T H E N I H C A T A L Y S T | M A Y J U N E 2006 |
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ON THE ROAD TO DOCTORAL DEGREES: NIH GRADUATE STUDENTSEMERGE FROM THEIR LABS TO REVEAL THEIR RECENT FINDINGS |
by Fran Pollner |
The Graduate
Partnerships Program (GPP) is NIH's contribution to the training of graduate
students who are working toward a degree in the biomedical sciences at accredited
universities in the United States and abroad. The university partners provide
the coursework and the degree, and, in some cases, research advisors; NIH provides
the labs, NIH research mentors, and hands-on research training.
There are now about 370 students in the GPP, and that number
will top 400 when the new students arrive this summer. The students come
from more than 100 universitiesabout 62 percent based in the United States
and 38 percent elsewhere.
The third annual GPP graduate student research symposium took
place May 5. Seventy-six of the students presented posters; 11 gave talks on
their research.
Judged on the basis of "organization, clarity, and scientific
significance," 20 of the posters were designated "finalists."
From this cohort, three were selected as winners (see footnote).
Following
are brief reports on two of the 76 posters.
HARNESSING THE ANTITUMOR EFFECT OF AN IMMUNOSUPPRESSANT FOR LUNG CANCER PREVENTION
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Now
a fourth-year student in the graduate genetics program at George Washington
University in Washington and already the holder of a master's degree in
public health, Courtney Granville has been working in the NCI lab of Phillip
Dennis for three years, drawn there, she says, by the lab's "emphasis
on tobacco-related lung cancer and the environmental causes of disease
in general." Equally important is the "translational nature of the lab's research." The science, Granville says, "is very real and very applicable." She wants to focus her career on chemoprevention and can envision working in academia or a regulatory agency. |
Courtney
Granville
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"Rapamycin,
an inhibitor of mTOR, decreases tobacco carcinogen-induced lung tumorigenesis"
Courtney
Granville, George Washington University, Washington, D.C., Graduate Program
in Genetics
NIH
research advisor: Phillip
Dennis, investigator, Medical
Oncology Branch, NCI-CCR
Granville's
research project, which was one of 14 selected for oral presentation at the
GPP Research Symposium, explored further the role of tobacco-activated mTOR
in the induction of lung cancer, as well as the inhibition of mTOR in the prevention
of lung cancer and the amelioration of existing tumors.
The Dennis lab had previously shown that tobacco components
activate the Akt/mTOR pathway.
In the current project, the team treated mice that had been
exposed to a specific tobacco carcinogen with rapamycin, an mTOR inhibitor that
is also an immunosuppressant approved by the FDA to prevent post-transplantation
graft rejection and to coat arterial stents.
Rapamycin works as an immunosuppressant by squelching T-cell
proliferation and function, Granville noted; it has been studied in tumor models
and found to shrink existing tumors.
In the current study, Granville and her colleagues showed
that tobacco carcinogeninduced lung tumorigenesis depends on mTOR and
that rapamycin-mediated inhibition of mTOR prevented the development of lung
lesions in carcinogen-exposed mice. The action of rapamycin before the emergence
of observable lesions had not previously been demonstrated, Granville noted.
This ability to suppress tumorigenesis "provides a
rationale to test mTOR inhibitors in smokers at high risk for lung cancer,"
Granville wrote in her abstract. She noted in an interview, however, that
the immunosuppressive action of rapamycin would necessarily inspire great caution
in considering it as a preventive agent, even in heavy smokers.
That rapamycin might be useful as a cancer preventive was
suggested, however, in a study reported last year: Transplant patients who received
rapamycin exhibited a decreased incidence of de novo malignancies, compared
with transplant patients who had received other immunosuppressive drugs.
Figuring out how to maximize rapamycin's antitumor effect while minimizing its immunosuppressive
effect would be a worthy pursuit for future studies, Granville said.
PARENTAL ALCOHOL USE REFLECTED IN BRAIN MEASUREMENTS OF ADULT ALCOHOLICS
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Jodi Gilman The field of neuroscience, Gilman says, is "awesome." One of the 20 or so finalists among the 76 graduate students who presented posters at the GPP Graduate Student Research Symposium, Gilman is in her second year of doctoral training at Brown University in Providence. Eventually, she says, she would like to work at NIH or in academia. |
"Influence
of parental alcoholism on brain volumes in alcoholics"
Jodi
Gilman, Brown University, Providence, R.I. Graduate Program in Neuroscience
NIH
research advisor: Daniel
Hommer, chief, Brain
Electrophysiology and Imaging, Laboratory
of Clinical and Translational Studies, NIAAA
Images
of the brains of alcoholics pose general questions regarding cause and effect
and particular questions regarding genetic versus environmental causes.
Jodi
Gilman and her NIAAA co-workers aimed to tease out the effects of alcoholism
and the influence of parental history on brain structure and function in adult
alcoholics.
Study
volunteers were alcoholics seeking inpatient treatment at the NIH Clinical Center.
Sixty-four men and 27 women had no family history of parental alcoholism; 96
men and 60 women had at least one heavy-drinking or alcoholic parent.
Using
MRI, the team measured intracranial volume (ICV), cerebral brain volume, and
white and gray matter volume.
Consistent
with reported findings in previous studies, the entire cohort of alcoholics
had smaller-than- average brain volumes. Beyond that, however, the alcoholics
with a positive family history had significantly smaller ICVs than those with
unaffected parents, a finding not previously demonstrated.
Unlike
the cerebral cortex, which is subject to alcohol-induced atrophy, ICV is a particularly
intriguing measure, Gilman said, because it reaches its permanent size by about
age 12 to 16. Factors operating during the time between conception and puberty,
thereforenot the individual's alcoholismwould be in play.
"We have a lot more to study," Gilman noted, listing
functional MRI studies; looking at the influence of family history on the size
of different parts of the brain, such as the frontal lobe; looking more deeply
at the cogitive and emotional impact of family history; analyzing the impact
of age at drinking onset on measures; and, of course, "everyone is still
looking for genetic factors."
The
fact, however, that people have been looking for genetic factors for decades
inclines Gilman to accord a greater role to environmental reasons to account
for why children of alcoholics are at a fivefold increased risk of becoming
alcoholics themselves.
The
stress of growing up in an environment where heavy alcohol consumption is a
fact of daily life might account, too, for the
physical brain findings, she remarked.
Not
only does stress affect brain growth and development in animals, she observed,
but there are studies showing that children subjected to abuse and other experiences
associated with post-traumatic stress disorder have reduced ICVs.
*At the
end of the GPP poster day, three of the 76 graduate student poster presenters
were declared winners. In alphabetical order, they are:
Kristina Buac,
George Washington University graduate program in genetics, Washington, D.C.,
"Wireless, a novel ENU-induced allele of ErbB3 gene exhibiting neural
crest defects distinct from the null allele." NIH research advisor, Bill
Pavan, senior investigator, Genetic
Disease Research Branch, NHGRI.
Daniel
Spellman, New York University School of Medicine graduate program
in structural biology, "Stable isotopic labeling of amino acids in
cultured primary neurons for the study of protein turnover and neuronal signal
transduction." NIH research advisor, Alfred
Yergey, Head, Section
on Mass Spectrometry and Metabolism, NICHD.
Honghong
Zhu, Johns Hopkins University School of Public Health graduate
department of epidemiology, Baltimore, "Secondhand smoke and breast
cancer risk: a population-based prospective cohort study." NIH research
advisor, Kenneth
Cantor, senior investigator, NCI-DCEG.