Researchers have shown that the Zika virus, which causes severe defects in the brains of foetuses, is able to kill brain cancer stem cells, which have so far been highly resistant to standard treatment.
The findings from researchers at Washington State University
School of Medicine in St. Louis and the University of California San Diego
School of Medicine suggest that the virus could be engineered to infect malignant
cells in the brain, potentially improving brain cancer survival.
Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine at Washington University School of Medicine and the study's co-senior author said, "We showed that Zika virus can kill the kind of glioblastoma cells that tend to be resistant to current treatments and lead to death."
Current standard of care for brain cancer usually involves surgery, followed by chemotherapy and radiation. Unfortunately, the majority of tumours return within six months. That’s because glioblastoma stem cells often survive conventional treatment, producing new tumour cells to replace dead or removed ones.
Glioblastoma cells’ ability to create new cells, along with their neurological origins, reminded postdoctoral researcher, Zhe Zhu, Phd, of neuroprogenitor cells, which generate cells in the brains of foetuses. Zika virus specifically targets and kills neuroprogenitor cells.
Zhe Zhu, in collaboration with co-senior authors Diamond and
Milan G. Chheda, MD, of Washington University School of Medicine, and Jeremy N.
Rich, MD, of UC San Diego, tested whether or not Zika could kill stem cells in
glioblastomas removed from patients.
The tumours were infected with two different strains of
Zika. Remarkably, both strains effectively spread through the tumour leaving
healthy tissue largely untouched, while killing the brain cancer stem cells.
This suggests that Zika infection and chemotherapy/radiation
could have complimentary effects.
"We see Zika one day being used in combination with current therapies to eradicate the whole tumour," said Chheda, an assistant professor of medicine and of neurology.
To test the effectiveness of the virus on cancer cells in a
living animal, researchers injected one batch of mice with Zika, while the
other received saline. In all mice, the treatment was injected directly into
the brain. Two weeks after injection, the mice that received the Zika treatment
had significantly smaller tumours than the mice injected with saline.
To be effective in humans, researchers say the virus would need to be injected directly into the brain, most likely during surgery to remove the cancer. This would avoid the body’s own immune system killing the Zika virus before it could reach the brain.
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