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Abstracts of 2004-2005 Culpeper Biomedical Pilot Initiative
Grants
Deconstructing & Reconstructing Myelin-Regenerative Medicine in
the Brain
Amit Basu, PhD, Brown University
Every nerve in the body functions like a tiny electrical cord,
carrying impulses to the spinal cord and the brain. Just like
an electrical cord, these nerves have a protective and
insulating coating, which is called myelin. Many diseases of
the nervous system, such as multiple sclerosis, are caused by
the breakdown of myelin around the nerves. There is
considerable research around the world looking at ways to regrow
myelin on nerves, but so far none of it seems to work in
people. One issue is getting the first layer of new myelin
cells to stick to the nerves. Dr. Basu and his team have an
idea to overcome this problem. They will try to create a
variety of synthetic molecules that could be injected into a
patient and would strongly attach to the frayed part of the
nerve. This molecule would then serve as the “glue” to allow
new myelin cells that the body would produce to attach and build
up around the nerve, reversing the diseases of the nerves.
Early
Detection Test for SARS
Natalia E. Broude, PhD, Boston University
SARS is a deadly human illness that first appeared in 2002 in
China and has spread to more than 30 countries. SARS is caused
by a coronavirus, the genome of which has been sequenced.
Knowledge of the SARS genome makes it possible to develop an
early detection test for SARS, preventing the global spread of
SARS. This study will develop this innovative test for SARS,
which would hook a molecule that glows in the dark to a protein
that would attach a specific spot on the SARS gene. An infected
patient’s blood sample would immediately glow, simplifying and
speeding up detection at a very low cost. If this technology
works, it would open new doors for all kinds of instant
diagnostic medical and forensic tests at a much lower cost.
Vibrational Imaging: Making the Microscope Work Harder
Ji-Xin Cheng, PhD, Purdue University
This project will develop a new highly sensitive microscopy for
the imaging of molecules using vibrational imaging. Traditional
microscopy suffers from noticeable background noise that limits
its sensitivity when looking at the smallest molecules.
Vibrational imaging records simultaneous pictures of the
molecules and superimposes them on each other eliminating the
background noise. This imaging technique will “clearly” bring
microscopy to a new level.
Not only will this research help us to look at things we know
about now, it will undoubtedly lead to discoveries that would
otherwise be impossible. Once we are able to tune our vision to
look at things smaller than we’ve every seen before, we can tune
our minds to new frequencies of thought that will lead to better
treatments and cures.
A New
Self Monitor for Anemia
Gregory Crawford, PhD, Brown University
Anemia, the lack of healthy red blood cells, has long been
viewed as the innocent bystander of disease; however there is
compounding evidence indicating that anemia is a significant
free-standing health issue that is severely under diagnosed and
rarely managed properly in patients with life altering and
chronic diseases. Just as patients can monitor their own heart
rate, blood pressure, and blood sugar, enabling patients to
measure their own anemia by monitoring their red blood cells at
home will empower patients and improve their quality of life.
This proposal will create a device that will take a photo of the
lining of the lower eyelid using a small camera. A computer
program will compare the red color of the photo with a standard
to determine in real time how many red cells are present to
determine the patient’s anemia. The device could provide
accuracy similar to the current lab test when the physician
draws blood from the patient. Dr. Crawford and his research team
envision the final device to be small, inexpensive and
integrated onto a PDA (personal digital assistant) device or a
cell phone so that it can be integral to home health care
situations in helping people better manage the consequences of
life altering diseases.
A
Potential Cure for Colon Cancer
Benoit de Crombrugghe, MD, M.D. Anderson Cancer Center
The walls of gut are folded into numerous valleys and peaks that
increase surface area for absorbing nutrients. The surface
cells are consistently renewed from stem cells located toward
the bottom of the valleys. In most colorectal cancer, a protein
becomes abnormally active in these stem cells and they multiply
out of control.
Dr. de Crombrugghe and his team will discover whether control of
this protein could halt colorectal cancers. This research could
be a life-saver for the more than 130,000 American diagnosed
with colon cancer each year. Maybe more importantly, the
discovery that stem cells may play a role in cancer is important
to a wide variety of cancers, and may lead to discoveries that
can help not only cancer patients, but those of us who want to
keep from becoming a cancer patient.
Blocking the Molecules that Reduce the Effectiveness of
Chemotherapy
Stephen Kron, MD, PhD, University of Chicago
Most cancer therapy works by damaging the DNA of cancer cells.
When these cancer cells divide, the damaged DNA causes the cell
to die. All cells, especially cancer cells, have the ability to
repair the damaged DNA before the cell divides. If the DNA is
repaired before the cell divides, the cancer cell will not die.
Dr. Kron and his colleagues have discovered a key molecule in
cancer cells, HA2X, which is required to rapidly repair DNA
damage. This study will test over 20,000 small molecules that
can block the effectiveness of HA2X. A molecule that can block
HA2X will theoretically deliver the knock-out punch that would
allow chemotherapy or radiation therapy to kill all cancer
cells, especially in cancers that have spread around the body.
Dr. Kron’s breakthrough research could have a significant impact
on survival and quality of life of all cancer patients.
A New
Environment for Testing Drug Interactions
Brenda Mann, PhD, University of Utah
Drug development must identify compounds that are toxic to
healthy human cells. Early identification of toxicity reduces
the danger to patients and costs to the pharmaceutical
companies. Lab studies do not always predict how the drug will
affect cells when it is given to animals or humans in clinical
studies because cells tested in the lab are not in the actual
“body environment”.
This project will create a three dimensional structure in the
lab, in which test cells are in contact with each other,
mimicking the “body environment”. This tissue-like environment
should more accurately predict toxicity of drugs when they are
actually given to humans.
A New
Understanding of How Blood Vessels Work
Michael Marletta, PhD, University of California, Berkeley
Dilation of the blood vessels in the heart and other tissues is
controlled by a reaction inside cells that gives off the
chemical nitric oxide (NO). NO causes the muscle cells of the
blood vessel walls to relax so the vessel can expand. Dr.
Marletta and co-workers recently discovered that the accepted
mechanism for how NO causes this relaxation is fundamentally
incorrect. Determining the details of these new findings will
lead to a better understanding of normal heart and blood vessel
function, and to new approaches for treating heart disease and
other cardiovascular ailments. This proposal will explore the
action of NO on a specific enzyme target in the cardiovascular
system. Based on current data, the consensus opinion is that
nitric oxide directly activates the enzyme, and that another
molecule deactivates the enzyme. Pilot data suggests that a
novel feature of the enzyme itself controls both activation and
rapid deactivation. Confirming these results could provide
novel treatments of cardiovascular disease through manipulation
of the target enzyme.
Preventing Transmission of HIV
Malcolm Potts, PhD, University of California, Berkeley, CA
Sexual transmission of HIV and other sexually transmitted
diseases (STDs) continue at epidemic pace globally. HIV
researchers believe that microbicides, chemicals that can kill
bacteria and viruses, can reduce the transmission of HIV and
other STD pathogens when applied vaginally. Current academic
and pharmaceutical research is focusing on the lengthy and
expensive process of developing new microbicide drugs that will
make a large profit for these companies.
Women around the world have used diluted lemon or lime juice
vaginally as a microbicide for hundreds of years. Lemons and
limes are inexpensive and locally available in nearly every
country. In lab studies, lemon/lime juice kills HIV on contact
and has been proven safe when applied to the vaginas of
monkeys.
If lemon juice is effective in reducing HIV transmission in
humans, the world will have an inexpensive and life saving
technique for the reduction of a catastrophic disease, and a
benchmark of safety and effectiveness for testing futures
microbicides. Dr. Potts and his team will test whether lemon
juice is safe when self-applied to a woman’s vagina.
If this test proves that dilute lemon juice is safe, a human
clinical trial will begin to test whether lemon juice does
reduce HIV infections and other STD’s. Dr. Potts’ research has
the potential to introduce a safe, effective, available, and
inexpensive method years before a commercial microbicide becomes
available.
Stopping Spread of Multiple Myeloma Cells
Peter Rowley, MD, University of Rochester
Multiple myeloma is an incurable blood-bone cancer. The disease
is caused by two or more defective genes. One of the reasons it
is so hard to defeat is that these multiple gene defects create
a variety of pathways the disease uses to keep growing. There
are many therapies that can kill myeloma cells, but other
myeloma cells just keep growing using alternative pathways, and
eventually the patient succumbs to the disease.
Dr. Rowley and his team have developed a new technology that can
stop more than one defective gene at the same time. His team
has already shown that this therapy, a gene inhibitor called
peptide nucleic acid (PNA), can block one defective gene in
multiple myeloma cells.
This new project will create a PNA to the other major gene
defects, so that myeloma cells will be killed without having an
alternative path around the therapy. If this project is
successful, there is hope that this incurable disease will soon
be conquered, and that other resistant, incurable cancers can
also benefit from this powerful therapy.
Finding a Cure for Untreatable Non-Small Cell Lung Cancer
Sreenath V. Sharma, PhD, Massachusetts General Hospital Cancer
Center
Lung cancer is the leading cause of cancer-related deaths
worldwide. Non-Small Cell Lung Cancer (NSCLC) accounts for a
majority (80%) of cases of lung cancers. Overall, fewer than
10% of lung cancer patients are alive 5 years after initial
diagnosis and this number drops to less than 5% in individuals
with advanced-stage NSCLC. Even the most aggressive
conventional chemotherapy is excessively toxic and only
marginally improves survival rates. Thus, there is a tremendous
need to develop better therapies for lung cancer treatment.
Recent studies have identified Epidermal Growth Factor Receptor
(EGFR) as a protein that is found at high levels in NSCLC. This
formed the basis for the development of drugs that inhibit the
EGFR for the treatment of NSCLC. Two such drugs, namely,
Gefitinib/Iressa (AstraZeneca) and Erlotinib/Tarceva (OSI
Pharmaceuticals, Genentech and Roche), received “fast track”
approval from the US Food and Drug Administration (FDA) for use
as drugs of last resort in patients with advanced NSCLC. The
focus of this research is on these two drugs. Early experience
from clinical trials of these drugs indicated that they are able
to create dramatic clinical responses in about 10% of treated
patients - responses that could not be achieved by any other
treatments available to date. However, 90% of cases failed to
respond and even the 10% of cases that show response to the drug
were prone to developing resistance to the drug after some
time.
Dr. Sharma and his co-researchers observed that sensitive lung
cancer cells that become resistance to these two drugs, as well
as lung cancer cells that were insensitive to them in the first
place are effectively killed by combination of these drugs and a
well known anti-malaria drug. This combined drug approach might
expand considerably the range of lung cancers that can be
effectively treated by Iressa and Tarceva. In addition, adding
the anti-malaria drug might allow physicians to reduce the
dosage of Iressa and Tarceva to substantially decrease toxicity
and the cost of treatment. Finally, it is possible that other
tumors besides lung cancer may also be treatable by the
anti-malaria drug combination approach.
Using Nanotechnology to Cure Pediatric Cancer
Jason Shohet, MD, PhD, Baylor College of Medicine
Most of the time, when something goes wrong in a normal cell,
the cell is programmed to self-destruct. Cancer is caused when
something goes wrong in normal cells and they don’t
self-destruct. Neuroblastoma is a cancer which causes 15% of
all childhood cancer deaths. No new therapies for this cancer
have emerged in the last few years. This cancer is so difficult
to treat because the self-destructive capacity of these cancer
cells is totally ineffective. Dr. Shohet and his team recently
discovered a molecule, called MDM2, which helps keep cancer
cells from self-destructing. Neuroblastoma cells have an
abnormally high level of MDM2. Dr. Shohet’s lab recently tested
a molecule which blocked MDM2 in lab tests so that neuroblastoma
cells self-destructed. This project will use nanotechnology to
deliver this molecule to test animals to see if the lab success
will translate into success treating “patients”. If this works
on the test mice, the next step would be to get ready to test
this on humans with neuroblastoma, and to determine if MDM2
plays a role in other kinds of cancers.
Replacing Light Receptor Cells
Gabriel Silva, PhD, University of California, San Diego
More than 50 million people worldwide are going blind because
the light receptor cells in their eyes have broken down. There
are few treatments that can slow these diseases, and none that
can cure them. The most promising research is centering on
replacing the damaged light receptors cells. Researchers have
found certain blood cells from the bone marrow can be
transformed into light receptor cells. These blood cells are
called adult stem cells because they can turn into a wide
variety of cells in the body. Other researchers have made some
of these blood stem cells look like light receptor cells.
However, while they look like light receptor cells, they don’t
function like light receptor cells. Dr. Silva and his team have
hypothesized two breakthroughs that may lead them to rapidly
develop new light receptor cells that can be transplanted into
the eye to restore the vision that these patients have lost.
The first breakthrough that Dr. Silva and his team believe is
necessary is to provide these blood stem cells with the same mix
of chemical and other signals that normal light receptor cells
would receive as they are maturing.
More importantly, a second breakthrough is needed, to create a
special three dimensional nano-environment on which these blood
stem cells can grow. This three dimensional structure mimics
the structure of the retina where light receptor cells normally
grow. Dr. Silva and his team are trying to re-create the exact
environment in which normal light receptor cells grow, so these
stem cells can grow into functional light receptor cells.
If Dr. Silva and his team are correct, these new “Supercells”
will be able to save the sight that so many people continue to
lose.
Extra-Cellular Matrix
Randy Sigle, PhD, Fred Hutchison Cancer Center
The cells of the human body are held together by something we
call extra-cellular matrix. Extra-cellular matrix is a complex
of proteins and other components that not only provide structure
for the body, but also provide a way for nutrients and signals
to get from one cell to another. When the extra-cellular matrix
breaks down in a wound, or is pushed out of the way when a tumor
takes over, the body no longer functions normally.
The search is on to create a synthetic extra-cellular matrix
that we envision can be used for four purposes: 1) research on
how changes in the extra-cellular matrix affect the body, 2)
replacing damaged extra-cellular matrix in wound situations, 3)
as a therapy when drugs are incorporated into the synthetic
extra-cellular matrix before it is placed into the body, and 4)
as a scaffold for designing artificial body parts.
Silk from silkworms is a compelling candidate for this
synthetic extra-cellular matrix. It is abundant, nearly pure,
can be made in both water soluble and non-water soluble forms.
Dr. Sigle and his team will begin to determine whether or not
the biological activities of the human extra-cellular matrix can
be incorporated into silk. If their hypotheses are correct,
this research could lead to the development of new therapies for
wound healing and cancer, as well as the initiation of a new
paradigm for tissue engineering.
What
Can Stem Cells Teach us about Curing Cancer?
Yanhong Shi, PhD, City of Hope Medical Center
Stem cells have the unique abilities to self-renew and to change
into other kinds of cells. This is good. Cancer cells have the
same characteristics. This is bad. Dr. Shi and her colleagues
believe that many of the pathways that help stem cells
self-renew and change are the same pathways used by cancer
cells, especially brain tumor cells.
Dr. Shi has discovered a compound called TLX which is critical
to the self-renewal process in adult brain stem cells. When
cells don’t have TLX, they can’t grow. If you give these cells
TLX, they will begin to multiply. These discoveries have
created this research, through which the Dr. Shi team will
determine whether brain tumor cells use TLX to help them grow
and multiply.
If they team finds TLX is required for brain tumor growth, they
will find the genes that TLX affects in both brain stem cells
and brain tumor cells. Comparison of these two cell types will
allow researchers to create anti-tumor therapies that can attack
the TLX sensitive genes in brain tumor cells, creating
treatments for these devastating, incurable cancers, and for
other brain related diseases.
A
Cure for Mad Cow Disease
Gultekin Tamguney, PhD, University of California, San Francisco
Mad Cow Disease is a rare, fatal disorder in humans with no
current treatment or cure. The disease is caused by an
abnormally folded piece of cellular protein called a prion that
accumulates in the brain. Research has shown that antibodies, a
special molecule produced by the body’s immune system that
recognize and help fight infectious agents, can bind to the
prion to “cure” a prion infection in a cell culture model.
Until recently antibody therapy for human prion diseases did not
seem feasible since prion-binding antibodies could not cross the
blood-brain barrier.
The aim of this proposal is to link prion-binding antibodies
with a molecule that will cross the blood brain barrier, like
hooking a caboose (the prion-binding antibody) to an engine (the
molecule that will cross into the brain) so the caboose can get
to where it needs to go. The “engine” molecule will release the
antibody once it is inside the brain, so the antibody can bind
to and destroy the prions.
This type of treatment could either provide a vaccine that would
protect a person from prion disease or a treatment that would
cure prion disease after infection. Further, a successful
outcome for this project could open the door to novel treatment
strategies for similar brain diseases associated with the
accumulation of mis-folded proteins such as Alzheimer’s and
Huntington’s Disease.
Translating
Knowledge from One Disease to Cure Another
David Teachey, MD, University of Pennsylvania School of Medicine
Normally, the body creates new cells and eliminates worn out
cells in a process called apoptosis, or cell death. In ALPS
(Autoimmune Lymphoproliferative Syndrome), the body accumulates
old white blood cells, which damage organs and red blood cells
causing anemia, fatigue, internal bleeding, and infection. The
drug Rapamycin prevents organ transplant rejection and is also
effective in treating white blood cell cancers, by causing cell
death. Dr. Teachey and his colleagues believe Rapamycin might
be effective in treating ALPS. This study will first test the
drug in a mouse model of ALPS. If it works, the drug will be
tested on ALPS patients, who have no other effective form of
therapy and usually do not survive the disease.
Halting Malaria in Transmission
Joseph Vinetz, MD, University of California, San Diego
Malaria is one of the world’s most prevalent diseases, killing
1-3 million people (mostly children) annually. Mosquitoes
spread malaria to humans. This project will use genomics to
determine how malaria moves from humans to mosquitoes and back,
testing a breakthrough to keep the malaria parasite from
reproducing in the mosquito, breaking the transmission cycle.
After understanding this mechanism, novel methods of
interrupting the transmission of malaria can be created. If
this proves successful, this technique can be used to design a
cure for other insect borne diseases, such as West Nile Fever,
Eastern Equine Encephalitis, and Dengue Fever.
Eliminating Resistance to Chemotherapy
Steven J. Weintraub, MD, Washington University School of
Medicine, St. Louis
Unfortunately, chemotherapy agents do not cure most types of
cancer and their administration causes significant side
effects. These agents have many effects on cancer cells, and
little is known about which effects cause cancer cell death.
Many drugs kill cancer cells by modifying cell proteins that
make it impossible for the cell to survive. When the
modification of this protein is blocked, the cells become
resistant to chemotherapy. Recently, Dr. Weintraub and his team
discovered compounds found in many cancers that block the
chemotherapy protein changes. Cancers with these compounds are
quite resistant to chemotherapy. Understanding the mechanism by
which these cancer compounds block chemotherapy could lead to an
improvement in the treatment of a wide variety of cancers.
Abstracts of 2004-2005 Culpeper Medical Scholar Grants
Functional
Genomic Dissection of Human Mitochondrial Disorders
Vamsi K. Mootha, M.D. Massachusetts General Hospital, Harvard
Medical School, Broad Institute of MIT and Harvard
Mitochondria are tiny structures found in each of our body’s
cells. They are responsible for converting the food we eat into
“cellular fuels” that can be used by our muscle, brain, heart,
and other organs, to perform work. Recent studies have shown
that dysfunction of mitochondria can give rise to rare inherited
disorders, as well as some very common human diseases, such as
diabetes, neurodegeneration, and cancer. With funding from the
Charles E. Culpeper Scholarship, I plan to focus a portion of my
lab’s efforts on a class of mitochondrial disorders that are
characterized by devastating metabolic dysfunction, particularly
in children. At present, the diagnosis of these disorders is
extremely difficult, and we have no therapeutic options for
them. Although these disorders are due to mutations in single
genes, they give rise to a variety of symptoms – how lesions in
individual genes can give rise to such a spectrum of clinical
presentations remains a puzzle. Using new tools that enable
scientists to systematic disrupt individual genes my team will
create cellular models of mitochondrial disease that we can then
study in our laboratory. In particular, we will use new
technologies that enable us to monitor all the genes in the
human genome and their response to these single genetic
lesions. Through the combined use of biochemistry, genetics,
and mathematics, we then hope to identify the cellular pathways
that go awry in these disease models, with the goal of
identifying molecular targets against which rational therapies
can be designed.
Therapeutic discovery for obesity
Kevin
Niswender MD, PhD, Vanderbilt University, Department of
Medicine, Division of Diabetes, Endocrinology and Metabolism and
Department of Molecular Physiology and Biophysics
Obesity is both common and hazardous. The incidence of obesity
is increasing dramatically worldwide. Fully one-third of adults
in the U.S. are obese, and suffer a 3-4 fold increase in the
risk of stroke, coronary artery disease, hypertension and
diabetes mellitus. Despite annual obesity-related costs
approaching 240 billion in the US, effective treatments do not
yet exist for this disorder, which has emerged as one of the
greatest threats to human health worldwide.
Obesity does not result simply from a lack of will-power, but
from a strong regulatory system gone awry. Much like the blood
sugar level, body weight is normally maintained within a narrow
range by a powerful physiological regulatory system. When
tissues in the body become resistant to the effects of insulin,
the hormone that controls blood sugar, abnormally high blood
sugar results, a condition known as type II diabetes. Likewise,
most patients with obesity are resistant to the effects of the
critical hormone, leptin, which is made in fat cells and is
secreted into the blood stream in proportion to the amount of
energy stored in the body (in the form of fat). Through the
blood circulation, leptin enters a key brain region known as the
hypothalamus where it binds to its receptor on specific
hypothalamic brain cells (called neurons) and generates a signal
that ultimately decreases appetite and promotes weight loss.
When this signal does not work appropriately, leptin resistance
and obesity result. Interestingly, in addition to regulating
the blood sugar level, insulin has effects in the brain that are
very similar to the effects of leptin and insulin is considered
a second body weight regulating hormone.
Leptin (and insulin) resistance poses a major obstacle to
obesity treatment. Scientists have learned a great deal about
how the hypothalamus controls body weight, yet we still do not
understand how leptin and insulin control the function of
hypothalamic neurons, and therefore have little understanding of
resistance in obese individuals. The drug discovery approach
outlined in this proposal is based on new data generated by the
applicant regarding how these hormones normally work within
hypothalamic neurons, and how this normal function becomes
disrupted in obesity.
We have recently
discovered that a “signaling” molecule known as
phosphatidylinositol 3-kinase (PI3K) is critical for the ability
of leptin and insulin to cause animals to eat less. The first
step in understanding how leptin and insulin work and,
therefore, how to repair resistance, is to understand how these
two hormones translate an increase of body fat stores into a
message within the brain that results in decreased food intake.
We have demonstrated that a specific signaling molecule present
within hypothalamic neuron cells is necessary for leptin and
insulin to activate the neuronal cascade that leads to reduced
food intake. Surprisingly, this molecule, known as PI3K, is
also a critical mediator of the action of insulin in tissues
(like muscle) that help to lower blood glucose. As mentioned
above, the ability of insulin to activate PI3K in muscle cells
becomes impaired and leads to insulin resistance in obese
individuals, and this in turn favors the development of
diabetes. Just like in muscle, we have observed that in obesity
insulin and leptin no longer are able to activate PI3K within
the key cells in the hypothalamus and are therefore unable to
reduce food intake. We have also learned about the biochemical
mechanisms involved in this process.
With this information
we have developed an idea for the discovery of potential
medications to reverse this process in obesity. It turns out
that as with the analogies between muscle and brain mentioned
above, numerous similarities exist between pancreatic islet
cells, responsible for secreting insulin, and the important
nerve cells in the brain. Specifically, the processes whereby
the cell responds to the important hormones insulin and leptin
are very similar, including PI3K activation, and a similar
process causing hormone resistance also occurs in islet cells.
Thus, because pancreatic islets and hypothalamic neurons respond
to various stimuli, including insulin, leptin, glucose and fats
in a very similar way, a process called secretion-coupling, we
will utilize pancreatic islets to model neuronal function and to
screen for compounds that improve function. This is necessary
because it is not possible to purify sufficient quantities of
hypothalamic neuron cells to perform drug discovery work.
Furthermore, because we understand some of the processes
involved in the development of resistance, we can re-create
resistance in pancreatic islets by culturing them under specific
conditions.
High-throughput
screening as a mode of drug discovery is now possible at
Vanderbilt University because we have established a fully
operational facility and we own a 160,000 compound small
molecule library. This approach seeks to simply treat an
experimental sample with each of the 160,000 compounds to
determine whether any look promising as a new medication. The
160,000 compound library has been designed to be maximally
chemically diverse and also to have compounds with structures
that are likely to work as medications. Thus, we are
essentially performing in excess of 160,000 separate experiments
which is only feasible because this facility is fully automated
and has a number of instruments that are run by robots. Each
“experiment” is performed in a single well in a 384 well dish
and with this miniaturization and automation we are capable of
screening this complete library over the course of several
weeks.
Thus, the basic premise
is to detect an experimental response in islet cells that can be
measured by the robotic instruments. In our case, pancreatic
islets secrete insulin by having an increase in calcium levels
in the cell. Our instruments can measure this increase in
calcium and we can, therefore, easily and quickly determine when
a test compound has caused insulin secretion. The islets will
be treated to generate insulin resistance and then will be
plated in 384 well plates. In the screening facility, the
instruments will then add insulin and one of the 160,000
compounds from the library to a single well of the plate (all
384 wells simultaneously receive different compounds) and
determine whether these individual compounds restore the ability
of insulin to stimulate insulin secretion. Our first goal of
this project will be to adapt our concept to the robotic
instruments used within the screening facility. Once the assay
has been optimized, with the robots and “high-throughput”
instrumentation, we expect that completing the screen of the
160,000 compound library will take several weeks.
The use of “primary”
cells, or cells and tissues derived straight from an animal is
unique in high throughput screening, as is the concept of
re-creating the disease process in the cells to be screened.
This approach is considered to be cutting edge, and is not the
standard approach taken because it is technically more
difficult, and therefore risky. One very important reason we
have chosen this approach is that we will be able to discover
compounds that restore insulin secretion by acting anywhere in
the process, not just at specific points. Thus, we will not be
limited by our current understanding of the disease process; we
may actually identify completely new pathways and medicines for
the treatment of diabetes and obesity. We have already
developed important evidence in proof that this concept can be
utilized and are working to “miniaturize” the experiments to the
high-throughput screening format. Once the complete library has
been screened and we have identified compounds that potentiate
or improve insulin-stimulated insulin secretion in insulin
resistant islets, we will further characterize these compounds
to determine at what point in the insulin secretion pathway they
work. Ultimately, of course, we will test the effect of these
compounds in obese animals, and then begin to work with
pharmaceutical companies to develop any promising compounds for
the treatment of human obesity. Importantly, because we are
using pancreatic islets for this screen, we will also identify
compounds that may be useful in the treatment of diabetes.
The
Role and Regulation of Autophagy in Epithelial Cell Homeostasis
and Cancer
Jayanta Debnath, MD, Assistant Professor of Pathology at the
University of California San Francisco
Cancer is a deadly
disease because an individual’s own cells develop genetic and
biological changes allowing them to survive and grow in places
where they do not belong. Extensive research has shown that one
reason that cancer cells survive in unusual places is because
they are protected from a process called programmed cell death,
or apoptosis. Normally, apoptosis acts as a surveillance
mechanism in the body that kills excess cells to prevent them
from building up; this is not the case during cancer
progression.
Although reduced
apoptosis contributes to the ability cancer cells to survive,
recent evidence is now indicating that other, less appreciated
mechanisms, are also likely to regulate cancer progression.
Without clarifying how such critical processes work, we are
unlikely to develop effective treatments against cancer.
I recently found that
when apoptosis is blocked, a second process, called autophagy,
may act as a back-up mechanism to kill wayward tumor cells.
Autophagy is a widespread biological process in which a cell
digests its own contents in response to various stresses. When
excessive autophagy occurs within a cell, it dies, because the
cell literally “eats itself” to death. However, very little is
known about the function or regulation of autophagy in human
cells. My proposed studies intend to further explore the role of
autophagy during cell death in both normal and cancer cells as
well as determine how cancer genes and pathways regulate this
poorly understood process. These studies may provide novel
information about the survival of cancer cells during cancer
progression, and may enlighten the diagnosis and treatment of
many different kinds of human cancer.
Activating Apoptosis in Cancer Using Hydrocarbon-Stapled Helices
Loren David Walensky, MD, PhD, Harvard Medical School and
Attending Physician and Research Fellow in the Department of
Pediatric Hematology/Oncology at the Dana-Farber Cancer
Institute/Children’s Hospital Boston.
Whether our cells will live or die, and whether we are therefore
healthy or ill, is controlled by how proteins interact with each
other inside our cells. There are a huge number of proteins in
our cells, and each one has a specific job to do. Whether a
protein can do its job depends on which other proteins are
present inside the cell and what they are doing. Think of a
cell as the most complex assembly line in the world, and each
protein as a worker on that assembly line. How each protein
gets its job done inside a cell depends on how it communicates
with and interacts with the other proteins inside the cell.
Even a minor breakdown in communication between the proteins can
have a dramatic effect on cells, and on our health.
There are certain
proteins inside a cell called “BCL-2” proteins. These proteins
interact with one another to regulate whether a cell dies when
it is old, diseased or no longer needed. This cell death is
called “apoptosis”. Many human diseases directly results when
apoptosis does not occur the way it should. Premature cell
death that reduces the number of healthy cells needed to
continue important body functions can lead to illnesses like
Alzheimer’s disease or stroke. On the other hand, cancer occurs
when diseased and damaged cells don’t die on time. These and
other diseases are the direct result of BCL-2 protein
interactions that have gone awry. Cures can come from fixing
these BCL-2 protein problems.
BCL-2 proteins control
cell death through small protein subunits called “peptides” that
are helical, or spring-like, in shape. Scientists can create
other peptides that interact with these helical BCL-2 peptides
to slow down or speed up cell death. However, most current
attempts to manufacture these artificial peptides have failed
because the helical shape is so complex. Peptides that have
been manufactured in the right shape are so fragile that they
break down before they can do their job. Attempts to strengthen
these fragile peptides have made it impossible for the peptides
to get inside the cells to do their job.
Dr. Walensky’s research
focuses on developing and applying new approaches to this
problem. He will address two issues-using natural versus
artificial peptides, and strengthening them without destroying
their effectiveness. Dr. Walensky will use a new process to
chemically brace these natural peptides so that their shape, and
therefore their curative activity, can be maintained. He has
used this chemical strategy, called “hydrocarbon-stapling”, to
make a number of peptides with dramatically improved
properties.
Dr. Walensky has
demonstrated that the stapled peptides are the right helical
shape, are sturdy, and can enter and kill leukemia cells by
turning on the BCL-2 death pathway. When he administered these
stapled peptides to mice with leukemia, the stapled peptide
successfully blocked cancer growth and prolonged the lives of
treated animals. As a Culpeper awardee, Dr. Walensky’s future
work will employ this new peptide-stapling strategy to produce a
wide array of peptides that can interact with the BCL-2 pathway,
in order to control cell death in a variety of human cancers.
The goal of Dr. Walensky’s research is to produce an arsenal of
new compounds, a “peptide toolbox,” to block protein
interactions that cause cancer, as illustrated by the
anti-leukemia effect of his stapled BCL-2 peptide.
Treatment of Preeclampsia by sFlt1 Knock-Down Using RNA
Interference
Sharon Maynard, MD,
Assistant Professor in the Renal Division, George Washington
University Medical School
Preeclampsia is a life threatening condition that affects
pregnant women and their babies. It occurs in 3-5% of all
pregnancies and has no effective treatment except immediate
delivery of the baby, no matter how far the pregnancy has
progressed and whether or not the baby is ready to be born.
Preeclampsia causes high blood pressure in the mother and
protein in her urine. If untreated, it can cause seizures,
stroke, kidney failure, liver failure, and clotting/bleeding
disorders in the mother. Often the baby needs to be delivered
prematurely to preserve the health of the mother, resulting in
serious consequences for the newborn. A treatment which could
allow physicians to safely delay delivery would make a
significant impact on the health of the mother and of the
newborn.
Dr. Maynard helped discover that a protein found in the blood of
pregnant women, called sFlt1, is overproduced in women who have
preeclampsia. Pregnant rats exposed to high levels of the sFlt1
protein develop hypertension, protein in the urine, and
microscopic changes in the kidney, all symptoms characteristic
of preeclampsia. This suggests that the sFlt1 protein may
actually be the cause of preeclampsia, and blocking the
production or action of sFlt1 may create an innovative treatment
or cure. Dr. Maynard is researching whether RNA interference
could block the production of sFlt1.
RNA interference is a technique that stops a specific portion of
a bad gene from creating a protein that can damage in the body.
Think of this defective gene as a locksmith shop gone bad. The
locksmith shop employs an evil locksmith, who will make a key
that will unlock your door for a criminal. A defective gene
employs an evil RNA messenger molecule, which makes a protein
that can unlock a damaging process inside your cell. At the
locksmith shop, if the police interfere with the evil locksmith,
he cannot make a key and your door cannot be unlocked. At the
gene, if the RNA interference police tie up the evil RNA
messenger molecule, it cannot make the protein and the bad
process in your cell cannot be unlocked.
RNA interference appears to be an innovative way to reduce the
levels of sFlt1in the blood. Dr. Maynard will study how RNA
interference will significantly reduce production of the sFlt1
protein in the cells of a woman with preeclampsia. She will
first use cells in the lab to design and optimize an RNA
interference molecule that will interfere with the bad gene RNA
messenger that produces the protein sFlt1. She will then use an
animal model of preeclampsia to determine if RNA interference of
sFlt1 can reverse the hypertension and kidney damage that occur
in these animals. If this works in the animal model, it may
prove that the protein sFlt1 is the culprit that causes
preeclampsia, and a human clinical trial will be considered. If
preeclampsia is truly a result of overproduction of this single
protein, reducing its production may be an effective treatment,
which could have a great impact on clinical outcomes in this
important
Mechanism and Significance of Adult Excitation-Neurogenesis
Coupling
Karl Deisseroth, MD, PhD,
Assistant Professor of Medicine, Stanford University, Assistant
Professor of Bioengineering and Psychiatry
Scientists have recently made an astounding discovery-adult
brains can and do produce new brain cells, called new neurons.
Until now scientists believed that once a newborn’s brain
development ended, no new brain cells were ever created. In
humans, these new adult neurons are created from adult stem
cells in a region of the brain called the hippocampus. The
hippocampus helps control memory and mood, which makes it an
important area of the brain to study when looking for cures for
anxiety, depression, suicide, and memory loss.
Dr. Deisseroth and his colleagues have found that the brain’s
own electrical activity can cause adult stem cells to turn into
new neurons, and have begun to figure out how and why this
occurs. These findings have huge scientific and clinical
significance because scientists and doctors know how to control
brain electrical activity using a variety of behavioral and
clinical techniques that don’t require surgery or other invasive
procedures. Dr. Deisseroth and his colleagues will further
describe how and why electrical activity in the brain causes
adult stem cells to change into new neurons. These discoveries
will lead to methods of controlling new neuron development in
adults who have memory loss or mental illness. This research
will lead to a deeper understanding of the function of the
hippocampus and to new treatments for major depression and other
disorders of the brain.
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