Neoplasia 3 Flashcards
Causes of neoplasia
Intrinsic vs extrinsic
Much of the increased cancer incidence over the last century is due to ?
intrinsic: age, sex, heridetery
Extrinsic: environemnt, lifestyle
Prolonged life span!
About 30% of cancer deaths are due to the 5 leading behavioural and dietary risks:
- high bMI
- Less fruit and veggie intake
- increased tobacco
- alcohol use
- lack of moving
Explain how migration studies illustrate the relative contribution of intrinsic and extrinsic factors
?
Extrinsic carcinogens agents fall into 3 main categories: list them
- infection
- radiation
- chemicals
what is the marvellous story behind 2-napthylamine?
what type of cancer does it cause?
2-napthylamine is an Industrial carcinogen used in the dye manufacturing industry.
it was a good starting material for the chemical “aniline purple” which was used for colour dye for ppl’s clothes.
2-napthylamine causes bladder carcinoma
those ppl working in those factories soon deveoped bladder cancer!
This is an exposure of some with 2-napthylamine:
what 3 things does this tell us about the cancer?
(1) theres a long delay (sometimes decades) between carcinogen exposure and malignant neoplasm onset.
(2) the risk of cancer depends on total carcinogen dosage
(3) there is sometimes organ specificity for particular carcinogens, e.g. 2-napthylamine causes bladder carcinoma
explain how chemicals cause cancer?
u have to give ur initiator and promotor for a prolonged period of time!
what r initiators and promotors?
& what did the Ames test show?
Ames test shows wether a mutagen shows mutagenesis
u take a strain of salmonella which requires histidine, u expose it to a mutagen,
Initiators are mutagens
Promotors r just things that promote growth!
how are mutagenic chemical carcinogens (i.e. initiators) classified?
what a pro-carcinogen? complete carcinogen?
give examples
pro-carcinogon is where we ingest a chemical, but on itself it isn’t carcinogenic! (only converted to carcinogens bu the cytochrome P450 in the liver)
Complete carcinogens have both initiator and promotor effects! EX: tobacco!
what is radiation?
what is Ionising radiation? what does it do?
what is nucleur radiation?
how do they damge the dna?
is any type of energy travelling through space and some forms are mutagenic
ionising radiation: strips electrons from atoms & includes Xrays & nuclear radiation arising from radioactive elements.
Nuclear radiation: comprises alpha particles, beta particles and gamma rays. …
ionising radiation damages DNA bases and causes single and double strand DNA breaks.
what is the most important type of radiation and why?
what 2 types of radiation r we exposed to?
UV light>> bc we r exposed to it everyday, leading to increased risk of skin cancer
what is radon?
You can’t see radon. And you can’t smell it or taste it. But it may be a problem in your home. Radon comes from the natural breakdown of uranium in soil, rock, and water. Radon is the second leading cause of lung cancer in the United States.
what type of infections r carcinogenic?
human papilloma virus, Epstein Barr virus, hepatitis B and C
viruses, HIV, Helicobacter pylori, parasites
which infections act direct and indirect carcinogens?
HPV> DIRECT> because it expresses the E6 and E7 proteins that inhibit p53 and pRB protein function respectively, both of which are important in cell proliferation
The role of certain tumour suppressor genes and oncogenes.
Genes that inhibit neoplastic growth.
Because they act like brakes on tumour growth, both alleles must be inactivated, which explains why they need two hits, i.e. one for each allele.
Genes that enhance neoplastic growth are known oncogenes and are abnormally activated versions of normal genes called proto-oncogenes. Only one allele of each proto-oncogene needs to be activated to favour neoplastic growth.
