May 9, 2006
Researchers at Wake Forest University possess a remarkable strain of mice. They appear to be resistant to injections of cancer cells that kill all ordinary mice. Even better, the researchers say, the immune system cells from these mice, when injected into nonresistant mice, will cure their cancers.
The researchers, led by Dr. Zheng Cui, are reporting this finding today in The Proceedings of the National Academy of Sciences.
At a news conference last week, Dr. Cui and a colleague, Dr. Mark C. Willingham, speculated on the possibility of applying their findings to human patients.
They have named the animals S.R./C.R. mice. The designation stands for spontaneous remission/complete resistance mice. All are descendants of a BALB/c mouse, a standard laboratory strain, a batch of which arrived in Dr. Cui's laboratory in 1999 to be injected with a lethal strain of mouse cancer cells.
Liya Qin, a postdoctoral fellow in the lab, reported that one mouse, labeled No. 6, had survived the injection. Given even larger injections of the usually lethal cells, the mouse remained hale and hardy.
Having failed in several attempts to make the mouse die of cancer, Dr. Cui hit on the better idea of breeding it. He and Dr. Willingham reported in 2003, also in The Proceedings of the National Academy of Sciences, that the descendants of mouse No. 6 possessed the patriarch's serene immunity to cancer.
The property was inherited in a pattern suggesting that it resided on a single dominant gene, they said, implying that it should be fairly straightforward to identify.
Three years have now passed, but the gene has not been identified. Nor have researchers in other laboratories replicated the 2003 claim, an essential step in the scientific process.
Nevertheless, Dr. Cui and Dr. Willingham have now published a second remarkable claim about the No. 6 progeny. They report that white blood cells of these mice can be injected into ordinary mice with tumors and will cause the tumors to vanish.
The white blood cells are of types that confer innate immunity, meaning that they do not have to be exposed to the cancer cells first.
Dr. Cui and Dr. Willingham said the gene that conferred the immunity had not been identified because it appeared to move from one chromosome to another. Mobile genes of this nature are known as transposons.
Although a colony of 2,000 mice now exists, they have not been shared with other researchers for a variety of reasons, Dr. Willingham said. It took many months to develop mice that were germ-free, as required by mouse-colony regulations, and Wake Forest had difficulty reaching agreements with other institutions on protecting its intellectual property.
Dr. Lloyd J. Old, a member of the National Academy of Sciences who submitted both reports to the journal, said he had been pressing for the mice to be distributed to other researchers because of the importance of having the results confirmed independently. "I agree," Dr. Old said, "that now is the time for confirmation, and steps have been taken for that to occur."
Derry Roopenian, an expert on mouse immunology at the Jackson Laboratory, said it was "perplexing" that the Wake Forest team had not identified the gene that confers the resistance.
The data were remarkable, he said, but "this is an isolated publication from an isolated laboratory."
"It certainly would have been better, given the novelty of their observations, that it had been confirmed by an outside group," he said.
