20. Carcinogenesis - causes of cancer Flashcards Preview

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Flashcards in 20. Carcinogenesis - causes of cancer Deck (71)
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1

Give some examples of occupational carcinogens

- cadmium and nickel
- radon (mining)
- solvents and preservatives (painters and furniture makers)
- tannins (leather footwear manufacture)

2

Give examples of chemical carcinogens

- PAHs
- nitrosamines

3

Give examples of infectious agents as carcinogens

- HPV
- H. pylori

4

Give examples of radiation as a carcinogen

- UV light
- radon

5

Give examples of mineral carcinogens

- asbestos
- heavy metals

6

Give examples of physiological carcinogens

- oestrogen
- androgens

7

What are the carcinogens involved in chronic inflammation?

- free radicals
- growth factors

8

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

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

9

Which organ does aflatoxin target?

Liver

10

Which organs does alcohol target?

Pharynx, larynx, oesophagus, liver

11

Which organ does asbestos target?

Lung pleura

12

Which organ do X-rays target?

Bone marrow (leukaemia)

13

Which organ does UV light target?

The skin

14

Which organ does oestrogen target?

Breast

15

Which organs does tobacco smoke target?

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

16

Which organ does HBV (hepatitis B virus) target?

Liver

17

Which organ does HPV (human papilloma virus) target?

Cervix

18

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

Induce proliferation and DNA replication

19

What is an INITIATOR?

A carcinogen that can modify or damage DNA (genotoxic)

20

What is a PROMOTER

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

21

What is a "complete" carcinogen?

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

22

What does mutation induction (initiation) require?

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

23

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

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

24

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

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

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