Oestrogen Receptors

Question 1

What are the 2 versions of the oestrogen receptor?

Answer 1

ERB and ERA (alpha and beta)

Question 2

What does type of oestrogen receptor does healthy breast tissue express?

Answer 2

ERB

Question 3

What type of oestrogen receptor does breast cancer tissue strongly express?

Answer 3

ERA

Question 4

How does oestrogen promote growth of cancer cells?

Answer 4

Oestrogen promotes rapid division of ERa-positive breast cancer cells by binding to receptor, resulting in growth

Question 5

How can ERa-positive cells be detected in tumour biopsies?

Answer 5

Staining sections of tumour biopsies with antibodies against the oestrogen receptor - ERa-positive cells are stained brown

Question 6

What is an anti-oestrogen drug that can inhibit growth and spread of these cancers?

Answer 6

Tamoxifen

Question 7

Tamoxifen is a pro-drug. What does this mean?

Answer 7

It is covered to an active form within the body

Question 8

How does normal oestrogen binding work?

Answer 8

1. Oestrogen binds to oestrogen receptor
2. Oestrogen receptors changes shape
3. Oestrogen receptor binds to co-activatiors (other proteins)
4. Transcription occurs - growth

Question 9

How does oestrogen binding occur if tamoxifen is present?

Answer 9

1. Tamoxifen binds to oestrogen receptor
2. Oestrogen receptor cannot undergo shape change
3. Tamoxifen-receptor complex cannot bind to co-activators
4. Inhibits growth of cancer