Transcript Of Mice and Men: The Art and Science of

Of Mice and Men:
The Art and Science of
Finding, Making, and
Testing
Anti-Tumor Agents
William A. Price, Ph.D.
Department of Chemistry & Biochemistry
Sponsored by C.A.R.E.
Chymian Society
Number of Deaths/100,000 in U.S.A.
Year
1950
1970
1990
2002
Heart Disease
590
490
410
240
Cancer
195
200
210
200
Since 1950:
Heart disease rates cut by 59%
Stroke rates cut by 69%
$200,000,000,000 spent since 1970 for cancer
research
Care to Smoke?
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87% of lung cancers and 30% of all cancers are
due to smoking.
438,000 people die each year in the U.S. as a
result of smoking.
Half of all smokers will die prematurely – half
of those will die of cancer.
Smoking causes reduced fertility in women,
together with higher risks of miscarriage, stillbirth and low birth weight.
A Public Health Issue
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In the Year 2000, the
CDC estimates that 8.6
million people were
suffering from chronic
illnesses due to smoking.
Addiction to nicotine, a
CNS stimulant,
significantly contributes
to the public health
problem.
N
H
N
nicotine
CH3
Nicotine mimics Acetylcholine
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Activates neurological reward pathways similar
to cocaine and MDMA
These cholinergic pathways are artificially
stimulated and cause an unnatural release of
dopamine (pleasure) thus causing a need for
more of these “pseudo-neurotransmitters”.
Biochemical addiction
What is Cancer?
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Develops from a single cell that has undergone a
genetic mutation
Rapid, unregulated cell division is stimulated by
a combination of genetic and environmental
influences.
Begins locally and usually spreads through
lymph nodes – metastasis
There over 150 different types of cancer.
What is an Anti-Tumor Agent?
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Toxic compound that can penetrate a cell wall,
Can disrupt the physiology and/or chemistry of
DNA in order to prevent cell replication by
either:
covalently and irreparably binding to DNA
 inhibiting enzymes or proteins responsible for premitotic DNA unraveling
 causing hyper-coiling of chromatin around histones
by affecting phosphorylation or acetylation
 cutting off blood supply to tumors (angiogenesis)
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Ideally…
Antitumor agents are:
 non-toxic to healthy cells,
 are particularly toxic to rapidly-dividing cells
 delivered safely (e.g. IV, injection, organ-targeted
pill) and preferably to the afflicted cells.
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Weed Killer and Rat Poison
Trisenox
As2O3 is still used to treat acute
promyelocytic leukemia, APL, a cancer of
the bone marrow due to a chromosomal
translocation.
Patient receives roughly 60 daily injections
of ~10mg doses over a period of 2 months.
Side effects include suppressed immune
system, heart irregularities, internal
bleeding, high blood pressure, confusion,
fainting, dizziness, eye pain, blurred vision,
excessive weakness, excessive fatigue, or
excessive drowsiness. Yikes!
How do We Find Cancer Drugs?
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We take a cue from Nature.
Compounds found in plants,
mold, bacteria, algae, some
insects, marine mammals and
even snake venom are often
excellent growth inhibitors.
 From the Pacific Yew tree, some
300 different organic
compounds were isolated and
characterized and tested.
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From the Bark of the
Pacific Yew Tree
O
O
O
NH
OH
O
O
O
OH
O
OH O O
O
Taxus brevifolia
O
How Taxol Works
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A large number of microtubules are formed
at the start of cell division, and as cell
division comes to an end, these
microtubules are normally broken down into
tubulin – a protein responsible for the cell’s
structural stability.
Taxol binds to the microtubules and inhibits
their depolymerization into tubulin.
The cell can't divide into daughter cells and
therefore the cancer can’t spread.
Tubulin with
Taxol bound to
one of the
Functional
Domains
Taxol Causes Cells’ Tubulin
Skeleton to Aggregate in Spindles
May be More Effective than Taxol
Epothilone B
inhibits tubulin aggregation
O
S
H
OH
N
O
O
OH
O
DNA Cross-linker
21
O
CH3O
O
O
O
O
N
CH3
OH
N
H
AcO
H
N
10
HO
Azinomycin B
Streptomyces sahachiroi
O
Replication
Prevents DNA from Unraveling
O
O
OH
OH
OH
OCH3 O
OH
O
CH3
NH2
Doxorubicin (adriamycin)
OH
Binds to DNA and inhibits the enzyme topoisomerase II
Radiosensitization
and Chromatin Compaction
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At FCCC, our group studied the effects of
compounds that affected a cell’s chemistry by
inhibiting enzymes that allow for specific
chemical reactions to occur.
Without these reactions occurring, the DNA in
the cells tended to hyper-coil around proteins
called histones. Compacted Chromatin
With a preponderance of our cancer cells now
hypercoiled, they presented an unusually dense
target for ionizing radiation. Hence these cells
were radiosensitized.
FR 901228
Histone Deacetylase Inhibitor
H
O
N
H
N
O
S
O
S
N
H
N
H
O
O
O
from Chromobacterium violaceum
A Radiosensitizer
Protein Phosphatase Type 1 and 2a
Inhibitor
HOOC
O
O
OH
O
OH
H
H
OH
O
O
H
O
H
O
OH
Okadaic acid
Marine natural product
causes diarrhetic shellfish poisoning
Two Phosphatase Inhibitors
O
O
O
O
O
S
O
O
CH3
CH3
Cantharidin
H
H
LS-5
LS-16
exo, exo, exo 6,7-dicarbomethoxy-3,8-diaxatricyclo[3.2.1.0
2,4
]octane
Animal Models
Researchers use SCID mice onto which human
tumors can be xenografted.
Cytotoxicity
of asynchronous DU-145
prostate cancer cells
exposed to drug for
o
2-h at 37 C
Cantharidin
Cantharidic acid
LS-5
.
Survival Curves
HT-29 colon cancer cells
Irradiated after 2-h exp.
to 2 M drug
.
Control (no drug)
LS-1
LS-2
LS-5
LS-5 (1 M)
Survival Curves of
G1 phase HT-29 cells
after 2-h exposure
to LS-5
.
Control (no drug)
0.2 M
0.5 M
1.0 M
2.0 M
Radiation Inactivation
of DU-145 cells
by 4 Gy Cs-137
after treatment with
30 M drug
LS numbers
Thank You!
J.D. Chapman, R. Schneider, C. C. Stobbe
 Fox Chase Cancer Center
 CHM 320 class
 Michael Prushan, Ph.D.
 National Institutes of Health (#CA06927)
 La Salle University
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