L9 - Reprorgamming Metabolism Flashcards
Two ways ATP is generated
Glycolysis and aerobic respiration (TCA)
Net yield from glycolysis
2 ATP
2 NADH
Net yeild from krebs cycle
2 ATP
Then 6NADH generates 34 ATP
What can be said RE the efficiency of cancer cells metabolism
Low efficiency
What metabolism do cancer cells use - whiy is this unsual
What is this known as
Glycolysis - they use this even in the presence of oxygen
This is the WARBURG EFFECT
Upregulation of _____ helps the cancer cell to deal with
GLUT1
Lack of ATP
Role of GLUT-1
Glucose in
How can we see this upregulation of GLUT1 (two wasy)
Immunohistochemsitry
Histochemical in-situ hybridisation
Radio-RNA - massive upregulation
GLUT1 upregualtion can be used as a
Diagnostic marker
How can GLUT1 upregulation be used as a diagnostic marker
Use radio-F and then PET scan
Glucose will accumulate in cells where this upregulation has happened - marks turmours
What is the role of high glucose flux in cancer cell
To fascilitate the higher levels of ATP production anaerobically
Describe what is seen when performing metabolic studies of thymocytes which have been isolated by density gradient centrifugation
Addition of glucose - reduces O2 consumption - CRAB TREE EFFECT - suggests things slighlty different in proliferating cells
Huge increases in lactate
See most ATP comes from glycolysis
When cells are proliferating the main way of producing ATP is through
High flux glycolysis
This is where the same ammount of ATP is generated - just from more glucose since the process is so inefficient
What can explain metabolic repurpossing
Oncogenes and loss of tumour supressor genes
What signalling promotes metabolic transformation
PI3K and Akt
This is through multiple signalling pathways
What multiple pathways can lead to metabolic repurpossing
Increase expression of nutrient transporters enabling increased uptake
Akt dependent stimulation of hexokinase and phosphfructokinase - drives glycolysis
Enhanced transcription involved in glycolysis and lipogenesis
Enhanced translation through mTOR pathway
What is pyruvate used for
Many processes such a lipid synthesis
What is myc
What is it required for
Early serum response transcription
Required for proliferation
Describe the structure of Myc
Alpha helix with a leucine zipper
What does myc dimerise with
MAX
Describe what happens in ordinary circumstances
Myc present in limited amounts (unlike MAX)
Levels increase in presence of serum
Promotes proliferative genes
Explains its protooncogenic status
Myc mutated in how many tumours
30%
Myc upregulates ….
By ….
Glycolytic enzyme transcription by binding to an upstream consensus sequence
How was it shown Myc binds to a sensensus sequence - upregulating proliferative genes
Using a chromatin IP workflow
Cross DNA-protein using cross linking agents
Sheer DNA strands by sonication
Add AB to immunoprecipitate with DNA - wash to reverse linkage
Can isolate DNA
PCR to amplify
Identification of the gene
What is the chromatin IP workflow a useful model for
Burkitts lymphoma
What genes coprecipate with Myc antibodies
Enolase
Hexokinase
Lactate dehydrogenase
Myc is
Strongly growth promoting
HIF is
Strongly growth inhibiting
Describe the P493-6 cell model of Burkitts lymphoma
Tetracycline represses Myc expression
Kim et al. introdcued oxygen insensitive HIF1 to avoid complications with feedback
HIF1 promotes
Myc-induced tumourigenesis
THIS IS THROUGH PROMOTING EXPRESSIONS OF
Hexokinase 2 and pyruvate dehydrogenase 1
Describe what is seen in tumours with HIF1 as well
Volume of tumours with HIF1 are even bigger
What is the effect of the expression of hexokinase and lactatate dehydrogenase
Encourages glycolysis whilst simulatenaeously shutting down oxidative phosphorylation
