Common human virus kills cancer stem cells
7 May 2009
Reovirus, a common virus in humans that does not cause disease,
effectively targets and kills cancer stem cells in breast cancer tissue.
The finding was made by Dr Patrick Lee of the Dalhousie Medical School
in Halifax, Nova Scotia, Canada and has been published in the journal Molecular Therapy.
It is only within the past few years that the scientific community
has understood the full significance of cancer stem cells and the urgent
need to find a means of eliminating them.
“Cancer stem cells are essentially mother cells,” explains Dr Lee,
Cameron Chair in Basic Cancer Research at Dalhousie Medical School.
“They continuously produce new cancer cells, aggressively forming
tumours even when there are only a few of them.”
Cancer stem cells are difficult to kill as they respond poorly to
chemotherapy and radiation. As Dr Lee notes, “You can kill all the
regular cancer cells in a tumour, but as long as there are cancer stem
cells present, disease will recur.”
Dr Lee is optimistic that his team has found the key to destroying
cancer stem cells.
“We suspected that reovirus might be effective against cancer stem
cells, because we have shown time and again how well it destroys regular
cancer cells,” remarks Dr Lee, who was the first in the world to
discover that a benign and naturally occurring virus could selectively
infect and kill cancer cells without harming healthy cells. A
Calgary-based company, Oncolytics Biotech Inc., is testing reovirus in
clinical trials to prove the treatments are safe and effective.
Unlike most cancer studies, which use cancer cell lines developed for
laboratory use, this study used fresh breast cancer tissue. This cancer
tissue was removed from a patient of Dr Carman Giacomantonio, a Capital
Health surgical oncologist who is working with Dr Lee on the reovirus
research, along with post-doctoral fellow Dr Paola Marcato and research
assistant Cheryl Dean.
In addition to its ability to kill cancer cells and cancer stem
cells, reovirus stimulates the anti-cancer immune system. Since virus
therapy also invokes an anti-virus response, Dr Lee and post-doctoral
fellow Dr Shashi Gujar are working on a way to harness the immune system
so it attacks cancer cells while allowing the virus to freely infect and
destroy cancerous cells.
“Refining this two-pronged approach to killing cancer is our next
step,” says Dr Lee. “We are taking advantage of the natural
characteristics of reovirus and the immune system itself to create a
powerful virus-based anti-cancer therapy."
Dr Lee’s discovery that reovirus effectively targets breast cancer
stem cells has captured the attention of LeadDiscovery, a UK-based
organization dedicated to promoting drug discovery and development.
LeadDiscovery has identified the finding to be of particular interest to
the drug development sector and will feature it in its next update to
the global scientific community and pharmaceutical industry.
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