New technique cuts time to screen cancer genes, drugs
By Ruth SoRelle, M.P.H.
A new technique that uses a bird virus to take genes into breast cells may shorten the time it takes to determine whether the genes are cancer-causing (oncogenes), said Baylor College of Medicine researchers in a recent report in the Proceedings of the National Academy of Sciences.
"It will also help us create better models for preclinical testing of drugs to fight breast cancer," said Yi Li, Ph.D., an assistant professor in the Baylor College of Medicine Breast Center. Currently, most mouse models of human cancers do not mimic the characteristics of human breast tumors well, he said.
His technique delivers the cancer-causing genes directly to a small number of cells. "By making the model this way, it more closely recapitulates the way that human cancers are made," he said.
The technique can also short-circuit the process. Making a mouse model of human breast cancer the usual way may take several years. Li's method takes only a few weeks.
Li started working on the process a decade ago in the laboratory of Harold Varmus, Ph.D., then director of the National Institutes of Health. Li even moved to the Memorial Sloan-Kettering Cancer Center when Varmus took over the leadership of that institution.
When he arrived at BCM, Li found that Ricardo Moraes, a research associate in Dr. Michael Lewis's lab, had refined the technique of intraductal injection and was willing to teach it to Zhijun Du, Ph.D., a researcher doing postdoctoral studies in Li's lab. That solved a stumbling block to the effectiveness of the technique.
Li said they used a bird retrovirus to take the gene into the cells because the virus does not usually infect mice or people. For that reason, the mice would not transmit the virus to other mice. The retrovirus incorporates the gene into the genetic material of the mice, which are specially bred to be susceptible to the virus.
"It allows us to achieve cell-type specific delivery in the mammary gland," he said.
In fact, he said, they could deliver the gene to different subset of cells in mammary gland.
"In humans, the popular notion is that breast cancer arises from individual stem cells," he said. "Until now, we had no way to test that in mice. Now, we potentially have a method."
Others who participated in the research include BCM Breast Center researchers Shixia Huang, Amanda McGrath, Michael J. Toneff, Ekaterina Bogoslovskaia, Xiaomei Zhang and D. Craig Allred as well as Michele Fluck of Michigan State University and Katrina Podsypanina and Varmus of Memorial Sloan-Kettering Cancer Center in New York.
