Increasing numbers of Zika virus in Central and South America over the last two years has made headlines and caused alarm in the healthcare field. The primary cause of this alarm is that Zika virus in pregnant women have been linked to microcephaly, a devastating birth defect where the child’s brain does not develop correctly. However, a new study published in The Journal of Experimental Medicine on Sept. 5 by researchers from Washington University in St. Louis and the University of California San Diego suggests the destructive power of Zika could serve as a weapon against the most common form of brain cancer, glioblastoma, which is notoriously difficult to treat.
The reason Zika wreaks havoc on infant brains is because the virus attacks undifferentiated cells which they have in high numbers; its similar in gliboblastoma. Undifferentiated cells are precursor cells and their function is to multiply themselves quickly and give rise to specialized cells. Infant brains have many undifferentiated cells in the form of neural progenitor cells which develop into the neurons and other nervous system cells seen in adults, and glioblastomas have them in the form of glioblastoma stem cells which give rise to glioblastoma tumor cells.
To determine the ability of the Zika virus to target and destroy glioblastoma stem cells, researchers performed two tests. In the first, they introduced one of two different strains of the virus to groups of glioblastoma cells derived from patient cells. Both strains of Zika were found to attack and destroy glioblastoma stem cells, but neither targeted regular glioblastoma tumor cells. For the second test, the researchers injected a form of the Zika virus into the brains of 18 mice with glioblastoma tumors; 15 other mice with tumors received a placebo injection. Two weeks after the injections, tumors in the mice who received the Zika injection were significantly smaller and those mice lived longer than the ones who received the placebo.
To test the safety of injecting the Zika virus into a patient’s brain, the researchers introduced the virus to samples of human brain tissue and found that the virus did not infect normal adult brain cells. To further increase safety, the researchers created another strain of the Zika virus containing two gene mutations which reduced the virus’ ability to fight the defense systems of regular human cells. They introduced to the new Zika strain to a group of glioblastoma cells and the original strain to another group. The original strain was more potent, but both strains were successful in attacking the glioblastoma stem cells.
Glioblastoma stem cells have always presented the greatest challenge to effectively treating the cancer. According to an article by Tamara Bhandari published on the Washington University School of Medicine’s website on Sept. 5, 12,000 people in the United States are diagnosed with glioblastoma annually and typical treatment consists of surgery to remove the tumor followed by chemotherapy and radiation. However, in the majority of cases, some glioblastoma stem cells survive these treatments and cause another tumor within six months.
The published study referred to earlier states that the median survival rate for glioblastoma patients is less than two years.
If the Zika virus continues to be proved a safe and effective weapon against glioblastoma by future studies, it could be combined with traditional therapies, such as chemotherapy and radiation, to provide a more comprehensive attack on the cancer. Traditional therapies would target regular tumor cells, which the Zika virus does not infect, while the virus targeted glioblastoma stem cells, which traditional therapies often fail to destroy. This could lead to a significant increase in the survival rate.
According to Bhandari’s article, the researchers are currently working to create a strain of Zika with several additional mutations which would make the virus even more vulnerable to the human immune system. This would ensure the virus stays localized around the brain tumor and does not cause any disease symptoms in the patient. An article by Michelle Roberts published on the BBC website on Sept. 5 states that the researchers hope to begin human trials within 18 months.
Abbey Bigler is a fourth year English major with minors in business and technical writing, communication studies, and biology. She can be reached at AB842693@wcupa.edu.