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Unit 8 > Cancer and the environment > Flashcards

Cancer and the environment Flashcards

1
Q

What is neoplasia?

A

Idependant growth of an abnormal cell/tissue, more rapid than normal tissue and continues when growth factor signalling is removed

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2
Q

What are the three main broad category of factors contributing to why some people are more likley to develop cancer than others?

A

1) hereditary factors
2) Environment/lifestyle
3) Age

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3
Q

What factor interact the contribute to the development of cancers?

A

Host genetics are influenced by
Exogenous factors (radiation)
Endogenous process (semi conservative replication)

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4
Q

What environmental factors can increase risk of cancer?

A

Exposure to carcinogenic substances
Radiation
Oncogenic viruses

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5
Q

What lifestyle factors are most commonly associated with cancer risk?

A

Diet
Smoking
Weight
Exercise

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6
Q

What exogenous sources can cause DNA damage?

A

Chemicals and radiation

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7
Q

What endogenous processes can cause DNA damage?

A

Cellular metabolism
Replication stress
Spontaneous mutation

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8
Q

What are sources of endogenous mutations?

A

Errors in DNA replication by DNA polymerase
Deamination (cytosine to uracil)

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9
Q

What exogenous forces can induce cancer mutation?

A

Exposure to endogenous carcinogens (from food or metabolism)
Exposure to environmental carcinogens

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10
Q

What are the different ways that carcinogens can cause mutations?

A

Chemically modify bases - point mutations
Strand break - deletion, chromosome translocation mutation

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11
Q

Give an example of a carcinogenic polycyclic aromatic hydrocarbon and where it might be found.

A

Cigarette smoke and burnt toast
Contains benzo[a]pyrene

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12
Q

How does benzo[a]pyrene cause DNA damage?

A

Activates by cytochrome p450
Large and complicated metabolic pathway
Intercalates into DNA by forming adducts by covalently bonding to adenine and guanine bases.
Mutated strand is replicated results in transversion mutation in new daughter strand
New daughter strand is then replicated - results in transversion from original base in new strand
Overall effect is a transversion mutation at same base number in each DNA strand
These mutations accumulate and can affect gene expression.

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13
Q

How does UV lead to DNA damage?

A

Sun beds are a risk for Direct absoprtion of IV
Results in cross linking of adjacent thymine bases (thymine-thymine pyrimidine dimer)
This inhibits DNA polymerases

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14
Q

How does ionising radiation lead to DNA damage?
How are you exposed to it?

A

Direct and indirect effects results in single and double stranded DNA strand breaks
Exposure is from underground radon gas, medical procedures, cosmis radiation and radioactive sites

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15
Q

What types of cancer are ionising radiation associated with?

A

Leukemia
Breast
Thyroid

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16
Q

What types of cancer are UV radiation associated with?

A

Basal call carcinoma
Squamous cell carcinoma
Melonoma

17
Q

How are people normally exposed to polycyclid hydrocarbons are what cancers are these related to?

A

Buidling, fuel and dye
Related to skin, lung and bladder cancer

18
Q

How are people normally exposed to aromatic amines 2-napthylamine?
What cancers is it linked to?

A

Found in rubber and plastic
Bladder

19
Q

How are people normally exposed to benzene?
What cancer is it related to?

A

Found in drugs, plastic, rubber and dyr
Linked to leukemia

20
Q

How are people normally exposed to asbestos and what cancer is it related to?

A

Construction (insulation in ships and buildings)
Mesothelioma

21
Q

In relation to lung cancer what are the biggest risk factors?

A

Majority of risk factors are avoidable environmental exposures
1) smoking
2) radon
3) asbestos
4) passive tobacco
5) genetics
6) other lung diseases
7) lung radiation in the chest area

22
Q

What is xeroderma pigmentosum?

A

Autosomal recessive inherited condition
Mutation results in defects in NER (nucletoide excision repair).
have a higer sensitivity to sunlight, 1000x increase in skin cancers
More common amongst the Japanese population

23
Q

What viral infections are linked to cancer?
What types of cancer?

A

HPV - cervical cancer
Hepatitis B/C - liver cancer
Epstein-Barr virus - Burkitt lymphoma
HIV - kaposi sarcoma

24
Q

How does HPV16 increase the risk of cervical cancer?

A

Produces two oncoproteins E6 and E7
E6 - binds to Rb results in the release of E2F1
E7 - binds to p53, degrades p53 so TSG function is lost

25
Q

What are the different methods of DNA repair?

A

Base excision repair
Nucleotide excision repair
DNA double stranded breaks repair

26
Q

What is the process of base excision repair?

A

Removes modified DNA bases such as adducts

27
Q

What is the process of nucleotide excision repair?

A

Repairs bulky DNA distortiona
Involves xeroderma pigmentosum protein

28
Q

How are DNA double stranded breaks repaired?

A
  1. rapid non-homylogous end joining
  2. slower homologous recombinanat repair involving BRCA.

Unit 8 (22 decks)

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