L5 - Cancer and genome Flashcards
which mechanisms zorgen ervoor dat de errors uit het DNA worden gehaald tijdens DNA raplicatie?
- polymerase
- exonuclease
- Mismatch repair systeem (MMR)
function exonuclease
does proofreading and deletes mis-incorporated basen
Function translesion polymerase
able to bypass DNA damages during translesion
examples of translesion polymerases
- Pol E
- REV1
- Pol n
- Pol k
- Pol L
- Pol O
Pol n function + what happens when mutated?
can deal with UV damages
- When mutated –> xeroderma pigmentosum ( =sunsensitive and high chance of cancer)
most common causes of spontaneous mutations
depurination (guanine becomes lost)
Deamination of 5mcystosine ( cytosine becomes thymine)
Types of DNA repair pathways
- Base excision repair (BER)
- Nucleotide excision repair (NER) (UV light, cigarette smoke)
- Double strand break repair (ionization radiation)
- ICL repair
Whar causes Lynch?
MMR mutation
Gene panel sequencing
you sequence the genes that are frequently mutated in a certain type of cancer to see if there are mutations
Passenger mutations
don’t contribute to the pathogenesis of cancer
driver mutations
give a growth or survival advantage
There are different mutation processes during cancer development.
- Deamination of methylated cytosines (C>T)
- Signatures of tobacco smoking (C>T)
- Burst of APOBEC induces deanimation (C>A)
- awry DNA repair pathway (C>T and C>G)
Mutational signatures: SBS4
C>A mutation, associated with smoking.
Found in lung adenocarcinoma, lung squamous carcinoma, small cell lung carcinoma, neck cancer, liver cancer
Mutational signatures: 4
frequent in smokers
Mutational signatures: SBS7
in skin cancers and cancers of the lip, due to UV light
