Crystals may hold cancer key
by Kim Irwin
ucla todAY
UCLA nanotechnologists and cancer researchers are partnering on
the promise of qdots — nano-sized crystals that may one day
be used to diagnose and treat cancers. The new technology may enable
researchers to locate a tumor, determine at the molecular level
what type of cancer it is and arm the qdots with toxic therapies
to kill the disease.
Qdots, fluorescent semiconductor quantum dots, have such potential
because they can be color-encoded to use different colors to label
different cell processes, different cancers or stages of the same
cancer, said Shimon Weiss, a Jonsson Cancer Center researcher and
leader of a team studying qdots. Currently, doctors use positron
emission tomography (PET) to locate tumors throughout the body.
With qdots, however, several different markers of the same tumor
could be simultaneously “painted,” generating a color
barcode for real-time “optical biopsy” and diagnosis,
without the need for tissue removal and analysis.
This research is the first result of a new joint effort between
UCLA’s Jonsson Cancer Center and the California NanoSystems
Institute (CNSI). The creation of the UCLA Cancer Nanotechnology
Partnership signals a long-term commitment to and investment in
nanotechnology and its applications in cancer research, said Judith
C. Gasson, cancer center director.
“This partnership has enormous potential, and I’m very
excited to see the advances in cancer diagnosis and treatment to
come,” Gasson said.
This is the way qdots would work, said Weiss, professor of chemistry,
biochemistry and physiology and a CNSI member.
“Humans have close to 40,000 genes,” explained Weiss.
“A large group of these genes operates at every moment, in
every cell of our body, in very complicated ways. By color-encoding
a subset of proteins in the cell with different colored qdots, we
can follow molecular circuitry — the dynamic rearrangement
of molecular interactions
and the interactions that reprogram cells to gain or lose function
in disease — in short, oversee the ‘molecular dance’
that defines life itself.”
Using qdots, researchers can track receptors on a cell surface
and watch them interact. As the receptors move on the cell membrane,
researchers would be able to determine their function and test whether
they may be sensitive to outside molecules. Such studies would provide
new clues about molecularly targeted therapies that could be effective
in fighting cancer.
Before qdots, researchers could track individual receptors and
proteins on cell surfaces, but for seconds only; they were unable
to view their interactions. Using qdots, Weiss and his colleagues
were able to watch cell processes for many minutes, processes that
had been theorized, but not
actually seen before.
For tumor immunologist Anna Wu, qdots open up new avenues of research.
“Qdots give you a way of looking at many different things,
very specific things, all at the same time,” said Wu, also
a Jonsson Cancer Center member. “We’ve been imaging
in black and white. Now we’re able to see the world in color.”
There are hurdles. For example, qdots are toxic. If toxicity can
be conquered, patients may one day be injected with a cocktail of
different colored qdots that would “label” their cancerous
cells. Once gathered at the tumor, the positrons emitted from the
qdots could be imaged by PET scan. The scan would show the presence
and location of a tumor and provide an optical barcode of different
colored qdots. Doctors could then identify tumor type and stage.
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