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MOD > MOD 20 - carcinogenesis: causes of cancer > Flashcards

MOD 20 - carcinogenesis: causes of cancer Flashcards

1
Q

what are the different categories of human carcinogens

A

chemical, infectious agent , radiation, minerals, physiological, chronic inflammation

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2
Q

what cancer does aflatoxin cause?

A

liver cancer - aflatoxin produced from mould found on corn etc

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3
Q

what cancer does alcohol cause?

A

pharynx, larynx, oesoph, liver

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4
Q

what does asbestos cause

A

lung pleura - eventually cause lung cancer

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5
Q

what cancer does X-ray cause

A

bone marrow (leukaemia)

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6
Q

what cancer does UV light cause

A

skin

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7
Q

what cancer does oestrogen cause

A

breast

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8
Q

what cancer does tobacco cause?

A

mouth, lung, oesophagus,

pancreas, kidney, bladder, etc.

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9
Q

what cancer does HBV cause

A

liver

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10
Q

What cancer does HPV cause?

A

cervix

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11
Q

definition of carcinogen?

A

any agent which significantly increases the risk of developing cancer

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12
Q

definition of initiators in terms of cancer?

A

carcinogen which chemically modify or damage DNA

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13
Q

definition of promoters in terms of cancer?

A

carcinogens which induce proliferation and DNA replication

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14
Q

what is a complete carcinogen

A

a carcinogen which can initiate and promote

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15
Q

what does initiation of mutation requires

A

chemical modification of DNA, replication of moditfied DNA and mis-incorporation by DNA polymerase

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16
Q

why are promotors important?

A

1 - they can stimulate DNA replication required for mutation fixation

2- they can stimulate clonal expansion of mutated cells which enables the accumulation of further mutations

17
Q

how does initiation, promotion and progression lead to cancer?

A

genotoxic initiating agent damages DNA

promoting agent fixes damage as a mutation and converts normal cell into mutant initiated cells

promoting agent stimulates clonal expansion of initated cell to produce benign cancer

further rounds of mutations and clonal expansion allows benign cancer to progress to carcinoma

18
Q

what are some common genetic abnormalities which have potential to cause a tumour?

A

base pair substitution, frameshift, deletion, gene amplification, chromosomal translocation, chromosomal inversion, aneuploidy (the presence of an abnormal number of chromosomes in a cell)

19
Q

how is a section of a gene being switched off

A

methylation of the CpG islands in the promoter sequences

20
Q

how does tumour cells cause the switching off of the tumour suppresser genes

A

by causing malfunction of the methylation of the CpG island in the promoter region of the tumour suppressor genes and so they are switched off

21
Q

what is the most common way of causing the tumour suppressor genes to switch off?

A

aberrent methylation of gene promoters - leads to epigenetic inactivation of the tumour suppressor genes

22
Q

what is oncogenes

A

genes which has the potential to cause cancer

23
Q

what does mutation of the oncogenes lead to?

A

gain of function - Base pair substitutions, amplification, translocations, inversions

24
Q

what does mutation of the tumour suppressor gene lead to?

A

loss of function - Base pair substitutions, frameshifts, deletions, insertions, chromosomal rearrangements, chromosome loss, promoter methylation

25
Q

which one of all the genetic mutation will cause activation of the genes

A

amplification

26
Q

what is direct acting carcinogens

A

interact directly with DNA, e.g. oxygen radicals, nitrosomines, UV light, ionising radiation

27
Q

what is procarcinogens carcinogens

A

require enzymatic (metabolic) activation before they react with DNA, e.g. aromatic amines, polycyclic aromatic hydrocarbons (PAHs)

28
Q

how is benzopyrene produced?

A

through combustion of most organic material such as meat, tobacco and fuel

29
Q

what type of carcinogen is benzopyrene

A

pro-carcinogen

30
Q

which enzyme is required in the transformation of benzopyrene

A

P459 mixed function oxidase

31
Q

what chemical will benzopyrene be turned into

A

BPDE

32
Q

how does BPDE work?

A

react with TP53

33
Q

how is the normal genes be protected?

A

repair process

base - excision repair
nucleotide - excision repair
recombinational repair
mismatch repair

34
Q

which repair process is malfunctioning for HNPCC

A

mismatch repair

35
Q

what are some of the defence against carcinogenesis

A
  • dietary antioxidants, -detoxification -mechanisms
  • DNA repair enzymes
  • apoptotic response to unrepaired genetic damage
  • immune response to infection and abnormal cells
36
Q

what is benzopyrene presence in?

A

tobacco smoke

37
Q

what can alcohol be converted into which can cause DNA damage

A

acetaldehyde

38
Q

what can alcohol do to the body in order to produce cancer

A
  • incr oestrogen and testosterone
  • incr carcinogenic chemical uptake into cells in upper GI
  • redu lev of folate needed for accurate DNA replication
  • can kill surface epithelium leading to unscheduled proliferation
39
Q

what can oestrogens casuse

A

stimulate cell division and induce DNA damages

MOD (19 decks)

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