Genetics And Cancer

Question 1

How do genes cause cancer

Answer 1

Caused by post-zygotic mutations

Inherited pathway deficiency causes cancer syndromes

Question 2

Stages of the multistep progression of a cell to cancer

Answer 2

Proliferation -> Invasion -> Metastasis

Cells also:
Evade immune response
Acquire a vascular supply
Avoid apoptosis

Question 3

Types/mechanisms of mutations that are involved in cancer progression

Answer 3

Driver mutations
- Genes that drive carcinogenesis
- E.g oncogenes and tumour suppressors

Passenger mutations
- Incidental mutations that happen because tumour is unstable

Question 4

Two hit hypothesis

Answer 4

Mutation in both alleles required to inactivate tumour suppressors - mutations can be inherited or acquired

Question 5

DNA repair teams

Answer 5

For DNA breaks:
- HRR
- Non-homologous end joining

Nucleotide damage:
- Mismatch repair
- Nucleotide extension repair
- Base excision repair

Synthesised through damage:
- Translesional synthesis

Repair genes in use:
- Transcription couples repair

When it doesn’t work:
- Checkpoints
- Apoptosis