TY - JOUR
T1 - A Bioluminescent transposon reporter-trap identifi es tumor-specifi c microenvironment-induced promoters in salmonella for conditional bacterial-based tumor therapy
AU - Flentie, Kelly
AU - Kocher, Brandon
AU - Gammon, Seth T.
AU - Novack, Deborah V.
AU - McKinney, Jeffrey S.
AU - Piwnica-Worms, David
PY - 2012/7
Y1 - 2012/7
N2 - Salmonella specifi cally localize to malignant tumors in vivo, a trait potentially exploitable as a delivery system for cancer therapeutics. To characterize mechanisms and genetic responses of Salmonella during interaction with living neoplastic cells, we custom-designed a promoterless transposon reporter containing bacterial luciferase. Analysis of a library containing 7,400 independent Salmonella transposon insertion mutants in coculture with melanoma or colon carcinoma cells identifi ed fi ve bacterial genes specifi cally activated by cancer cells: adiY, yohJ, STM1787, STM1791, and STM1793. Experiments linked acidic pH, a common characteristic of the tumor microenvironment, to a strong, specifi c, and reversible stimulus for activation of these Salmonella genes in vitro and in vivo. Indeed, a Salmonella reporter strain encoding a luciferase transgene regulated by the STM1787 promoter, which contains a tusp motif, showed tumor-induced bioluminescence in vivo. Furthermore, Salmonella expressing Shiga toxin from the STM1787 promoter provided potent and selective antitumor activity in vitro and in vivo, showing the potential for a conditional bacterial-based tumor-specifi c therapeutic. SIGNIFICANCE: Salmonella, which often encounter acidic environments during classical host infection, may co-opt evolutionarily conserved pathways for tumor colonization in response to the acidic tumor microenvironment. We identifi ed specifi c promoter sequences that provide a platform for targeted Salmonella-based tumor therapy in vivo.
AB - Salmonella specifi cally localize to malignant tumors in vivo, a trait potentially exploitable as a delivery system for cancer therapeutics. To characterize mechanisms and genetic responses of Salmonella during interaction with living neoplastic cells, we custom-designed a promoterless transposon reporter containing bacterial luciferase. Analysis of a library containing 7,400 independent Salmonella transposon insertion mutants in coculture with melanoma or colon carcinoma cells identifi ed fi ve bacterial genes specifi cally activated by cancer cells: adiY, yohJ, STM1787, STM1791, and STM1793. Experiments linked acidic pH, a common characteristic of the tumor microenvironment, to a strong, specifi c, and reversible stimulus for activation of these Salmonella genes in vitro and in vivo. Indeed, a Salmonella reporter strain encoding a luciferase transgene regulated by the STM1787 promoter, which contains a tusp motif, showed tumor-induced bioluminescence in vivo. Furthermore, Salmonella expressing Shiga toxin from the STM1787 promoter provided potent and selective antitumor activity in vitro and in vivo, showing the potential for a conditional bacterial-based tumor-specifi c therapeutic. SIGNIFICANCE: Salmonella, which often encounter acidic environments during classical host infection, may co-opt evolutionarily conserved pathways for tumor colonization in response to the acidic tumor microenvironment. We identifi ed specifi c promoter sequences that provide a platform for targeted Salmonella-based tumor therapy in vivo.
UR - http://www.scopus.com/inward/record.url?scp=84866341332&partnerID=8YFLogxK
U2 - 10.1158/2159-8290.CD-11-0201
DO - 10.1158/2159-8290.CD-11-0201
M3 - Article
C2 - 22728436
AN - SCOPUS:84866341332
SN - 2159-8274
VL - 2
SP - 624
EP - 637
JO - Cancer discovery
JF - Cancer discovery
IS - 7
ER -