Bifidobacterium longum as a delivery system for gene therapy of chemically induced rat mammary tumors.

A fundamental obstacle in cancer gene therapy is the specific targeting of therapy directly to a solid tumor, and no systemic delivery system yet exists. A strain of domestic bacteria, Bifidobacterium longum, which is nonpathogenic and anaerobic, selectively localized to and proliferated in 7,12-dimethylbenz[a]anthracene-induced rat mammary tumors after systemic application. We further ascertained the tumor specificity of genetically engineered, as well as wild-type, Bifidobacterium longum. This is the first demonstration that Bifidobacterium longum can be utilized as a specific gene delivery vector for gene therapy on solid breast tumors.