Cancer Flashcards
certain cancer cells produce more __ under aerobic conditions than do normal cells. Why?
certain cancer cells produce more lactic acid under aerobic conditions than do normal cells
This is because the glycolytic pathway in these cells produce pyruvate more rapidly then the citric acid cycle can accommodate
is TCA and glycolysis coupled in cancer cells?
They do not couple glycolysis to TCA even if the cells were under aerobic conditions
What is tumor
Another name neoplasm
Relentlessly growing mass of abnormal cells
How the tumor is called if it is clustered together in a single mass
Benign tumor
Characteristics of malignant tumor
Reproducing and
Have an ability to invade surrounding tissues
If malignant tumor invade and form secondary tumors, it is called
Metastases
When a tumor is considered a cancer
Only if malignant
Three pathways in which cancer cells have alterations
- Glycolysis
- Corresponding effects on TCA cycle
- Pentose phosphate pathway (PPP)
What alternations cancer cells in glycolysis
Cells do not couple glycolysis to TCA cycle even if the cells are under aerobic conditions
The convert pyruvate to lactate through fermentation pathway
Why glycolysis and fermentation, not TCA?
glycolysis ATP very rapidly in cytoplasm
Cancer cells grow more rapidly than the blood vessels to nourish them; thus, as solid tumors grow, they are unable to obtain oxygen efficiently. In other words, they begin to experiencehypoxia. Under these conditions, glycolysis leading to lactic acid fermentation becomes the primary source ofATP.
Cancer cells use glycolytic intermediates to feed other pathways. Example PPP pathway
Increased uptake of carbons is needed to build the constituents of rapidly multiplying cells
The TCA cycle which eventually generates NADH and ATP is a major regulator of glucose metabolism
-> no glycolysis inhibition
What was discovered and developed using HeLA cells
Vaccine for polio
Was proved that HPV caused cancer
TCA cycle does not function in cancer cells, what is done to acetyl-CoA then
Acetyl-CoA is used for the denovo synthesis of FAs ( usually low production of FAs in normal cells) to supply lipids for cell membrane formation in rapidly proliferating cells
Describe glycolysis and PI3K in cancer cells
Often a mutation in PI-3K is found in cancer cells
Kinase is more active
PI3K signalling acts as a regulator of glucose uptake by promoting the expression of GLUT1 mRNA and translocation of the protein to the cell surface
Also affects GLUT 4
Mutations in PI3K affect __ and __
Mutations in PI3K affect glucose transport and downstream signalling related to cell survival, proliferation, and growth
What changes happen in PPP in cancer cells
Overexpression of transketolase and transaldolase
what pathway yields more ATP : glycolysis or PPP
Net ATP with PPP: 3 atp
Net ATP from glycolysis : 2
Why is there an increased denovo synthesis of fatty acids?
increased levels of Acetyl Co-A, and
increased rates of the PPP pathways, which increase NADPH production
What is another reason the PP pathway is so important (for both normal and cancer cells
PPP is a very critical pathway because it is capable of forming Glutathione-S-Transferase (GST).
PPP is essential for tumor cell immortality
Reduced glutathione (GSH) protects the cell by destroying hydrogen peroxide and hydroxyl free radicals.
As there is an increased glycolysis rate, what mutations cancer cells have
-Glut mutations for increased glucose uptake
glucose transporter expression in healthy vs. cancerous cells
Basal glucose uptake in
healthy epithelial cells is mediated mostly through GLUT1, with contributions from other GLUTs depending on the tissue type.
Fructose uptake is mediated mainly by GLUT2 and GLUT5 in these epithelial cells.
Compared to normal cells, glucose and fructose uptake is much higher cancerous epithelial cell. GLUT proteins are expressed at higher levels and in abnormal tissue patterns when healthy cells become cancerous,
