Theranostic protein targeting ErbB2 for bioluminescence imaging and therapy for cancer

Assessing the Accuracy of Bioluminescence Image-Guided Stereotactic Body Radiation Therapy of Orthotopic Pancreatic Tumors Using a Small Animal Irradiator

Stereotactic body radiation therapy (SBRT) has shown promising results in the treatment of pancreatic cancer and other solid tumors. However, wide adoption of SBRT remains limited largely due to uncertainty about the treatment's optimal fractionation schedules to elicit maximal tumor response while limiting the dose to adjacent structures. A small animal irradiator in combination with a clinically relevant oncological animal model could address these questions. Accurate delivery of X rays to animal tumors may be hampered by suboptimal image-guided targeting of the X-ray beam in vivo. Integration of bioluminescence imaging (BLI) into small animal irradiators in addition to standard cone-beam computed tomography (CBCT) imaging improves target identification and high-precision therapy delivery to deep tumors with poor soft tissue contrast, such as pancreatic tumors. Using bioluminescent BxPC3 pancreatic adenocarcinoma human cells grown orthotopically in mice, we examined the performance of a small animal irradiator equipped with both CBCT and BLI in delivering targeted, hypo-fractionated, multi-beam SBRT. Its targeting accuracy was compared with magnetic resonance imaging (MRI)-guided targeting based on co-registration between CBCT and corresponding sequential magnetic resonance scans, which offer greater soft tissue contrast compared with CT alone. Evaluation of our platform's BLI-guided targeting accuracy was performed by quantifying in vivo changes in bioluminescence signal after treatment as well as staining of ex vivo tissues with γH2AX, Ki67, TUNEL, CD31 and CD11b to assess SBRT treatment effects. Using our platform, we found that BLI-guided SBRT enabled more accurate delivery of X rays to the tumor resulting in greater cancer cell DNA damage and proliferation inhibition compared with MRI-guided SBRT. Furthermore, BLI-guided SBRT allowed higher animal throughput and was more cost effective to use in the preclinical setting than MRI-guided SBRT. Taken together, our preclinical platform could be employed in translational research of SBRT of pancreatic cancer.

The Weak Link: Optimization of the Ligand-Nanoparticle Interface To Enhance Cancer Cell Targeting by Polymer Micelles

Many promising targeting ligands are hydrophobic peptides, and these ligands often show limited accessibility to receptors, resulting in suboptimal targeting. A systematic study to elucidate the rules for the design of linkers that optimize their presentation on nanoparticles has not been carried out to date. In this study, we recombinantly synthesized an elastin-like polypeptide diblock copolymer (ELP_BC) that self-assembles into monodisperse micelles. AHNP and EC1, two hydrophobic ErbB2-targeted peptide ligands, were incorporated at the C-terminus of the ELP_BC with an intervening peptide linker. We tested more than 20 designs of peptide linkers, where the linker could be precisely engineered at the gene level to systematically investigate the molecular parameters-sequence, length, and charge-of the peptide linker that optimally assist ligands in targeting the ErbB2 receptor on cancer cells. We found that peptide linkers with a minimal length of 12 hydrophilic amino acids and an overall cationic charge-and that impart a zeta potential of the micelle that is close to neutral-were necessary to enhance the uptake of peptide-modified ELP_BC micelles by cancer cells that overexpress the ErbB2 receptor. This work advances our understanding of the optimal presentation of hydrophobic ligands by nanoparticles and suggests design rules for peptide linkers for targeted delivery by polymer micelles, an emerging class of nanoparticle carriers for drugs and imaging agents.

Inhibition of cell proliferation, migration and invasion by a glioma-targeted fusion protein combining the p53 C terminus and MDM2-binding domain

OBJECTIVES

The aim of this study was to develop multifunctional fusion proteins for targeting and delivering therapy elements into glioma cells.

MATERIALS AND METHODS

Multifunctional fusion proteins were expressed in Escherichia coli and purified using Ni-NTA resin affinity chromatography. Human glioma cells and primary astrocytes were used to analyse their functions. Targeting proteins location to glioma cells was observed by confocal microscopy. Effects of cell viability and proliferation were evaluated using the Cell Counting Kit 8 and colony formation assays. Glioma cell migration and invasion were assessed using transwell assays, and apoptosis was analysed by flow cytometry. In addition, changes in expression of proteins related to the cell cycle and apoptosis were determined by Western blotting.

RESULTS

The protein with highest bioactivity was GL1-riHA2-p53c+m-TAT (GHPc+mT), which combines glioma-targeting peptide GL1 (G), and C terminus (Pc) and mouse double minute domains (Pm) of p53, with the destabilizing lipid membrane peptide riHA2 (H) and cell-penetrating peptide TAT (T). The purified fusion protein was stable in cell culture medium and specifically targeted, and was internalized by, epidermal growth factor receptor (EGFR)-overexpressing glioma cells (U87ΔEGFR). It inhibited cell proliferation, migration and invasion, while flow cytometric analysis showed increased apoptosis. In addition, GHPc+mT caused significant changes in expression of proteins related to the cell cycle and apoptosis.

CONCLUSION

GHPc+mT is a multifunctional protein combining targeting, inhibition of glioma cell proliferation and induction of apoptosis, providing some potential to be developed into an effective protein drug delivery system for glioma therapy.

Introducing Cytology-Based Theranostics in Oral Squamous Cell Carcinoma: A Pilot Program

We aimed to evaluate the feasibility and reliability of brush cytology in the biomarker expression profiling of oral squamous cell carcinomas within the concept of theranostics, and to correlate this biomarker profile with patient measurable outcomes. Markers representative of prognostic gene expression changes in oral squamous cell carcinoma was selected. These markers were also selected to involve pathways for which commercially available or investigational agents exist for clinical application. A set of 7 markers were analysed by immunocytochemistry on the archival primary tumour material of 99 oral squamous cell carcinoma patients. We confirmed the feasibility of the technique for the expression profiling of oral squamous cell carcinomas. Furthermore, our results affirm the prognostic significance of the epidermal growth factor receptor (EGFR) family and the angiogenic pathway in oral squamous cell carcinoma, confirming their interest for targeted therapy. Brush cytology appears feasible and applicable for the expression profiling of oral squamous cell carcinoma within the concept of theranostics, according to sample availability.

Development of a novel liposomal nanodelivery system for bioluminescence imaging and targeted drug delivery in ErbB2-overexpressing metastatic ovarian carcinoma

Liposomes as targeted drug delivery systems are an emerging strategy in the treatment of cancer to selectively target tumors or genes. In this study, we generated the recombinant protein, EC1-GLuc, by fusing the EC1 peptide, an artificial ligand of ErbB2, with Gaussia luciferase (GLuc). The purified EC1-GLuc was conjugated with a nickel-chelating liposome to construct the EC1-GLuc-liposome. In vitro experiments revealed that the EC1-GLuc-liposome selectively targeted and internalized into ErbB2-overexpressing SKOv3 cells for bioluminescence imaging. A cell-impermeable fluorescence dye (HPTS) encapsulated in the EC-GLuc-liposome was efficiently delivered into the SKOv3 cells. In addition, the EC1-GLuc-liposome also targeted metastatic SKOv3 tumors for bioluminescence imaging and effectively delivered HPTS into metastatic tumors in vivo. Therefore, the present study demonstrates the novel EC1-GLuc-liposome to be an effective theranostic system for monitoring and treating ErbB2-overexpressing metastatic ovarian carcinoma through a combination of targeted molecular imaging and DDS.