Scientists testing a malaria vaccine for pregnant
women made a surprising discovery that shows promise
for treating cancer.
When the danish scientists from the University of
Copenhagen and the University of British Columbia (UBC)
created the protein the malaria parasite uses to
adhere to the placenta and added a toxin, they
discovered that the protein is identical to a
carbohydrate found in cancer cells.
This combination of malaria protein and toxin seeks
out the cancer cells, is absorbed, the toxin
released inside, and then the cancer cells die. This
process has been witnessed in cell cultures and in
mice with cancer. The discovery is described in an
article in Cancer Cell.
“For decades, scientists have been searching for
similarities between the growth of a placenta and a
tumor. The placenta is an organ, which within a few
months grows from only few cells into an organ
weighing approx. two pounds, and it provides the
embryo with oxygen and nourishment in a relatively
foreign environment. In a manner of speaking, tumors
do much the same, they grow aggressively in a
relatively foreign environment,” says Ali Salanti
from the Department of Immunology and Microbiology
at the University of Copenhagen.
Ali Salanti’s team is currently testing a vaccine
against malaria on humans, and it was in connection
with the development of this drug that he discovered
that the carbohydrate in the placenta was also
present in cancer tumors. Ali Salanti immediately
contacted his former fellow student and now cancer
researcher, Mads Daugaard, who is head of the
Laboratory of Molecular Pathology at the Vancouver
Prostate Center at UBC in Canada. In collaboration,
the two groups have generated results, which they
hope will provide the basis for a drug against
cancer.
“We examined the carbohydrate’s function. In the
placenta, it helps ensure fast growth. Our
experiments showed that it was the same in cancer
tumors. We combined the malaria parasite with cancer
cells and the parasite reacted to the cancer cells
as if they were a placenta and attached itself,” Ali
Salanti explains.
In collaboration, the two university research groups
have tested thousands of samples from brain tumors
to leukemias and a general picture emerges to
indicate that the malaria protein is able attack
more than 90% of all types of tumors.
The drug has been tested on mice that were implanted
with three types of human tumours.
With non-Hodgkin’s lymphoma, the treated mice’s
tumours were about a quarter the size of the tumours
in the control group.
With prostate cancer, the tumours disappeared in two
of the six treated mice a month after receiving the
first dose.
With metastatic bone cancer, five out of six of the
treated mice were alive after almost eight weeks,
compared to none of the mice in a control group.
It would appear that the only snag is the fact that
the treatment would not be available for pregnant
women.
“Expressed in popular terms, the toxin will believe
that the placenta is a tumor and kill it, in exactly
the same way it will believe that a tumor is a
placenta,” explains Salanti.
“The earliest possible test scenario is in four
years time. The biggest questions are whether it’ll
work in the human body, and if the human body can
tolerate the doses needed without developing side
effects. But we’re optimistic because the protein
appears to only attach itself to a carbohydrate that
is only found in the placenta and in cancer tumors
in humans,” Salanti says.
For more information
Targeting Human Cancer by a Glycosaminoglycan
Binding Malaria Protein
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University of Copenhagen
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University of British Columbia (UBC)
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