By using light to control electrical signaling among cells on a frog model, researchers have demonstrated that it is possible to use optogenetics to prevent tumors from forming and to normalize tumors after they have formed. The work is the first reported use of optogenetics to specifically manipulate bioelectrical signals to both prevent and cause regression of tumors induced by oncogenes. Researchers from Tufts University first injected cells in Xenopus laevis (frog) embryos with RNA that encoded a mutant RAS oncogene known to cause cancer-like growths. Setup for delivering spatiotemporally precise light stimulation of optogenetic proteins expressed in tadpole embryo induced tumor-like structures. Courtesy of Brook T. Chernet et al./Oncotarget. They then used blue light to activate positively charged ion channels, which induced an electric current that caused the cells to go from a cancer-like depolarized state to a normal, more negative polarized state. They repeated this process using a green light-activated proton pump, Archaerhodopsin. Activation of both agents significantly lowered the incidence of tumor formation and also increased the frequency with which tumors regressed into normal tissue. Virtually all healthy cells maintain a more negative voltage in the cell interior compared with the cell exterior. However, the opening and closing of ion channels in the cell membrane can cause the voltage to become more positive (depolarizing the cell) or more negative (polarizing the cell). This allows tumors to be detected by their abnormal bioelectrical signature before they are otherwise apparent. "These electrical properties are not merely byproducts of oncogenic processes. They actively regulate the deviations of cells from their normal anatomical roles towards tumor growth and metastatic spread," said professor Michael Levin. "Discovering new ways to specifically control this bioelectrical signaling could be an important path towards new biomedical approaches to cancer." "This provides proof of principle for a novel class of therapies which use light to override the action of oncogenic mutations," Levin added. "Using light to specifically target tumors would avoid subjecting the whole body to toxic chemotherapy or similar reagents." The research was published in Oncotarget (doi: 10.18632/oncotarget.8036).