Cancer therapy using bacteria that selectively accumulate, grow, and proliferate in hypoxic tumors is attracting attention. Conventional cancer bacteriotherapy did not go beyond the concept of a drug delivery system that provides anticancer agents to specific parts of the body because they were not proven to be effective enough. It has also been clarified that each type of tumor has its own bacterial microbiota within the tumor tissue, and the microbiota are factors that support or inhibit anticancer drugs. However, there have been no studies concerning the bacteria extracted from within the tumor tissue to treat cancer.
To address this issue, the research group led by Associate Professor Eijiro Miyako of the Graduate School of Advanced Science and Technology at the Japan Advanced Institute of Science and Technology successfully isolated three main types of bacteria from colon cancer-derived tumor tissues in mice and named the groups A-gyo, UN-gyo, and AUN (a mixture of the A-gyo and UN-gyo groups), in analogy with Buddhist statues and Komainu-dogs placed in temples and shrines.
After administration of these bacteria to mice that had been subcutaneously implanted with colorectal cancer cells, the high antitumor effect in the hypoxic tumor environment was confirmed. In particular, even a single administration of the AUN group effectively activated cytotoxic immune cells through the concerted actions of A-gyo and UN-gyo and was effective against various cancers other than colon cancer. Additionally, biocompatibility tests using mice have confirmed that AUN itself has very little effect on the body.
These results are expected to contribute to the establishment of cancer diagnosis and treatment methods using bacteria discovered in tumors as well as the creation of new concepts in bacteriology and tumor microbiology.
