Pre- dispositions to cancer Flashcards
what is a proto-oncogene
normal genes that we all have that regulate normal cell growth and differentiation
however mutations in these genes can turn them into ONCOGENES
examples are growth factors, gf receptors and signal transduction
what is an oncogene
derived from proto-oncogenes
- they accelerate cell division and when they’re stuck in ‘on’ mode ie expressed for a long time they can lead to/ cause cancer development
only needs ONE mutation to cause cancer in ONE hit
tumour suppressor genes
normally prevent cancer development/ tumour growth
they are the cell’s ‘brakes’ for growth
when this gene mutates it no longer suppresses tumour growth
need 2 hits from them for cancer to be caused ie both copies of genes need to be mutated and fail
2nd hit- process will begin that leads to tumour formation
think car- 1 hit (tyre) can still drive
2 hits- crash- cancer
DNA damage and response genes
you can’t repair DNA quickly
mutations in the gene continue and then accumulate before DNA can repair
what is a predisposition gene
a gene that increases the likeliness to have a disease
but not everyone that has these genes go on to get cancer- you can be a carrier but unaffected
what are the main risk factors of Breast cancer
ageing
family
history
dietary factors
what things have resulted in improved outcomes for cancer
surveillance
surgery
chemoprevention
what has improved outcomes for adenomatouos polyposis (benign polyps on glands)
glands like colon or rectum
anti-inflammatory drugs reduce polyp formation
what is so bad about mutations, polymorphisms and variants in genes?
mutations that change DNA sequences or genes can cause a massive difference to cell function and be very detrimental
MYH polyposis
is a hereditary condition
people with this tend to get adenomatouos polyposis and have increased risk of colorectal cancer if they are not monitored/removed
it is an autosomal recessive condition- takes 2 mutations
BRAF
BRAF is a proto-oncogene
if mutations occur in this gene then it can cause cancer development by causing over proliferation
BRAC1 and BRAC2
are examples of tumour suppressor genes
normally carry out DNA repair
where do de novo mutations arise
de novo (new) mutations occur in germ cell of parent they can pop up at random even if no family history of it
what type of gene is retinoblastoma gene (RB1)
is a tumour suppressor
causing eye tumour
2 hit gene
TP53 and PTEN?
tumour suppressors for breast cancer
