cancer module 3- the tumour microenvironment

Question 1

What is the key feature of the tumour microenvironment that contributes to cancer?

Answer 1

The chemokines and cytokines in the microenvironment are vital to the growth and formation of the tumour.

Question 2

Do tumours have a particular microenvironment that they prefer to grow in?

Answer 2

Yes. Different cancer types prefer different microenvironments in the body. This is most evident in metastasis.

Question 3

What other microenvironment is the cancer microenvironment likened to?

Answer 3

The cancer microenvironment is likened to the wound healing microenvironment.

Question 4

What are EPC’s and how do they effect the tumour microenvironment?

Answer 4

EPC stands for an endothelial progenitor cell. The endothelial progenitor cells are recruited to the tumour site in vast quantities for angiogenesis.

Question 5

Which growth factor found in the tumour microenvironment is responsible for EPC recruitment?

Answer 5

VEGF- it is responsible for the recruitment of EPC’s from the bone marrow in to the tumour site via the bloodstream.

Question 6

What are some tumours known to do if they are undergoing angiogenesis but don’t have access to EPC’s?

Answer 6

These tumours are known to recruit their own stem cells for endothelial cell production from the organ that it’s growing in.

Question 7

What is a cancer associated fibroblast (CAF)?

Answer 7

Cancer associated fibroblasts are modified fibroblasts that reside in tumour masses. They provide oncogenic signals that assist in tumour growth.

Question 8

How are cancer associated fibroblasts made?

Answer 8

CAF’s are produced by epithelial-mesenchymal transformation or from direct instruction from normal fibroblasts.

Question 9

What are some of the specific functions of CAF’s?

Answer 9

CAF’s do the following:

1. Recruit inflammatory cytokines to the tumour
2. Secrete VEGF for angiogenesis at the tumour site
3. Involved in physical development of the tumour, such as tumour solidity, metastasis and immunity.

Question 10

What are some of the specific functions of the tumour associated macrophages, or TAM’s?

Answer 10

1. TAM’s secrete metalloproteinases that enable the tumour cells to digest through the basement membrane for metastasis.
2. They also secret CSF-1, colony stimulating factor required for macrophage recruitment to the tumour site.

Question 11

How are tumour associated macrophages produced?

Answer 11

They are produced through the exposing normal macrophages to high levels of IL-4. This induces the change.