When a bad bacterium infects tumor cells, it can signal the body to fight the deadliest form of skin cancer.
Scientists already knew that diarrhea-causing Salmonella typhimurium helps the immune system recognize melanoma, but a paper in the Aug. 11 Science Translational Medicine shows how. The finding may point to a new human vaccine for melanoma and possibly other kinds of cancer.
“In combination with other therapies, it could improve survival,” says tumor biologist Meenhard Herlyn of the Wistar Institute in Philadelphia. But melanoma is such a complex cancer that a vaccine probably couldn’t cure the disease permanently, adds Herlyn, who was not involved with the study.
When Salmonella was injected into mouse melanoma tumors, those tumors shrank, as did untreated tumors in other parts of the body. Experiments showed that the process relied on the presence of a protein channel called connexin 43 on the surface of melanoma cells.. That protein channel allows the cells to connect to similar channels in immune cells, forming ‘gap junctions’ that allow the two cells to share their contents.