Conditional constitutive expression system of a drug protein in vivo by positive feedback loop using an...

Area of Science:

• Biotechnology
• Molecular Biology
• Cancer Therapy

Background:

• Bacterial-mediated drug delivery offers targeted cancer treatment using genetically encoded proteins.
• Current systems rely on exogenous inducers (e.g., arabinose) for protein expression, requiring repeated injections.
• In vivo inducer administration can lead to inefficient and non-uniform therapeutic protein expression due to diffusion and dilution.

Purpose of the Study:

• To design and construct a novel conditional constitutive expression system for bacterial drug delivery.
• To overcome the limitations of exogenous inducer dependency in bacterial cancer therapy.
• To achieve arabinose-independent, self-sustaining therapeutic protein expression in vivo.

Main Methods:

• Engineered an artificial transcription factor, AraC^C, with dual operator-binding domains.
• Developed a self-positive feedback system by linking AraC^C and wild-type AraC expression under the P_BAD promoter.
• Achieved arabinose-independent gene expression via AraC^C binding to P_BAD promoter operators (I₁ and I₂).

Main Results:

• Demonstrated arabinose-independent gene expression using the engineered AraC^C transcription factor.
• Established a self-positive feedback loop enabling constitutive therapeutic protein expression after a single initial induction.
• Validated the system's potential for sustained drug delivery in bacterial cancer therapy.

Conclusions:

• The developed conditional constitutive expression system provides a robust platform for bacterial cancer therapy.
• This system eliminates the need for repeated inducer injections, improving drug delivery efficiency and uniformity.
• It holds significant promise for advancing in vivo bacterial drug delivery strategies for cancer treatment.