Podnoszenie odpornosci usuwa raka!
- From: Me <agnescherry@xxxxxxxxx>
- Date: Fri, 4 Sep 2009 09:04:07 -0700 (PDT)
Not exactly vacination helps to eliminate
cancer cells
From The Times August 11, 2009
Bee venom destroys cancer cells in tests on mice
Bee venom can be engineered to target tumours and could prove an
effective future treatment for cancer, a study has found.
During a trial, the poisonous chemical in a bee’s sting, melittin, was
attached to tiny molecules or “nanoparticles” that then attack and
destroy cancer cells, leaving healthy cells intact. The carrier
particles, dubbed “nanobees”, were also effective in targeting pre-
cancerous cells.
Nanobees could eventually replace conventional therapy for certain
types of cancer, according to scientists behind the study, which is
published today in the Journal of Clinical Investigation. They said
that the treatment would have fewer side-effects than chemotherapy.
“The nanobees fly in, land on the surface of cells and deposit their
poisonous cargo,” said Professor Samuel Wickline, a specialist in
nanomedicine at Washington University in St Louis, who led the
research.
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The treatment was tested on two groups of mice with cancerous tumours.
One group had melanoma skin cancer, the other had been implanted with
human breast-cancer cells. After four to five injections of the
nanobees, the breast-cancer tumours were 25 per cent smaller, and the
melanoma tumours were 88 per cent smaller, compared with untreated
mice.
The carrier particles used in the study have already been approved for
clinical use in various other medical applications. The team plans to
begin human trials with the nanobees next year.
They predict that the treatment could be effective in treating a wide
range of cancers and that it would have fewer side-effects than
chemotherapy. They say the treatment could also be more effective than
chemotherapy, because it is more targeted. With chemotherapy, patients
are given the largest tolerable dose of medication, but because
nanobees specifically attack tumours, doses could be much lower.
Melittin works by attaching itself to the surface of cells and ripping
holes in the membrane. “In high enough concentration it can destroy
any cell it comes into contact with,” said Professor Paul Schlesinger,
a cell biologist at Washington University and a co-author of the
paper.
Most cancer treatments target DNA, but cancer cells are frequently
able to adapt and develop resistance to DNA damage. It is much harder
for cells to defend against damage to the membrane, however, making
melittin an attractive treatment.
Despite the high toxicity of the bee venom, the mice suffered few side-
effects and there appeared to be little damage to non-cancerous
cells.
Leaky blood vessels around tumours mean that nanoparticles build up
there in high enough quantities to do damage. A chemical tag enhanced
this effect by increasing nanobees’ affinity for cancerous cells
compared with normal cells.
“It’s like molecular Velcro,” Professor Wickline said. “The toxin
doesn’t come off the bee until it finds its target.”
If the melittin had been injected into the bloodstream in its normal
form it would lead to widespread destruction of red blood cells. But
following the nanobee injection, the blood count of mice was normal,
and they showed no signs of organ damage.
A concern with some nanomedicines is that nanoparticles are left
circulating in the body after treatment. They are biologically inert,
meaning they are do not get metabolised and cleared from circulation
in the normal way.
The spherical nanobees, which are about six millionths of an inch in
diameter, are, however, quickly cleared from the system after
treatment. They are made of perfluorocarbon, an inert non-toxic
compound used in artificial blood. Once the melittin has been removed
from the nanobee, it dissolves and is evaporated in the lungs.
.
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