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Pmcol 200 > l26 cancer > Flashcards

l26 cancer Flashcards

1
Q

t/f: cancer is the leading cause of death in Canada

A

t

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2
Q

There are over _____ types of cancers

A

100

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3
Q

metastasis

A

Cancer Characterized by abnormal cell growth with potential to spread to other parts of the body

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4
Q

Causes of cancer (4)

A
  1. Environmental and genetic factors
  2. Tobacco, ionizing radiation, environmental pollution (asbestos, radon)
  3. Viral infections (HIV with Hodgkin’s and Non-Hodgkin’s lymphoma; human papilloma virus with cervical cancer)
  4. Genetics (BRCA 1 in breast cancer)
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5
Q

Cancer is fundamentally a disease of cell _____ regulation. It arises when genes that regulate cell growth are _____

A

Growth; mutated

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6
Q

Cell cycle definition

A

Series of events leading to duplication of DNA and division of cytoplasm to produce two daughter cells

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7
Q

cell cycle phases

A
  1. GI phase: checkpoint to ensure cell ready for DNA synthesis
  2. S phase: DNA synthesis
  3. G2 phase: checkpoint to ensure cell ready for mitosis
  4. M phase: mitotic phase (cell divides into two daughter cells)
  5. G0 phase: quiescent state
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8
Q

Genes important to the regulation of cell cycle are divided into which two groups?

A

Tumour suppressor genes and oncogenes

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9
Q

Tumour suppressor genes

A

Both these genes and the proteins they encode repress cell cycle or promote apoptosis by:
inhibiting cell division;
initiating apoptosis following irreversible DNA damage;
DNA repair proteins (BRCA)

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10
Q

p53

A

tumour suppressor protein that regulates cell cycle; mutated in 50% of all tumours

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11
Q

Proto-oncogenes

A

normal genes involved in cell growth and proliferation or inhibition of apoptosis

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12
Q

oncogenes produced by

A

Mutations (point mutations, chromosomal translocation) can increase expression

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13
Q

Point mutations

A

Small-scale deletions or insertions which effect expression

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14
Q

Chromosomal translocation

A

When to separate chromosomal regions become abnormally fused

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15
Q

Philadelphia chromosome

A

Specific genetic abnormality in chromosome 22 found in leukaemia cancer cells (abnormal translocation of chromosome 9 and 22)

Broken end of chromosome 22 contains the BCR Gene which fuses with a fragment of chromosome 9 that contains the ABL1 gene

Fusion creates a new Gene: BCR-ABL

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16
Q

Philadelphia chromosome leads to

A

unregulated expression of protein tyrosine kinase activity leading to unregulated cell cycle and cell division

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17
Q

t/f: usually multiple oncogenes and mutated tumour suppressor genes will act in concert to cause cancer

A

t

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18
Q

t/f: 1/3 of cancer patients are cured with local treatment strategies (surgery, radiotherapy)

A

t

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19
Q

t/f: anticancer drugs alone cure a majority of all cancer patients in tumour is diagnosed at Advanced stage; why

A

f: anticancer drugs alone cure less than 10% of all cancer patients when tumour is diagnosed at Advanced stage (usually given in combination surgery and radiation)

20
Q

How do anti-cancer drugs interfere with cell cycle? (2)

A

Some anti-cancer drugs act at specific phases in the cell cycle, mainly at the S and M phase

other drugs are cytotoxic at any point in the cell cycle (ex: estrogen receptor antagonist tamoxifen)

21
Q

Tumour cells generally have a _____ (lower/higher) percentage to proliferating cells than normal cells, so are (more/less) susceptible to S&M phase anticancer drugs

A

Higher; more

22
Q

t/f: normal tissues that proliferate rapidly (bone marrow, hair follicles, intestinal epithelium) are more susceptible to damage from cytotoxic drugs

A

t

23
Q

t/f: few categories of medication have a narrower therapeutic index and Greater potential for causing harmful effects than anti cancer drugs

A

t

24
Q

four bases form DNA:

A

two pyrimidines (thymine and
cytosine) and two purines
(guanine and adenine)

25
Q

RNA incorporates _

instead of thymine

A

uracil

26
Q

•pyramidine analogues compete with

normal__ precursors for the enzyme __

A 
pyrimidines
thymidylate synthase (TS)
27
Q

•TS required for the conversion of __ to __ (i.e.

thymine+deoxyribose sugar)

A

dUMP to dTMP

28
Q

example of pyrimidine analogue, what happens

A

5-fluorouracil (5-FU)
•inactive in its parent form and
requires activation to active
metabolite FdUMP

29
Q

__ inhibits purine nucleotide biosynthesis and metabolism by inhibiting an enzyme called __

rate limiting factor for purine
synthesis, alters the synthesis and function of RNA and DNA

A

6-mercaptopurine;

phophoribosyl pyrophosphate amidotransferase (PRPP amidotransferase);

30
Q

•Alkylating agents are highly __ compounds which__ link to chemical groups (phosphates, amines, sulfhydryl and hydroxyl groups) commonly found in _ _
•Lead to __ between
strands of DNA and strand__

A 
reactive
covalently
nucleic acids
cross-linking
breakage
31
Q

_ particularly susceptible to the
formation of covalent bond
with alkylating agents

A

N7 atom of guanine

32
Q

cancer cells are most

susceptible to Alkylating Agents are in __ stage of cell cycle

A

G1 and S

phases

33
Q

Alkylating Agents example:

• i.e. Cisplatin

A

platinum analogue
• lead to inter-strand crosslinks leading to
inhibition of DNA synthesis and function

34
Q

Folic acid is an essential _ _ that is converted by enzymatic_ to_ _

provide_ groups for the
synthesis of precursors of_ and_ (thymine or uracil).

A

dietary factor
reduction
FH4 cofactors

methyl
DNA, RNA

35
Q

Folic acid analogues interfere

with

A

FH4 metabolism thereby

inhibiting DNA replication

36
Q

Anti-folates: methotrexate

folic acid _ that bind
with _ affinity to the active
catalytic site of _ _

effective during _ phase and
are most effective when cells
are proliferating _

A

folic acid analogue that bind
with high affinity to the active
catalytic site of dihydrofolate
reductase

effective during S phase and
are most effective when cells
are proliferating rapidly

37
Q

Vinca Alkaloids

  • derived from
  • inhibit _ polymerization
  • disrupts the assembly of _ involved in _ _ _ (_ phase)
A

derived from the periwinkle plant (Vinca rosea)
• inhibit tubulin polymerization
•disrupts the assembly of microtubules involved in mitotic spindle apparatus (M phase)

38
Q

Taxanes

  • derived from
  • promote __ assembly through _ affinity binding
  • inhibits _ and _ _ (_ phase)
  • i.e. __
A
  • derived from the Pacific yew tree (Taxus brevifolia)
  • promote microtubule assembly through high affinity binding
  • inhibits mitosis and cell division (M phase)
  • i.e. paclitaxel
39
Q

Camptothecins

• derived from the
• DNA topoisomerases are nuclear enzymes that __ _ stress in _ DNA (through _ _ and _)
• Camptothecins bind and _ the normally transient DNA–topoisomerase _ _.
• Although the _ _action of topoisomerase is not affected, the _ step is inhibited, leading to the accumulation
of __ breaks in DNA
• These are _-phase specific drugs because ongoing _ _ is necessary for cytotoxicity

A

• derived from the Camptotheca acuminata tree
• DNA topoisomerases are nuclear enzymes that reduce torsional stress in supercoiled DNA (through strand breakage and resealing)
• Camptothecins bind and stabilize the normally
transient DNA–topoisomerase I complex.
• Although the initial cleavage action of topoisomerase is not affected, the re-ligation
step is inhibited, leading to the accumulation
of single-stranded breaks in DNA
• These are S-phase specific drugs because ongoing DNA synthesis is necessary for
cytotoxicity

40
Q

Antibiotics
products of the soil
microbe _

bind DNA through
_, block DNA _ and cell _

A

products of the soil
microbe Streptomyces

bind DNA through
intercalation, block DNA
synthesis and cell replication

41
Q 
Antibiotics
• i.e.: Anthracyclines
(doxorubicin)
• _ widely used anti-cancer
drug
• 4 mechanisms of action:
1.inhibit _
2.generate \_\_ _ (DNA _)
3._ affinity binding to DNA
4.bind _ membrane to alter _ and _ transport
A

Antibiotics

• i.e.: Anthracyclines
(doxorubicin)
• most widely used anti-cancer
drug
• 4 mechanisms of action:
1.inhibit topoisomerases
2.generate free radicals (DNA
mutagenesis)
3.high affinity binding to DNA
4.bind cellular membrane to alter
fluidity and ion transport
42
Q

tyrosine kinase inhibitors
(i.e. imantinib)
•inhibits the _ _ _of the _ _
•treat _

A 
tyrosine kinase inhibitors
(i.e. imantinib)
•inhibits the tyrosine kinase
domain of the Bcr-Abl
oncoprotein
•treat leukemia
43
Q

epidermal growth factor
receptor (EGFR) inhibitors

• EGFR is _-expressed in a
number of _ tumors
• Activation of EGFR promotes
_ _ and _, _, and _, and
_
• i.e. Cetuximab is a _ _ directed against the _ domain of EGFR
A 
epidermal growth factor
receptor (EGFR) inhibitors
• EGFR is over-expressed in a
number of solid tumors
• Activation of EGFR promotes
cell growth and proliferation,
invasion, and metastasis, and
angiogenesis
• i.e. Cetuximab is a monoclonal
antibody directed against the
extracellular domain of EGFR
44
Q 
•hormonal anti-cancer
agents
•i.e.: tamoxifen
• selective _ receptor antagonist
•blocks binding of _
to _ sensitive
cancer cells in breast tissue
A 
•hormonal anti-cancer
agents
•i.e.: tamoxifen
• selective estrogen
receptor antagonist
•blocks binding of estrogen
to estrogen sensitive
cancer cells in breast tissue
45
Q

Primary Resistance:

A

develops spontaneous in the absence of prior

exposure to anti-cancer drugs (i.e. p53 mutations)

46
Q

Acquired Resistance:

A

develops in response to a given anticancer agent

47
Q

Adverse Effects - 4

A 
• dose related
• occur primarily in rapidly growing
tissues, such as bone marrow,
intestinal mucosa, and reproductive
system
• symptoms include impaired immune
system, diarrhea, hair loss, nausea
and vomiting
• many anti-cancer drugs are
carcinogenic in nature, thus increased
risk of secondary malignancies

Pmcol 200 (12 decks)

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