Can Virus Cure Cancer

Posting Date: 02/04/2004

Since Sindbis is a virus, the researchers were concerned that the immune system might attack it, thwarting any therapeutic effect. However, tests on genetically modified mice, which grow tumors but have fully working immune systems, were also successful.

To build upon Sindbis?s natural cancer-killing skills, Dr. Meruelo and his colleagues also engineered the virus to carry a gene that makes a protein called IL-12. This protein has proven to be a good cancer killer but is also toxic to normal tissues. By putting the IL-12 gene into Sindbis, the gene was only activated after it had been carried into cancerous tissues by the virus. The combination was even more effective than Sindbis alone at killing tumors, and it did not poison surrounding areas.

It is not known exactly why the virus prefers to bind to tumor cells. But Sindbis enters cells through a receptor for laminin, a substance that helps to glue cells together to form tissues, and tumor cells tend to over-express this receptor. Dr. Meruelo theorizes that since tumor cells are far more likely than healthy cells to have free laminin receptors on their surfaces, they are more likely to take up the virus.

The virus may also be a good tracking device for cancer. Dr. Meruelo and his colleagues attached to Sindbis a gene that makes fireflies glow, which was only activated in cells that the virus entered, making them glow enough to be detected by an external sensor. ?We showed that we knew exactly where the virus was, and the virus was only in the tumors,? says Dr. Meruelo.

Despite the need to demonstrate the virus?s effectiveness in humans, Dr. Meruelo is hopeful about Sindbis?s future: ?The combination of this virus?s exquisite targeting of tumors with its ability to kill them says that this has the potential to be a human therapy.?

The other authors of the study at NYU School of Medicine are Herman Yee, M.D., Ph.D., Assistant Professor of Pathology, Peter Shamamian, M.D., Associate Professor of Surgery, Richard P. Novick, M.D. Professor of Microbiology and Medicine, Angel Pellicer, M.D., Ph. D., Professor of Pathology, Jen-Chieh Tseng, graduate student and first author, Brandi Levin, supervisory research technician in Pathology, Alicia Hurtado, Assistant Research Scientist in Pathology, and Ruzhong Jin, graduate student. Authors Ignacio Perez de Castro and Maria Jimenez are former fellows who are now at the National Center of Oncology in Madrid, Spain.

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