Tumor Metabolism

Question 1

after initial increase in glucagon, what is maintaining blood glucose?

Answer 1

glycogenolysis

Question 2

prolonged increases in glucagon, what maintains blood glucose?

Answer 2

gluconeogenesis

Question 3

why is gluconeogenesis slower than glycogenolysis?

Answer 3

gluconeogenesis enzymes are induced, meaning they have to be transcribed and translated before they are active

Question 4

what do tumors use for energy?

Answer 4

glucose only

never switch to alternate fuel sources- not responsive to glucagon

Question 5

how do surface tumor cells do metabolism?

Answer 5

aerobically

Question 6

how do deep tumor cells do metabolism?

Answer 6

anaerobically

tumor induced cytokines promote cachexia by activating muscle proteolysis and adipose lipolysis

Question 7

what is cachexia?

Answer 7

unexplained weight loss

Question 8

what is hypoxia inducing factor?

Answer 8

allows tumors to adapt to hypoxic conditions
switches surface cells to lactate usage by increasing GLUT1 transporters and inducing glycolytic enzymes to inhibit PDH–>forcing everything to lactate usage (takes lactate from cells under hypoxic conditions)

Question 9

when does the brain switch to ketone body usage?

Answer 9

3 days after depletion of dietary glucose, shortly after depletion of body glycogen

Question 10

how many ATPs are obtained from full oxidative phosphorylation? how many are obtained under anaerobic conditions?

Answer 10

aerobic- 30-32 depending on which shuttle is used

anaerobic- 2 from substrate level phosphorylation

Question 11

what are products of muscle proteolysis and adipose lipolysis used for and why?

Answer 11

muscle proteolysis- tumor protein synthesis
adipose lipolysis- body energy production
to same glucose for tumor