Exercise and Cancer Flashcards
What is cancer?
- In a nutshell, cancer is a mass of cells that grow rapidly, refuse to die, and spread to a secondary site
- Cancer is a genetic disorder
- Mutations give cancer cells a survival advantage
- Tumour derived from Latin = meaning swelling
Which hormone is associated with the greatest influence on preventing cancer growth by exercise?
- adrenaline, released from adrenal gland is a key molecule in the exercise associated improved tumor control by cells of the immune system.
- because elicits fight-or-flight response
Which interleukin is increased during exercise?
why?
How might this impact tumour growth?
- IL-6, in an intensity dependent manner
- anti-infammatory by inhibiting TNF-α and IL-1, and activation of immune suppressive IL-10
- this increases NK cell release from thymus as they have the IL-6 receptor
Which is the main cell that kills tumour growths in non-specific immunity?
- NK cells
- high level of cytotoxic activity among peripheral blood lymphocytes was associated with a lower risk of cancer
- suggests NK cells as active in early tumor surveillance.
- NK cells cause cytotoxic T cell infiltration
Name 2 cancer stem cells:
- CD44+
- CD24-
What is the role of tumour suppressor genes?
- Tumour suppressors genes - prevent inappropriate growth of cells, need for them to be switched back on to stunt growth
- Suppressor genes stops scar skin from getting too big
- P53 prevents tumours from sunburn
- Switched on and off
What percent can exercise reduce tumour growth rate?
The control of tumor growth by exercise
training in established tumors may be as high as a 67% reduction in growth rate
Explain the role of the Akt/mTOR pathway during exercise in relation to cancer?
- Akt/mTOR pathway has been shown to
be deactivated with endurance exercise in several tumour models - Plays a central for control of growth and protein synthesis and plays a pivotal role in the muscular response to resistance training
- However, no causation effects have been found
Describe Oncogenes:
DNA mutations can cause cancer:
* Oncogenes – ”mitogenic” signals - growth promoting, drive cell growth & division without repair
* Tend to be always switched on
* Mutations –> inappropriate activation of cell growth/division, preventing DNA repair
Describe
- germline
- somatic
mutations
- germline e.g.: braca 1 & 2 is inherited & occur in the DNA of an organism’s reproductive cells(Cystic fibrosis)
- Every cell in tumour mass carries the same mutation
- Somatic are acquired throughout life
- only cells daughter cells of the cell will carry the mutation = polyclonal mass created
e.g.: damage from UV rays, P53 is the guardian of the genome, facilitates the repair of damaged DNA, can trigger apoptosis if not= pealing after sunburn & increases sensitivity to breast cancer
What immunological issue can lead to cancer?
- Termed Thymic involution
Thymus is in middle of the sternum, which produces T-cells, shrinking by about half every 16 yrs. - Faster in men than women
- Aging decreases immune function
- Immune system keeps it in check
How does the non-specific immune system protect us against cancer?
- Innate immunity contributes to inflammation, creating an environment hostile to tumor development.
- natural killer (NK) cells look for virus infected/cancer cells.
- NK cells have inhibitory receptors & activating receptors
- inhibitory receptors bind to MHC class 1 on cancer cells
- activatory receptors activated as MHC class 1 is down regulated on cancer cells = detection that it is a bad cell
- causes NK cell to kill off tumour cell by 2 mechanisms
1. secreting of granzymes - an enzyme triggering cell death in target cell
2. secreting cytokines e.g.: TNF-α, CCL 1,2,3,4,5 = recruitment of specific immunity
What is the only cell in the body that does not present MHC class 1?
- red blood cells
How does our specific immune system protect us against cancer?
involves dendritic cells(APC’s), T cells & B cells
- dendritic cells have antigens that are from dying tumour cells presented on its surface. Presented on MHC class 1/2 molecules
- Activates T effectors: Cytotoxic T(CD8+), T helper(CD4+) & Tregs
- Cytotoxic T cells (CD8+ T cells) recognize MHC class I and directly kill cancer cells by inducing apoptosis. They release perforin and granzymes to induce apoptosis in target cells.
- MHC class II cells are recognised by CD4+ OR B cells, producing antibodies that can recognize other cancer cells & facilitate their destruction
- all of these responses store memory cells
Describe
- cancer metastasis
- cancer stem cells
- process when cancer cells spread from the primary site of origin to other parts of the body, forming secondary tumors.
- 90% of cancer-related deaths caused by secondary metastasis NOT primary tumour
- tumour made up of tumour cells, stromal cells, stem cells
Cancer stem cells give rise to a new tumour - Different expression patterns
