CELL
BIOLOGY: Substitute Protein in Energy Pathway Stalls Cancer Growth
Cancer cells may switch to a glucose-dependent route to satisfy their energy
needs, a phenomenon first observed nearly 80 years ago by Otto Warburg. It now
appears that they do so by reverting to the embryonic form of a key protein in
the glycolytic pathway. Lewis Cantley (front), Matthew Vander Heiden, Heather
Christofk, and colleagues found that they could turn off glycolysis in cancer
cell lines by replacing the embryonic (M2) version of the protein pyruvate kinase
(PK) with the adult (M1) form. The findings appear in the March 13 Nature.
PUBLIC
HEALTH: PTSD: The Suffering Continues for Vets
More than 30 years after the Vietnam War ended, a substantial minority
of veterans suffer from chronic combat-related posttraumatic stress disorder
(PTSD) and from associated long-term negative effects in all aspects
of life, report Karestan Koenen and her co-authors in the February Journal
of Traumatic Stress. The longitudinal follow-up study helps fill
gaps in understanding the long-term outlook for combat-related PTSD.
The findings also have implications for the new generation of war veterans
and their health care providers.
IMMUNOLOGY:
Immune System Taught to Play Nice with Unrecognized Protein
There is an increasing need in medical science to tweak the immune
system toward tolerance. This need stems from transplant medicine as
well as from efforts to cure or control autoimmune diseases and allergic
reactions. Researcher Irina Apostolou has recently moved immune tolerance
research a step forward by the in vivo creation of regulatory T cells
that suppress immune reactions to a specific transplantation antigen.
This technique of inducing immune tolerance has the potential to dampen
a great range of unwanted immune responses, though the researchers
caution the procedure may not work for all antigens, and each clinical
application will likely have its own complexities.
BIOLOGICAL
CHEMISTRY: Inhibitor Found for Family of MicroRNAs
Investigating the role of microRNA in development, (clockwise from
lower left) George Daley, Srinivas Viswanathan, and Richard Gregory
discovered that the let-7 family of miRNAs was absent from embryonic
stem cells and rare in certain tumor cells. The let-7 levels increase
as cells differentiate. The researchers identified a factor abundant
in embryonic stem cells, Lin-28, that binds to let-7 and prevents it
from being processed. This is the first miRNA inhibitor to be discovered,
said the scientists. The study, published in the Feb. 21 Science,
raises the intriguing possibility of keying on Lin-28 to manipulate
the miRNA pathway, which might be instrumental in reprogramming stem
cells or in slowing cancer growth.
Copyright 2008 by the President and Fellows of Harvard College