Cancer lecture 3

Question 1

Two types of damage to keratinocytes

Answer 1

• mechanical damage ( scratches, wounds etc..)
• physical damage (solar UV radiation)

Question 2

How do keratinocytes respond to epidermal wounding?

Answer 2

• activate
• stem cell keratinocytes proliferate
• keratinocytes migrate to wound edge
• once wound is covered, cells enter quiescence and differentiate to rebuild suprabasal layer

Question 3

What is UV radiation?

Answer 3

• type of ionizing radiation
• causes cell damage

Question 4

What does UV radiation do to cellular DNA?

Answer 4

• Causes dimers to be created in DNA sequences which will prevent DNA replication and also change the amino acid being coded for
• UVB directly damages DNA molecules (creates dimers) (causes direct mutations like changing Cytosine to Guanine)
• UVA/UVB both creating ROS which then damages DNA (changes Cytosine to Thymine)

Question 5

What two ways can genetic mutations lead to cancer?

Answer 5

• activate oncogenes
• suppress tumour suppressor genes

Question 6

What is a proto-oncogene?

Answer 6

• a gene that codes for cellular growth, development, division etc…
• a mutation to these types of genes can result in a cell being cancerous
• mutated version of a proto-oncogene is an oncogene

Question 7

What types of mutations can cause a proto-oncogene to become an oncogene?

Answer 7

• point mutations (hyperactive gene product, increased/deregulation of transcription)
• gene amplification (additional copies of oncogene)
• chromosomal rearrangements (higher expression/different location of gene)
• chromosomal translocation ( produces fusion protein w oncogenic activity)