8.4 Gene expression and cancer

Question 1

How do tumours and cancers form?

Answer 1

• Mutations in DNA / genes controlling mitosis, leading to uncontrollable cell division
• Tumour formed if this results in mass of abnormal cells

Question 2

Benign tumours

Answer 2

Grow slowly
Cells are differentiated
Normal, regular nuclei
Don’t invade surrounding tissue
Don’t spread by metastasis

Question 3

Malignant tumours

Answer 3

Grow faster
Poorly differentiated
Irregular, darker nuclei
Invade surrounding tissue
Spread by metastasis

Question 4

What is the function of tumour suppressor genes?

Answer 4

• Code for proteins that inhibit cell cycle or cause apoptosis of potential tumour cells
• Mutation, decreased acetylation of histones or increased methylation of DNA can prevent production of protein, leading to uncontrollable cell division

Question 5

What is the function of (proto)oncogenes?

Answer 5

• Code for proteins that stimulate cell division
• Mutation, decreased acetylation of histones or increased methylation of DNA can increase production of protein, leading to uncontrollable cell division

Question 6

What is the role of oestrogen in development of breast cancer?

Answer 6

• Some breast cancer cells have oestrogen receptors which are inactive TFs
• If oestrogen concentration is increased, more oestrogen binds to receptors and more oestrogen-receptor complexes, activating the TFs