Bifidobacterium longum as a delivery system for gene therapy of chemicallyinduced 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 exis ts. A strain of domestic bacteria, Bifidobacteriumlongum, which is nonpatho genic and anaerobic, selectively localized to and proliferated in 7,12-dime thylbenz[a]anthracene-induced rat mammary tumors after systemic application . We further ascertained the tumor specificity of genetically engineered, a s well as wild-type, Bifidobacterium longum. This is the first demonstratio n that Bifidobacterium longum can be utilized as a specific gene delivery v ector for gene therapy on solid breast tumors.