L23-Tumour microenvironment Flashcards
What is the tumour microenvironment?
The non malignant cells and extracellular matrix that make up the rest of the tumour.
Why are tumours heterogeneous?
The cancer stem cell phenomenon means that they can give rise to many different populations of cells.
How are stromal cells affected by tumours?
They may co-evolve with tumours. This is called stromagenesis and normal stromal cells can change their phenotype so that they become abnormal (still non-malignant)
What is the link between cancers and inflammation and what is the effect of medication on this?
Many cancers are associated with inflammation such as IBD and colon cancer. This means that cancer risk is reduced with NSAIDS and Cox-2 inhibitors.
What is the structure of the microenvironment in hodgkin’s lymphoma?
It mimics a chonic inflammatory process in order to create a microenvironment that it is unable to survive without.
In hodgkin’s lymphoma and other cancers what prevents the immune system from killing the tumour?
The tumour cells produce cytokines that suppress the immune response of surrounding cells. They also sometimes incorperate T reg cells that prevent cytotoxic t cells destroying the tumour.
How is lymphocyte entry into and exit from the tumour controlled?
It is controlled by lipids: lysophosphatic acid promotes entry of lymphocytes into the tumour, sphingosine-1-phosphate promotes lymphocyte exit. As tumour progresses then there is increased LPA production and decreased S1P resulting in lymphocyte retention.
What are myofibroblasts and what role do they play in tumours?
They are an altered form of fibroblast that have hybrid properties of both fibroblasts and smooth muscle cells. Important for contraction in wound healing.
What is the role of cancer associated fibroblasts in tumour growth?
They produce a desmoplastic dense ECM which contains growth factors so is growth promoting.
What is the link between collagen and tumour cell growth?
Collagen has been shown to cause tumour cell growth. Does this by binding oncogenic tyrosine kinases.
What are the two types of macrophages and what are their effects on tumours?
M1 macrophages produce ROS and are pro-inflammatory. They are cytotoxic and found in acute inflammation.
M2 macrophages are immunosupprsive and involved in tissue remodelling and angiogenesis. (mainly found in cancer)
