Carcinogenesis : Causes of Cancer

Question 1

What is the strongest association with eating red meat?

Answer 1

Colorectal cancer

Question 2

The categories of human carcinogens are as follows. Give an example for each.
Chemicals
Infectious Agents
Radiation
Minerals
Physiological
Chronic Inflammation

Answer 2

1) Chemicals:
- PAHs (Polycyclic aromatic hydrocarbons)
- nitrosamines

2) Infectious agents
- human papilloma virus
- Helicobacter Pylori

3) Radiation
- UV light
- Radon

4) Minerals
- asbestos
- heavy metals

5) Physiological
- oestrogen
- androgens

6) Chronic Inflammation
- free radicals
- growth factors

Question 3

PAHs are chemical carcinogens. What does it stand for?

Answer 3

Polycyclic aromatic hydrocarbons

Question 4

Aflatoxin is associated with

Answer 4

Liver

Question 5

Alcohol is associated with

Answer 5

Pharynx, Larynx, oesophagus, liver

Question 6

Asbestos is associated with

Answer 6

Lung pleura

Question 7

Xrays are associated with

Answer 7

bone marrow (leukaemia0

Question 8

UV-Light is associated with

Answer 8

skin

Question 9

Oestrogen is associated with

Answer 9

breast

Question 10

Tobacco smoke is associated with

Answer 10

mouth, lung, oesophagus, pancreas, kidney, bladder

Question 11

Hepatitis B virus is associated with

Answer 11

Liver

Question 12

Human papilloma virus is associated with

Answer 12

cervix

Question 13

What are initiators?

Answer 13

carcinogens that are genotoxic that can modify or damage DNA

Question 14

What are promoters

Answer 14

carcinogens that induce proliferation and DNA replication.

Question 15

What are complete carcinogens

Answer 15

They can both initiate (modify DNA) and promote (induce proliferation) e.g. UV light

Question 16

What makes a carcinogen a good promoter?

Answer 16

1) can stimulate 2 rounds of DNA replication requires for mutation fixing
2) can stimulate clonal expansion of mutated cells

Question 17

What are the common genetic abnormalities? (there are 7)

Answer 17

1) Base pair Substitution
2) Frameshift
3) Deletion
4) Gene amplification
5) Chromosomal translocation
6) Chromosomal inversion
7) aneuploidy

Question 18

The term given to “the smallest change in the DNA sequence that can give rise to a change in gene function. They can result in an amino acid substitution (missense) or can introduce a stop condon into the coding sequence of a gene resulting in a truncated protein product”

Answer 18

Point mutation (or base pair substitution)

Question 19

What is a frameshift mutation?

Answer 19

Gain or loss of one to several base pairs that results in a shift in the reading frame of a gene transcript

Question 20

What does aberrent methylation of gene promoters leads to ……..

Answer 20

inactivation of Tumour Suppressor Genes (TSGs)

Question 21

How are Tumour Suppressor Genes most commonly inactivated?

Answer 21

Methylation of gene promotors causes inactivation of TSGs

Question 22

What are oncogenes?

Answer 22

oncogene is a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels.

Question 23

Mutuations in which genes lead to a GAIN of function

Answer 23

Oncogenes

oncogenes have a potential to cause cancer. If there is a mutation in the gene it becomes overactive&raquo_space;>cancer

Question 24

Mutations found in XXX lead to a LOSS of function

Answer 24

Tumour suppressor genes

if there is a mutation in TSGs then it can’t work properly&raquo_space;>cancer

Question 25

what are procarcinogens?

Answer 25

Pro-carcinogens require enzymatic (metabolic) activation before they react with DNA. e.g. PAHs (polycyclic aromatic hydrocarbons)

Question 26

What are direct carcinogens?

Answer 26

Direct carcinogens interact directly with DNA e.g oxygen radicals, UV light

Question 27

What is benzopyrene?

Answer 27

Benzopyrene is a PAH that can be generated through the combustion of most organic material such as meat, tobacco and fuel.
It is a PRO CARCINOGEN.

Question 28

What is also known as Lynch Syndrome?

Answer 28

HNPCC (Hereditary non-polyposis colorectal cancer).

It is an autosomal dominant disorder.