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Biochemistry 2 > Cancer > Flashcards

Cancer Flashcards

1
Q

Two general characteristics how cancer is defined

A

Reproduce beyond the restraints of normal cell division

Invade and colonize territories reserved for other cells

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2
Q

What is tumor

A

Another name neoplasm

Relentlessly growing mass of abnormal cells

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3
Q

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

A

Benign tumor

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4
Q

Characteristics of malignant tumor

A

Reproducing and

Have an ability to invade surrounding tissues

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5
Q

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

A

Metastases

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6
Q

How malignant tumors are spread

A

Usually by blood steam or lymphatic vessels

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7
Q

When a tumor is considered a cancer

A

Only if malignant

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8
Q

As single mutation is not enough to

A

Convert a healthy cell into a cancer cell

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9
Q

What give rise to cancerous cells (hint: errors)

A

Several, independent, rare, unexpected accidents that occur in a cell and during cell division

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10
Q

What is the most widespread cancers among men and women (3 of each)

A

Males: prostate, lung, colon

Women:Breast, lung, colon

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11
Q

What cancers are rising in numbers

A

Liver

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12
Q

Why there are picks and then ascending of incidence of some cancer?

A

Because new technologies were discovered to help to diagnose

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13
Q

Groups of cancer risk factors (5)

A
  • Biological (sex, age, gender, etc.)
  • Environmental
  • Exposure to known carcinogens
  • Bacteria and viruses
  • Lifestyle
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14
Q

Three pathways in which cancer cells have alternations

A
  • Glycolysis
  • Corresponding effects on TCA cycle
  • Pentose phosphate pathway (PPP)
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15
Q

What alternations cancer cells in glycolysis

A

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

The convert pyruvate to lactate through fermentation pathway

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16
Q

Why we have an overall trend of increasing cancer cases

A

The population age, people live longer

17
Q

cancer cells do not use TCA, so they do not have it?

A

No, they have it, just do not use it

18
Q

Why cancer cells prefer to use glycolysis and fermentation, though it produces 15 times smaller ATP

A

So it uses glycolysis , because it produces ATP very rapidly in cytoplasm . 10 times faster

Also, some cancer might have a limited access to oxygen -> Anoxic theory

By converting pyruvate into lactate, the negative feedback from the TCA cycle does not occur and glucose metabolism can continue at an accelerated rate

Puryvate->lactate also preserves a pool of NAD+ that can still be used for glycolysis. Drives step 6 of glycoslysis, which then allows for step 7 to synthesize of ATP

Glycolysis continues to make important intermediates that can be used for eventually cell replication, this ensures that cancer cells continues to thrive

19
Q

What happened to cancer cells where mitochondrial DNA was depleted?

A

Decreased the tumorigenic potential of the cells invitro and invivo

20
Q

What happens to pyruvate apart from being converted to lactate

A

It is converted to citrate, and along with other intermediates these are used to increase the presence of acetyl-CoA

21
Q

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

A

Acetyl-CoA is used for the denovo synthesis of FAs ( usually low production of FAs in normal cells)

22
Q

Cancer cells need more FAs for

A

synthesis of more phospholipid bilayer for division

23
Q

What mutation is usually found in cancer cells

A

PI3K, kinase is more active

24
Q

Why PI3K is important

A

PI3K signalling act 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

25
Q

Downstream signalling of PI3K ( affect)

A

regulate cellular processes

Cell survival, proliferation, and growth

26
Q

Ribose 5 phosphate: how it can be used and why it is so important for cancer cells

A

Structural component of nucleotides

Cancer often has elevated DNA synthesis rates, and therefore require more nucleotides

Increased arability of nucleotides allows for increased bioactivity, proliferation and growth

27
Q

What changes happen in PPP in cancer cells

A

Overexpression of transketolase and trans aldolase

28
Q

what pathway yields more ATP : glycolysis or PPP

A

Net ATP with PPP: 3 atp

Net ATP form glycolysis : 2

29
Q

Why PPP is needed for cancer cells apart form energy and ribose-5 -phosphate

A

Increassed denovo synthesis of FAs because increased levels of Acetyl-CoA
and
Increased rates of the PPP pathways, which increassed NADPH production

30
Q

Connection of cancer, PPP and glutathione

A

PPP is essential for tumor cell immortality

Reduced glutathione protects the cell by destroying hydrogen peroxide and hydroxyl free radicals

Regeneration of GSH from its oxidized form GSSH reqiures NADPH-> A decrease in GSH/GSSG ration , leads to an increased susceptibility to oxidative stress (which is implicated in the progression of cancer)

Although, elevated GSH levels increase the antioxidant capacity and the resistance to oxidative stress which has been observed in many cancer cells

31
Q

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

A

-Glut mutations for increased glucose uptake

32
Q

Two well-known GLUT 1 inhibitors

A

Flavonoids (apegenin) by decreasing expressionof the protein

Fasentin (inhibits transporter function)

33
Q

Cancer cells increase production of FA for the lipid bilayer with what enzymes (3)

A

ACLY (ATP citrate lyase) ( conversion of citrate to acetyl-CoA)

ACC (acetyl-CoA carboxylase)
FAS ( fatty acyl synthase complex)

34
Q

How PPP yields more ATP than glycolysis

A

It skips the step of PFK-1 that uses ATP, from glucose 6-phosphate to ribulose 5 phosphate and then immediately to G3P

Biochemistry 2 (17 decks)

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