52
Rather than metabolic activation leading to DNA damage, what else may occur?
Detoxification Excretion (eg. glutathione S-transferase)
53
At which stages of the pathway from carcinogen exposure to cancer may genetic modulation occur?
- metabolic activation - detoxification and excretion - DNA repair (may explain why exposure does not always lead to cancer)
54
Give some defences against carcinogenesis
- dietary antioxidants - detoxification mechanisms - DNA repair enzymes - apoptotic response to unprepared genetic damage - immune response to infection and abnormal cells
55
Which cancers is alcohol linked to?
``` Oral Oesophageal Pharynx Larynx Breast Bowel Liver (Pancreatic) ```
56
What is alcohol converted into that can cause DNA damage?
Acetaldehyde
57
Alcohol increases levels of which hormones?
Oestrogen and testosterone
58
Alcohol increases the uptake of what?
Carcinogenic chemicals into cells within the upper GI
59
Alcohol reduces levels of what?
Folate, needed for accurate DNA replication
60
Alcohol can kill what?
Surface epithelium leading to unscheduled proliferation
61
All of the strongest risk factors for breast cancer are associated with what?
Increased exposure to oestrogen - can both stimulate cell division and induce DNA damage
62
Breast cancer risk decreases 20% for what?
Risk decreases 20% for each year that menarche is delayed
63
What procedure leads to 90% decrease in risk of breast cancer?
Oopherectomy | removal of ovaries
64
What procedure reduces incidence of prostate cancer?
Orchidectomy | removal of a testis
65
Which types of chronic inflammation have an association with cancer?
- colitis - hepatitis - Barret's oesophagus - metaplasia - gastritis - gallstones
66
Inflammatory response results in a 'double whammy'. What does this mean?
- DNA damage from release of free radicals by immune cells - initiation - growth factor induced cell division to repair tissue damage - promotion
67
Which cell is key in the link between inflammation and cancer?
Tumour-associated macrophages (TAMs)
68
What do TAMs release?
- TNFa - ROS - RNS
69
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are released by TAMS. What do they do?
They can act as complete carcinogens, resulting in mutation by damaging DNA and stimulating proliferation through induction of growth factors ROS can also induce fibroblasts to undergo autophagy, which releases important nutrients that tumour cells can "feed" on
70
TNFa is also released by TAMs. Why does this do?
It is a cytokine that induces and maintains the inflammatory response
71
What are TAMS recruited by?
Recruited by cytokines released by tumour cells

EMS - MoD (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions