Carcinogenesis : Causes of Cancer Flashcards
What is the strongest association with eating red meat?
Colorectal cancer
The categories of human carcinogens are as follows. Give an example for each. Chemicals Infectious Agents Radiation Minerals Physiological Chronic Inflammation
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
PAHs are chemical carcinogens. What does it stand for?
Polycyclic aromatic hydrocarbons
Aflatoxin is associated with
Liver
Alcohol is associated with
Pharynx, Larynx, oesophagus, liver
Asbestos is associated with
Lung pleura
Xrays are associated with
bone marrow (leukaemia0
UV-Light is associated with
skin
Oestrogen is associated with
breast
Tobacco smoke is associated with
mouth, lung, oesophagus, pancreas, kidney, bladder
Hepatitis B virus is associated with
Liver
Human papilloma virus is associated with
cervix
What are initiators?
carcinogens that are genotoxic that can modify or damage DNA
What are promoters
carcinogens that induce proliferation and DNA replication.
What are complete carcinogens
They can both initiate (modify DNA) and promote (induce proliferation) e.g. UV light
What makes a carcinogen a good promoter?
1) can stimulate 2 rounds of DNA replication requires for mutation fixing
2) can stimulate clonal expansion of mutated cells
What are the common genetic abnormalities? (there are 7)
1) Base pair Substitution
2) Frameshift
3) Deletion
4) Gene amplification
5) Chromosomal translocation
6) Chromosomal inversion
7) aneuploidy
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”
Point mutation (or base pair substitution)
What is a frameshift mutation?
Gain or loss of one to several base pairs that results in a shift in the reading frame of a gene transcript
What does aberrent methylation of gene promoters leads to ……..
inactivation of Tumour Suppressor Genes (TSGs)
How are Tumour Suppressor Genes most commonly inactivated?
Methylation of gene promotors causes inactivation of TSGs
What are oncogenes?
oncogene is a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels.
Mutuations in which genes lead to a GAIN of function
Oncogenes
oncogenes have a potential to cause cancer. If there is a mutation in the gene it becomes overactive»_space;>cancer
Mutations found in XXX lead to a LOSS of function
Tumour suppressor genes
if there is a mutation in TSGs then it can’t work properly»_space;>cancer
what are procarcinogens?
Pro-carcinogens require enzymatic (metabolic) activation before they react with DNA. e.g. PAHs (polycyclic aromatic hydrocarbons)
What are direct carcinogens?
Direct carcinogens interact directly with DNA e.g oxygen radicals, UV light
What is benzopyrene?
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.
What is also known as Lynch Syndrome?
HNPCC (Hereditary non-polyposis colorectal cancer).
It is an autosomal dominant disorder.
