Viruses Eradicate Cancer Cells, Not Healthy Tissue

Posted by Admin on September 5, 2011
Researchers have genetically engineered a new strain of virus that seeks out and destroys cancer cells while leaving normal, healthy cells alone. Scientists at the Mayo Clinic developed the genome of the oncolytic (or cancer dissolving) virus to recognize the so-called microRNAs of normal tissue and therefore ignore those cells, infecting only tumor cells. MicroRNAs are tiny segments of 20 or so nucleotides that don' code for proteins but instead seem to impact the expression of genes.

Mayo scientist and lead author of the study, Stephen Russell claims that the findings demonstrate a new vessel for delivering molecular medicine that should also allay concerns over using viruses in a complex therapy system. The research team claims that the mice in their study, which were suffering from melanoma, or malignant skin cancer, were exposed to the genetically modified virus. The mice were subsequently cured of all established tumors, without any noticeable side effects.

The research team look at specific muscle tissue and discovered that the virus avoided it entirely, instead targeting only cancerous tissues. Unengineered viruses attack a variety of tissues indiscriminately. Therefore, it’s not surprising to see numerous symptoms associated with viral disease.

However, since viruses are emerging as a tool for vaccination, cancer therapeutics, and gene therapy delivery agents, it’s becoming increasingly necessary to find means of restricting viruses’ activities to only the target tissues. This research appears to be successful in accomplishing this feat. Russell’s work may be a step toward safer vaccines, more effective gene therapy, and better cancer treatment.

In the case of brain cancer, Ohio State University researchers have developed a tumor-attacking virus that kills brain-tumor cells and blocks the growth of new tumor blood vessels. This research demonstrates that viruses engineered to kill cancer cells might be more effective against aggressive forms of brain tumors if they also carry a gene for a protein that inhibits blood-vessel growth

The protein, known as vasculostatin, is produced normally in the brain. For this study, an oncolytic virus containing the gene for this specific protein was able to eliminate human glioblastoma tumors growing in animals and significantly slow cancer recurrence in others.

Glioblastomas normally have a high number of blood vessels and are the most common and devastating form of human brain cancer. People diagnosed with this form of brain cancer survive less than 15 months on average following diagnosis.

Study author, Balveen Kaur says this study is the first to report the effects of vasculostatin delivery into established tumors and it further supports development of oncolytic viruses as a possible form of cancer treatment. These findings suggest that this engineered virus is a safe and promising strategy to pursue for the treatment of human brain tumors.

Kaur also adds that the study demonstrates the potential for combining an oncolytic virus with a natural blood-vessel growth inhibitor such as vasculostatin. Future studies will help clarify the potential for safety and efficacy with used in conjunction with chemotherapy and radiation therapy.

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