title: Use of genetically encoded, light-gated ion translocators to control tumorigenesis.
abstract: It has long been known that the resting potential of tumor cells is depolarized relative to their normal counterparts. More recent work has provided evidence that resting potential is not just a readout of cell state: it regulates cell behavior as well. Thus, the ability to control resting potential in vivo would provide a powerful new tool for the study and treatment of tumors, a tool capable of revealing living-state physiological information impossible to obtain using molecular tools applied to isolated cell components. Here we describe the first use of optogenetics to manipulate ion-flux mediated regulation of membrane potential specifically to prevent and cause regression of oncogene-induced tumors. Injection of mutant-KRAS mRNA induces tumor-like structures with many documented similarities to tumors, in Xenopus tadpoles. We show that expression and activation of either ChR2D156A, a blue-light activated cation channel, or Arch, a green-light activated proton pump, both of which hyperpolarize cells, significantly lowers the incidence of KRAS tumor formation. Excitingly, we also demonstrate that activation of co-expressed light-activated ion translocators after tumor formation significantly increases the frequency with which the tumors regress in a process called normalization. These data demonstrate an optogenetic approach to dissect the biophysics of cancer. Moreover, they provide proof-of-principle for a novel class of interventions, directed at regulating cell state by targeting physiological regulators that can over-ride the presence of mutations.
authors.affiliation: Center for Regenerative and Developmental Biology and Department of Biology Tufts University, Medford, MA 02155, U.S.A.
authors.forename: Brook T
authors.initials: BT
authors.lastname: Chernet
authors.affiliation: Center for Regenerative and Developmental Biology and Department of Biology Tufts University, Medford, MA 02155, U.S.A.
authors.forename: Dany S
authors.initials: DS
authors.lastname: Adams
authors.affiliation: Center for Regenerative and Developmental Biology and Department of Biology Tufts University, Medford, MA 02155, U.S.A.
authors.forename: Maria
authors.initials: M
authors.lastname: Lobikin
authors.affiliation: Center for Regenerative and Developmental Biology and Department of Biology Tufts University, Medford, MA 02155, U.S.A.
authors.forename: Michael
authors.initials: M
authors.lastname: Levin
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D019843:Archaeal Proteins / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D008027:Light; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D009154:Mutation; D062308:Optogenetics / Q000295:instrumentation / Q000379:methods*; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012243:Rhodopsin / Q000235:genetics; D014982:Xenopus laevis; D017494:Proton Pumps
chemical_list: D000970:Antineoplastic Agents; D019843:Archaeal Proteins; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger; D012243:Rhodopsin; C055476:archaerhodopsin protein, Archaea; D017494:Proton Pumps
keywords: RAS; Vmem; bioelectricity; optogenetics; voltage