Horizontal transfer of tumorigenesis

Apoptotic bodies are rapidly cleared in the body by phagocytosis. In the May 22 Proceedings of the National Academy of Sciences, Bergsmedh et al. provide evidence that the uptake of apoptotic bodies can deliver oncogenes to the phagocytotic host cell (Proc Natl Acad Sci USA 2001, 98:6407-6411). They could detect the horizontal transfer of H-rasV12 or c-myc oncogenes from dying, transformed rat fibroblast cells to recipient mouse fibroblasts. DNA transfer was detected by PCR analysis and fluorescent in situ hybridization staining. Transferred DNA caused the formation of foci and of tumorigenic cell lines. The authors defined the conditions necessary for transferring tumorigenesis. The recipient phagocytic cell required a mutated p53 gene, and long-term propagation of the transferred DNA was only observed when it conferred a selective advantage. It remains to be determined whether horizontal genetic transfer plays a role in tumour progression in vivo.