MOD 20 - carcinogenesis: causes of cancer Flashcards Preview

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Flashcards in MOD 20 - carcinogenesis: causes of cancer Deck (39):
1

what are the different categories of human carcinogens

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

2

what cancer does aflatoxin cause?

liver cancer - aflatoxin produced from mould found on corn etc

3

what cancer does alcohol cause?

pharynx, larynx, oesoph, liver

4

what does asbestos cause

lung pleura - eventually cause lung cancer

5

what cancer does X-ray cause

bone marrow (leukaemia)

6

what cancer does UV light cause

skin

7

what cancer does oestrogen cause

breast

8

what cancer does tobacco cause?

mouth, lung, oesophagus,
pancreas, kidney, bladder, etc.

9

what cancer does HBV cause

liver

10

What cancer does HPV cause?

cervix

11

definition of carcinogen?

any agent which significantly increases the risk of developing cancer

12

definition of initiators in terms of cancer?

carcinogen which chemically modify or damage DNA

13

definition of promoters in terms of cancer?

carcinogens which induce proliferation and DNA replication

14

what is a complete carcinogen

a carcinogen which can initiate and promote

15

what does initiation of mutation requires

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

16

why are promotors important?

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

how does initiation, promotion and progression lead to cancer?

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

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

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

19

how is a section of a gene being switched off

methylation of the CpG islands in the promoter sequences

20

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

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

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

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

22

what is oncogenes

genes which has the potential to cause cancer

23

what does mutation of the oncogenes lead to?

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

24

what does mutation of the tumour suppressor gene lead to?

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

25

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

amplification

26

what is direct acting carcinogens

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

27

what is procarcinogens carcinogens

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

28

how is benzopyrene produced?

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

29

what type of carcinogen is benzopyrene

pro-carcinogen

30

which enzyme is required in the transformation of benzopyrene

P459 mixed function oxidase

31

what chemical will benzopyrene be turned into

BPDE

32

how does BPDE work?

react with TP53

33

how is the normal genes be protected?

repair process

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

34

which repair process is malfunctioning for HNPCC

mismatch repair

35

what are some of the defence against carcinogenesis

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

36

what is benzopyrene presence in?

tobacco smoke

37

what can alcohol be converted into which can cause DNA damage

acetaldehyde

38

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

- 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

what can oestrogens casuse

stimulate cell division and induce DNA damages