naling between stem cells and their niche have been associ- tifi ed unique molecular features of malignant stem cells be- ated with cancer, which also suggests a...

Strona startowa Ludzie pragną czasami się rozstawać, żeby móc tęsknić, czekać i cieszyć się z powrotem.Phase 2 is the addition of high-speed backbone technology and routing between switches...You must by now be very clear about the distinction between bilabial and labiodental articulation...challenges associated with energy, land use public health...Printing DocumentsConcerning printing, common features are only mentioned, special features are described below...Brodząc we mgle i rozganiając przerażone stada, jak zdążająca ku morzu bramba rozpędza ławice mniejszych ryb,Szardik opuścił południowe brzegi Wąsa i...W związku z powyższym postanowieniem trzeba przede wszystkimiuważyć, że wbrew jego dosłownemu brzmieniu, skarga Komisji obej-ować może nie tylko naruszenie...12GRE Real 19 Directions: Each passage in this group is followed by questions based on its content...łem do drugiego – embarras de richesse tematów i zagadnień...{ case 1 : cerr << "Error opening file... 
 

Ludzie pragną czasami się rozstawać, żeby móc tęsknić, czekać i cieszyć się z powrotem.

For example, if malignant
that the cancer stem cells could be preferentially targeted by
stem cells were being held in check by the niche but the niche
specifi c drugs. Last year they reported their discovery that a
was somehow altered and expanded, the malignant stem cell
compound derived from the feverfew plant induces AML
pool would have room to grow as well. Another possibility is
stem cells to commit suicide while leaving normal stem cells
that certain oncogenic mutations within cancer stem cells
unaffected.
could permit them to adapt to a different niche, again letting
Some research groups are hoping to train immune cells to
them increase their numbers and expand their territory. Still
recognize and go after cancer stem cells. Still others are ex-
a third alternative is that mutations might allow the cancer ploring the use of existing drugs to alter niche signaling in the stem cells to become independent of niche signals altogether, hope of depriving cancer stem cells of the environmental cues lifting environmental controls on both self-renewal and that help them thrive. Yet another idea under investigation is proliferation.
that drugs could be developed to force cancer stem cells to dif-
ferentiate, which should take away their ability to self-renew.
Closing In
Most important is that cancer investigators are now on the
t h e i m pl ic at ion s of a stem cell model of cancer for the
suspects’ trail. With a combination of approaches, aimed at
way we understand as well as treat malignancies are clear and
both targeting genetic pathways unique to the maintenance of
dramatic. Current therapies take aim against all tumor cells, cancer stem cells and disrupting the cross talk between tumor but our studies and others have shown that only a minor frac-cells and their environment, we hope to be able soon to fi nd
tion of cancer cells have the ability to reconstitute and per-
and arrest the real culprits in cancer.
petuate the malignancy. If traditional therapies shrink a tumor
but miss these cells, the cancer is likely to return. Treatments
M O R E T O E X P L O R E
that specifi cally target the cancer stem cells could destroy the
The Reversal of Tumor Growth. Armin C. Braun in Scientifi c American,
engine driving the disease, leaving any remaining nontumori-
Vol. 213, No. 5, pages 75–83; November 1965.
genic cells to eventually die off on their own.
The Proteus Effect: Stem Cells and Their Promise for Medicine. Ann B.
Parson. Joseph Henry Press, 2004.
Circumstantial evidence supporting this approach already
Context, Tissue Plasticity, and Cancer: Are Tumor Stem Cells Also
exists in medical practice. Following chemotherapy for tes-
Regulated by the Microenvironment? Mina J. Bissell and Mark A.
ticular cancer, for example, a patient’s tumor is examined to
LaBarge in Cancer Cell, Vol. 7, pages 17–23; January 2005.
assess the effects of treatment. If the tumor contains only ma-
Leukaemia Stem Cells and the Evolution of Cancer-Stem-Cell
ture cells, the cancer usually does not recur and no further
Research. Brian J. P. Huntly and D. Gary Gilliland in Nature Reviews
Cancer, Vol. 5, No. 4, pages 311–321; April 2005.
treatment is necessary. But if a large number of immature-
Stem Cells and Cancer: Two Faces of Eve. Michael F. Clarke and
looking—that is, not fully differentiated— cells are present in
Margaret Fuller in Cell, Vol. 124, pages 1111–1115; March 24, 2006.
w w w. s c i a m . c o m
S C I E N T I F I C A M E R I C A N 59
COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC.
THE QUEST FOR THE
CUBE OF ME TAMATERIAL consists of a three-
dimensional matrix of copper wires and split
rings. Microwaves with frequencies near 10
gigahertz behave in an extraordinary way in the
cube, because to them the cube has a negative
refractive index. The lattice spacing is 2.68