Cancer

Question 1

certain cancer cells produce more __ under aerobic conditions than do normal cells. Why?

Answer 1

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

Question 2

is TCA and glycolysis coupled in cancer cells?

Answer 2

They do not couple glycolysis to TCA even if the cells were under aerobic conditions

Question 3

What is tumor

Answer 3

Another name neoplasm

Relentlessly growing mass of abnormal cells

Question 4

How the tumor is called if it is clustered together in a single mass

Answer 4

Benign tumor

Question 5

Characteristics of malignant tumor

Answer 5

Reproducing and

Have an ability to invade surrounding tissues

Question 6

If malignant tumor invade and form secondary tumors, it is called

Answer 6

Metastases

Question 7

When a tumor is considered a cancer

Answer 7

Only if malignant

Question 8

Three pathways in which cancer cells have alterations

Answer 8

• Glycolysis
• Corresponding effects on TCA cycle
• Pentose phosphate pathway (PPP)

Question 9

What alternations cancer cells in glycolysis

Answer 9

Cells do not couple glycolysis to TCA cycle even if the cells are under aerobic conditions

The convert pyruvate to lactate through fermentation pathway

Question 10

Why glycolysis and fermentation, not TCA?

Answer 10

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

Question 11

What was discovered and developed using HeLA cells

Answer 11

Vaccine for polio

Was proved that HPV caused cancer

Question 12

TCA cycle does not function in cancer cells, what is done to acetyl-CoA then

Answer 12

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

Question 13

Describe glycolysis and PI3K in cancer cells

Answer 13

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

Question 14

Mutations in PI3K affect __ and __

Answer 14

Mutations in PI3K affect glucose transport and downstream signalling related to cell survival, proliferation, and growth

Question 15

What changes happen in PPP in cancer cells

Answer 15

Overexpression of transketolase and transaldolase

Question 16

what pathway yields more ATP : glycolysis or PPP

Answer 16

Net ATP with PPP: 3 atp

Net ATP from glycolysis : 2

Question 17

Why is there an increased denovo synthesis of fatty acids?

Answer 17

increased levels of Acetyl Co-A, and

increased rates of the PPP pathways, which increase NADPH production

Question 18

What is another reason the PP pathway is so important (for both normal and cancer cells

Answer 18

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.

Question 19

As there is an increased glycolysis rate, what mutations cancer cells have

Answer 19

-Glut mutations for increased glucose uptake

Question 20

glucose transporter expression in healthy vs. cancerous cells

Answer 20

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,