Marcus Banks in The Scientist:
Cancer metastasizes through the fusion of tumor cells with immune cells, according to a case report published online May 28 in Cancer Genetics. “We think what is happening is the initial cancer cells from the primary tumor are blending or hybridizing with immune system cells that respond to the tumor as nonself. By hybridizing with those immune system cells, it looks like ‘self’ so that the immune system doesn’t attack and destroy [the tumor],” says first author Greggory LaBerge, a medical geneticist at the University of Colorado School of Medicine who also directs the Denver Police Department’s Forensics and Evidence Division. LaBerge and his colleagues analyzed the DNA of a woman in her late 70s who had received a bone marrow transplant from an anonymous male donor several years earlier as treatment for her chronic myelomonocytic leukemia. She later developed metastatic melanoma.
…The authors used this sample to test a theory that immune cells and cancer cells fuse to lead to metastasis. Because the immune cells had the genome of the donor, while the cancer cells had the genome of the patient, it was possible to track the relative proportion of each at every stage in the metastatic journey. The team’s hypothesis was that, if patient and donor cells were fused together at every point in metastasis, this would support the idea that the patient’s metastasis occurred due to such fusion. If only the patient’s DNA were evident at later steps of metastasis, then this would disprove the hypothesis that fusion fuels metastasis.
More here.