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Updated: May 17, 2026
Dual Bioluminescence Imaging of Tumor Progression and Angiogenesis
Published on: August 1, 2019
Dual systemic tumor targeting with ligand-directed phage and Grp78 promoter induces tumor regression
Azadeh Kia1, Justyna M Przystal, Nastasia Nianiaris
1Centre for Neuroinflammation and Degeneration, Division of Brain Sciences, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, United Kingdom.
Abstract:
The tumor-specific Grp78 promoter is overexpressed in aggressive tumors. Cancer patients would benefit greatly from application of this promoter in gene therapy and molecular imaging; however, clinical benefit is limited by lack of strategies to target the systemic delivery of Grp78-driven transgenes to tumors. This study aims to assess the systemic efficacy of Grp78-guided expression of therapeutic and imaging transgenes relative to the standard cytomegalovirus (CMV) promoter. Combination of ligand and Grp78 transcriptional targeting into a single vector would facilitate systemic applications of the Grp78 promoter. We generated a dual tumor-targeted phage containing the arginine-glycine-aspartic acid tumor homing ligand and Grp78 promoter. Next, we combined flow cytometry, Western blot analysis, bioluminescence imaging of luciferase, and HSVtk/ganciclovir gene therapy and compared efficacy to conventional phage carrying the CMV promoter in vitro and in vivo in subcutaneous models of rat and human glioblastoma. We show that double-targeted phage provides persistent transgene expression in vitro and in tumors in vivo after systemic administration compared with conventional phage. Next, we showed significant tumor killing in vivo using the HSVtk/ganciclovir gene therapy and found a systemic antitumor effect of Grp78-driven HSVtk against therapy-resistant tumors. Finally, we uncovered a novel mechanism of Grp78 promoter activation whereby HSVtk/ganciclovir therapy upregulates Grp78 and transgene expression via the conserved unfolded protein response signaling cascade. These data validate the potential of Grp78 promoter in systemic cancer gene therapy and report the efficacy of a dual tumor targeting phage that may prove useful for translation into gene therapy and molecular imaging applications.
Insights
This study developed a dual-targeted phage for systemic cancer gene therapy. The Grp78 promoter effectively delivered therapeutic genes to tumors, showing significant tumor killing and a novel activation mechanism.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- The Grp78 promoter is overexpressed in aggressive tumors, presenting a target for cancer gene therapy and molecular imaging.
- Systemic delivery of Grp78-driven transgenes to tumors remains a challenge, limiting clinical applications.
- Targeted delivery strategies are crucial for enhancing the efficacy of Grp78 promoter-based cancer therapies.
Purpose of the Study:
- To assess the systemic efficacy of Grp78-guided transgene expression compared to the cytomegalovirus (CMV) promoter.
- To develop and evaluate a dual tumor-targeted phage vector combining ligand and Grp78 transcriptional targeting.
- To investigate the potential of this dual-targeted phage for gene therapy and molecular imaging applications.
Main Methods:
- Generation of a dual tumor-targeted phage incorporating an arginine-glycine-aspartic acid (RGD) ligand and the Grp78 promoter.
- In vitro and in vivo evaluation using flow cytometry, Western blot, bioluminescence imaging (luciferase), and HSVtk/ganciclovir gene therapy in glioblastoma models.
- Comparison of the dual-targeted phage with conventional phage carrying the CMV promoter.
Main Results:
- The dual-targeted phage demonstrated persistent transgene expression in vitro and in vivo.
- Significant tumor killing was achieved in vivo using HSVtk/ganciclovir gene therapy driven by the Grp78 promoter.
- A systemic antitumor effect was observed against therapy-resistant tumors, with a novel Grp78 promoter activation mechanism identified via the unfolded protein response (UPR) signaling cascade.
Conclusions:
- The Grp78 promoter holds significant potential for systemic cancer gene therapy and molecular imaging.
- The developed dual tumor-targeting phage is effective for delivering therapeutic transgenes systemically.
- The findings support the translation of this dual-targeted phage strategy into clinical applications for cancer treatment.
