|
Killing
cancer without harming healthy cells
A
major medical breakthrough in the United Kingdom could lead to the
successful treatment of viral cancers, without causing
side-effects.
Researchers funded by Yorkshire Cancer Research and working at York
University in northern England used a new technique called RNA
interference to destroy human cervical cancer cells grown in culture
without causing damage to healthy cells.
The discovery could have major implications, potentially leading to
the successful treatment of cancers caused by viral infection
without any harmful side-effects. The research, carried out by
Professor Jo Milner and Dr Ming Jiang and published recently in the
journal Oncogene, is the first of its kind to use RNA (ribonucleic
acid) interference to attack cancerous cells. The impact of the
technique – complete elimination of all cancerous cells-was
unexpected.
”Our work has identified a novel agent with major therapeutic
potential for the treatment and, possibly, also the prevention of
human cervical cancer,” said Professor Milner who leads the
team.
Human cervical cancer, caused by viral infection, is the second most
common form of cancer in women worldwide and kills about 1,250 women
in the UK alone each year. Cervical cancer develops when the virus
attacks the body‘s two front lines of defence, its two tumour
suppressors, the proteins p53 and retinoblastoma (Rb).
In normal cells, Rb controls cell division; p53 has the ability to
kill damaged cells that might become cancerous. The virus attacks
both these proteins and takes over the reins of cells growth,
driving continual out-of-control cell proliferation.
Dr Jiang and Professor Milner wanted to know if the use of RNA
interference - never before used on mammalian cells - could knock
out viral genes in the infected cells and restore the body‘s
normal defence mechanism.
The silencing of one viral gene - HPV E6 - caused the growth of the
tumour cells to slow and some cells died. Remarkably, when the
second viral gene (HPV E7) was silenced, all the cancer cells
died.
Using RNA interference, the infected cells died by a regulated
self-destruct process known as apoptosis which enables cells to be
removed without inflammatory side-effects.
It was important to establish that normal healthy cells remained
unaffected. In control experiments, researchers found that the
anti-viral treatment had no effect on the normal growth and
behaviour of non-infected human cells.The successful elimination of
cancer cells without adverse effects on normal cells was described
by Professor Milner as “absolutely remarkable”.
”These cancer cells were not engineered in the laboratory,” she
said. “They were derived from a human tumour many years ago.
Despite growing as cancer cells for years (caused by the viral
infection) our work demonstrates that the cells‘ normal control
systems have remained intact. As soon as we silenced the viral
genes, the infected cancer cells ‘committed suicide‘.”
Elaine King, chief executive of Yorkshire Cancer Research (YCR) the
charity which funded the research said: “This really is
encouraging news and proves once again that the research we fund in
Yorkshire really is world class. The hard work and dedication of YCR-funded
scientists is unwavering and it is this on-going research process
that brings about these breakthroughs.
”While such breakthroughs, by their nature, don‘t happen every
day, it is crucial that we continue to fund research for which we
continue to rely on the generosity of the people of Yorkshire. I
would like to offer my sincere congratulations to Professor Milner,
Dr Jiang and their team at York and my thanks to our supporters who
have made it all possible.”
Professor Milner and Dr Jiang are now working on other types of
tumours to see if the technique is as effective. Meanwhile,
researchers in the United States have found that RNA interference is
showing promising results in protecting cells from infection with
the HIV virus, signalling that many types of human viral infection
could be cured in the future by drugs based on the technique.
The YCR p53 Research Group in the Department of Biology at York
focuses its work on the tumour suppressor p53 present in all tissues
of the human body. When p53 is damaged it can no longer protect and
this loss of function is linked with the development of more than
half of all human cancers. Trying to restore the normal function of
p53 is the central tenet of the YCR p53 research group‘s
work.
Yorkshire Cancer Research was founded in 1925 and is the largest
independent, regional medical research charity in England and the
fourth largest cancer research charity in the UK. It raises about
four million pounds sterling annually in Yorkshire and which is used
to fund internationally renowned research at five universities in
Yorkshire - Bradford, Hull, Leeds, Sheffield and York - and their
associated teaching hospitals. |
