Genetic Programming by Nitric Oxide-Sensing Gene Switch System in Tumor-Targeting Bacteria

Area of Science:

• Synthetic biology
• Bacterial therapeutics
• Molecular engineering

Background:

• Tumor microenvironments often exhibit elevated nitric oxide (NO) levels.
• Salmonella Typhimurium (S. Typhimurium) colonization of tumors increases NO production.
• NO is a potential signaling molecule for tumor-specific gene expression.

Purpose of the Study:

• To develop a nitric oxide (NO)-sensing genetic switch system.
• To engineer an attenuated S. Typhimurium strain for tumor-specific gene expression.
• To utilize NO as an inducer for targeted gene delivery in cancer.

Main Methods:

• Designed a genetic circuit sensing NO via NorR to express FimE DNA recombinase.
• Implemented unidirectional inversion of the fimS promoter region to control gene expression.
• Validated NO-induced gene expression in vitro using DETA/NO and in vivo after S. Typhimurium tumor colonization.

Main Results:

• The NO-sensing gene switch successfully triggered target gene expression in bacteria.
• In vitro studies confirmed NO-dependent gene expression.
• In vivo experiments demonstrated tumor-targeted and NO-specific gene expression mediated by inducible nitric oxide synthase (iNOS).

Conclusions:

• Nitric oxide (NO) is a viable inducer for fine-tuning gene expression in tumor-targeting bacteria.
• The developed NO-sensing system enables precise control of therapeutic gene delivery.
• This synthetic biology platform holds promise for advanced bacterial cancer therapies.