Programming the lifestyles of engineered bacteria for cancer therapy

Abstract

Bacteria can be genetically engineered to act as therapeutic delivery vehicles in the treatment of tumors, killing cancer cells or activating the immune system. This is known as Bacteria-Mediated Cancer Therapy (BMCT). Tumor invasion, colonization and tumor regression are major biological events, which are directly associated with antitumor effects and are uncontrollable due to the influence of tumor microenvironments during the BMCT process. Here, we developed a genetic circuit for dynamically programming bacterial lifestyles (planktonic, biofilm or lysis), to precisely manipulate the process of bacterial adhesion, colonization and drug release in BMCT process, via hierarchical modulation of the lighting power density (LPD) of near-infrared (NIR) light. The deep tissue penetration of NIR offers us a modality for spatiotemporal and noninvasive control of bacterial genetic circuits in vivo. By combining computational modeling with high throughput characterization device, we optimized the genetic circuits in engineered bacteria to program the process of bacterial lifestyle transitions by altering the illumination scheme of NIR. Our results showed that programming intratumoral bacterial lifestyle transitions allows precise control of multiple key steps throughout the BMCT process, and therapeutic efficacy can be greatly improved by controlling the localization and dosage of therapeutic agents via optimizing the illumination scheme.

Remotely Controllable Engineered Bacteria for Targeted Therapy of Pseudomonas aeruginosa Infection

“…In addition to its use as a live vaccine, Salmonella has been proven to be the most effective bacteria for bacterial-mediated cancer therapy. − Furthermore, Salmonella -based cancer therapies have already been tested in a few human clinical trials . In our research, although our host strain ExoST is an attenuated strain of wild-type P. aeruginosa PAO1 (genomic knockout of exoS , exoT , and vfr genes), we did not observe that our engineered strain C1028 itself or its lysates delayed wound healing and reduced body weight in the mouse model (Figure and Figure S7).…”

“…51−53 Furthermore, Salmonella-based cancer therapies have already been tested in a few human clinical trials. 54 In our research, although our host strain ExoST 35 is an attenuated strain of wild-type P. aeruginosa PAO1 (genomic knockout of exoS, exoT, and vfr genes), we did not observe that our engineered strain C1028 itself or its lysates delayed wound healing and reduced body weight in the mouse model (Figure 5 and Figure S7). Particularly, we treated both PAO1-infected and uninfected wounds with the strain C1028 and found that the wounds healed faster than those in the uninfected group (Figure 5D,G and Figure S5B), which may be associated with the immune response.…”

“…To produce chimeric pyocin ChPy at high levels and avoid toxicity to the producer, we chose different constitutive promoters to express ChPy and its immune protein, Imm E3 (drug production module). The release of the chimeric pyocin ChPy was remotely and precisely regulated through the NIR light-responsive, c -di-GMP-mediated bacterial lysis system: briefly, the phosphodiesterase, FscR, will hydrolyze the intracellular c -di-GMP into pGpG, maintaining a bare level of intracellular c -di-GMP in the dark. Upon NIR light irradiation, the c -di-GMP synthase BphS will be activated and synthesize two molecules of GTP into c -di-GMP.…”

Genetically engineered bacteria: a new frontier in targeted drug delivery

“…This triggers the release of therapeutic agents specifically in the tumor regions. 16 Notably, GEB can be engineered to specifically penetrate, degenerate, invade, and colonize tumor tissues. They have the ability to penetrate the tumor mass and establish themselves within it, allowing for sustained drug release and localized antitumor therapeutic effects.…”

“…These circuits can be designed to activate the generation and release of therapeutic agents in response to specific cues, improving their targeting properties. 16 The penetration potential of bacteria can be improved via suitable modifications, which enhance their motility/ability for traversing biological barriers to reach and target specific cells/tissues. 18,19 GEB penetrate tumors through the employment of their self-propelled ability, sensing the tumor microenvironment, invading and colonizing tumor tissues, inducing immune responses, and enhancing their tumor-targeting capabilities.…”