An emerging hallmark of cancer Flashcards
reprogramming of energy metabolism is classed as?
a new emerging hallmark of cancer
under oxygenated conditions how does cell metabolism work? be quite brief
under aerobic conditions, oxygenated non-malignant cells process glucose to pyruvate via glycolysis in the cytosol then to CO2 in the mitochondria
in anaerobic conditions, embryogenesis or exercise, what is the favoured metabolic pathway? how much pyruvate is used here?
glycolysis
relatively little pyruvate used
what is the Warburg effect?
cancer cells can reprogram glucose metabolism to predominantly glycolysis
regardless of oxygen availability
what is the product of glycolysis
lactate
how many ATP molecules are produced in oxidative phosphorylation compared to glycolysis?
op: 36 ATPs
glycolysis: 2 ATPS
how do cancer cells compensate for this decreased efficiency of glycolysis?
they compensate by upregulating glucose transporters
how can PET imaging be used to show where a cancer is?
can monitor glucose uptake
4 functional rational for the glycolytic switch?
rapid ATP synthesis
biosynthesis
tumour microenvironment
cell signalling
- Rapid ATP synthesis:
how much faster is glycolysis than op?
10-100 times faster
- Rapid ATP synthesis:
what advantage does a faster production of ATP provide tumour cells?
selective advantage when competing for shared and limited resources
- Rapid ATP synthesis:
can glycolysis produce as much ATP as respiration in the same time?
yes, occurs very rapidly and the cells are rapidly proliferating so their rate of metabolism is higher
- Rapid ATP synthesis:
why does the cancer cells want a selective advantage over other cells in the TME?
compete with cancer fighting cells
immune cells would need the same nutrient supply as tumour cells
- Biosynthesis:
explain why this is an advantage for cancer cells
glycolytic intermediates supply subsidiary anabolic pathways
- Biosynthesis:
example of a pathway glycolytic intermediates can supply
Pentose phosphate pathway
- Biosynthesis:
what des the pentose phosphate pathway support?
DNA and RNA replication
NADP production
- Tumour microenvironment:
how does the glycolytic switch help the TME?
decrease in pH due to lactate secretion which enhances invasiveness
increases NADPH and glutathione produced to counteract oxidative stress
successful seeding to organs may require low oxygen and nutrients so this prepares the cells for this
- Tumour microenvironment: what does lactate accumulation in the TME do? talk macrophages
suppress the anti cancer immune response by promoting M2 macrophage emergence= PROCARCINOGENIC
- Tumour microenvironment: M2 macrophages are good or bad for the tumour cells?
good
secrete high levels of pro carcinogenic cytokines
- Tumour microenvironment: what is the acid-mediated invasion hypothesis?
decreased pH due to lactate secretion enhances invasiveness
2 ways of cell signalling? (4th rational)
VIA ROS species
through chromatin remodelling
4a) Cell signalling through ROS:
effect of glycolysis on ROS? leads to?
produces it
cell signalling
4a) Cell signalling through ROS: how are ROS formed? examples of ROS?
reduction of O2
O2’, H202, OH’-
4a) Cell signalling through ROS: are ROS all toxic species?
no recently found that hydrogen peroxide can have a role as a 2ndary messenger which reversibly oxidises cystine In proteins to regulate response to metabolic stress
4a) Cell signalling through ROS: 2 ways of ROS production?
mitochondria complex I and II
NADPH oxidases (NOX) PPP
4a) Cell signalling through ROS: molecules leading to ROS elimination
glutathione peroxidase
4b) Cell signalling through chromatin remodelling: explain how glycolysis is linked to chromatin?
remodelling
lactate derived lactylation of histone lysine residues serves as an epigenetic modification which stimulates gene transcription for chromatin in macrophages
4b) Cell signalling through chromatin remodelling: which cells does chromatin get remodelled
macrophages
4b) Cell signalling through chromatin remodelling:
what happens to the macrophages after this change in DNA expression?
turn to inflammatory state
TF all tumours have the same pH levels. what does this suggest?
no they are all unique
suggests metabolic heterogeneity- multiple metabolic pathways used at once